What If-Finland had been prepared for the Winter War?

Discussions on the Winter War and Continuation War, the wars between Finland and the USSR.
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CanKiwi2
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The 1934 Ilmavoimat Procurement Program

Post by CanKiwi2 » 24 Jun 2011 21:08

The 1934 Ilmavoimat Procurement Program

As in 1932 and 1933, the Ilmavoimat continued to search for high-performance Fighter aircraft as well as good effective light to medium bombers. Additionally, the 1934 program was to include the purchase of a small number of transport aircraft – the Ilmavoimat had bought 10 Junkers W.34 transport aircraft in 1930 and these had proven useful in flying logistical support into remote areas and in evacuating casualties in exercises.

In 1934 the Procurement Team settled on the Czechoslovakian designed and built Avia B-532 Fighter. The Ilmavoimat had previous experience with Czech aircraft – the Smolik trainers and the Aero Light Bombers – aircraft which had proved reliable and effective. In addition, the Maavoimat had been purchasing weapons from Skoda and the Czechs were a well-known quantity. This was not a leap in the dark but part of an ongoing relationship between the two countries that, while not close, was cooperative, friendly and business-like – and the Avia B-532 Fighter had stood out in a class of its own in the evaluation and test flight program that had been carried out.

In looking at light to medium Bombers, the Fokker C.X was selected and built under license in Finland. The engine used for the Fokker CX was the Finnish-manufactured Bristol Bristol Pegasus XII 850hp nine cylinder radial engines built under license in Finland.

In assessing transport aircraft, the Procurement Team looked at a considerable ange of aircraft, initially with a strong bias towards the Junkers Ju-52 that was already used extensively by Aero Oy. What was wanted was a robust twin-engined aircraft that was reliable, tough, had a good range and could easily be adapted as a floatplane or skiplane. With a wide range of aircraft available, the assessment process too some time, with the short-list consisting of the three-engined Junkers Ju-52, consideration being given to the rather newer Junkers Ju-86 (a 10 passenger civil transport which was still at the design stage) at the request of Junkers, the Boeing Model 247, the Lockheed Model 10 Electra and the de Havilland D.84 Dragon, the de Havilland DH.86, the Handley Page HP.42, the Vickers Valentia, the Douglas DC2, the General Aviation GA-43, the Caprioni Ca132 abd Ca133, the Savoia-Marchetti S.73 and also the designs of the Heinkel He111 transport – all of which were in service or in the prototype or late design stages. The older Junkers W.35 already in service with the Ilmavoimat was also considered.

In the end, with a considerable range of types to evaluate and some promising developments in the pipeline, the evaluation and testing program for a transport aircraft dragged on into 1935 before a decision was made.

Avia B-532 Biplane Fighter – 24 ordered in July 1934, 24 ordered in July 1935

By late 1933, the front-line fighter strength of the Ilmavoimat consisted of one squadron of now-obsolete Martinsyde F4 Buzzards, two squadrons of Haukka II Fighters and two squadrons of Bristol Bulldogs – both already beginning to be outclassed by the newer fighters – and a single squadron of Fairey Firefly II Fighters which entered service only in March 1934. The Ilmavoimat’s budget for 1934 and 1935 made provision, among other things, for the acquisition of one additional squadron of modern fighter aircraft in each year and in July 1934, after a series of evaluations and discussions with a number of potential suppliers, the Finnish Defence Ministry placed an order with Avia for 24 Avia B-534 Fighters. These were built in conjunction with the first order placed for these aircraft by the Czechosolvak Ministry of National Defence and were the first aircraft delivered from the initial batch, arriving in Finland in the summer of 1935. At this stage, the aircraft had proven themselves as excellent Fighters and a second order for a further 24 aircraft was placed with these were delivered in March 1936. Both squadrons saw combat in the Winter War and proved to be effective fighters, particularly against the Soviet Polikarpovs.

The Avia B.534 series of biplane fighters was at the time a highly regarded (though now often forgotten) aircraft. Some reports make it the best aircraft of its category during its early run in the mid-1930s. Such was the performance of the machine that the German Luftwaffe would briefly setup a fighter squadron utilizing captured B.534 aircraft after the annexation of the Czechs. Simply put, the Avia B.534 can be thought of as a melding of two ages in aviation history. The B.534 featured a fixed undercarriage and a biplane wing assembly but under that outdated facade were four 7.92mm synchronized machine guns located in the sides of the fuselage and firing through the propeller, a powerful 850 horsepower license-built Hispano-Suiza liquid cooled V12 inline engine capable of 245 miles per hour and the ability for the aircraft to also carry six 44lb bombs. The B-534’s combination of speed, handling and firepower was highly respected. Fuselage construction was a unique mix of fabric-covered steel-structured wing assemblies while the fuselage as a whole was highly aerodynamic in nature, complete with an enclosed cockpit (the operational flight ceiling of 34,800 feet necessitated this feature). The B-534 had a range of 360 miles. In 1935 the Avia B-534 was well ahead of its contemporaries. Britain was still dependent on Hawker Furies, with the first Gloster Gladiators being produced at this time. The Soviet Union was placing its hopes on its Polikarpov aircraft designs. The United States was still using descendants of the Curtiss Hawk series, with the Seversky P-35 and Curtiss P-36 prototypes just about to fly.

The manufacturer, Avia, was a Czech company, founded by Miroslav Hajn and Pavel Beneš in 1919 and became part of Škoda in 1928. During the 1930s the factory became the biggest aircraft producer in Czechoslovakia. The B-534 prototype flew on 25 May 1933. It was first displayed to the public on 10 September 1933 at an Army air day, five days after the first flight of the second prototype. More work followed and the first order for 147 aircraft for the Czechoslovakian Air Force was placed by the Czechoslovak Ministry of National Defence to the Avia Company on 17 July 1934. These were delivered in the autumn of 1935. The Czechoslovak Ministry of National Defence ordered the procurement of a second batch of 46 B-534’s in 1936, receiving these in March and April 1937. In 1936 a third order for 134 aircraft was placed. Owing to the growing German menace a fourth contract was almost immediately thereafter placed for a further 50 machines. A fifth procurement order was placed in August 1938 for 68 machines, bringing the overall total ordered by the Czechoslovak Air Force to 445. It can be seen then, that Avia was well-able to produce large numbers of these aircraft in a short timeframe.
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Ilmavoimat Avia B-534 Fighters shortly after delivery – not yet painted in Ilmavoimat colours – this was actually a batch built for the Czechosolvakian Air Force and diverted to fill the Finnish order

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Ilmavoimat Avia B-534 being serviced

The abrupt partition of Czechoslovakia in 1939 prevented the use of the B-534 in combat by the nation that had produced it. By then, high performance monoplanes such as the German Messerschmitt Bf 109, Hawker Hurricane and Supermarine Spitfire were in service. The B-534 was first used in combat by the Slovak Air Force. Slovakia had acquired some 80 B-534s and Bk-534s from the Czech Air Force and used them against Hungary during the border war of 1939. Later, two squadrons of B-534s assisted the German Luftwaffe during the Invasion of Poland in September 1939 (The same squadrons served with the Germans in the Ukraine during the summer of 1941, with one squadron returning in 1942 for anti-partisan duty).

The two squadrons of Ilmavoimat Avia B-534’s saw service in the Winter War – in 1939 the engines were replaced with the latest Finnish-manufactured Hispano-Suiza 12Y (with the work being rushed through urgently as the threat of war loomed ever larger) which had given them another 30mph, bringing their performance up to 275mph which, with their manouverability, meant that they fought through the Winter War as an effective second-line fighter, more or less on a par with the Fokker D.XXIs which the Ilmavoimat had purchased in 1936. The B-534’s fought on for the duration of the Winter War and, like many of the Ilamvoimat’s older aircraft were only phased out in 1944 as they were superceded by large numbers of modern aircraft from Britain and the United States.

Fokker C.X Biplane Scout and Light Bomber – ordered 1934

In looking for further bombers, the Ilmavoimat initially considered simply buying more Hawker Harts. However, even with the Hawker Hart’s excellent performance, aircraft technology was moving ahead rapidly, with advances occurring on an ongoing basis and in the end, the Ilmavoimat procurement team opted for the Fokker CX. Four C.X’s were purchased as “pattern” aircraft along with a manufacturing license and the Ilmavoimat ordered a further 20 from VL, who started building the C.X in the last half of 1934. These were equipped with Bristol Pegasus XII 850hp nine cylinder radial engines built under license in Finland and were delivered in mid-1935. A further 20 were built through 1935 and early 1936 but with the move of VL to Tampere and the startup of Fokker D.XXI and Bristol Blenheim manufacturing, production was discontinued as the emphasis was placed on the construction of more modern aircraft. However, the C.X was kept in service and used in its intended role as a scout and light bomber in the Winter War, but post-Winter War was relegated to the training and target-towing role.
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The Fokker C.X was a biplane scout and light bomber designed in 1933. It had a crew of two (a pilot and an observer). It was originally designed for the Royal Dutch East Indies Army, and, like all Fokker aircraft of that period, it was of mixed construction, with wooden wings and a welded frame covered with aluminium plates at the front of the aircraft and with linen at the back. The prototype was built in 1934 with a Rolls-Royce Kestrel V engine.

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The Ilmavoimat Fokker C.X had a maximum speed of 211mph, a range of 522 miles and a service ceiling of 27,230 feet. Armament consisted of 2x 7.9mm machine guns fixed on top of the front fuselage and a third manually aimed from rear cockpit. Underwing racks for two 385lb (175kg) or four 221lb (100kg) bombs were fitted. During the German attack on the Netherlands in May 1940, the C.Xs served in the Netherlands Air Force in their intended role as scouts and light bombers. They were far too slow to compete with German aircraft such as the Messerschmitt Bf 109, but the tactic of hu-bo-be (huisje-boompje-beestje), Dutch for "house-tree-animal" or "hugging the ground", allowed the C.Xs to achieve some measure of success.

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Fokker C.X being escorted home – in the later stages of the Winter War

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3/Lentolaivue 16:n Fokker C.X Äänislinnassa kesällä 1940 /. 3/Lentolaivue 16 - Fokker C.X at Äänislinna in the summer of 1940
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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Re: What If-Finland had been prepared for the Winter War?

Post by CanKiwi2 » 28 Jun 2011 20:48

This is an extension of the earlier post on the August 1936 Air Show....

The Winch Car

The Winch Car (a Marmon E-75) shown in the photos was originally used by Marshall Mannerheim in the late 1920s and early 1930s. After Mannerheim, the car belonged to a Baron Aminoff. Ten years later, when the Marmon actually was a rather old car, it was donated to an aviation club. They used it to pull gliders up in the air. The big and heavy car with a strong and slowly turning engine was ideal for that purpose. During the war it was stored in a hangar at the airport. This is the story of the car.....

Marmon Cars

Many people have never heard of the MARMON automobile but it was one of the premier vehicles of its time. It was in the class of the Pierce Arrow, Peerless, Lincoln and Packard and was even compared to a Rolls Royce and used by many European royal families. The Marmon Motor Car Company was an automobile manufacturer founded by Howard Marmon and owned by Nordyke Marmon & Company of Indianapolis, Indiana, USA. It was established in 1902 and was merged and renamed in 1933. They produced cars under the Marmon brand. Marmon's parent company was founded in 1851 manufacturing flour grinding mill equipment, and branching out into other machinery through the late 19th century. Small limited production of experimental automobiles began in 1902, with an air-cooled V-twin engine. An air-cooled V4 followed the next year, with pioneering V6 and V8 engines tried over the next few years before more conventional straight engine designs were settled upon. Marmons soon gained a reputation as a reliable, speedy upscale car.

The Model 32 of 1909 spawned the Wasp, winner of the first Indianapolis 500 motor race. This car featured the world's first rear-view mirror. The 1913 Model 48 was a left-hand steering tourer with a cast aluminum body and electric headlights and horn, as well as electric courtesy lights for the dash and doors. The 48 came in a variety of models: two-, four-, five-, or seven-passenger tourers at US$5000, seven-passenger limousine at US$6250, seven-passenger landaulette at US$6350, and seven-passenger Berlin limousine at US$6450. The 1916 Model 34 used an aluminum straight-6, and used aluminum in the body and chassis to reduce overall weight to just 3295 lb (1495 kg). New models were introduced for 1924, replacing the long-lived Model 34, but the company was facing financial trouble, and in 1926 was reorganized as the Marmon Motor Car Co.

In 1929, Marmon introduced an under-$1,000 straight-8 car, the Roosevelt, but the stock market crash of 1929 made the company's problems worse. Howard Marmon had begun working on the world's first V16 engine in 1927, but was unable to complete the production Sixteen until 1931. By that time, Cadillac had already introduced their V-16, designed by ex-Marmon engineer Owen Nacker. Peerless, too, was developing a V16 with help from an ex-Marmon engineer, James Bohannon. Marmon discontinued automobile production in 1933, the worst year of the Great Depression. Marmon was notable as having introduced the rear-view mirror as well as pioneering both the V16 engine and the use of aluminum in auto manufacturing.

Between the years of 1903 and 1933 Marmon Motor Cars (previously Nordyke and Marmon), made approximately 250,000 cars...fewer than 350 exist today. The Model 74 series was produced in 1925 and 1926. It was powered by the six-cylinder engine used in the Model 34. The Model E-75 was introduced in 1927 and produced until 1928; it too was powered by the Model 34 six-cylinder engine. It was fitted with a custom body constructed by the Locke Coachbuilding Company. The Locke company had facilities in New York City and Rochester. The Rochester facility handled mostly convertible bodies as well as series production and they built their bodies atop of many prestigious marque's during their long career, lasting from the early 1900's through 1937. The Great Depression was a difficult time for the company and forced them to close their facilities. From 1932 through 1937, they painted and refurbished cars.

While the Marmon Company discontinued auto production, they continued to manufacture components for other auto manufacturers and manufactured trucks. When the Great Depression drastically reduced the luxury car market, the Marmon Car Company joined forces with Colonel Arthur Herrington, an ex-military engineer involved in the design of all-wheel drive vehicles. The new company was called Marmon-Herrington. Marmon-Herrington got off to a successful start by procuring contracts for military aircraft refueling trucks, 4x4 chassis for towing light weaponry, commercial aircraft refueling trucks, and an order from the Iraqi Pipeline Company for what were the largest trucks ever built at the time. In addition to large commercial and military vehicles, company leaders recognized a growing market for moderately priced all-wheel drive vehicles. This gave birth to the Marmon-Herrington Ford. The installation of all-wheel drive to commercial truck chassis is the primary focus of the Marmon-Herrington Company today. In the early 1960s, Marmon-Herrington was purchased by the Pritzker family and became a member of an association of companies which eventually adopted the name The Marmon Group. In 2007 the Pritzker family sold major part of Group to Warren Buffet's firm Berkshire Hathaway.

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Photo taken at the Driving School of V. Gestrin in Helsinki. The first car looks to be a Franklin, second car is a German Wanderer and cars four to six are Benz or Mercedes cars. The car facing front is a Wanderer Puppchen. The big American car third from right is a Marmon Model 34, available from 1916.

Although one article says that the first Marmons were imported to Finland in 1926 by "Autokeskus OY", the Finnish Marmon dealer, the above photo would indicate that at least some Marmon’s were arriving in Finland before this. The technical magazine "Moottori" published a very flattering article of Marmons in August 1926, "Marmon Porvoo." It hailed the Marmon in the following words: "The Marmon's ability to absorb shock was truly amazing, and I agreed to drive the car to Porvoo. Driving the Marmon can be compared to sailing, because the cars movements on uneven surfaces and on sharp corners resembled very much a big sailboat gliding across the sea. Climbing hills presented no challenge and on downhills the car seemed lighter than ordinary."

Alongside the description of the test drive was a photo of the Marmon engine. It clearly showed the oil coolers found in the model E-75. What’s amazing is how the 1927 model, Marmon was test-driven in Finland in the summer of 1926! It seems that as with the new year models of cars today, they went on sale in the autumn of the previous year. In the 1920s and 1930s some 36 Marmons were brought to Finland. Of these, two were the E-75 speedster models with the Locke body. One belonged to a well-known Jyväskyläläiselle Commercial Counsellor Hanna Parviainen, and the second is the one used by Mannerheim.

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Kauppaneuvos Hanna Parviainen Marmonissaan -30 luvun alussa - Commercial Councillor Hanna Parviainen and her Marmon –In the early 1930’s

In the picture below one can clearly see that the Marmon model featured in the article is an E-75.

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The technical magazine "Moottori" published a very flattering article of Marmons in August 1926, "Marmon Porvoo."

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The Oil Purifier, device seen in the middle, was first introduced in the model E-75

The Marmons were known as a very technically advanced car brand. Marmon were early to use engine lubricating oil under pressure, as well as two spark plugs for each cylinder. Today, this "twin spark" ignition is used, for example in the Alfa-Romeo. Marmons were also lighter than other similar cars and therefore achieved a higher performance due to the generous use of aluminum. For example, the engine block was made of aluminum, as were body panels – this at a time when aluminium was rarely used for cars. Marmon was also renowned for its excellent travel comfort and the rare occurrence of tire punctures. In fact, most technical features found in modern cars were invented in the late twenties and these were used in the later Marmons of that period. The Marmon was truly an advanced technology platform of the era and steered lighter and was easier to drive than many of its contemporaries.

The Marmon E-75, 7-passenger Speedster (body by Locke), License Id number 10RA84, was first used by the Marshal of Finland, C.G.E. Mannerheim. After the end of the Civil War and resigning as Regent of Finland, Mannerheim was a civilian and so he had no official car in his use. Even though he had no official position Mannerheim was a very highly respected person and the owner of a large (and still existent) Finnosh Car Dealership, Autokeskus Oy, Lieutenant Fred Geitel, was very good friend of Marshal Mannerheim and generously offered him a car and a driver when ever he wanted. It is somewhat unclear if the Marmon ever really belonged to Mannerheim, but he used it as if it was his own car on his trips around the country and also through Europe including at least one journey to Switzerland.

On the tenth anniversary of the end of the civil war on 16th May 1928, Mannerheim participated in the celebration and in the parade. In the following photos of the event, Mannerheim is seen in the Marmon.

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Mannerheim Esplanadilla tervehtimässä yleisöä - Mannerheim greets the crowd

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Marsalkka Mannerheim tervehtimässä nuoria neitosia. Vieressä seisomassa kenraali Martin Wetzer. Edessä istumassa kenraali Hannes Ignatius sekä autonkuljettaja Lehtinen tai Tulander (kumpi?). Marshal Mannerheim greets the young maidens. Standing next to him is Gen. Martin Wetzer. Sitting in front is General Hannes Ignatius, as well as a chauffeur, or Tulander Lehtinen (which one?).

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Kuva heti neitosten tervehtimisen jälkeen./ Marshal Mannerheim in the Marmon E-75 in the parade of 16th May 1928 after having been greeted by two young ladies…

The Marmon was specially customized for Marshal Mannerheim. He was a rather tall man and the mounting points for the folding dickey seats were moved in order to provide more room for his legs on long trips (and incidentally less room for his adjutants and for random additional passengers...). Mannerheim was also known as a very accurate and strict person and he always wanted to be aware of the speed and schedule of the trip. Thus an extra speedometer was installed in the passenger compartment and Mannerheim watched this closely, commenting to the driver if he was driving too fast or too slow. Mannerheim had the Marmon treated with special care. On one of his trips to Europe, the journey began with a trip by ship from Helsinki. A tale told by the son of a person who was on the same trip relates how the Mannerheim car (a big sedan) was being loaded when a halyard broke and the car dropped to the ship's deck. Mannerheim was angry, and remained so all the way to Germany.

After Mannerheim, the Marmon was sold to a Baron Aminoff. This phase of the Marmon's history is still obscure but at some stage it is hoped by Finnish restorers working on restoring the car that some light will be shed on this period. In the mid-thirties the Marmon reappears again. A Turku manufacturer, a Mr. Rettig, donated the car to the Turku Flying Club, where it played a part in a film made about gliding, "Karmankolon Kuningas". As a Glider Launcher, the Marmon was undoubtedly an excellent solution with its large and robust engine and huge torque. The following pictures show how the launching was very organized. The car is stationary while the winch drum is fitted on the rear wheel to wind in the tpw rope. The driver takes care of glider towing with the success depending on controlling the speed of winding in the tow rope. The driver also has a cut-out switch, ie the image of which appears as a thin wire, which when pulled drops a weight and a guillotine blade then cuts through the tow rope.

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Marmon Turun Artukaisten lentokentällä purjekoneiden hinauslaitteena vuonna 1938 / The Marmon at Turku Artukainen Airport being used as a glider aircraft towing device in 1938.

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Yksityiskohtia vinssin kelasta ja hätäkatkaisulaitteesta. / Details of the winch reel and emergency shut down device

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Yksityiskohtia vinssin kelasta ja hätäkatkaisulaitteesta. / Details of the winch reel and emergency shut down device

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Yksityiskohtia vinssin kelasta ja hätäkatkaisulaitteesta. / Details of the winch reel and emergency shut down device

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Artukaisten kentällä 1938. Kuljettajana Mikko Moisio, kyydissä istumassa Veikko Linnaluoto / The Marmon at Turku’s Artukainen Airport in 1938. The driver is Mikko Moisio, seated in the rear is Veikko Linnaluoto

A post-war note on the fate of the Marmon

During WW2 the car was stored in a hangar at the airport. After some years - in 1959 - a group of young students from the Helsinki University of Technology bought the Marmon. Every year on the 1st of May the Asociation of Technology Students (SiMiLi) publish a fun magazine called "ÄPY". The Marmon was used to arouse peoples interest when selling these magazines. A large and dark old car was really a head turning sight when roaring down the streets among the small european post-war cars like Fiats and Volkswagens. The Student Union used it also in different kinds of student campaigns and festivals and for driving around just for fun. Maintenance of the old car was rather difficult and time consuming. The radiator was leaking, the water pump had been corroded, the electricity system behaved oddly etc. The students who bought the Marmon graduated and moved away and after a while there was nobody left to take care of the car.

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The Marmon in a Student Campaign, "Teekkaritempaus". Year is 1960

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The Marmon in 1965 at restaurant Kaivohuone, Helsinki

The Marmon was just forgotten in a garage and it was removed from the Finnish vehicle register in 1967. Nothing was heard of the Marmon until 1980 when a magazine called "Ratto" published an article "Marshals Car in a Pile of Junk!" That woke up the Espoo Car Museum and they offered Marmon a better place to stay.

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The Marmon in a Pile of Junk. This 1980 article in a Finnish magazine "Ratto" aroused a great concern for the Marmons future among the Students of Technology and so it was hauled of to the Espoo Car Museum where it sat for the next ten years. This is where the where members of the Automobile Club (TAK) of the Helsinki University of Technology found it and began restoration work.

Some ten years later the president of the Automobile Club (TAK) of the Helsinki University of Technology was participating in an automobile club get-together (a discussion about cars, a Finnish sauna and, of course, lots of beer...) where the chief editor of a veteran car magazine gave us a presentation on antique cars. At the end of the presentation he asked us: "...by the way, how is Marshal Mannerheims Marmon doing nowadays? The one that belongs to you students?" The students had to admit that they had never even heard of the car. Then they found the Marmon in the Espoo Car Museum and were really astonished by its majestic looks. After a few more years thinking about the idea of restoring the Marmon they found a suitable garage and some skillful people to do the job and got the Student Unions permission to restore the car.

The project begun by repairing the garage over the winter of 1990-1991. The restoring itself started in the spring 1991. The Marmon was looking pretty good, but when the restoration started, the truth was revealed: the engine worked all right, but the water pump was corroded beyond reparation, the radiator had several leaks, the distributor cap was cracked, and all the moving parts were more or less worn out. When the engine as opened up it was found that all bearings were cracked and worn and somebody had put the pistons in the wrong order. The car had been in an accident at some time and the front end of the chassis was twisted. As a consequence of the accident one of the running boards had been replaced. The interior of the car was made of cheap imitation leather and the canvas top and the top mechanism and many of the smaller parts were missing. The restoreres realized that they had a lot bigger mission ahead of them than they thought when starting the project.

It has taken quite a long time to restore it, but as of 2011 the car has been restored, although some parts are still missing. Go to http://marmon.ayy.fi/Marmon_main.htm for the current status. It’s a fascinating story.

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Marshal Mannerheim’s Marmon restored….
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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Transport Aircraft Evaluation and Assessment through 1934

Post by CanKiwi2 » 29 Jun 2011 21:18

Transport Aircraft Evaluation and Assessment through 1934

The earlier Junkers W.34 transport aircraft purchased in 1930 had proved very useful in support for the Maavoimat and, as mentioned, the 1934 Procurement Program made provision for the purchase of additional transport aircraft. Immediate consideration was given to purchasing further Junkers W.34’s, or the Junkers 52, which was already in servive with Aero Oy. However, the Procurement Team also looked at other transport aircraft available and decided that the scope of evaluation and testing should be broadened given the new aircraft coming onto the market and either already available or with prototypes being tested or in development. In essence, over 1934 as aircraft were evaluated and test-flow, the specification on what the Ilmavoimat wanted evolved into a requirement for a robust twin-engined aircraft that was reliable, tough, had a good range with a reasonable carrying capacity (set at approx. 16 soldiers) and could easily be adapted as a floatplane or skiplane.

The ability to operate in all Finnish weather conditions and to be able to takeoff and land on wheels, skis or floats had been a criteria set from the start, eliminating from consideration the range of seaplanes used by many of the commercial operators of the time. The first aircraft that were looked at, early in the year, were a series of older transport aircraft that were almost immediately eliminated from consideration. These included the now rather dated Vickers Valentia and the Handley Page HP42 as well as the Junkers W.34 (of which the Ilmavoimat had 10 in service – this was a single-engined aircraft with a maxium speed of 165mph, a range of 487 miles and able to carry only 6-8 passengers). The W.34 was a useful smaller aircraft, but the Ilmavoimat was at this stage looking for something larger and with a longer range.
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Junkers W34

The Vickers Valentia

The Vickers Valentia was considered, and having been introduced in 1934 it was relatively new, but the design, based as it was on the earlier Vickers Victoria, was an older biplane design. The Valentia was essentially a Victoria with a strengthened airframe and with the more powerful Bristol Pegasus engines replacing the old and now obsolete Napier Lion engines. The RAF ordered 28 new-build Valentia’s and a further 54 were converted from the old Victorias. Within the RAF, the Valentia’s were used extensively for transport operations in the Middle East and were also, incidentially, used for early experiments in aerial refuelling by Alan Cobham. With a crew of 2, a maximum speed of 130 mph (cruising speed of 117mph) and a range of 800 miles, they could carry 22 troops. They could also carry 2,200lbs of bombs on underwing racks in a bomber role.

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Vickers Valentia unloading British Troops in Iraq

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Passengers inside a Vickers Valentia in-flight.

While the Vickers Valentia was considered, the Ilmavoimat team considered the design antiquated in light of aircraft such as the Junkers Ju52, the new Boeing Model 247 and the Italian Caprioni Ca132. An evaluation was carried out, but it was considered unlikely that the aircraft could successfully operate from floats or skis and it was therefore eliminated from consideration early on, as was the Handley Page HP42. However, the Ilmavoimat were extremely interested in the aerial refuelling experiments being carried out by Alan Cobham (this came up in the Vickers sales pitch) and this interest was followed up on (again, something that will be covered in another post).

The Handley Page HP42

The Handley Page HP42 was a British 4-engined long range biplane airliner designed in 1928 and introduced in 1931. At the time the Ilmavoimat looked at the aircraft, all the in-service planes were in civilian use, operated by Imperial Airlines. With a crew of 4, a speed of 120 mph (cruise speed of 100moh) and a range oif 500 miles), it carried 24 passengers. Again, an evaluation was carried out, but as with the Valentia, it was considered unlikely that the aircraft could successfully operate from floats or skis and it was therefore eliminated from consideration.
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The Handley Page HP42

The Procurement Team was familiar with the Junkers Ju52 – this was already in service with Aero Oy as a commercial airliner in Finland and with the Valentia and HP.42 eliminated from consideration, was at the top of the list as further aircraft began to be evaluated. These next evaluations included a series of transport aircraft that were coming into service in 1934 or for which prototypes were available. In mid-1934, the aiircraft being considered included the Boeing Model 247, the Lockheed Model 10 Electra, the de Havilland D.84 Dragon, the Douglas DC2, the General Aviation GA-43, the Caprioni Ca132 and Ca133 and the Savoia-Marchetti S.73

The Junkers Ju52

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A photo we’ve already seen – an Aero Oy Junkers Ju-52 Floatplane “Kaleva”: Photo taken at Katajannokka, Helsinki, 1936

The Junkers Ju 52 was a German transport aircraft manufactured from 1932 to 1945. It saw both civilian and military service during the 1930s and 1940s. In a civilian role, it flew with over 12 air carriers including Finland’s Aero Oy as an airliner and freight hauler. In a military role, it flew as a troop and cargo transport. The Ju 52 was similar to the company's previous Junkers W33/W34, although larger. Powered by three BMW engines, it had a maximum speed of 168mph, a cruising speed of 138 mph and a range of 590 miles with a Crew of 2 and 17 passengers. Aero Oy had already proven the aircraft was suitable for operations in Finnish conditions, operating the aircraft using floats and skis.

The Boeing Model 247

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The Boeing Model 247 was an early US passenger aircraft, considered the first such aircraft to fully incorporate advances such as all-metal (anodized aluminum) semi-monocoque construction, a fully cantilevered wing and retractable landing gear. Other advanced features included control surface trim tabs, an autopilot and deicing boots for the wings and tailplane.

Ordered off the drawing board", the Boeing 247 first flew on February 8, 1933 and entered service later that year. Subsequently, development in airliner design saw engines and airframes becoming larger and four-engine designs emerged, but no significant changes to this basic formula appeared until cabin pressurization and high altitude flight were introduced in the early 1940s. When first built, the Boeing 247 was faster than most fighter aircraft of the day and in addition, it was the first twin-engine passenger transport able to fly on one engine. Air carriers considered its limited capacity a drawback since it only carried 10 passengers, in five rows with a seat on each side of the aisle, as well as a flight attendant. Compared to the more capacious DC-2 and later DC-3, the passenger count was too few to make it a commercially viable airliner. At a unit cost of USD$65,000 and seventy-five 247s were built; by contrast, Douglas collected 800 civil orders for DC-3s before the Pearl Harbor attack. Powered by two Pratt & Whitney S1H1-G Wasp radial engine, 550 hp (410 kW) each, the Boeing 247 had a crusing speed of 188 mph, a maximum speed of 200mph, a range of 745 miles and with a crew of 3, could carry 10 passengers.

The Ilmavoimat Procurement Team evaluated and test flew the Boeing Model 247 but while the speed and range were considered excellent, its carrying capacity was too small, particularly in comparison to the Junkers Ju52 and it was thus eliminated from the short list.

The Lockheed Model 10 Electra

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The Lockheed Model 10 Electra was a twin-engine, all-metal monoplane airliner developed by the Lockheed Aircraft Corporation in the 1930s to compete with the Boeing 247 and Douglas DC-2.

The Electra was Lockheed's first all-metal and twin-engine design by Hall Hibbard. The prototype made its first flight on February 23, 1934. Wind tunnel work on the Electra was undertaken at the University of Michigan with much of the work performed by a student assistant, Clarence “Kelly” Johnson. He suggested two changes to the design: changing the single tail to double tails (later a Lockheed trademark), and deleting oversized wing fillets. Both of these suggestions were incorporated into the production aircraft. After October 1934 when the US government banned single-engined aircraft for use in carrying passengers or in night flying, Lockheed was perfectly placed in the market with their new Model 10 Electra. In addition to deliveries to US based airlines, several European operators added Electras to their prewar fleets. Besides airline orders, a number of non-commercial civil operators also purchased the new Model 10.

While the aircraft was still at the protoype stage in 1934 (production began in 1935) the design was evaluated but as with the Boeing Model 247, while the maximum speed of 202mph and the ramge of 713 miles were considered excellent, the carrying capacity of 2 crew and 10 passengers was considered too small. The Model 10 Electra was thus also eliminated from consideration.

The de Havilland D.84 Dragon

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de Havilland DH.84M Dragon’s with the Iraqi Air Force

The de Havilland DH.84 Dragon 2 was a successful small commercial aircraft designed and built by the de Havilland company that entered service in April 1933. The twin-engined aircraft was a a simple, light biplane design with a plywood box fuselage with a maximum speed of 133mph, a crusing speed of 109mph, a range of 545 miles and a sewrvice ceiling of 12,500 feet. With a crew of one, it carried 6-10 passengers. A military transport version was available as the DH84M Dragon and this was evaluated by the Ilmavoimat Procurement Team. While the Dragon was very attractive as a short-haul low capacity airliner, the evaluation team considered it too small and with insufficient cargo / troop transport capacity for the Ilmavoimat’s needs.

The General Aviation GA-43

The General Aviation GA-43 was an airliner produced in small numbers in the United States in the mid 1930s The prototype was developed and built by Fairchild's American Pilgrim division, but the programme was taken over by General Aviation when the firm purchased American Pilgrim shortly before it had flown. Although this first flight took place in 1932, manufacture did not commence until 1934, by which time General Motors had, in turn, gained a controlling interest in North American Aviation and merged it with General Aviation that they already owned. The upshot of this was that the GA-43 became the first aircraft produced by North American. The GA-43 was a conventional low-wing cantilever monoplane of all-metal construction. The prototype had fixed tailwheel undercarriage, but the main units of this were later changed to be made retractable, and three of the four production examples also had retractable mainwheels, the fourth aircraft having twin pontoons instead. The oval-section fuselage contained a ten-seat passenger cabin, and the cockpit (with 2 crew) was located atop the fuselage under a separate canopy. The GA-43 was single-engined, with a maximum speed of 195mph and a range of 425 miles. Swissair purchased two aircraft.
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The Ilmavoimat evaluation team considered it too small and with insufficient cargo / troop transport capacity for the Ilmavoimat’s needs. The single engine was also seen as undesirable and while the speed was good, the maxium range was also limited. The GA-43 was not seen as worth additional evaluation and testing.

The Caproni Ca132 and Ca133

Caproni was a firm with a lengthy history in the aviation industry, having started building aircraft in 1908. During WW1 Caproni was, along with FIAT, one of the most important aircraft manufacturers in Italy. After the war, they converted a number of their bomber designs to civilian passenger aircraft. By the late 1920s they were building smaller (but far more successful in terms of sales) passenger aircraft and coming up with some good designs (such as the Caproni CA 123 – thought to be a “copy” of the American DC2). The Ca 132 was a smaller version of the CA 123.
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The Caproni Ca.132 was a prototype for a large aircraft built in Italy in 1934, intended for use as either a bomber or airliner. It was a conventional low-wing cantilever monoplane powered by radial engines on each wing and in the nose. The main undercarriage was housed within large streamlined spats. Configured as an airliner, it would have seated 20 passengers together with a crew of 4 and was again designed to compete with the Douglas DC2. Powered by 3 Piaggio Stella IX engines of 418 kW (560 hp) each, the Ca.132 had a maximum speed of 196 mph.

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The Ca 133 on the other hand was a high wing monoplane powered by three 460hp Piaggio Stella P.VII C.16 radial engines. the aircraft was of welded steel-tube construction and fabric-covered except for the forward fuselage, which had sheet metal skin. The wheels were fitted in large spats and there was a steerable tail wheel.

The Ca 133 prototype first flew in December 1934 and production began in 1934 fgor both civil and military use. While the military version could carry 18 fully equipped soldiers, the civilian version had a cabin for sixteen passengers and saw service with the Italian airline Ala Littoria SA, which used a fleet of thirteen aircraft. The aircraft were mainly operated on the African routes and it is known that they have flown on the line Rome – Benghazi – Caïro – Wadi Halfa – Khartoum – Asmara – Addis Ababa and in East Africa including Asmara – Assab – Diredawa, Diredawa – Gorrohei – Belet’Ven – Mogadiscio, Asmara – Assab – Djibouti and Addis Ababa – Diredawa – Djibouti. They operated these services until 1939 and only one was recorded as lost: In this time, the aircraft carried 10,000 passengers and operated with a regularity of 99.9 %. The Ca 133 was operated in large numbers by the Regia Aeronautica. It was a robust and inexpensive aircraft, designed to be easily maintained in difficult conditions and economical to operate.

The Caproni Ca 123

The Caproni Ca 123 was based on the Ca 122 bomber and was thought to be a “copy” of the Douglas DC2. The all-metal aircraft was constructed to carry a crew of three (pilot, co-pilot and radio operator) and 28 passengers over long distances. The aircraft was to be powered by two Gnome & Rhone 14Krs (65okW/870hp) engines with three bladed propellors. It was also designed with retractable landing gear. Maximum speed was 211mph with a range of 932 miles.
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Design sketch drawings for the Caproni Ca 123

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A Caproni 122 (fixed undercarriage) at an Air Display

The Savoia-Marchetti S.73

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The Savoia-Marchetti S.73 was an Italian three-engined airliner that first flew as a prototype on 4 July 1934 (the aircraft entered service in March 1935 with a production run of 48 aircraft). The aircraft was developed in only four months in parallel with a bomber version (the SM.81) thanks to the use of the S.55 wing, combined with a much more conventional mixed-construction fuselage (a skeleton of steel covered by wood and fabric for the fuselage, wood for the three-spar wing).

The S.73 was a low-wing monoplaNe with a braced tailplane and fixed undercarriage. The pilot and co-pilot were seated side-by-side in an enclosed cockpit, with a compartment for a radio operator and a mechanic (for a total of 4 crew). A passenger compartment could house 18 passengers in two rows. The prototype had French Gnome et Rhône Mistral Kfr engines, but further aircraft were fitted with Piaggio P.X Stella 522 kW (700 hp), Wright R-1820 574 kW (770 hp), Walter Pegasus III MR2V 544 kW (730 hp) and Alfa Romeo AR 125 and 126 engines. Fitted with the Wright R-1820 engines (1,723 kW / 2,310 hp in total), the SM.73 could fly at a maximum speed of 210 mph or cruise at 170mph, had a range of 620 miles and a ceiling of 20,670 feet.

In Ilmavoimat Procurement Team test flights carried out in late September 1934, the SM.73 proved to be easy to fly with reliable controls and handling, well able to fly from short airfields and from airfields with bad terrain conditions, easy to operate on the ground and to maintain and not too costly, particularly when compared to American and German aircraft. Conversion to operate using floats or skis was a relatively straightforward operation, similar to the Junkers Ju52. The mixed construction and fixed landing gear were not seen as major shortcomings at the time of the evaluation.

The Douglas DC2

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The first KLM DC-2 PH-AJU Uiver (Stork) in flight

The Douglas DC-2 was a 14 seat, all-metal structured twin-engine cantilever low-wing transport aircraft produced by the Douglas Aircraft Corporation starting in 1934. In the early 1930s, fears about the safety of wooden aircraft structures (responsible for the crash of a Fokker Trimotor) compelled the American aviation industry to develop all-metal types. With United Airlines having a monopoly on the Boeing 247, rival Transcontinental and Western Air issued a specification for an all-metal trimotor. The response of the Douglas Aircraft Company was more radical. When it flew on July 1, 1933, the prototype DC-1 had a highly robust tapered wing, a retractable undercarriage, and only two 690 hp (515 kW) Wright radial engines driving variable-pitch propellers. It seated 12 passengers.

TWA accepted the basic design and ordered 20, with more powerful engines and seating for 14 passengers, as DC-2s. The design impressed a number of American and European airlines and further orders followed. Those for European customers KLM Royal Dutch Airlines, LOT, Swissair, CLS and LAPE were assembled by Fokker in the Netherlands. 156 DC-2s were built. Although overshadowed by its ubiquitous successor, it was the DC-2 which first showed that passenger air travel could be comfortable, safe and reliable. As a token of this, KLM entered their first DC-2 PH-AJU Uiver (Stork) in the October 1934 MacRobertson Air Race between London and Melbourne. Out of the 20 entrants, it finished second behind only the purpose built de Havilland DH.88 racer Grosvenor House. During the total journey time of 90 h 13 min, it was in the air for 81 h 10 min, and won the handicap section of the race. (The DH.88 finished first in the handicap section, but the crew was by regulation allowed to claim only one victory). As with other prospective buyers, the Ilmavoimat evaluation and testing teasm were highly impressed with the DC2 and towards the end of the evaluation and testing program, the DC2 was at or near the front of the pack on almost everything except price.

As evaluations were carried out, the Procurement Team also found themselves on the receiving end of requests to also include for consideration aircraft that were currently being designed and were close to having a prototype built. These included the Junkers Ju-86 (a 10 passenger civil transport which was still at the design stage), the de Havilland DH.86 and also the newly-designed Heinkel He111 transport. These all looked promising and as a result, the evaluation and testing program dragged on into 1935 before a decision was made.

The Junkers Ju86

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At the end of 1933, the the Reichsluftfahrtministerium (RLM) was looking for a twin-engined bomber aircraft while Lufthansa was looking for a modern quick passenger aircraft with two engines. On November, 4th 1934 the Ju86 bomber prototype was first flown and on March 22nd 1935 the second prototype (c/n 4902) was ready for its first flight. This second prototype was the civil passenger airliner version of the Ju86. However, at the time of the Ilmavoimat Procurement Team’s evaluation, this aircraft was drawing-board only and was eliminated from consideration as what was wanted was an aircraft that could be test-flown before a decision was made. The Koolhoven debacle of the late 1920’s had cured the Ilmavoimat of any tendancy to buy “on spec”. While the design was evaluated, as with the American Boeing Model 247 and Lockheed Electra the carrying capacity of 2 crew and 10 passengers was considered too small. However, the maximum speed of 260mph and the range of 980 miles were considered excellent and further consideration would be given to this aircraft once a prototype was available.

The de Havilland DH.86 and DH.89

Two de Havilland aircraft were considered – the four-engined DH.86 and the twin-engined DH.89. After the initial assessments and test flights, both were removed from consideration.

The de Havilland DH.86 Express was a four-engined passenger aircraft from the 1930s manufactured by the de Havilland Aircraft Company. During 1933, talks between the governments of United Kingdom, India, Malaya, the Straits Settlements and Australia resulted in an agreement to establish an Empire Air Mail Service. The Australian Government called for tenders on 22 September 1933 for the Singapore-Australia legs of the route, continuing as far south as Tasmania. On the following day Qantas, anticipating success in contracting for the Singapore-Brisbane leg, placed an order with de Havilland for an as-yet non-existent aircraft to be designated the de Havilland 86, the prototype to fly by the end of January 1934. This order was soon followed by one from Holyman's Airways of Launceston, Tasmania to operate the Bass Strait leg of the service. The D.H.86 was initially styled the Express or Express Air Liner although the name was soon discontinued.

The D.H.86 was conceptually a four-engined enlargement of the successful de Havilland Dragon, but with a more streamlined appearance with tapered wings and extensive use of metal fairings around struts and undercarriage. The most powerful engine made by de Havilland, the new 200 hp (149 kW) Gipsy Six, was selected. For long-range work the aircraft was to carry a single pilot in the streamlined nose, with a wireless operator behind. Maximum seating for ten passengers was provided in the long-range type, however the shorter-range Holyman aircraft were fitted with twelve seats.

The prototype D.H.86 first flew on 14 January 1934, but the Qantas representative Lester Brain immediately rejected the single pilot layout because he anticipated pilot fatigue over long stretches, and the fuselage was promptly redesigned with a dual-pilot nose. Only four examples of the single-pilot D.H.86 were built, and of these the prototype was rebuilt as the dual-pilot prototype. When she entered service in October 1934 the first production aircraft, Holymans' single-pilot D.H.86 Miss Hobart, was the fastest British-built passenger aircraft operating anywhere in the world. Despite de Havilland's predictions to the contrary, the dual pilot type with its lengthened nose proved to be even faster. However, on 19 October 1934 Holyman's VH-URN Miss Hobart was lost in Bass Strait with no survivors.At the time Miss Hobart disappeared the design of the aircraft was not suspect, and it was thought that an accident may had occurred when Captain Jenkins and the wireless operator/assistant pilot Victor Holyman (one of the proprietors of Holyman Airways) were swapping seats in mid flight.

However following the loss of Qantas' VH-USG near Longreach four weeks later while on its delivery flight, it was found that the fin bias mechanisms of the crashed aircraft and at least one other were faulty, although it is doubtful that this had any direct bearing on the accidents other than perhaps adding to the aircraft’s lack of inherent stability. Further investigation revealed that VH-USG had been loaded with a spare engine in the rear of the cabin, and that one of the crew members was in the lavatory in the extreme aft of the cabin when control was lost. It was theorised that the aft centre of gravity condition that thus existed resulted in a loss-of-control at an altitude insufficient for recovery (the aircraft was at an estimated height of 1,000 ft (300 m) prior to the crash).

In fact, the D.H.86 had approached the limits to which traditional "plywood and canvas" aircraft construction could be taken, and was obsolete compared to all-aluminium stressed-skin aircraft like the Boeing 247 and the Douglas DC-1 that were already flying before it was even designed (and the immortal Douglas DC-3 had its first flight just four days after the forced-landing of VH-USW). Under pressure from Holymans and other companies, the Australian Government rescinded its ban on the import of American aircraft during 1936, and for the next 25 years most large commercial aircraft imported into Australia were of American manufacture.
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The DH.86 carried a crew of 2 and 10 passengers at a maximums peed of 166 mph. With a range of 748 miles and a service ceiling of 17,400 feet, it didn’t compare well with the Italian and American passenger aircraft. As a result, it was removed from consideration.

The de Havilland DH.89 Dragon Rapide was a British short-haul passenger airliner of the 1930s. Designed by the de Havilland company in late 1933 as a faster and more comfortable successor to the DH.84 Dragon, it was in effect a twin-engined, scaled-down version of the four-engined DH.86 Express. It shared many common features with the larger aircraft including its tapered wings, streamlined fairings and the Gipsy Six engine, but it demonstrated none of the operational vices of the larger aircraft and went on to become perhaps the most successful British-built short-haul commercial passenger aircraft of the 1930s. The prototype first flew on 17 April 1934 and 205 were built for owners all around the world before the outbreak of World War II. Originally designated the "Dragon Six" it was first marketed as "Dragon Rapide" although was later just called a "Rapide".

The DH.89 carried a crew of 1 and 8 paasengers at a maximums peed of 157 mph. With a range of 573 miles and a service ceiling of 16,700 feet, it was an economical and very durable aircraft despite its relatively primitive plywood construction.

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The Ilmavoimat Flight Test Team with the de Havilland DH.89, summer 1934. The test team considered the aircraft a useful and capable small transport aircraft, but it did not meet the stated requirements for the Ilmavoimat’s transport aircraft and was not considered further. However, while this aircraft type was not purchased for the Ilmavoimat, Veljekset Karhumäki Oy purchased six of these aircraft in 1936 with a state-guaranteed loan. Te aircraft were used to service Government mail contracts, for scheduled passenger flights and for aerial mapmaking. During the Winter War, the DH.89’s were used for ongoing aerial mapmaking of areas captured from the USSR.

The Heinkel 111

In the early 1930s Ernst Heinkel decided to build the world's fastest passenger plane, a goal met with scepticism by Germany's aircraft industry and political leadership. Heinkel entrusted development to Siegfried and Walter Günter, both fairly new to the company and untested. In June 1933 Albert Kesselring visited Heinkel's offices. Kesselring was head of the Luftwaffe Administration Office: at that point Germany did not have a State Aviation Ministry but only an aviation commissariat, the Luftfahrtkommissariat. Kesselring was hoping to build a new air force out of the Flying Corps being constructed in the Reichswehr ]and convinced Heinkel to move his factory from Warnemunde to Rostock and turn it over to mass production with a force of 3,000 employees who would produce the first He 111. Heinkel began a new design for civil use in response to new American types that were appearing, the Lockheed 12, Boeing 247 and Douglas DC-2. The first single-engined Heinkel He 70 Blitz ("Lightning") rolled off the line in 1932 and the type immediately started breaking records. In its normal four-passenger version its speed reached 380 km/h (230 mph), powered by a 447 kW (600 hp) BMW VI engine. The elliptical wing that the Günther brothers had already used in the Bäumer Sausewind sports plane before they joined Heinkel became a feature in this and many subsequent designs they developed. The design drew the interest of the Luftwaffe, which was looking for an aircraft with dual bomber/transport capabilities.
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The He 111 was a twin-engine version of the Blitz, preserving the elliptical inverted gull wing, small rounded control surfaces and BMW engines, so that the new design was often called the Doppel-Blitz ("Double Blitz").

Heinkel spent some 200,000 hours developing it. At the time the Ilmavoimat were evaluating transport aircraft, the Heinkel 111 was still in the design stage. Based on the bomber design, the aircraft was a wolf in sheeps clothing – as a civilian airliner it remained close to its military origins – while designed for ten passengers, the bomb bay remained as a four-seat "smoking compartment", with another six seats behind it in the rear fuselage. The projected design had a speed of 193mph and a range of 621 to 1,367 miles depending on the fuel capacity. As such, while the speed and range were acceptable, the passenger / cargo capacity was somewhat limited and no further consideration was given to this type by the Ilmavoimat.

The Shortlist

After the first round of evaluations and testing was concluded, the Ilmavoimat shortlist consisted of the following:
Junkers Ju52: Crew of 3, 17 passengers, maximum speed of 168mph, range of 590 miles, service ceiling of 18,000 feet.
Caproni Ca 133: Crew of 4, 18 passengers, maximum speed of 196 mph, range of 838 miles, service ceiling of 18,000 feet;

Savoia-Marchetti S.73: Crew of 4, 18 passengers, maximum speed of 210 mph, range of 620 miles, ceiling of 20,670 feet;
Douglas DC2: Crew of 3-4 (military version, 14 passengers, maximum speed of 210mph, combat radius of 1,085 miles, service ceiling of 22,750 feet;
However, the design for the Caproni Ca123 was also considered highly attractive. With a crew of 3, 28 passengers, maximum speed of 211mph, range of 932 miles and a service ceiling of 20,000 feet, it was priced at considerably less than the Douglas DC2 and looked very similar.

And the decision was…….

Based on a combination of cost, carrying capacity, handling, ease of maintenance and ability to operate from rough airfields, on balance, the Savoia-Marchetti S.73 emerged as the lead contendor and the Ilmavoimat Procurement Team ordered 6 in July-1935 for use as transports. However, they also decided to hedge their options and based on the ability of Douglas to supply aircraft quickly, they ordered 2 Douglas DC2’s and 2 Caproni Ca123’s at the same time. While the Caproni Ca123 was a “paper” aircraft at the time of the order, the test flights and evaluations of the other two Caproni aircraft that were available had proved them to be well-designed and built. However, the larger carrying capacity along with the good performance of the Ca123 appealed – the aircraft could carry an entire Platoon in one lift and so, 2 examples were ordered “on spec.” In Italy, the Finnish order, while not large, received a great deal of publicity, with the success of Italian aero-technology feated. Combined with the ever increasing build-up of Italian-Finnish trade through the 1930’s (and the links with the Finnish IKL political party covered earlier), this was heralded as the beginning of even closer ties between the two countries.

However, the first aircraft of this order to be delivered were actually the 2 Douglas DC2’s – ordered in July 1935, they were delivered “off the shelf” in September of the same year – a speed of delivery which gave rise to the Ilmavoimat taking a long and detailed look at American manufacturing capabilities. This ability of the Americans to delivery quickly and the large industrial capacity available within the USA would have ramifications over the remainder of the 1930’s as the Ilmavoimat considered alternative aircraft and looked at both availability and the ability to deliver.

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Ilmavoimat Douglas DC2 shortly after delivery – late 1934

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The two Douglas DC2’s ordered were delivered in September 1935 With a crew of 2-3, plus capacity of 14 passengers, powered by 2× Wright Cyclone GR-F53 9-cylinder radial engines of 730 hp (540 kW) each giving a maximum speed of 210mph, a combat radius of 1,085 miles and a service ceiling of 22,750 feet, the DC2 was an effective light transport aircraft which the Ilmavoimat kept in service through the war years. With somewhat of a sense of humor, the first DC2 to enter service was named “Hanssin Jukka” after a famous Finnish knife-fighter, while the second was named “Isontalon Antti”

Not wanting to be outshone by the Americans, and also seeing the prospect of further sales in the future, the Italians accelerated the delivery of the 6 Savoia-Marchetti S.73 aircraft by the simple expedient of redirecting 6 of the aircraft that were near completion and intended for Italian civil aviation use to meet the Finnish order instead. The aircraft were consequently delivered in October 1935.
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Ilmavoimat Savoia-Marchetti S.73

The Caproni 123 was another story. The Finns had specified that a prototype would be built at the cost of the Italians and tested, with any faults rectified, before they would accept delivery of the 2 aircraft ordered. Caproni excelled themselves and built a single prototype in 6 months. Testing by an Ilmavoimat test crew took place over February-March 1936, with a number of faults rectified. The aircraft met or exceeded all expectations, and the 2 aircraft ordered were completed and delivery in June 1936. In fact, they looked remarkably similar to the Douglas DC2/DC3. In service, the Caproni Ca123 would proved to be a remarkably tought and versatile aircraft. The Ilmavoimat would go on to order more of these aircraft.
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Ilmavoimat Caproni Ca 123

Next. Returning to the 1935 Ilmavoimat Procurement Program
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The 1935 Ilmavoimat Procurement Program

Post by CanKiwi2 » 30 Jun 2011 15:19

The 1935 Ilmavoimat Procurement Program

The 1935 Ilmavoimat Procurement Program was fairly conservative, with the first order being 40 additional Tuiska Advanced Trainers ordered from VL. With the planned buildup of the Ilmavoimat on track, and the lengthy training period required for Pilots, building up the training infrastructure needed to be addressed early and the decision to buy an additional 40 advanced trainers reflected this. An additional 24 of the Avia B-532 Fighters were also ordered. The Avia had proved itself in service and its performance surpassed that of all its competitors at the time of the order.
The Ilmavoimat also continued its search for a good modern tactical medium bomber. A wide range of bombers were evaluated through the first half of the year – many of those available were eliminated immediately as being too small, restricted in range, speed or bombload or of antiquated design. Among those that were considered were the Junkers Ju86, the designs for the Heinkel-111, the Dornier DO 13 and DO 23, the Bloch MB.200, the Potez 540, the Bristol Bombay, the Fairey Hendon, the designs for the Armstrong-Whitworth AW.23, the Handley Page Heyford, the Martin B-10, the Caproni 122 bomber and the Savoia-Marchetti SM.81.

And there was another issue that the Ilmavoimat now had to face in buying aircraft. By 1935, with the German resurgence under the leadership of Hitler, rearmament was beginning to take center stage for the major European powers and with manufacturing capacity for military aircraft having been run down in the 1920s and early 1930s, Germany, Britain and France in particular were focused largely on their own needs. Foreign sales were at best incidental and the Ilmavoimat’s problem was that even if an order was placed, it might be deferred or taken over right up until the last minute. Economically, Finland in 1935 had very little leverage and so a major factor in the procurement program decisions became to minimise the risk of an order being deferred, cancelled or taken over – and this meant looking for aircraft that could either be licensed and manufactured in Finland (with a slow lead-time as a result) or that were available from smaller countries or from manufacturers that were not supplying aircraft and components critical to the countries own rearmament program – or the United States with its massive industrial capacity. (Incidentally, this was also a factor in the Finnish decision to set up their own aircraft engine factories – one of the major bottlenecks in aircraft manufacturing was the supply of aircraft engines – and by supplying their own engines, Finland could broaden their options somewhat going forward).

As with the 1934 transport aircraft purchase, by the middle of the third quarter of 1935 the bomber-candidate list was whittled down to a shortlist which consisted of the the Martin B-10, the Caproni 122 bomber and the Savoia-Marchetti SM.81. In looking for a transport aircraft through 1934 and finally deciding on the SM.73, the Ilmavoimat Procurement Team had dealt with Savoia-Marchetti on an ongoing basis. The final decision was to purchase 15 Savoia-Marchetti SM.81s – with a large part of the decision being based on compatability and versatility – and another large part being based on the attractiveness of the pricing (the Martin B-10 for example had a unit cost of USD$52,000 - the SM.81's were considerably less). A further consideration was that the Italians were eager to secure export orders and rapid delivery to Finland was guaranteed personnally by Mussolini, alleviating concerns on this aspect of the order. The aircraft were ordered in September 1935 and were delivered in January 1936, entering service shortly afterwards.

VL Tuiska Advanced Trainers – 40 ordered in January 1935

As mentioned for the 1933 Procurement Program, an additional 40 VL Tuiska Advanced Trainers were ordered early in 1935. These were built by VL and delivered in batches over 1935 and into 1936.

Avia B-532 Biplane Fighter –24 ordered in March 1935

As mentioned for the 1934 Procurement Program, the performance of the Avia-B532 was such that 24 further aircraft of this type were ordered in July 1935. The aircraft were delivered in late 1935 and entered service almost immediately, giving the Ilmavoimat two full squadrons of this front-line fighter aircraft.

Savoia-Marchetti SM.81 – 15 ordered in September 1935

The SM.81 was a militarised version of Savoia-Marchetti's earlier SM.73 airliner, having cantilever wings, three engines and a fixed undercarriage with the main wheels enclosed in large spats to reduce drag. The origins of this version were the need for a fast and efficient aircraft that was capable of serving in the vast Italian colonies in Africa. The SM.81 had wings that were identical to those of the SM.73, but had a much simpler fuselage. Around six months after the SM.73s first appearance, the SM.81 prototype (MM.20099) first flew on 8 February 1935, flown by test pilot Adriano Bacula. The first series ordered in 1935 was for 115 aircraft (100 for the Regia Aeronatutica, 15 for the Ilmavoimat) and was quickly put into production as a result of the international crisis and the embargo caused by the war in Ethiopia.

The SM.81 was of mixed construction: the fuselage had a framework of steel tubes with a metallic-covered aft portion, while the rest was wood- and fabric-covered - and it proved to be remarkably robust. It had a relatively large fuselage, this was an unnecessary characteristic for a bomber but derived from its civilian passenger origins – but which meant it could also make an effective transport aircraft. Since the engines were quite small in size, the fuselage did not blend well with the nose engine, even less so than with the SM.79. Many windows were present to provide the fuselage interior with light, giving the impression that it was a passenger aircraft. The aircraft had a crew of six, with the pilot and co-pilot eated side-by-side in an enclosed cockpit, with separate cabins for the flight engineer and the radio-operator/gunner behind the cockpit. The bombardier's position was located just below the cockpit, in a semi-retractable gondola in a location which was favourable for communicating with the crew, and provided excellent visibility thanks to the glazed panel. Both this position and the cockpit had escape hatches, but for normal entry and exit there was a door in the left, mid-fuselage, and one in the aft fuselage.

The bomb bay was behind the cockpit, together with a passage which linked to the aft fuselage, where there were three further defensive positions. Equipment included an RA 350I radio-transmitter, AR5 radio-receiver, and a P63N radiocompass (not always fitted), while other systems comprised an electrical generator, fire extinguishing system, and an OMI 30 camera (in the gunner's nacelle). The aircraft, with its large wing and robust undercarriage, proved to be reliable and pleasant to fly, and could operate from all types of terrain. It was surprisingly fast for its time, with a maximum speed of 211mph and a combat range of 1240 miles. The service ceiling was 23,000 feet and a maximum of 2,000kg of bombs could be carried. As designed, defensive armament consisted of 6 machineguns – 4 of them in two powered retractable turrets (one dorsal, just behind the pilots seats, and one ventral-aft) and 2 mounted to fire through lateral hatches. The ventral turret was operated in a different fashion to those fitted to other aircraft where the gunner occupied the ball- or dustbin-shaped structure; instead, due to lack of space, the gunner crouched in the fuselage with his head down inside the turret. This proved to be not very effective as were most ventral turrets, and they were not fitted to the Ilamvoimats SM-81s. No armour was fitted, except for the self-sealing fuel tanks.

Operationally, the SM.81 first saw combat with the Regio Aeronautica during the Second Italo-Abyssinian War, where it showed itself to be versatile serving as a bomber, transport and reconnaissance aircraft. SM.81s also fought in the Spanish Civil War with the Aviazione Legionaria and were among the first aircraft sent by the fascist powers to aid Franco. Ilmavoimat volunteer pilots and crew gained considerable experience in combat flying Italian-supplied SM-81s in the Spanish Civil War – combat experience that was put to good use in the Winter War. By the last stages of the Spanish Civil War, the SM.81s low speed and vulnerability to fighter aircraft meant that during daytime it was restricted to second line duties, finding use as a transport. At night the SM.81 was however still an effective bomber. Within the Ilmavoimat, this experience was incorporated into the tactical use of the SM.81s in the Winter War, where they were generally used for night-bombing and as a transport. Despite the SM.81s being obsolescent by late 1939 some 300 SM.81s were in service with the Regia Aeronautica and some 35 were sold by the Italians to the Ilmavoimat after the outbreak of the Winter War.
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Finnish-volunteer flown Savoia-Marchetti SM.81 bomber during a bombing raid in the Spanish Civil War (1936-39). The distinctive black crosses on the tails are the Saint Andrew's Cross, the insignia of the Spanish Nationalist Air Force (Francos side). The accompanying Fighters are Fiat CR.32s of the “Italian” XVII Gruppo Autonomo Pohjoimaiset Sudet (“Wolves of the North”)

In hindsight, it’s interesting to look at the SM.81’s leading competitors in 1934. As mentioned previously, among those that were considered were the Junkers Ju86, the designs for the Heinkel-111, the Dornier DO 13 and DO 23, the Bloch MB.200, the Potez 540, the Bristol Bombay, the Fairey Hendon, the designs for the Armstrong-Whitworth AW.23, the Handley Page Heyford, the Martin B-10 and the Caproni 122 bomber as well as a range of other aircraft rapidly being outdated. Aircraft technology in the 1930’s was progressing rapidly and what was leading edge in one year was often second-rate by the next year and obsolete by the third. Lets take a quick look at these….
In 1934, a specification for a modern twin-engined aircraft capable of operating both as a high speed airliner for the German airline Lufthansa and as a medium bomber for the still-secret Luftwaffe was issued to both Junkers and Heinkel. Five prototypes of each of the the Junkers Ju 86 and Heinkel He 111 were ordered from each company; .

The Junkers Ju86:

The Junkers design was a low-winged twin engined monoplane, of all-metal Stressed skin construction. Unlike most of Junkers previous designs, it discarded their typical corrugated skinning in favour of smooth metal skinning which helped to reduce drag. The craft was fitted with a narrow track retractable tailwheel undercarriage and twin fins and rudders. It was intended to be powered by the Junkers Jumo 205 diesel engines, which although heavy, gave superior fuel consumption to conventional petrol engines. The bomber aircraft had a crew of four; a pilot, navigator, radio operator/bombadier and gunner. Defensive armament consisted of three machine guns, situated at the nose, at a dorsal position and within a retactable ventral position. Bombs were carried vertically in four fuselage cells behind the cockpit.

The first prototype Ju 86, the Ju 86ab1, fitted with Siemens SAM 22 radial engines as airworthy Jumo 205s were unavailable, flew on 4 November 1934, in bomber configuration, with the second prototype, also a bomber, flying in January 1935. The third Ju 86, and the first civil prototype, flew on 4 April 1935. Production of pre-series military and civil aircraft started in late 1935 with full production of the Ju 86 bomber commencing in April 1936. The bomber was field tested in the Spanish Civil War, where it proved inferior to the Heinkel He 111. In January 1940, the Luftwaffe tested the prototype Ju 86P with a longer wingspan, pressurized cabin, Jumo 207A1 turbocharged diesel engines, and a two-man crew. The Ju 86P could fly at heights of 12,000 m (39,000 ft) and higher on occassion, where it was felt to be safe from Allied fighters.
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Specs for the the Ju86R indicate a crew of 2, a maximum speed of 260mph with a range of 980 miles, a service ceiling of 42,650 feet and a 1,000kg bombload. The Ju 86 was sold to airlines and air forces from several nations, including Bolivia, Chile, Hungary, Manchukuo, Portugal, the South African Air Force (SAAF), Spain, and Sweden. The Ju 86K was an export model, also built under license in Sweden by Saab as the B 3 with (905 hp) Bristol Mercury XIX radial engines.

The Heinkel-111:
The Ju86’s competitor within Germany was the Heinkel He 111, designed by Siegfried and Walter Günter in response to the same requirement. In 1935, comparison trials were undertaken with the He 111. At this point, the Heinkel was equipped with two BMW VI engines while Ju 86A was equipped with two Jumo 205Cs, both of which had 492 kW (660 hp). The He 111 had a slightly heavier takeoff weight of 8,220 kg (18,120 lb) compared to the Ju 86's 8,000 kg (17,640 lb) and the maximum speed of both aircraft was 311 km/h (193 mph). However the Ju 86 had a higher cruising speed of 177 mph (285 km/h), 9 mph (14 km/h) faster than the He 111. This stalemate was altered drastically by the appearance of the DB 600C, which increased the He 111's power by 164 kW (220 hp). In production terms the He 111 went on to dominate with 8,000 examples produced while just 846 Ju 86s were produced. The Ju 86's weak performance could not match that of the He 111. Having dropped out of the race, Junkers concentrated on the Junkers Ju 88 design. It would be the He 111 that entered the Luftwaffe as the dominant numerical type at the beginning of the Second World War.
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Heinkel He111 of the Condor Legion in Spain. Ilmavoimat volunteers had the opportunity to fly the aircraft operationally in Spain and praised its performance highly. However, despite a number of evaluations which gave the aicraft high marks, it was never purchased by the Ilmavoimat.

The first He 111 flew on 24 February 1935 and while the Ilmavoimat had rejected the civilian passenger aircraft as too small, they were interested in the bomber version. In May 1935 evaluation flights of both the Junkers Ju86 and Heinkel He111 were flown. Performance was good – a speed of 255mph, a range of 1429 miles with maximum fuel and a bomb loand of 2000kg internally (8 x 250kg bombs). However, the aircraft was still in development, delivery times could not be guaranteed and the cost as compared to the Italian SM.81 aircraft was on the high side. However the Ilmavoimat remained interested and would look at the aircraft again in 1936.

The Dornier Do13 and Do23

During the late 1920s the German Dornier Metallbauten set up a subsidiary at Altenrhein in Switzerland to build heavy aircraft expressly forbidden under the terms of the Versailles Treaty. Three aircraft were produced - The Do P, the Do Y and the Do F (a large twin) All were described as freight aircraft, but their suitability as bombers was obvious. In late 1932 it was boldly decided to put the F into production at the German factory at Friedrichshafen, and the designation was changed to Do 11. The Do 11 had a slim light-alloy fuselage, high-mounted metal wing with fabric covering carrying two 484.4kW Siemens Sh 22B engines (derived from the Bristol Jupiter), and a quaint retractable landing gear whose vertical main legs were laboriously cranked inwards along the inner wing until the large wheels lay flat inside the nacelles. There was obvious provision for a bomb bay and three gun positions. The first customer was the German State Railways which under the cover of a freight service actually enabled the embryo Luftwaffe to begin training future bomber crews.

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The Dornier Do11

It had been planned to deliver 372 Do 11s in 1934 but delays, plus grossly unpleasant handling and structural qualities, led to the substitution first of the short-span Do 11D and then the Do 13 with 559kW BMW VI water-cooled engines and fixed (often spatted) landing gear. At least 77 Do 11Dswere delivered, some later being passed on to another clandestine air force, that of Bulgaria. The Do 13 was wholly unacceptable, but in September 1934 testing began of a completely redesigned machine called the Do 13e with stronger airframe, Junkers double-wing flaps and ailerons and many other changes. To erase the reputation of its forbear this was redesignated Do 23 and in March 1935 production restarted of Do 23F bombers.
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Dornier Do23

No attempt was made to disguise the function of the bomber: the fuselage having a glazed nose for visual aiming of the 1,000kg bomb load housed in vertical cells in the fuselage, and nose, mid-upper and rear ventral positions each being provided with a 7.92mm MG 15 machine-gun. After building a small number the Dornier plant switched to the Do 23G with the BMW VIU engine cooled by ethylene-glycol. By late 1935 more than 200 had been delivered and these equipped the first five named Fliegergruppen - although about two-thirds of their strength comprised the distinctly preferable Ju 52/3m. Although it played a major part in the formation of the Luftwaffe and continued to the end of World War II to serve in training, trials and research roles, the Dornier Do 23 was not much better than its disappointing predecessors
With a maximum speed of 161mph, a range of 932 miles, a service ceiling of 13,779 feet, a crew of 4 and a bomb load of 1000kg, the Dornier Do23 had a mediocre performance and at the time of the Ilmavoimat evaluation was already dated. After an evaluation that was rather cursory, it was dropped from consideration, although another Dornier aircraft, the Do17, was considered in 1936.

The Bloch MB.200

The MB.200 was a French bomber aircraft of the 1930s designed and built by Societé des Avions Marcel Bloch in response to a 1932 requirement for a new day/night bomber to equip the French Air Force. A twin-engined high-winged all-metal monoplane with a a slab-sided fuselage and a fixed undercarriage, powered by two Gnome-Rhône 14K radial engines, over 200 MB.200s were built for the French Air Force, and the type was also licence built by Czechoslovakia. It had a fixed tailwheel undercarriage and featured an enclosed cockpit for the pilots. Defensive machine guns were in nose and dorsal gun turrets and a under fuselage gondola.

The first of three prototypes flew on 26 June 1933. As one of the winning designs for the competition, an initial order for 30 MB.200s was placed on 1 January 1934, entering service late in that year. Further orders followed, and the MB.200 equipped 12 French squadrons by the end of 1935. Production in France totalled over 208 aircraft (4 by Bloch, 19 by Breguet, 19 by Loire, 45 by Hanriot, 10 by SNCASO and 111 by Potez. Czechoslovakia chose the MB.200 as part of a modernisation program for its air force of the mid 1930s. Although at the rate of aircraft development at that time, the MB.200 would quickly become obsolete, the Czechoslovakians needed a quick solution involving the license production of a proven design, as their own aircraft industry did not have sufficient development experience with such a large aircraft, or with all-metal airframes and stressed-skin construction, placing an initial order for 74 aircraft. After some delays, both Aero and Avia began license-production in 1937, with a total of about 124 built. Czechoslovakian MB.200s were basically similar to their French counterparts, with differences in defensive armament and other equipment.
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With a crew of 4, the MB.200 had a maximum speed of 178mph, a range of 621 miles, a service ceiling of 26,200 feet and could carry 1200kg of bombs. The Ilmavoimat Procurement Team evaluated the aircraft and considered it already obsolete. By this time, with a good three years of experience in aircraft evaluations and with the need to keep abreast of current designs and aircraft, the team probably had a better and broader knowledge than most other Air Forces of what was available and the potential of upcoming designs. This was particularly so as they were constantly evaluating aircraft and designs from manufacturers from every major country with the exception of the USSR and Japan, as well as smaller suppliers from neutral countries such as Fokker, Avia and Aero – and indeed, they also looked at Polish aircraft.

The Potez 540

Introduced into service in 1934, this two-engine aircraft was built by the French Potez company to fulfill a 1932 specification for a new reconnaissance bomber. Built as a private venture, this aircraft, designated the Potez 54, flew for the first time on 14 November 1933. Designed by Louis Coroller, it was intended as a four-seat aircraft capable of performing duties such as bomber, transport and long-range reconnaissance. The Potez 54 was a high-wing monoplane, of mixed wood and metal covering over a steel tube frame. The prototype had twin fins and rudders, and was powered by two 515 kW (690 hp) Hispano-Suiza 12Xbrs V-12 engines in streamlined nacelles, which were connected to the fuselage by stub wings. The main landing gear units retracted into the nacelles, and auxiliary bomb racks were mounted beneath the stub wings. There were manually-operated turrets at the nose and dorsal positions, as well as a semi-retractable dustbin-style ventral turret. During development, the original tailplane was replaced by a single fin and rudder, and in this form, the type was re-designated the Potez 540 and delivered to the Armee de I'Air on 25 November 1934. A total of 192 Potez 540s were built.

Their first combat uses was in the Spanish Civil War, where they were employed by the Spanish Republicans. In the late 1930s, these aircraft were becoming obsolete so they were withdrawn from reconnaissance and bombing duties and were relegated to French transport units. They were also employed as paratrooper training and transport aircraft. By September 1939 and the beginning of World War II, they had been largely transferred to the French colonies in North Africa, where they continued to function in transport and paratrooper service. Their role in even these secondary assignments was problematic given their poor defensive armament and vulnerability to modern enemy fighters. Following the French capitulation to Germany in June 1940, those Potez 540s still flying served the Vichy French Air Force mainly in the French overseas colonies. Most of these machines were retired or destroyed by late 1943.
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With a crew of 4 of 7, the Potez 540 had a maximum speed of 193mph, a range of 777 miles and a service ceiling of 32,810 feet. They carried 4 x 225kg bombs on external racks. As with the Bloch MB.200, at the time of evaluating the aircraft in 1935, the Ilmavoimat considered the aircraft almost obsolete in design and unsuited to the tactical bombing requirements of the Ilmavoimat.

We'll take a quick look at some other aircraft that were considered - the Bristol Bombay, Fairey Hendon, Armstrong Whitworth AW.23, Handley Page Heyford and lastly the Martin B.10 in the next Post, after which we will move on to the 1936 Ilmavoimat Procurement Program.
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1935 Ilmavoimat Procurement Program - continued

Post by CanKiwi2 » 04 Jul 2011 13:43

A description of some of the other aircraft considered as bombers in the Ilmavoimat's 1935 procurement program.

The Bristol Bombay

The Bristol Bombay was built to Air Ministry Specification C.26/31 for a monoplane aircraft capable of carrying bombs or 24 troops. Bristol's early experience with monoplanes was dismal — both the 1922 racer prototype and the 1927 Bagshot fighter suffered from lack of torsional rigidity in the wings. Based on this experience, Bristol over-engineered the Bombay's wing to include no less than seven spars made from high-strength steel. Not surprisingly, the end product was a very heavy aeroplane. The prototype Type 130 first flew on 23 June 1935 and an order for 80 was placed as the Bombay. As Bristol's Filton factory was busy building the more urgent Blenheim, the production aircraft were built by Short & Harland of Belfast. However, the complex nature of the Bombay's wing delayed production at Belfast, with the first Bombay not being delivered until 1939 and the last 30 being cancelled.

Despite the all-metal, monoplane construction, the Bombay retained some features which were becoming outdated by the time of the order and obsoletre by delivery in 1939, such as its fixed undercarriage. Although it was outclassed for the European theatre, it saw some service ferrying supplies to the British Expeditionary Force in France in 1940. Its main service was in the Middle East, replacing the Vickers Type 264 Valentia. The Bombay was capable of dropping 250 lb (110 kg) bombs held on external racks, and was also used to drop 20 lb (20 kg) anti-personnel mines, which were armed and thrown out of the cargo door by hand. The aircraft flew bombing sorties in Abyssinia, Italian Somaliland, Iraq, and Benghazi. Obsolete as a bomber by European standards, the Bombays were predominately used as transports, ferrying supplies and evacuating the wounded.

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The Bristol Bombay flew with a crww of 3-4 and could carry 24 armed troops or 10 stretchers. Powered by 2× Bristol Pegasus XXII radial engines of 1,010 hp (755 kW) each. It had a service deiling of 24,850 feet and a maximum speed of 192mph, a cruising speed of 160mph and a range of 2,230 miles with overload fuel. The Bombat could carry 2,000lbs of bombs and was armed with 2 × 0.303 in (7.7 mm) Vickers K machine guns in powered nose and tail turrets.

At the time of the Ilmavoimat evaluation, the Bombay prototype had just flown and the RAF order had just been placed. Evaluation flights proved that the Bombay was not as “rough field capable” as the SM-81 and in addition, its bomber role seemed to be more of an add-on to the basic transport design. The SM-81 had a better maximum speed and the long range was not as much of a consideration for the Ilmavoimat as it was for the RAF. As such, the Bombay was eliminated from consideration after the Ilmavoimat evaluation flights. However, the ongoing contacts with Bristol had also resulted in the Ilmavoimat evaluation team taking a good look at the Bristol Blenheim – more on this later….

The Fairey Hendon

The Fairey Hendon was a British monoplane heavy bomber of the Royal Air Force designed by Fairey Aviation in the late 1920s, which served in small numbers with one Squadron of the RAF between 1936 and 1939. It was the first all-metal low-wing monoplane to enter service in the RAF. The Hendon was built to meet the Air Ministry Specification B.19/27 for a twin-engine night bomber to replace the Vickers Virginia, competing against the Handley Page Heyford and Vickers Type 150. The specification required a range of 920 mi (1,480 km) at a speed of 115 mph (185 km/h), with a bombload of 1,500 lb (680 kg). To meet this requirement, Fairey designed a low-winged cantilever monoplane with a fixed tailwheel undercarriage. The fuselage had a steel tube structure with fabric covering and housed the crew of five, consisting of a pilot, a radio operator/navigator, and three gunners, manning open nose, dorsal and tail positions. Bombs were carried in a bomb-bay in the centre-fuselage. Variants powered by either radial engines or liquid cooled V12 engines were proposed.

The prototype K1695 (which was known as the Fairey Night Bomber until 1934 first flew on 25 November 1930, from Fairey's Great West Aerodrome in Heathrow, and was powered by two 460 hp (340 kW) Bristol Jupiter VIII radial engines. The prototype crashed and was heavily damaged in March 1931, and so was re-built with two Rolls-Royce Kestrel engines replacing the Jupiters. After trials, 14 production examples, now named the Hendon Mk.II were ordered. These were built by Fairey's Stockport factory in late 1936 and early 1937 and flown from Manchester's Barton Aerodrome. Orders for a further 60 Hendons were canceled in 1936, as the prototype of the first of the next generation of British heavy bombers - the Armstrong Whitworth Whitley - had flown, and it showed much higher performance. The Hendon Mk.II was powered by two Rolls-Royce Kestrel VI engines. It had a fixed undercarriage and a crew of five while the production Hendon Mk.II included an enclosed cockpit for the pilot and navigator.

In practice, the type was delayed by the crash and rebuild of the prototype, so the Heyford received the majority of the orders needed to replace the RAF's heavy bombers, the Hendon coming into service three years later. The single Hendon-equipped unit began operational service based in November 1936, replacing Heyfords. The type was soon obsolete and replaced from late 1938 by the Vickers Wellington. By January 1939, the Hendons had all been retired and were then used for ground instruction work, including the radio school at RAF Cranwell.

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The Fairey Hendon had a crew of 5 and was powered by 2× Rolls-Royce Kestrel VI inline piston V12 engines of 600 hp (447 kW) each, giving a maximum speed of 152moh and a cruising speed of 133moh with a range of 1,360 miles. The service ceiling was 21,400 feet and a 1,660lb bombload could be carried. Armament consisted of 3× .303 in (7.7 mm) Lewis guns in nose, dorsal and tail positions.

At the time of the Ilmavoimat evaluation in early 1935, the Hendon’s performance was already sadly outdated. In addition, it was a “heavy” bomber, and the Ilmavoimats objective was to purchase fast “medium” bombers for tactical use in support of ground operations – the antithesis of the RAF’s intent for heavy bombers. The Ilmavoimat evaluation team performed only a cursory assessment of the Hendon (as they did with a number of other such aircraft) and eliminated it from consideration immediately.

The Handley Page Heyford

The Handley Page Heyford was a twin-engine British biplane bomber of the 1930s. Although it had a short service life, it equipped several squadrons of the RAF as one of the most important British bombers of the mid-1930s, and was the last biplane heavy bomber to serve with the RAF. The Heyford was built to meet Air Ministry specification B.19/27 for a heavy night bomber to replace the Vickers Virginia, which required a twin-engined aircraft capable of carrying 1,546 lb (700 kg) of bombs and flying 920 miles at 115 mph (185 km/h). The specification resulted in a large number of proposals being submitted by the British aircraft industry, with designs by Fairey (the Fairey Hendon) and Vickers (the Type 150 and Type 163) being built as well as Handley Page's design. The prototype, the Handley Page HP.38, was designed by Handley Page's lead designer G R Volkert and first flew on 12 June 1930 at Handley Page's factory at Radlett, powered by two 525 hp (390 kW) Rolls-Royce Kestrel II engines driving two-blade propellers.

The aircraft was of mixed construction having fabric-covered, two-bay metal-frame wings, while the fuselage had an aluminium monocoque forward section with a fabric-covered frame to the rear. It had a crew of four, consisting of a pilot, a bomb aimer/navigator/gunner a radio operator and a dorsal/ventral gunner. Open positions were provided for the pilot and both the nose and dorsal gunners. The Heyford had a novel configuration, with the fuselage attached to the upper wing and the bomb bay in the thickened centre lower wing. This provided a good defensive field of fire for the nose and dorsal guns as well as the ventral retractable "dustbin" turret, each equipped with a single .303 in (7.7 mm) Lewis Gun. The fixed undercarriage consisted of large, spat-covered wheels. The design allowed ground crews to safely attach bombs while the engines were running, but the result was that the pilot was some 17 ft (5 m) off the ground.

The HP.38 proved successful during service trials and was chosen as the winner of the B19/27 competition, being ordered as the HP.50 Heyford. Production Heyford Is were fitted with 575 hp (429 kW) Kestrel III engines and retained the two-blade propellers, while the IAs had four-blade propellers. Engine variations marked the main Mk II and III differences; the former being equipped with 640 hp (480 kW) Kestrel IVs, supercharged to 695 hp (518 kW) in the Heyford III. The Heyford I entered service in November 1933, with further aircraft entering service in August 1934 and April 1935 respectively. As part of the RAF's Expansion scheme, orders were placed for 70 Heyford IIIs in 1936, with steam condenser-cooled Rolls-Royce Kestrel VI engines. The delivery of these aircraft allowed the RAF to have nine operational Heyford Squadrons by the end of 1936. These squadrons of Heyfords formed the major part of RAF Bomber Command's night bomber strength in the late 1930s. Heyfords flew many long night exercises, sometimes flying mock attacks against targets in France. The Heyford started to be replaced in 1937, with the arrival in service of Armstrong Whitworth Whitleys and Vickers Wellesleys, finally being retired from frontline service in 1939. They were well-liked in service, being easy to maintain, sturdy and agile and they could even be looped, as was done at the 1935 Hendon Air Pageant.

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With a crew of 4 (Pilot, Navigator/bomb-aimer/forward gunner, Wireless operator/mid-upper gunner, Rear-gunner) and powered by 2× Rolls-Royce Kestrel III-S liquid-cooled V12 engines of 525 hp (392 kW) each, the Heyford had a maximum speed of 142mph, a ramge of 920 miles and a service ceiling of 21,000 feet. It could carry a 3,500lb bombload and was armed with 3 × .303 in (7.7 mm) Lewis guns (in nose, dorsal and ventral 'dustbin' positions). The Heyford was introduced into service in 1934.

As with the Hendon, at the time of the Ilmavoimat evaluation in early 1935, the Heyford’s performance was already sadly outdated even though it had only just entered service. Again as with the Hendon, it was a “heavy” bomber, and the Ilmavoimats objective was to purchase fast “medium” bombers for tactical use in support of ground operations – the antithesis of the RAF’s intent for heavy bombers. The Ilmavoimat evaluation team performed only a cursory assessment of the Heyford (as they did with a number of other such aircraft) and eliminated it from consideration immediately.

The Armstrong-Whitworth AW.23

The Armstrong Whitworth AW.23 was a prototype bomber/transport aircraft produced to specification C.26/31 (which required a dual-purpose bomber/transport aircraft for service with the RAF, with the specification stressing the transport part of its role) for the British Air Ministry by Armstrong Whitworth Aircraft. While it was not selected to meet this specification, it did form the basis of the later Armstrong Whitworth Whitley aircraft. The AW.23 was designed by John Lloyd, chief designer of Armstrong Whitworth to meet this specification, competing with the Handley Page HP.51 and the Bristol Bombay. The AW.23 was a low-wing twin-engine monoplane, powered by two Armstrong Siddeley Tiger engines. It had a fabric covered braced steel fuselage accommodating a large cabin to fulfill its primary transport role, but with room for internal bomb racks under the cabin floor. The aircraft's wings used a novel structure, patented by Armstrong Whitworth, which used a massive light alloy box-sparbraced internally with steel tubes. This structure was extremely long but required a thick wing section, increasing drag. This wing structure was re-used in Armstrong Whitworth's Whitley bomber. The AW.23 was the first Armstrong Whitworth Aircraft to be fitted with a retractable undercarriage.

A single prototype, K3585, was built first flying on 4 June 1935 and this was the aircraft evaluated by the Ilmavoimat. Owing to its unreliable Tiger engines, its delivery to the RAF for testing was delayed, with the Bombay being declared the winner of the specification.

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With a Crew of 4, the AW.23 could carry 24 troops or 2,000lbs of bombs. Maximum speed was 162mph, range was 790 miles and the service ceiling was 18,100 feet. There was provision for single machineguns in nose and tasil turrets.
While the Ilmavoimat evaluation team rated this aircraft considerably higher than the Hendon and the Heyford, it again failed to make the grade as far as “tactical” bombing and rough field capability was concerned. Maximum speed was also considered to be poor compared to other aircraft on the shortlist. The AW.23 was therefore eliminated from coinsideration.


Interestingly, the prototype would however see service in Finland. Earlier, it was mentioned that the Ilmavoimat had become aware of the inflight refuelling experiments starting to be conducted by Sir Alan Cobham at this time. By the start of 1939 these had progressed to the stage where Cobham’s company, Flight Refuelling Ltd, were using the AW.23 (which they had acquired and which had been given the civil registration G-AFRX) for inflight refuelling tests with a Short Empire flying boat. And in 1939, with the threat of war from the USSR looming ever more ominously over Finland, the nacent Finnish Special Operations Command established in 1938 were looking at every option they could imagine, however wild. One of these was extending the range of the Ilmavoimat’s bombers to allow for strikes at Soviet sites of strategic vulnerability such as military factories and power plants, hydro-electric dams and other key chokepoints of the Soviet economy. The Baku oilfields were also considered as a target at this stage – some 80-90% of the USSR’s oil supplies came from these fields and the vulnerability to an attack had been exposed by Neste (the Finnish Oil Company, who sourced much of their oil from these fields) engineers.

The problem was how to attack them? Baku was completely out of range of even the longest ranged Ilmavoimat bombers and thus the eyes of the Finnish Special Operations Command turned to the inflight refuelling experiements being carried out in Britain. In early 1939, the Ilmavoimat contracted Flight Refuelling Ltd to work with them on evaluating and testing inflight refuelling for the newest Ilmavoimat bombers that were just coming into service. As part of this contract AW.23 G-AFRX was sent to Finland in May 1939 and the experimental program got underway. This will be covered in detail in a later post.

The Martin B-10

The Martin B-10 was the first all-metal monoplane bomber to go into regular use by the United States Army Air Corps, entering service in June 1934. It was also the first mass-produced bomber whose performance was superior to that of the Army's pursuit aircraft of the time The B-10 began a revolution in bomber design. Its all-metal monoplane build, along with its features of closed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay, and full engine cowlings, would become the standard for bomber designs worldwide for decades. It made all existing bombers completely obsolete. The B-10 began as the Martin Model 123, a private venture by the Glenn L. Martin Company of Baltimore, Maryland. It had a crew of four: pilot, copilot, nose gunner and fuselage gunner. As in previous bombers, the four crew compartments were open, but it had a number of design innovations as well included a deep belly for an internal bomb bay and retractable main landing gear.

The Model 123 first flew on 16 February 1932 and was delivered for testing to the U.S. Army on 20 March as the XB-907. After testing it was sent back to Martin for redesigning and was rebuilt as the XB-10. The XB-10 delivered to the Army had major difference from the original aircraft full engine cowlings to decrease drag, a pair of 675 hp (503 kW) Wright R-1820-19 engines, and an eight-foot increase in the wingspan, along with an enclosed nose turret. When the XB-10 flew during trials in June, it recorded a speed of 197 mph (317 km/h) at 6,000 ft (1,830 m). This was an impressive performance for 1932. Following the success of the XB-10, a number of changes were made, including reduction to a three-man crew, the addition of canopies for all crew positions, and an upgrade to 675 hp (503 kW) engines. The Army ordered 48 of these on 17 January 1933. The first 14 aircraft were designated YB-10 and delivered starting in November 1933. The production model of the XB-10, the YB-10 was very similar to its prototype.

In 1935, the Army ordered an additional 103 aircraft designated B-10B. These had only minor changes from the YB-10. Shipments began in 1935 July. In addition to conventional duties in the bomber role, some modified YB-10s and B-12As were operated for a time on large twin floats for coastal patrol. The Martin Model 139 was the export version of the Martin B-10 and with the advanced performance, the Martin company fully expected that export orders for the B-10 would come flooding in. Once the Army's orders had been filled in 1936, Martin received permission to export Model 139s, and delivered versions to several air forces. For example, six Model 139Ws were sold to Siam in April 1937; 20 Model 139Ws were sold to Turkey in September 1937 and aircraft went on to be sold to Argentina, China and the Netherlands.

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With a Crew of 3, the B-10 was powered by 2× Wright R-1820-33 (G-102) "Cyclone" radials of 775 hp (578 kW) each giving a maximum speed of 213mph, a cruising speed of 193mph amd a range of 1240 miles with a 2,260lb bombload. Service ceiling was 24,200 feet and armament consisted of 3 × .30 in (7.62 mm) Browning machine guns.

At the time of its creation, the B-10B was so advanced that General Henry H. Arnold described it as the air power wonder of its day. It was 1.5 times as fast as any biplane bomber, and faster than any contemporary fighter. The B-10 began a revolution in bomber design; it made all existing bombers completely obsolete. However, the rapid advances in bomber design in the 1930s meant that the B-10 was eclipsed by the B-17 Flying Fortress and Douglas B-18 Bolo before the United States entered World War II. The B-10's obsolescence was proved by the quick defeat of B-10B squadrons by Japanese Zeros during the invasions of the Dutch East Indies and China. An abortive effort to modernize the design, the Martin Model 146 was entered into a USAAC long-distance bomber design competition 1934–1935 but lost out to the Douglas B-18 and revolutionary Boeing B-17. The sole prototype was so similar in profile and performance to the Martin B-10 series that the other more modern designs easily "ran away" with the competition.

The Ilmavoimat evaluation team rated the B-10 the best of all the aircraft they evaluated in terms of meeting the Ilmavoimat’s bomber requirement. However the cost was prohibitively high – even with increased defence budgets, the Ilmavoimat needed to keep a tight rein on expenditure and the end result was that the SM-81 was selected over the B-10. However, the many advamced features of the B-10 made their way into the Ilmavoimats list of requirements for future bombers, with interesting results, as we will see.

The Caproni 122 bomber

The Caproni Ca 122 was a bomber version of the Ca 123 transport that the Ilmavoimat had ordered. However, the procurement team felt that enough risk had been taken in ordereding the Ca 123 transport before a prototype had even been built and the Ca 122 was thus eliminated without further consideration.

But as a result of the 1935 evaluations for a medium bomber, the Ilmavoimat Procurement Team was well aware of a range of new aircraft in the development pipeline and most of these would be evaluated in 1936, with some interesting results.
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The 1936 Ilmavoimat Purchase Program

Post by CanKiwi2 » 04 Jul 2011 17:41

The 1936 Ilmavoimat Purchase Program

1936 was a key year for the Ilmavoimat. This was the year in which the first monoplane fighters – the Fokker D.XXI, the Bristol Blenheim medium bombers and the new VL Viima II Trainers were all ordered – and all were to be built by the new VL Factory outside Tampere. A very small number of other aircraft types were also ordered in 1936, mostly for further and much more detailed evaluation. The outbreak of the Spanish Civil War in July 1936 would also have its impact, with the Defence Budget for 1937 being substantially increased and additional funding for the 1937 procurement program being made available to the Ilmnavoimat.

In addition, 1936 was also the year in which financial provision was made for the first aircraft purchases for the Merivoimat Air Arm, establishing this as a combat force in its own right.

VL Viima (‘Wind”) II Primary Trainers – ordered 1936

The Viima I and II aircraft were two-seat mixed structure bi-plane primary trainer aircraft with a fixed undercarriage. Design by A. Ylinen (VL’s chief designer at this stage) the type was developed by VL to augment and eventually to replace the Smolik primary trainers. A prototype of the aircraft was ordered by the Ilmavoimat on 7 Feb, 1934 and the first flight occurred on 11 Jan, 1935. The second prototype flew for the first time on 12 Oct, 1935. The Viima had unequal span, staggered single bay wings built around two box spars with plywood ribs. The interplane struts were N shaped. The wings were fabric covered and carried four ailerons in all; the upper and lower ailerons were externally linked. The fuselage and tail unit were constructed of chrome-molybdenum steel and fabric covered. The tailplane, mounted on the top of the fuselage, was wire braced to the small triangular fin. Both fin and tailplane were adjustable on the ground. The wide chord, deep rudder reached to the bottom of the fuselage between divided elevators. The rudder carried a trim tab and the elevators a Flettner flap. The cockpits were close together, the forward one at mid-chord with a cut-out in the upper wing to enhance visibility. Dual control was fitted. The undercarriage was of the split axle type, with the faired main legs attached to the fuselage forward of the wings and braced by rearward struts. It used low pressure tyres and rubber in compression springing. A tailwheel was fitted. The Viima was powered by an uncowled Siemens-Halske Sh 14 radial engine
Evaluation proved the aircraft to be satisfactory and the Ministry of Defense ordered 60 Viima IIs on 27 June, 1936. They were delivered over December 1936 to July 1938. An additional 10 Viima IIs were ordered by the Ministry of Defence at the same time for the Air Defence League and these were delivered over the same period. Small numbers continued to be built to replace Viima’s lost or heavily damaged in training accidents. The Viima II remained in use as a basic trainer until 1962.

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The VL Viima II was a 2-seater, powered by a single Siemens-Halske Sh 14A 7-cylinder single row radial, air cooled, 110 kW (150 hp) with a maximum speed of 121mph, a range of 311 miles and a service ceiling of 14,764 feet.

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VL Viima II in service

VL Pyry Advance Trainer – Commissioned in 1936 (First Ordered 1938)

In 1936 it was also decided that in light of the rapid advances in aircraft technology and designs and the decision to purchase monoplane fighter aircraft for the first time, a newer monoplane Advanced Trainer was needed. On 23 Oct, 1936 the Ilmavoimat commissioned a design and a single prototype from the State Aircraft Factory (VL). Work on this aircraft, designated the Pyry began shortly after the decision was made. Conceptually, the aircraft was to be a two-seated mixed-structure cantilever low wing advanced trainer aircraft with a fixed landing gear.

Fokker D.XXI Fighter – ordered 1936

From 1931 on, the Ilmavoimat had worked hard to continually acquire new aircraft with the limited (but increasing) annual budget at their disposal. Up until 1935, the fighter aircraft purchased had been biplane fighters, in-line with the air forces of other countries. However, by 1936 it was becoming accepted that future fighters would be more modern monoplane designs with enclosed cockpits, higher speeds and heavier armament. The Ilmavoimat had conducted an evaluation program for fighter aircraft in early 1936, focusing largely on a small number of the more modern aircraft available. While biplan aircraft such as the Fiat CR.32 were also considered, it was decided that the performamce of the newer monoplane fighters was such that the focus should be on these. Thanks to Finland’s rapidly expanding exports and friendly relations with all the major european countries (the USSR excepted) as well as with the USA, the Ilmavoimat had the opportunity to test and evaluate all of the most modern fighter aircraft then either in prototype stage or being manufactured. These included the British prototype Hawker Hurricane, the German Me109 and Heinkel He112, the French Dewoitine D.500 and Morane-Saulnier MS.405 and the American Seversky P-35, Vought V-141 and the Curtiss P-36 Hawk as well as the Fokker D.XXI.

While the competing aircraft were all good designs, as far as the Ilmavoimat Procurement Team were concerned the Fokker D.XXI had four major advantages – it was half the price of the comparable British, German, French and American aircraft, it not just a prototype but a finished design, it was available immediately and the aircraft structure was such that it could be manufactured by VL without major technical innovations. There was also the ongoing “will it be delivered or won’t it” issue with Britain, France and Germany as their rearmament programs began to gear up. The Fokker D.XXI also met a good number of the Ilmavoimat’s other criteria for a fighter aircraft including being able to operate under primitive conditions and thus being a rugged and simple design. Another important requirement was that the fighter be able to combat the slow but heavily armed Soviet Tupolev TB-3 bombers. As such, knowing that the Fokker D.XXI would rapidly become obsolete, the decision was made to purchase the Fokker D.XXI’s as an interim aircraft and to follow up on other fighter aircraft as they moved from prototype to production.

On the 15th of March 1936, the Ilmavoimat signed a deal to purchase twenty aircraft outright and simultaneously acquired an unlimited license for Fokker D.XXI production by Valtion Lentokonetehdas (VL). An initial 20-aircraft Series was ordered from VL on March 31st, 1936. Finland was the first export customer for the Fokker D.XXI (and indeed the first production customer - with the Netherlands Luchtvaartafdeling only placing an order after Finland). While consideration was given to a retractable undercarriage, in the end it was agreed that the additional 300kg in weight vs the speed advantages of a retractable undercarriage would cancel each other out. The construction of the D.XXI was typical of all Fokker planes at the time. Fokker had made its name and fame with monoplane airliners in the 1920s and these were all built with a fabric-covered steel tube framework and with wooden wings. Allmost all pre-war Fokkers built in this way and the D.XXI was no different. The rear fuselage was build of steel tubes, with a fabric covering while the wings were made of wood and the front part of the fuselage with the engine-mounting was made of metal, mainly aluminum. The moving parts like the ailerons and ruders were fabric covered as well. The whole construction was not entirely unlike the British Hurricane. Although the whole construction seems to be obsolete compared to the contemporary monocoque built Bf109 and Spitfire, this method of constructing an airplane had its advantages – primarily in that it was relatively easy both to construct and to repair. The engine for the aircraft was specified as the Bristol Mercury VIII nine-cylinder radial engine (825hp) which was being license-manufactured in Finland (although the Fokker Sales Team at the May 1936 Internationella Luftfartsutstallningen held in Stockholm had offered the DXXI with the 1,100HP Hispano Suiza 14Ha radial, or the 925HP Hispano Suiza liquid cooled engine as alternatives to the Mercury – either would have offered increased performance).

The Netherlands built fighters were transported to Finland between 4 Nov and 13 Nov, 1936. When the first consignment was ready in the Netherlands, Ilmavoimat Capt. G. E. Magnusson together with a small number of other pilots flew the acceptance test flights over late 1936. Capt. Magnusson had been attached for five months to the best French fighter regiment in 1933, flying in the "Georges Guynmer" squadron and was to go on to fly as a volunteer in the Spanish Civil War, bringing valuable lessons back to the Ilmavoimat. Capt. Magnusson thought that it was as important to check the capabilities for possible fighter-to-fighter combat so he flew a rigorous test profile for the Fokker. He noticed that it was possible to disengage the fighter against faster fighters by diving the Fokker. This observation turned out to be very important in the Winter War against the faster Soviet fighters. Capt. Magnusson also wasn't happy with the idea of using long range gun shooting in the Fokkers. He thought that the aircraft would be more successful in close-range machine gun intercepts. Test flights proved that he was right.

These aircraft were the first monoplane fighter aircraft acquired by the Ilmavoimat and they formed the initial nucleus on which to train pilots, build experience and develop fighter tactics. The State Aircraft Factory (VL) found the Fokker D.XXI relatively straightforward to build, indeed they managed to improve substantially on Fokker’s production times and deliver the aircraft at an even cheaper unit price. Partially as a result of this, and partially due to the ever increasing prospect of a European-wide war, the initial VL order for 20 of the aircraft (in addition to the 20 purchased outright from Fokker) was increased by another 20 in mid-1936 and VL went on to build and deliver forty Fokker D.XXI’s over the period late-1936 to early 1938, with one per week rolling of the construction line by mid-1937 (at which time, 60 Fokker D.XXI’s were in service, equipping three fighter squadrons).

Overall, the Fokker D.XXIs were not quite obsolete as the Winter War broke out – they lacked armour and the effectiveness of the weapons (four 7.7 mm Browning machine guns configured with either 4 in the wings or 2 in the wings and 2 on the fuselage) was questionable. However, in 1936 they were cheap, they were available and they could be constructed and delivered quickly. A further production run was considered in mid 1937 but at this time it had been decided to switch the construction line over to a newer Fighter which had just been successfully prototyped and had far better performance. However, the sixty Fokker D.XXI’s equipping three Ilmavoimat Reserve Squadrons were used to great effect in the air fighting throughout the Winter War, scoring an impressive kill ratio of 16:1 against Soviet aircraft.

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As purchased by the Ilmavoimat, the Fokker D.XXI had fixed landing gear and a relatively underpowered engine (1× Bristol Mercury VIII air-cooled, 9-cylinder, radial, 619 kW-830 hp) for interceptions, it lacked armour and the effectiveness of the weapons was questionable. The radios were limited in range in the beginning and the max level speed was only 285mph.

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When the Fokker D.XXI flew its first flight it was already bordering on obsolete, the Me-109, Heinkel He-112, Hurricane and Spitfire had already flown with much higher maximum speeds. The maximum speed for the Ilmavoimat Fokkers was 285mph, with a range of 574 miles and a service ceiling of 30,675 ft. Armament consisted of 4 × 7.92 mm FN Browning M36 machine guns, two being fuselage mounted and two wing mounted.

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In Ilmavoimat service, the Fokker D.XXI performed better and for much longer than for the Dutch. Against the aircraft of the Soviet Air Force, the Fokker was more evenly matched than it had been against the Luftwaffe, and its rugged design with a radial engine and fixed undercarriage made it very suitable for Finnish conditions.

The Fokker D.XXI was of straightforward construction, reliable and easy to maintain and served admirably ove the duration of the Winter War. Later in the war, as newer models of Soviet fighters appeared, the Fokker D.XXI was underpowered and too lightly armed (with only four .30 caliber machine guns) to compete. In Finland, at a later stage the retractable landing gear was tested and the Fokker D.XXI gained some 20 km/h in speed - but lost a lot of climbing speed. After the end of the Winter War, two Fokker D.XXIs were tested with the Finnish-manufactured Hispano Suiza 12Y engine and a considerable performamce increase was achieved. However, an upgrade program was cancelled as Finland was supplied with lend-lease aircraft from Britain and the United States.

Bristol Blenheim Light Bomber – ordered 1936

The Bristol Blenheim was a twin-engined three-seat all-metal structured bomber and long range reconnaissance aircraft. The Blenheim was one of the first British aircraft to have all-metal stressed skin construction, to utilise retractable landing gear, flaps, have a powered gun turret and variable-pitch propellers. The aircraft was powered with two Bristol Mercury VIII air-cooled radial engines, each of 860 hp (640 kW) and carried a crew of three – pilot, navigator / bombardier and telegraphist / air gunner. Armament as designed comprised a single forward-firing 7.7 mm Browning machine gun outboard of the port engine and a 7.7 mm Lewis gun in a semi-retracting dorsal turret firing to the rear. A 1,000 lb (454 kg) bomb load could be carried in the internal bay (in various configurations (4x250lb, 2x500lb internally and 8x40lb externally). The Blenheim had a maximum speed of 266mph, a ceiling of 27,260 feet and a range of 1,460 miles.

When it first flew on 12 April 1935, the Blenheim proved to be faster than any fighter in service with the Royal Air Force at the time. To achieve its relatively high speed, the Blenheim had a very small fuselage cross-section. Pilot's quarters on the left side of the nose were so cramped that the control yoke obscured all flight instruments while engine instruments eliminated the forward view on landings. Most secondary instruments were arranged along the left side of the cockpit with essential items like propeller pitch control actually placed behind the pilot where they had to be operated by feel alone. Like most contemporary British aircraft, the bomb bay doors were kept closed with bungee cords and opened under the weight of the released bombs. Because there was no way to predict how long it would take for the bombs to force the doors open, bombing accuracy was consequently poor.

The Ilmavoimat had spent considerable time evaluating bombers in 1935 and indeed had evaluated the Blenheim and considered it an excellent light bomber. In discussions with Bristol in early 1936, assurances were made that any Finnish order would be rapidly delivered and accordingly and without further ado, Finland bought 20 Mk. I Blenheims from Britain, with the order placed on 6 Matrch 1936. These aircraft were delivered progressively between 26 March, 1937 and 27 March, 1938. At the same time, VL purchased a manufacturing license from the Bristol Aeroplane Company and the Ilmavoimat simultaneously placed an order for 40 Mk I’s with VL. At the same time, VL also obtained a manufacturing license for the Bristol Mercury VIII air-cooled 860hp radial engine. In 1936, the State Aircraft Factory was continuing to expand aggressively, using additional Government funding to build new production facilities, purchase machinery and hire overseas engineers as well as setting up of training programs and expanding hiring to cope with the multiple lines of aircraft being manufactured.

Work on setting up VL’s Blenheim production line started in mid 1936 and production commenced in January 1937, with approximately two aircraft per month being completed. However, while the aircraft purchased from the UK were as designed, VL and the Ilmavoimat embarked on some redesign. In the Ilmavoimat, unlike many other European Air Forces, the lessons of the WWI ground attack aircraft had not been forgotten – indeed, the Ilmavoimat’s Junkers J1ground attack aircraft while retired, still sat in a hanger and the reasons for the “armored bathtub” that protected the crew were known (a subsequent post will expore doctrine, including the uses of ground-attack aircraft, in greater detail). The 40 Blenheims to be constructed in Finland had design modifications made to equip them as armored ground attack aircraft. They were built with a solid nose containing four 20 mm Hispano-Suiza HS-9 cannon and featured a strengthened structure, pilot armor and better self-sealing fuel tanks. In addition, the dorsal turret was rebuilt to hold two 7.7 mm Lewis gun’s rather than the single gun with which it was originally supplied. This also eliminated one crew position. Vulnerability to flak was reduced by fitting flexible, self-sealing liners in to the fuel tanks but they were still not fully protected.

By the end of 1937, 22 locally built Blenheims had been completed with a further 20 were completed up to October 1938, bringing the total delivered by VL to some 42, in addition to the 20 delivered from Britain. Production of Bristol Blenheims by VL was discontinued in October 1938 in order to concentrate on production of the new VL Wihuri fighter-bomber. However, following the outbreak of the Winter War, Britain agreed in December 1939 to sell 12 British-manufactured Blenheims to Finland. These were flown to Finland arriving on 17th January 1940, with one disappearing in transit and one beng badly damaged. In February 1940 Britain agreed to sell a further 12 and these arrived on 26 Feb, 1940. This was a welcome augmentation to the Ilmavoimat’s bomber fleet, bringing the in-servivce total to 84 Blenheims.

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British-supplied MkI Bristol Blenheim prior to being retrofitted with Ilmavoimat ground-attack modifications

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Ilmavoimat Bristol Blenheims returning from a ground attack mission on Red Army forces on the Syvari - coming in low across Lake Laatoka– Summer 1940

1936 – The foundation of the Mervoimat Air Arm

As you may recall from an earlier post, when the Finnish Marine Jaegers (Rannikkojääkärit) were formed as the elite marine infantry arm of the Finnish Navy in late 1934, a small integrated Merivoimat Air Arm was formed up on paper at the same time, with an allocated Table of Organisation of Two Fighter Squadrons, Two Dive Bomber Squadrons, One Reconnaisance Squadron and One Transport Squadron. Initially there were no aircraft or personnel but in 1936, that would begin to change. The Defence Budget of that year allocated funds to the Merivoimat for the initial establishment of one transport squadron and one reconnaissance squadron. (The 1937 budget included provision for one fighter squadron and one dive-bomber squadron while the 1938 budget provided for a further dive-bomber squadron and a further fighter squadron).

In addition, the existing Maritime Patrol aircraft were transferred from the control of the Ilmavoimat to the control of the Merivoimat while at the same time all of the remaining and now completely obsolete VL A.22 Hansa aircraft were retired – with the personnel from the remaining Hansa-equipped squadrons transferred to the new Merivoimat Air Arm. The remaining aircraft consisted of the 40 Backburn Ripon IIF’s and the six VL Kotka aircraft that had been built in 1931 as an interim measure until the Ripon’s entered service. With the now strong ties to the US Marines, the joint Merivoimat / Rannikkojääkärit procurement team looked to the Americans among others for aircraft for the new reconnaissance squadron. They were not to be disappointed.

The Merivoimat had differing requirements from the Ilmavoimat. While the Ilmavoimat was largely focused on supporting the Army, the Merivoimat’s focus was on a triad of objectives – keeping the Soviet Navy in their bottle in Kronstadt, securing maritime trade routes for Finland and protecting Finland’s coastline. A new requirement was now providing support for the Rannikkojääkärit (Marines) in combat operations along the littoral, and some of the Merivoimat Air Arm funding would in future be allocated to the purchase of aircraft with this role in mind. However, in 1936 the focus was on reconnaissance and transport aircraft. Securing the maritime trade routes was in 1936 largely focused on the Baltic. The exisiting Blackburn Ripon’s didn’t have the range to do more than patrol the Gulfs of Finland and Bothnia – and in determining the specifications for the aircraft for the reconnaissance squadron, one of the key criteria was to extend the range at which athe aircraft could patrol, both to provide intelligence on ship movements and to support Merivoimat operations in the southern Baltic.

Consolidated PBY Catalina – 10 ordered in December 1936 (a further 10 were purchased in early-1939 as the threat of war with the USSR increased)

After extensive investigation and evaluations of a number of different aircraft for use on long-range reconnaisance and patrolling, the Merivoimat settled at last on the Consolidated PBY Catalina. By and large, it was an easy choice to make in the end – while there were many small floatplanes on the market, there were few large seaplanes with an extended range in existence. Almost all, such as the Short Empire, had been designed for civilian passenger use rather than as a military aircraft while those that had, like the Consolidated P2Y and Martin P3M, were underpowered and carried lower payloads when compared to the newer PBY Catalina.

The Catalina was the exception – it had originally been designed for the US Navy as a patrol bomber, an aircraft with a long operational range intended to locate and attack enemy transport ships at sea in order to compromise enemy supply lines. With a mind to a potential conflict in the Pacific Ocean, where troops would require resupply over great distances, the U.S. Navy had in the 1930s invested millions of dollars in developing long-range flying boats for this purpose. Several different flying boats were adopted by the US Navy, but the PBY was the most widely used and produced. The design included a number of new features such as stabilizing floats which were retractable in flight to form streamlined wingtips - another aerodynamic innovation and one which was licensed from the Saunders-Roe company. The first US Navy PBY Catalina’s had entered service with VP-11F in October 1936 and the final evaluation of the aircraft was carried out by two Merivoimat crews attached to this Squadron. The final reports from the aircrews were enthusiastic, confirming the results of the evaluation and test programs, and an order for 10 aircraft was placed in December 1936 (at a not insignificant cost of USD$90,000 per aircraft plus a like amount for spares – close to USD$200,000 per aircraft in the end). In fact, the cost was such that the purchase of other aircraft for the Merivoimat Air Arm was postponed, with all the available funding going to the purchase of the Catalina’s.

The Merivoimat aircraft however had several differences from the basic PBY. The most obvious upgrades were to the bow, which was sharpened and extended by two feet, and to the tail, which was enlarged and featured a new shape. Other improvements included larger fuel tanks, increasing range by 50%, and stronger wings permitting a 2,000 pound (908 kg) higher gross takeoff weight. An auxiliary power unit was installed, along with a modernized electrical system, and the weapons were upgraded with continuous-feed mechanisms. While the base model had a range of 2,520 miles, the Merivoimat model as delivered could now operate with a range of 3,750 miles, making it capable of patroling not only the Baltic but also the Arctic and Northern Atlantic approaches to Finland’s Artic port of Petsamo – and Petsamo was increasingly being looked at as a strategic access point for Finnish trade in the event of a new European War.

With the large industrial capacity of the United States, the Merivoimat order was easily met and delivery of the aircraft took place in mid 1937. Merivoimat crews travelled to the US in early summer and undertook training with the US Navy VP-11F Squadron, then tested the aircraft at the Consolidated factory before carrying out a formation flight to Finland, flying to the Azores, then to Portugal, Britain, across the North Sea to Sweden and then to Helsinki, where they were greeted on arrival by crowds of spectators as well as the President of Finland, the Prime Minister, the Minister of Defence, Marshal Mannerheim, the heads of the Merivoimat and Ilmavoimat and numerous other officials.

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Merivoimat PBY Catalina’s in the Hangers undergoing maintenance. Powered by 2 900 hp (671 kW) Pratt & Whitney R-1830-64 Twin Wasp engines, the Catalina’s had a maximum speed of 196 moh, a crusing speed of 125 mph, a range of 3,750 miles amd could carry 4,000 lbs of bombs, depth charges or torpedoes. They flew with a crew of 8 – a pilot, co-pilot, bow turret gunner, flight mechanic, radioman, navigator and two waist gunners - and were armed with 5 machines guns - two in the nose turret, one in a ventral hatch at the tail and one in each waist blister.

In Merivoimat Air Arm use during the Winter War, the PBY Catalinas patrolled much of the Baltic and were used extensively to combat Soviet submarines, a number of which they sank. The Catalinas were well-suited for their role as patrol aircraft,with the aircraft's parasol wing and large waist blisters allowing for a great deal of visibility and combined with its long range and endurance, made it well suited for the task. The Merivoimat Catalinas served for the duration of WW2 and well into the 1960’s – and they participated in some of the most notable engagements of the Merivoimat, including the famous Helsinki Convoy of late April 1940, where they provided early warning of the approaching German naval ships. They also patrolled the Arctic approaches to Finland (and later, as the Norwegian ports were used for imports and exports, to Norway), warning of the approaching Soviet invasion force heading for Petsamo at the start of the Winter War, spotted the German ships heading for Narvik in May 1940 and escorted convoys of Finnish merchant ships as far as Iceland and the UK for the duration of WW2, protecting them from German U-boats in the daylight hours.
Following Finland’s entry into WW2 on the side of the Allies, the US supplied the Merivoimat with an additional two squadrons of PBY Catalina’s as well as making up losses in the existing squadron.Later in WW2, with Finland at war with Germany, the Merivoimat Catalina Squadron developed specialist expertise as night convoy raiders. Equipped with state-of-the-art magnetic anomaly gear supplied by the US and painted flat black, these "Black Cats" attacked German supply convoys along the southern Baltic coast at night. They were surprisingly successful in this unorthodox role. They also carried out mine-laying operations along the German-held coasts of the Baltic, operating as far south as Denmark, bottling up ports and shipping routes. In late 1944, their precision mining flights sometimes exceeded 20 hours in duration from as low as 200 feet in the hours of darkness.

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June 1940: No war occurs without losses – an Ilmavoimat PBY Catalina shot down over the Gulf of Finland by Soviet fighters that had evaded the Ilmavoimat fighter patrols. The crew escaped and were later picked up by Merivoimat Patrol Torpedo Boats.

Next: the 1937 Ilmavoimat / Merivoimat Air Arm Procurement Program
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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the 1937 Ilmavoimat / Merivoimat Air Arm Procurement Program

Post by CanKiwi2 » 04 Jul 2011 21:23

The 1937 Ilmavoimat / Merivoimat Air Arm Procurement Program

1937 was a relatively straightforward year for VL (the State Aircraft Factory) – delivery of the Fokker D.XXI fighters, Bristol Blenheim bombers and Viima trainers continued, monopolising all of VL’s construction capacity. However, for the Procurement Team it was more challenging. Budgetary provisions for the Ilmavoimat in 1937 had increased and Somersalo and the Fighter advocates were pushing strongly for a frontline fighter which would be on a par with the more modern fighters that were even now beginning to supercede the Fokker D.XXI. In addition, the Merivoimat had a (what was for them) large budget allocation for aircraft for the Merivoimat Air Arm (the 1937 Merivoimat budget included provision for one fighter squadron and one dive-bomber squadron as well as a limited number of transport aircraft).

An additional and important factor was that in early 1937, as mentioned in an earlier Post, the Finnish Finance Minister, Risto Ryti scored a major coup in negotiating a thirty million dollar loan on very favorable terms from the United States Government for the purchase of military equipment from US suppliers. A good half of this loan was allocated to the acquisition of artillery, munitions and the like for the Maavoimat, twenty five percent to the purchase of industrial machinery and the remainder was allocated to the Ilmavoimat for the purchase of more modern aircraft, primarily fighters. In the same period (early 1937), the Finance Minister also negotiated a substantial loan under similar favorable conditions from the French government for the purchase of French weapons, armored vehicles, aircraft and munitions. While there were accusations from the left that the country was being bankrupted and mortaged to finance the military, this was an extreme left view that was largely ignored by the bulk of the electorate, many of whom were committed members of either the Civil Guard or the Active Reserves – which now included a sizable proportion of SDP members.

All that aside however, the first three orders placed in 1937 were actually for British and Italian aircraft.

The first of these orders was for an Advanced Training Aircraft. As mentioned, in 1936, with the rapid expansion of the Ilmavoimat well underway and with a rapidly increasing demand for training aircraft that was beginning to exceed availability, it had been decided that more Advanced Trainers were required and the VL Pyry prototype had been commissioned. However, this was not expected to be completed and throughly tested until 1938 and at the same time it was also recognized that the State Aircraft Factory was already heavily committed to construction to meet existing orders and, while expanding capacity rapidly, could not deliver additional Advanced Trainers quickly and in the numbers needed. A decision was therefore made in the first quarter of 1937 to purchase Advanced Trainers from abroad in addition to the Pyry.

Miles M.9 Kestrel Advanced Trainer – 40 Ordered 1937, further 20 ordered as a Glider Tug version later in 1937

In looking for a good low-wing monoplane trainer, the Ilmavoimat Procurement Team had sounded out their contacts in various countries. Within the UK, this led them to examine with Miles Magister which was designed specifically as a trainer for the RAF, serving as an ideal introduction to the Spitfire and Hurricane for new pilots. The Magister first flew in Marcg 1937 and the RAF ordered it in large numbers with production commencing in October 1937. At the same time, F.G, Miles, the designer, had been working on the design for the Miles Kestrel advanced trainer and at the time the Ilmavoimat Team contacted him (in July 1937), the prototype was about to fly – indeed, it was demonstrated at the Hendon Airshow (in the UK) in July 1937.

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The M.9 Kestrel, powered by the 745 hp (555 kW) Rolls-Royce Kestrel XVI V-12 engine, could reach 295 mph (475 km/h), had a range of 393 miles, a crew of two (Instructor and Student) and had a service ceiling of 28,000 feet. In trainer form, the Kestrel was equipped to carry eight practice bombs, plus one .303in Vickers machine gun mounted in the front fuselage. It was also modified for use as a Glider Tug and the Ilmavoimat aircraft were designed and built with six wing-mounted .303 in Browning machine guns to enable use as an emergency fighter. Kestrels were built by Phillips and Powis Aircraft Limited at Woodley, Berkshire (UK).

After evaluating a number of Advanced Trainer aircraft types from early to mid 1937, the Ilmavoimat knew a winner when they saw one and after a through evaluation and test flight program of their own, a decision was made by the Ilmavoimat to purchase the Miles M9 Kestrel as an Advanced Trainer. The Ilmavoimat placed an order for 40 of the Miles Kestrel Trainers in late 1937. These were built by Phillips and Powis Aircraft Limited at Woodley, Berkshire (UK) and delivered to Finland from early to mid-1938. The Ilmavoimat had had the design modified to include six wing-mounted .303 in Browning machine guns in all aircraft so as to enable use as an emergency fighter.

Also in early 1937, the newly formed Finnish Special Operations Command had begun experimenting with gliders and had purchased a small number of the German DFS230 Gliders from the Deutsche Forschungsanstalt für Segelflug for trials. By mid-1937 it had been decided to design and build gliders for the Special Operations units and the newly forming Paratroop Division, and with additional DFS230’s being built for training, tugs were needed. An additional order was placed towards the end of 1937 for a further 20 Miles Kestrel’ to be delivered specifically for the glider-towing role, with the bottom of the rudder cut away to allow fitting of a towing hook. These 20 aircraft were also delivered in mid-1938 and were used exclusively by the Glider Training School. The forty Advanced Trainers were later modified to allow them to also be used as Glider Tugs.

The Kestrel’s maximum speed of 295mph was actually higher than the Fokker D.XXI’s 280mph and its six machineguns compared favorably with the four mounted in the Fokker. In the event, all forty Kestrel Trainer’s were at various times thrown into the Winter War as fighters, primarily used in the air defence of Turku, Vaasa, Tampere and Helsinki, and were flown by Instructors and students near graduation from the Fighter Pilot Training School, achieving some significant successes in attacks on Soviet bomber formations in the early days of the war. The Kestrel’s performance was quite remarkable, only 15mph less than the concurrent version of the Hurricane and it was one of the fastest and most maneuverable trainers of its day. It would serve within the Ilmavoimat for the duration of WW2 and well into the 1950s before it was retired.

Curtiss Hawk Model 75 Fighter – 40 ordered in mid 1937

With substantial funding secured from both the United States in the form of a large loan in early 1937, the Finnish Air Force’s upgrading continued to move ahead at a consistent pace. As previously mentioned, by 1937 the Ilmavoimat was being allocated the financing to procure an additional 2 to 3 squadrons of imported fighter aircraft each year, in addition to whatever could be locally constructed. The securing of the huge US loan in 1937 made it possible to purchase aircraft from the United States, which was, as of the late thirties, the only western country capable of large scale aircraft manufacturing for export (Britain and France were both concentrating on rearmament of their own air forces with consequent impact on exports).

Now that it was possible to purchase more modern aircraft from the United States, albeit at a higher cost, the Ilmavoimat proceeded to do just that. The first truly modern fighter the Finns purchased was a direct result of this loan funding being made available. The Ilmavoimat procurement Team had been well aware of the Curtiss Hawks, and had also been informed that the aircraft was a private venture by the company and thus it turned out to be far easier to contract for the numbers of aircraft that they wanted as they were not then being produced for the US Armed Forces. For the Finns, one of the joys of buying from the United States was the sheer scale possible for industrial production of aircraft. Having sourced limited numbers of fighter and bomber aircraft from the British, Italians, Germans and Dutch in the past, and having struggled to acquire more than a few aircraft at a time over an extended period, the sheer scale of what was possible with such financing available overwhelmed them. The Curtiss Hawks were acquired for approximately $55,000 each (approximately the same as for the Hawker Hurricane) with an additional amount for spare parts and, having had the prototype built in 1934, were able to be rapidly manufactured and delivered to the Ilmavoimat. An order for Curtiss Hawks was placed in mid-1937.

However, the spanner in the works for this order was a combination of a French order for the Curtiss Hawk and opposition from the USAAC. France in 1937, as a result of industry nationalisation and the recent introduction of the forty hour working week, suffered from production bottlenecks due mainly to the lack of mass production techniques and was having great difficulty in meeting its own aircraft production needs. The only realistic answer was foreign purchase, and with Britain also rearming at full speed, the United States was the only source for combat aircraft supply. Even before the Hawk entered production, the French Air Force had entered negotiations with Curtiss for delivery of 300 aircraft. The negotiating process ended up being very drawn-out because the cost of the Curtiss fighters was double that of the French Morane-Saulnier M.S.406 and Bloch MB.150, and the delivery schedule was deemed too slow. Since the USAAC was unhappy with the rate of domestic deliveries and believed that export aircraft would slow things down even more, it actively opposed the sale to the French, which incidentally also impacted the Ilmavoimat order. Eventually, it took direct intervention from U.S. President Franklin Roosevelt to give the French test pilot Michel Detroyat a chance to fly the aircraft. Detroyat's enthusiasm, problems with the Bloch MB.150, and the pressure of continuing German rearmament finally forced France to purchase 100 aircraft and 173 engines.

The first Hawk 75A-1 arrived in France in December 1938 and they began entering service in March 1939. After the first few examples, aircraft were delivered in pieces and assembled in France. Officially designated Curtiss H75-C1 (the "Hawk" name was not used in France), the aircraft were powered by Pratt & Whitney R-1830-SC-G engines with 900 hp (671 kW) and had metric, translated instruments, a seat for French dorsal parachutes, a French-style throttle which operated in reverse from U.S. and British aircraft (e.g. full throttle was to the rear rather than to the front) and armament of four 7.5 mm FN-Browning machine guns. The aircraft evolved through several modifications, the most significant being the installation of the Wright R-1820 Cyclone engine. This variant, designated as Curtiss H751-C1, saw little operational use due to its late delivery and reliability problems with the new engine. A total of 416 H75s were delivered to France before the German occupation.

However, in the midst of all this the Finns had managed to have their order approved (after all, what use was a thirty million dollar loan for defence-related purchases if it couldn’t be used) and the forty Hawks ordered by the Ilmavoimat were the first off the production line. Subsequently, the shipment of forty Hawk 75A-1’s arrived in Turku in December 1938, and began entering service in March 1939. Delivery was completed with a second shipment of spare parts received in June 1939. The Curtiss Hawk Model 75A-1 made a welcome addition to the Ilmavoimat’s strength.

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Ilmavoimat Curtiss Hawk75

A contemporary of the Hawker Hurricane and Messerschmitt Bf 109, the Curtiss Hawk Model 75 was one of the first fighters of the new generation – sleek monoplanes with extensive use of metal in construction and powerful piston engines. The first prototype constructed in 1934 featured all-metal construction with fabric-covered control surfaces, a Wright XR-1670-5 radial engine developing 900 hp, and an armament of one 0.30-cal. and one 0.50-cal. machine guns firing through the propeller arc. Also typical of the time was the total absence of armor or self-sealing fuel tanks. The distinctive landing gear which rotated 90 degrees to fold the main wheels flat into the thin trailing portion of the wing was actually a Boeing-patented design for which Curtiss had to pay royalties.

The Hawk prototype had first flown in May 1935, reaching 281 mph (452 km/h) at 10,000 ft (3,050 m) during early test flights. The initial engine (the unreliable Wright XR-1670-5 radial engine) was replaced with a Pratt & Whitney R-1830-13 Twin Wasp engine producing 900 hp (671 kW) and the fuselage was reworked, adding the distinctive scalloped rear windows to improve rear visibility. Interestingly, a comparison of a Hawk with a Supermarine Spitfire Mk I revealed that the Hawk had several advantages over the early variant of the iconic British fighter. The Hawk was found to have lighter controls than the Spitfire at speeds over 300 mph (480 km/h), especially in diving attacks, and was easier to maneuver in a dogfight thanks to the less-sensitive elevator and better all-around visibility. The Hawk was also easier to control on takeoff and landing. Not surprisingly, the Spitfire's superior acceleration and top speed ultimately gave it the advantage of being able to engage and leave combat at will, but the Hawk turned out to be an excellent fighter that proved itself effective in combat.

The Royal Air Force also displayed interest in the aircraft, tested the Hawk H-75A's and found them to be generally inferior to both the Hurricane and Spitfire in both speed and armament. Comparison of a borrowed French Hawk 75A-2 with a Supermarine Spitfire Mk I revealed however that the Hawk did have several advantages over the early variant of the iconic British fighter. The Hawk was found to have lighter controls than the Spitfire at speeds over 300 mph (480 km/h), especially in diving attacks, and was easier to maneuver in a dogfight (thanks to the less sensitive elevator) and better all-around visibility - the Hurricane, Spitfire and the Bf-109 all tended to exhibit heavy control forces at these speeds. The Hawk was also easier to control on takeoff and landing and was found to be more maneuverable than the Spitfire at any speed, athough the Spitfire had a better sustained turn rate. The Hawk French pilots had also commented on the ease and rapidity of maneuvers. Not surprisingly, the Spitfire's superior acceleration and top speed ultimately gave it the advantage of being able to engage and leave combat at will. Although Britain decided not to purchase the aircraft, they soon came in possession of 229 Hawks comprised of diverted shipments to occupied France and aircraft flown by escaping French pilots.

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The Curtiss Hawk 75-A CU-558 in this picture achieved 13 victories in WW2. In Ilmavoimat service, the Hawk was well-liked, affectionately called Sussu ("Sweetheart"). The Ilmavoimat enjoyed success with the type, credited with 190 1/3 kills by 58 pilots over the course of the Winter War, for the loss of 15 of their own. Finnish ace Kyösti Karhila scored 13 1/4 of his 32 victories in the Hawk, while the top Hawk ace K. Tervo scored 15 3/4 victories.
Sourced from http://personal.eunet.fi/pp/gdes/gallery_eng.htm, the original is a painting by artist Sture Gripenberg. A limited edition of 200 copies has been printed. The proofs are numbered and they are signed by Finnish Air Force ace Kyösti Karhila and the artist.


The Ilmavoimat Hawks as delivered were armed with one 12.7 mm Colt machine gun in the fuselage and four 7.7 mm Browning machine guns on each wing. The Finnish Hawks were also equipped with Revi 3D or C/12D gunsight. As delivered they had a top speed of 322 mph (slightly slower than the Hurricane), a ceiling of 32,340 feet and a range of 650 miles. While sufficient during the Winter War, the increasing speeds and armor of aircraft soon showed this armament was not powerful enough. The installation of heavier armament did not cause changes to the very good flying characteristics of the fighter but the armament was much more powerful against German planes in the later stages of WW2. The Finnish Hawks were also equipped with Revi 3D or C/12D gunsight. Surviving Finnish aircraft remained in service with the FAF aviation units HLeLv 13, HLeLv 11 and LeSK until 1946.

In combat against the Soviet Air Force, the Hawk proved to be an excellent dogfighter, much more agile than the Soviet fighter aircraft and easily able to outturn Soviet aircraft in most manoeuvres. It also had a superior diving speed, which allowed the experienced Finnish pilots to break off an engagement at will provided that there was enough altitude. In terms of general reliability, the Curtiss fighter was strongly built, with a robust structure that could withstand a lot of combat damage and rough field handling. The aircraft was designed for ease of maintenance with excellent access to important components and the Twin-Wasp engines proved to be highly reliable. The armament was a weak point, with the 7.7mm machine guns proving (as they did in many other airforces) to be ineffective at longer range. However, the Ilmavoimat tactic of closing to practically point blank range wherever possible tended to reduce the impact of this weakness in practice.

Ilmavoimat Douglas DC-3 Transport Aircraft – ordered in early 1937

With the formation of the Finnish Army’s ParaJaeger Division in 1936, the Military Command started in 1937 to look at suitable aircraft for carrying paratroops as well as for towing the military gliders that were being assessed and tested from Germany or that were on the drawing board as part of the Special Operations Command programs. The results of the earlier transport aircraft evaluation were looked at but the major influencing factor this time around was the substantial loan made available by the US Government in early 1937 – tied to a proviso that the financing was available for purchases from US manufacturers only – and it was this loan which financed the purchase of the aircraft. Twenty Douglas DC3’s were ordered in the first quarter of 1937. They were built at the Douglas manufacturing plant at Santa Monica, California, Long Beach, California and shipped to Finland, arriving in Turku in late 1937, where they were freighted to the State Aircraft Factory for assembly and test flights, entering service with Aero Oy in the first quarter of 1938 and forming a Transport Squadron of the Air Force Reserve. The DC3’s were utlised as passenger aircraft by Aero Oy. In war, they were to be mobilised by the Ilmavoimat and would be allocated to a Reserve Squadron whose personnel were all Aero Oy aircrew and groundcrew.

The Douglas DC-3 was an American fixed-wing, propeller-driven aircraft whose speed and range revolutionized air transport starting in the mid-1930s. The DC-3 was engineered by a team led by chief engineer Arthur E. Raymond, and first flew on 17 December 1935. The aircraft was the result of a marathon phone call from American Airlines CEO Cyrus Smith to Donald Douglas requesting the design of an improved successor to the DC-2 (of which the Ilmavoimat already had a small number purchased in 1935). The DC3 had gone into production in 1936 and both civilian and military versions were available. The majority of military DC3’s used the Pratt & Whitney R-1830 Twin Wasp radial which offered better high-altitude and single engine performance. The aircraft quickly developed a reputation for ruggedness - enshrined in the lighthearted description of the DC-3 as "a collection of parts flying in loose formation." Its ability to take off and land on grass or dirt runways also mades it popular in countries such as Finland where the runway was not always a paved surface.

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"Sotka" The first DC-3 of Aero Oy (1938). OH-LCA "Sotka" was the first of a series of DC3 aircraft delivered to Finland prior to WW2. They flew as passenger aircraft prior to the Winter War, were mobilized by the Ilmavoimat for the duration of WW2 and post-war, after being refurbished, went back into passenger service with Aero Oy (which was be then renamed Finnish Air Lines). Ten of the DC-3s that survived the war were in operation from 1946 to 1965.
The depicted OH-LCA was destroyed in an accident in November 1963. The Print is by Sture Gripenberg, taken from a watercolour (http://personal.eunet.fi/pp/gdes/ENG/21.htm). The proofs are signed by captains Seppo Saario, Mauri Maunola and Börje Hielm, radio operator Kosti Uotila and stewardess Kirsti Müller.


The DC3 had a maximum speed of 237 mph, a range of 1,025 miles, a service ceiling of 24,000 feet and, with a Crew of 2, could carry 20 fully-loaded paratroops. They were powered by Pratt & Whitney R-1830 Twin Wasp radial engines of 1100hp each and could be fitted with skis or floats as well as wheels. They were taken too immediately by their pilots and served through the war years as the primary transport workhorse of the Ilmavoimat. The aircraft were allocated to LLv.18, (Flying Squadrons 18) – 6th Flight Regiment (Air Transport).

Merivoimat Douglas DC-3 Transport Aircraft – 10 ordered in 1937

The Merivoimat was also intent on purchasing a number of transport aircraft for use in a supporting role for the Rannikkojääkärit. With the Ilmavoimat’s decision to purchase DC3’s, the logical decision for the Meroivoimat was to follow suite, and this they did. The Merivoimat’s DC3’s were delivered together with the Ilmavoimat order in December 1937 and in service in early 1938. Unlike the Ilmavoimat, the Merivoimat retained their DC3’s and used them over 1938 and 1939 to develop tactical doctrine of both providing transport support for Rannikkojääkärit operations and for the evolving tactic of parachuting Rannikkojääkärit troops into operations.

De Havilland Wihuri (“Mosquito”) Medium Bomber – ordered mid-1937

A rather more innovative and also rather risky (in that it was unproven) acquisition by the Ilmavoimat was the purchase of a manufacturing license by the State Aircraft Factory for the De Havilland “Wihuri” in mid-1937 (built under license in Finland).

While the De Havilland Mosquito was first proposed to the UK’s Air Ministry in late 1938 and the first prototype flew in November 1940, 10 months after the actual go-ahead, it could have come about much sooner. Throughout the 1930s, de Havilland had established a reputation in developing innovative high-speed aircraft such as the DH.88 Comet mailplane and DH.91 Albatross airliner that had already successfully employed the composite wood construction that the Mosquito would use. There two earlier aircraft were instrumental in the emergence of the Mosquito. The de Havilland DH.88 Comet was a twin-engined British aircraft that won the 1934 MacRobertson Air Race. It set many aviation records during the race and afterwards as a pioneer mail plane. The airframe consisted of a wooden skeleton clad with spruce plywood, with a final fabric covering on the wings. A long streamlined nose held the main fuel tanks, with the low set central two-seat cockpit forming an unbroken line to the tail. The engines were essentially the standard Gipsy Six used on the Express and Dragon Rapide passenger planes, tuned for best performance with a higher compression ratio. The propellers were two-position variable pitch, manually set to fine before takeoff and changed automatically to coarse by a pressure sensor. The main undercarriage retracted upwards and backwards into the engine nacelles. The DH.88 could maintain altitude up to 4,000 ft (1,200 m) on one engine.

In 1935, de Havilland had already suggested a high-speed bomber version of the DH.88 to the RAF, but the suggestion was rejected (OTL, De Havilland later developed the de Havilland Mosquito along similar lines as the DH.88 for the high-speed bomber role). As it turned out, experience with the DH.88 would be put to use in designing one of the war's finest aircraft—the de Havilland Wihuri (“Mosquito”). A second aircraft developed along the same lines was the de Havilland DH.91 Albatross. This was a four-engine British transport aircraft developed in the 1930s. A total of seven aircraft were built in 1938-1939. The DH.91 was designed in 1936 by A. E. Hagg to Air Ministry specification 36/35 for a trans-Atlantic mail plane. The aircraft was remarkable for the ply-balsa-ply sandwich construction of its fuselage which was later made famous in the de Havilland Mosquito bomber. The first Albatross flew on May 20, 1937. Production was limited and the type was retired in 1943.

In June 1937, one of the small team of Ilmavoimat officers based in London and managing the procurement program from British aircraft manufacturers was invited to view the new De Havilland Albatross. Having already seen the De Havilland Comet, this officer was also aware of De Havilland’s 1935 proposal to the British Air Ministry for a high speed all-wooden bomber. Interested by the suitability for Finland of the Alabtross’s construction techniques and material composition, aware of VL’s research program with regard to the earlier Haukka II Fighter which had led to innovations in the Finnish timber industry and putting two plus two together, this officer made further inquiries about the possibility of designing and building such a high-speed bomber for the Ilmavoimat, along with licensing production by Finland.
He was impressed enough following initial discussions with De Havilland that he had recommended an urgent followup. In Helsinki, his immediate superior in the procurement program was convinced enough that he recommended a team visit De Havilland immediately. Somersalo (and Mannerheim himself) had become involved as it became obvious that the all-wood aircraft was uniquely suited to Finland’s resources and manufacturing capabilities and, together they joined the team that visited the De Havilland offices for initial discussions. At the same time, the Ilmavoimat was negotiating orders for the Miles Kestrel Advanced Trainers and Glider Tugs. Marshal Mannerheim and Somersalo, the head of the Ilmavoimat, used the opportunity to meet personally with Geoffrey de Havilland Sr. and discuss the possibility of contracting with de Havilland for the design and construction of a high speed medium bomber based on discussions the Ilmavoimat team had already had with De Havilland.

The interest was mutual, with De Havilland demonstrating the Comet and the Albatross and reviewing the construction techniques for the Albatross together with the conceptual work De Havilland had already done on a fast medium bomber. The end result of the intensive week-long series of meetings was a contract (signed in early July 1937) with De Havilland for the design and development of a prototype in an accelerated timeframe. A number of qualifiers were added – primarily the use of Bristol Blenheim cockpit instruments and the Blenheim undercarriage and the use of Merlin engines, the construction of which Finland had just signed a license for. Subject to acceptance of the prototype, the Ilmavoimat signed a statement of intent for the construction of forty aircraft and the purchase of an unlimited manufacturing license together with the immediate assistance of a De Havilland Team in setting up VL production facilities and starting construction in Finland. The cost of the prototype would be shared equally between both parties, but with Finland supplying the engines.

A joint team from the Ilmavoimat and from VL, including VL’s lead designer Arvo Ylinen, were on the way within days of the contract being signed, and worked closely with De Havilland over an intensive four month design and prototype construction period. While the Finnish aircraft started off as an adaptation of the Albatross, the Ilmavoimat was from the first, looking for a fast lightweight tactical medium bomber and fighter-bomber capable of also filling a ground-attack role rather than a strategic heavy bomber. The designers worked to remove everything that was unneeded in order to lower the weight. The initial design had started off as an adaptation of the Albatross, armed with three gun turrets and a six-man crew, and powered by two Rolls-Royce Merlin engines. The designers started removing everything that was unneeded in order to lower the weight. As each of the gun turrets was eliminated, the performance of the aircraft continued to improve, until they realised that, by removing all of them, the aircraft would be so fast it might not need guns at all. What emerged was the concept that the Ilmavoimat team had been grasping at but had not quite visualized, a small twin-engined, two crew aircraft so fast that nothing in the sky could catch it. It could carry 1,000 lb (454 kg) of bombs for 1,500 miles (2,414 km) at a speed of almost 400 mph (644 km/h), which was almost twice that of contemporary British bombers. And at the same time, three basic design variations had been mapped out – a fighter-bomber, a medium bomber and a recconnaisance version.

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A model of the prototype Wihuri

The original estimates at the time of the initial meetings had been that as the bomber prototype had twice the surface area and over twice the weight of the Spitfire, but also with twice its power, it would end up being 20 mph (32 km/h) faster than the Spitfire. By December 1937 the prototype had been completed. The bulk of the Wihuri, as it was now being called, was made of custom plywood – and from the start, the Finnish wood industry was closely involved. The fuselage was a frameless monocoque shell built by forming up plywood made of 3/8" sheets of Ecuadorean balsawood sandwiched between sheets of Finnish birch. These were formed inside large concrete moulds, each holding one half of the fuselage, split vertically. While the casein-based glue in the plywood dried, carpenters cut a sawtooth joint into their edges while other workers installed the controls and cabling on the inside wall. When the glue was completely dried, the two halves were glued and screwed together. A covering of doped Madapolam (a fine plain woven cotton) fabric completed the unit.

The wings were similar but used different materials and techniques. The wing was built as a single unit, not two sides, based on two birch plywood boxes as spars fore and aft. Plywood ribs and stringers were glued and screwed to form the basic wing shape. The skinning was also birch plywood, one layer thick on the bottom and doubled up on the top. Between the two top layers was another layer of fir stringers. Building up the structure used an enormous number of brass screws, 30,000 per wing. The wing was completed with wooden flaps and aluminium ailerons. When both parts were complete the fuselage was lowered onto the wing, and once again glued and screwed together. The remainder consisted of wooden horizontal and vertical tail surfaces, with aluminium control surfaces. Engine mounts of welded steel tube were added, along with simple landing gear oleos filled with rubber blocks. Wood was used to carry only in-plane loads, with metal fittings used for all triaxially loaded components such as landing gear, engine mounts, control surface mounting brackets, and the wing-to-fuselage junction. The total weight of metal castings and forgings used in the aircraft was only 280 lbs. The glue used was initially casein-based.

In testing of the first prototype over December 1937-January 1938, the prototype surpassed all estimates, easily besting the Spitfire in testing with a top speed of 392 mph (631 km/h) at 22,000 ft (6,700 m) altitude, compared to a top speed of 360 mph (579 km/h) at 19,500 ft (6,000 m) for the Spitfire. Construction of a prototype Wihuri fighter-bomber version was then carried out and in May 1938, Geoffrey De Havilland personally flew this off a 450 foot field. The first reconnaissance prototype followed on 10 June 1938. During testing of the bomber version, it was found that the Wihuri day bomber prototype had the power and internal capacity to carry not just the 1,000 lbs of bombs originally specified, but four times that figure. In order to better support the higher loads the aircraft was capable of, the wingspan was increased from 52 ft 6in (16.0 m) to 54 ft 2in (16.5 m). It was also fitted with a larger tailplane, improved exhaust system, and lengthened nacelles that improved stability.

Following the successful trials of the prototype day bomber, the prodution order for forty aircraft was confirmed and construction was started by De Havilland. The forty Wihuris were built as fast bombers with construction starting in March 1938, and all forty were completed and handed over by December 1938. They could carry a 4000 lb bomb load and the design team had worked in external drop tanks which extended the range to 2500 miles. The fighter-bomber version completed it’s trials in June 1938, by which time the Ilmavoimat had confirmed an order for twenty of this type - and De Havilland started construction of the remaining twenty aircraft of the order as the fighter-bomber variant in November 1938. The fighter-bomber version had a strengthened wing for external loads and along with its standard fighter armament of four 20 mm Hispano-Suiza HS-9 cannon mounted in the fuselage and a further four 7.7mm Brownings mounted in the nose, it could carry two 250 lb bombs in the rear of the bomb bay and two 250 lb bombs under the wings. These aircraft were delivered in April 1939. An order for a further twenty had been placed in October 1938 as it was realized that VL (the State Aircraft Factory) would not be able to commence production until at least the end of the second quarter of 1939. These additional twenty fighter-bombers were delivered in June 1939. An order for a further twenty had been placed by then but this was canceled and the order was taken over by the RAF. However, the British did offer the Finns other aircraft in compensation – something that will be covered when we review 1939. Attempts to order more Wihuri’s from de Havilland as the Winter War broke out were declined.

Within weeks of the fighter-bomber trials having been completed, a team from De Havilland was on their way to Helsinki to assist the State Aircraft Factory to start up production. Startup was slower than planned. Subcontractors had to be contracted and trained, local materials sourced, production facilities built, workers hired and trained. The De Havilland-VL Team worked around the clock, twelve hour days, seven day weeks. Fuselage shells were made by two local furniture companies. The specialized wood veneer used in the construction of the Wihuri was made by Tampere Wood Veneers, who had teams of dexterous young women ironing the (unusually thin) strong wood veneer product before shipping to the assembly plant. Wing spars and many of the other parts, including flaps, flap shrouds, fins, leading edge assemblies and bomb doors were also produced locally by the established furniture-manufacturing industry. The Merlin engines were produced by the State Aircraft Engine Factory, while VL supplied Blenheim instruments and undercarriages from the Blenheim production line.The first Finnish-built prototype flew almost a year later, in June 1939.

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A picture from the Finnish Central Air Museum warehouse in 1991 - the crates contain blue prints and original drawings of the de Havilland Wihuri that were used by VL in the manufacture of the aircraft

By October 1939, forty bomber versions and forty fighter-bomber had been delivered from De Havilland and were in service. And by October 1939, VL production had actually started, with two aircraft a month rolling of the VL production line. With Soviet threats becoming ever more blatant, VL made every effort to ramp up production but the Winter War broke out before this could be achieved. However, by the end of November 1939 the first four Finnish-built Wihuri’s (all fighter-bomber variants) had been completed and were in service, bringing the total number available to 84 – and an increase in production to four a month would take place from December 1939 on.

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December 1939 – an Ilmavoimat Wihuri at rest between missions

The performance of the VL Wihuri was a source of wonder to the Finnish pilots assigned to the aircraft. At 415 mph, the sheer speed of the plane and its ability to outfly anything and everything else the Finn’s had, even the fighters, was astounding. And the operational ceiling was outstanding. With no bombload, she could fly even higher and the Ilmavoimat put this capability to good use with reconnaisance flights over the Soviet Union taking place again and again in late 1939. Able to fly at over 40,000 feet, it let them watch everything the Soviet’s were up to with little or no suspicion they were being watched.

Stepping back a little, in August 1939 VL began to experiment with mounting a 37mm Anti-tank gun in the aircraft, intending to use this as a counter-measure to the overwhelming numbers of Soviet tanks should a war occur, as was seeming more and more likely. With the assistance of De Havilland, an auto-loader was designed and built by a British company, Molins, to allow both semi- or fully-automatic fire with the nose-mounted gun. Ground trials of the auto-loader proved successful, as did experiments in how best to mount the gun within the Wihuri. The November 1939 production run of two aircraft were fitted with the 37mm gun in the nose for air trials, along with two .303 in (7.7 mm) sighting machine guns. With the outbreak of the Winter War on the 30th of Novemer 1939, the trials were “live” – and higjly successful. But while highly effective, the 37mm gun did require a steady and vulnerable approach-run to aim and fire the gun and there was a weight penalty. Given the overwhelming numbers of tanks the Red Army was throwing at the Maavoimat, it was decided however that the benefits of an airborne anti-tank gun were well worth it and that the next series of Wihuri’s off the VL production line would be this version.

With 4 Wihuri’s a month rolling off the production line, 20 of these aircraft had been delivered by the time of the May 1940 “Spring Offensive” that recaptured the Karelian Isthmus from the Red Army. Overall, the Wihuri was an aircraft that was to prove of incalculable value to the Finns in the Winter War, and one which was a complete surprise both to the Soviet Air Force and to the Red Army. And it could also be effective on aircraft as well as ground targets. The effect of the new weapon on aircraft was demonstrated on 10 March 1940 when one 37mm-equipped Wihuri attacked 10 Soviet SB2 bombers. Three of the SB2’s were shot down. One SB2 was destroyed with four shells, one of which tore an entire engine off the SB2.

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Ilmavoimat Wihuri’s in action over the Karelian Isthmus – June 1940

However, at the time the Wihuri Project was started, there were no guarantees of its success and a number of other, smaller, aircraft orders were also initiated in 1937. We will look at these next.
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1937 Ilmavoimat and Merivoimat Air Arm Purchases - continued

Post by CanKiwi2 » 05 Jul 2011 14:22

1937 Ilmavoimat and Merivoimat Air Arm Purchases - continued

At the start of the previous Post, it was mentioned that there were two British aircraft and one Italian aircraft ordered almost immediately at the start of 1937. But I jumped to orders placed later in 1937…… So, to rectify the omission, here is one of those immediate orders…..

The Avro Anson Multi-role Aircraft – ordered January 1937

The Avro Anson was a British twin-engine, multi-role aircraft that served with the Royal Air Force, Fleet Air Arm and numerous other air forces during the Second World War and afterwards. The Anson was derived from the commercial six-seat Avro 652 and the militarised version, which first flew on 24 March 1935, was built to Air Ministry Specification 18/35. It was the first RAF monoplane with a retractable undercarriage. A distinctive feature of the Anson was its landing gear retraction mechanism which required no less than 140 turns of the hand crank by the pilot. To forgo this laborious process, Ansons often flew with the landing gear extended at the expense of 30 mph (50 km/h) of cruise speed.

In January 1937, the ilmavoimat ordered 10 Avro Anson I aircraft directly from the factory. The first was delivered in Manchester, U.K. on 25 April 1937 and flown to Finland via the route Croydon - Amsterdam - Malmö - Turku, where the aircraft arrived on 1 May. Delivery of all aircraft orded was completed by December 1937. It was originally designed for maritime reconnaissance but was soon rendered obsolete. However it was rescued from obscurity by its suitability as a multi-engine air crew trainer, and it was primarily for this purpose, with a secondary role as a light transport that the Ilmavoimat purchased the aircraft. All Anson’s purchased were attached to the Pilot Training School. The Ilmavoimat also at times used the Anson in operational roles such as coastal patrols and air/sea rescue. The aircraft's primary role, however, was to train pilots for flying the Ilmavoimat’s multi-engine bombers and transporst such as the Blenheim, SM-73 and DC3. The Anson was also used to train the other members of a bomber's air crew, such as navigators, wireless operators, bomb aimers and air gunners.

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The aircraft required a crew of 3-4, was powered by 2× Armstrong Siddeley Cheetah IX radial engines, 350 hp (260 kW) each, had a masimum speed of 188mph, a range of 790 miles, a service ceiling of 19,000 feet and was armed with 1× .303 in (7.70 mm) machine gun in the front fuselage and 1× .303 in Vickers K machine gun in the dorsal turret. The Anson could also carry one 360 lb (160 kg) bomb or depth charge.

The Anson was a maneoueverable aircraft - in January 1940, a training flight of three Ansons over the Gulf of Finland was attacked by nine Soviet Air Force fighters. Remarkably, the Ansons downed two Soviet aircraft "and damaging a third before the 'dogfight' ended", without losing any of their own. Incidentally the Eesti Õhuvägi (Estonian Air Force) also acquired a single Avro Anson.

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The Eesti Õhuvägi’s (Estonian Air Force) sole Avro Anson, acquired for evaluation. This aircraft escaped from Estonia when the Soviets attacked the country and made it to Finland, where it served with the Ilmavoimat until the liberation of Estonia.

Merivoimat Air Arm Fighter – the Brewster Buffalo, 20 ordered mid-December 1937, a further 20 ordered in April 1938

The 1937 budget included provision for the purchase of fighter aircraft to fit out one squadron for the Merivoimat Air Arm. The stated objectives for the Air Arm Fighters were to provide fighter cover for Merivoimat ships operating in the Baltic and to provide fighter cover for Rannikkojääkärit (Marine) operations, primarly along the Gulf of Finland littoral. To this end, a fighter with a relatively long “loiter” capability was needed and for this (as for their dive bomber), the Rannikkojääkärit looked to their US Marine Advisory and Training Team for advice. Never slow to push the superiority of US aircraft (even when they weren’t) the US Marines pointed the Merivoimat procurement team at the fighters being developed for the US Navy to replace the Grumman F3F biplane. The Merivoimat Air Arm Procurement Team spent a considerable amount of time with the US Navy – they also talked to the British Fleet Air Arm, but considered their procurement to be too restricted by the RAF to be of any use.

While the Merivoimat operated under far different conditions to the US Navy, the basic fighter requirement was similar, with the major diffence being that the Merivoimat did not need to operate of Aircraft Carriers and could dispense with much of the carrier-related requirements. As one member of the Merivoimat Procurement Team joked, “the Ahvenanmaa Islands are our aircraft carrier....”

In 1935, the U.S. Navy had issued a requirement for a carrier-based fighter intended to replace the Grumman F3F biplane. The Brewster XF2A-1 monoplane, designed by a team led by Dayton T. Brown, was one of two aircraft designs that were initially considered, together with the Grumma XF4F-1 - a "classic" biplane design with a double-row radial engine. The U.S. Navy competition was re-opened to allow another competitor, the XFNF-1, a navalized Seversky P-35, eliminated early on when the prototype could not reach more than 267 mph (430 km/h). The Brewster XF2A-1 first flew on 2 December 1937 and early test results showed it was far in advance of the Grumman biplane entry (while the XF4F-1 would not enter production, it would later re-emerge as a monoplane, the Wildcat).

The new Brewster fighter had a modern look with a stubby fuselage, mid-set monoplane wings and a host of advanced features. It was all-metal, with flush-riveted, stressed aluminum construction, although control surfaces were still fabric-covered. The XF2A-1 also featured split flaps, a hydraulically-operated retractable main undercarriage (and partially retractable tail wheel), and a streamlined framed canopy. However, the aircraft lacked self-sealing tanks and pilot armor. Fuel was only 160 U.S. gal (606 l), stored in the fuselage. Powered by an 950 hp (708 kW) single-row Wright R-1820-22 Cyclone radial engine, it had an impressive initial climb rate of 2,750 ft/min and a top speed of 277.5 mph (447 km/h), later boosted to 304 mph (489 km/h) at 16,000 ft (4,879 m) after improvements were made to the cowling streamlining and carburetor/oil cooler intakes. With only a single-stage supercharger, high-altitude performance fell off rapidly. Fuselage armament was one fixed .50 in (12.7 mm) M2 Browning machine gun with 200 rounds and one fixed .30 in (7.62 mm) AN Browning machine gun with 600 rounds, both in the nose. The US Navy awarded Brewster Aeronautical Corporation a production contract for 54 aircraft as the F2A-1.

Impressed by the prototype, the Merivoimat signed a statement of intent in December 1937 and concurrent with the US Navy order, ordered 20 of the F2A-1’s early in 1938 at an overall cost of US$1.5 million. The Merivoimat specified compatibility with 87-octane fuel and had the fighters de-navalized - removing all the naval equipment on the fighters, such as their tailhooks and life-raft containers, resulting in a somewhat lighter aircraft. The Finnish F2A-1s also lacked self-sealing fuel tanks and cockpit armor. After delivery to Finland, the Merivoimat Air Arm added armored backrests for the pilots, metric flight instruments, the Finnish Väisälä T.h.m.40 gunsight, and four .50 in (12.7 mm) machine guns. The top speed of the Finnish Buffalos, as modified, was 297 mph.

Service testing of the XF2A-1 prototype began in January 1938 (testing in which a Merivoimat Air Arm evaluation team participated) and in June, production started on the F2A-1. They were powered by the 940 hp (701 kW) Wright R-1820-34 engine and had a larger fin. The added weight of two additional .50 in (12.7 mm) Browning wing guns and other equipment specified by the Navy for combat operations reduced the initial rate of climb to 2,600 ft/min. Plagued by production difficulties, Brewster delivered all aircraft ordered by the Merivoimat but only delivered 11 F2A-1 aircraft to the US Navy (the remainder of the order was diverted to Finland in modified form to fill the additional Finnish order place in mid-1938).

The Buffalo fighter was never referred to as the "Buffalo" in Finland; it was known simply as the "Brewster" or sometimes by the nicknames Taivaan Helmi ("Sky Pearl") or Pohjoisten Taivaiden Helmi ("Pearl of the Northern Skies"). Other nicknames were Pylly-Valtteri ("Butt-Walter"), Amerikanrauta ("American hardware" or "American car") and Lentävä Kaljapullo ("flying beer-bottle"). In Merivoimat service, the Buffalos were regarded as being very easy to fly, a "gentleman's plane". The Buffalo was also popular because of their relatively long range and flight endurance, and also because of their low-trouble maintenance record. This was in part due to the efforts of the Finnish engine mechanics who solved a problem that plagued the Wright Cyclone engine simply by inverting one of the piston rings in each cylinder. This had a positive effect on engine reliability. The cooler weather of Finland was also a plus for the engine. In the end, the Brewster Buffalo gained a reputation in Finnish service as one of their more successful fighter aircraft.

The 1938 Procurement Program had made provision for a second fighter squadron for the Merivoimat Air Arm and in April 1938, an order for a further 20 Buffalos was placed. Manufacturing for the Meroivoimat order for 40 aircraft began in June 1938 and the aircraft were shipped in November 1938, arriving in Turku December 1938 and entering service between January-March 1939. Payment for the aircraft was made from the thirty million US Dollar loan negotiated in 1937 with the overall cost of the two orders amounting to some US$3.5 million. All 40 Buffalo fighters were in service with the Merivoimat Air Arm on the outbreak of the Winter War.

And after the actual outbreak of the Winter War on 30 November 1939, Finland worked furiously to acquire additional aircraft. On 16 December 1939, Finland signed a contract for the provision of a further 44 Model 239 fighters. The total price to be paid was US $3.4 million, and the deal included the provision of spare parts, 10 replacement engines and 20 Hamilton Standard propellers. These 44 Buffalos were fitted with the new 1,200 hp (895 kW) Wright R-1820-40 engines giving a maximum speed of 323mph and again, were stripped down and de-navalized for Finland. The aircraft were diverted from an order for the US Navy – who protested but who were overruled in this instance by Roosevelt. Built in four batches, the Brewster Buffalos were loaded aboard four merchant ships in New York and shipped for Bergen, in Norway, arriving in January-February 1940. The crates with the fighter were sent by railway to Sweden and assembled by SAAB, near Gothenburg. By April 1940, all 44 Buffalos had been assembled, flight tested and were in service with the Ilmavoimat in time for the May 1940 Spring Offensive, where they had their bapism of fire in combat.

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Meroivoimat Air Arm Buffalos formation flying early in the Winter War

The Merivoimat Air Arm Buffalos saw combat almost immediately on the outbreak of the Winter War - on 2 December 1939 a “parvi”of Merivoimat Buffalos intercepted 27 Soviet SBs from 201st SBAP over the Gulf of Finland and heading for Turku. Ten Tupolev SBs were shot down within as many minutes. The remaining Russian aircraft turned back. Attacking Soviet Air Force pilots using formulaic defensive tactics, many Finnish pilots racked up enormous scores on the Finnish front over the course of the Winter War. The default tactic was the four-plane "parvi" (swarm) with a pair flying low (but visible, not too close to the terrain) as the bait and a pair flying high to dive on the eventual interceptors. In the long run, the Soviet Air Force on the Finnish front never developed an efficient approach to counter this tactic. According to some reports, this tactic also inspired the German Luftwaffe's kette. Incidentally, many of the pilots of Lentolaivue 24 were Spnaish Civil War combat veterans. This squadron achieved a total of 459 Soviet aircraft kills with B-239s, while losing only 15 Buffalos in combat.

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Merivoimat Air Arm Buffalo in action during the Winter War

Heinkel He59 Maritime Aircraft – ordered early 1937

The Merivoimat Air Arm purchased 10 of these aircraft in early 1937 to use as a light transport and SAR aircraft. During the Winter War they were also used at times to ferry long range reconnaissance patrols behind enemy lines and to retrieve them.

The Heinkel He 59 was a German military aircraft designed in 1930 resulting from a requirement for a torpedo bomber and reconnaissance warplane able to operate with equal facility on wheeled landing gear or twin-floats. In 1930, Ernst Heinkel began developing an aircraft for the German Navy. To conceal the true military intentions, the aircraft was officially a civil aircraft. The He 59B landplane prototype was the first to fly, an event that took place in September 1931, but it was the He 59A floatplane prototype that paved the way for the He 59B initial production model, of which 142 were delivered in three variants. The Heinkel He 59 was a pleasant aircraft to fly; deficiencies noted were the weak engines (2× BMW VI 6.0 ZU water-cooled V12 engines, 660 hp each), the limited range, the small load capability and insufficient armament (Two or three machine guns).

The He 59B-2 was a four-seat mixed-structured twin-engined bi-plane maritime aircraft.. The wings were made of a two-beam wooden frame, where the front was covered with plywood and the rest of the wing was covered with fabric. The box-shaped fuselage had a fabric covered steel frame. The tail section was covered with lightweight metal sheets. The keels of the floats were used as fuel tanks - each one holding 900 liters of fuel. Together with the internal fuel tank the aircraft could hold a total of 2,700 liters of fuel. Two extra fuel tanks could also be placed in the bomb bay, bringing the total fuel capacity up to 3,200 liters. The propeller was fixed-pitch with four blades. With a crew of three, a speed of 146mph, a combat range of only 466 miles, a ferry range of 1,175 miles, and a service ceiling of only 16,400 feet, performance was limited. The aircraft could carry 4 × 250 kg (550 lb) bombs or 1 × 800 kg (1,760 lb) torpedo or 4 × 500 kg (1,100 lb) mines. Alternatively, 6-8 passengers could be carried.

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Merivoimat Air Arm Heinkel He-59

Next Post: the three remaining orders placed in 1937. The Ilmavoimat’s Fiat BR.20 Medium Bomber and Fokker G.1 Fighter and the Merivoimat Air Arm’s Dive Bomber – the Vought SB2U Vindicator
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The 1937 Procurement Program - Merivoimat Dive Bomber select

Post by CanKiwi2 » 12 Jul 2011 18:36

The 1937 Procurement Program – continued….

Merivoimat Dive Bomber - Vought SB2U Vindicator – 20 ordered in late 1937

In their search for a Dive Bomber to equip a single Merivoimat Dive Bomber Squadron in 1937, the Procurement Team evaluated a number of different aircraft before making a decision. Among these were the American Vought SB2U Vindicator, Northrop BT, Curtiss SBC-3 Helldiver, Brewster SBA and Grumman SBF, the British Blackburn Skua and Hawker Henley, the French Loire-Nieuport LN 410, the German Ju87 and the Italian Breda BA-65 ground attack fighter. The overall evaluatuion and flight testing program was lengthy, with a decision not reached quickly and an order was placed only shortly before the end of the year. And eventually, as with other purchasing decisions made in 1937, the final and major influencing factor was the sizable US loan that had been made available in 1937.

Vought SB2U Vindicator

The Vought SB2U Vindicator was a carrier-based dive bomber developed for the United States Navy in the 1930s, the first monoplane in this role. In 1934, the United States Navy issued a requirement for a new Scout Bomber for carrier use, and received proposals from six manufacturers. The specification was issued in two parts, one for a monoplane, and one for a biplane. Vought submitted designs in both categories, which would become the XSB2U-1 and XSB3U-1 respectively. The biplane was considered alongside the monoplane design as a "hedge" against the U.S. Navy's reluctance to pursue the modern configuration.

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The Vought SB3U-1 Corsair was a two seat, all metal biplane dive bomber built by Vought Aircraft Company of Dallas, Texas for the US Navy. The aircraft was equipped with a closed cockpit, had fixed landing gear, and was powered by a Pratt & Whitney R-1535 radial air-cooled engine. The SBU-1 completed flight tests in 1934 and went into production under a contract awarded in January 1935, with 125 being built. The Corsair was the first aircraft of its type, a scout bomber, to fly faster than 200 mph. Maximum speed was 205mph, range was 548 miles and armament consisted of 1x Fixed forward firing .30 in (7.62 mm) Browning machine gun and 1x machine gun flexibly mounted .30 in machine gun in rear cockpit and 1 x 500lb bomb. This aircraft was not evaluated by the Ilmavoimat – introduced into service in 1935, by 1937 it was already outdated.

By way of contrast, the Vought XSB2U-1 was a conventional low-wing monoplane configuration, with a retractable tailwheel undercarriage and the pilot and tail gunner seated in tandem under a long greenhouse-style canopy. The fuselage was of steel tube construction, covered with aluminum panels from the nose to the rear cockpit, and with a fabric covered rear fuselage, while the folding cantilever wing was almost completely fabric except for a metal leading edge. A 700hp Pratt & Whitney R-1535 Twin-Wasp Junior radial engine drove a two-blade constant-speed propeller, which was intended to act as a dive-brake during a dive bombing attack. A single 1,000 lb (450 kg) bomb could be carried on a swinging trapeze to allow it to clear the propeller in a steep dive, while further bombs could be carried under the wings to give a maximum bombload of 1,500 lb (680 kg).

Designated XSB2U-1, one prototype was ordered by the US Navy on 15 October 1934 and was delivered on 15 April 1936. Accepted for operational evaluation on 2 July 1936, the prototype XSB2U-1, BuNo 9725, crashed on 20 August 1936. During the Navy tests a number of problems were uncovered. It had been intended to equip the aircraft with a reversible propeller to act as a dive brake; however, this proved to be difficult to use and became technically unsatisfactory. As a replacement, Vought constructed a dive flap that consisted of a number of finger-like spars mounted near the wing leading edge that, during normal flight, were flush with the wing surface but during a dive could be extended at right angles to the wing surface to slow the aircraft. These flaps failed to work satisfactorily because they caused so much drag that full engine power was needed to maintain control. Additionally, the flaps caused severe aileron buffeting, and weighed some 140 pounds. As a result, the Navy decided to adopt a shallower dive angle and to extend the landing gear to act as a form of dive brake. The prototype was also modified to include additional bracing on the pilots and observers canopies. The successful completion of trials led to an initial order for 54 aircraft from the US Navy in October 1936.
The Ilmavoimat evaluated the Vindicator early in 1937. While they rated the aircraft highly, the Procurement Team went on to evaluate a number of other Dive Bombers before reaching a final decision to purchase the Vindicator in late 1937. An order was placed for 20 of the aircraft. Delivery took place in June 1938 and the Vindicators entered service shortly thereafter.

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Merivoimat Vought Vindicator escorting ships of the Helsinki Convoy through the Baltic north of Gotland, Spring 1940. With a crew of 2 (Pilot and Gunner) and powered by a single Pratt & Whitney R-1535-96 Twin Wasp Jr radial engine of 825 hp (616 kW), the Merivoimat Vindicators had a maxiumum speed of 251mph. Additional fuel tanks were added after delivery, increasing the range from 630 miles to some 800 miles and a service ceiling of 27,500 feet. The Merivoimat version was armed with four forward firing machineguns in the wings and one machinegun in a flexible mount for the rear-facing gunner. Bombload consisted of one 1,000lb or one 500lb bomb.

Within the US Navy, the Vindicator was by now well-tried and popular. However, by late 1938 it was beginning to be phased out as the new Douglas SBD Dauntless aircraft began to be delivered. Both the US Navy and Vought were wondering what to do with the surplus Vindicators. This was opportune for Finland. Early in 1939, with the threat of war with the USSR increasingly a risk and the deteriorating European situation, the Finnish Finance Minister, Risto Ryto, had negotiated a further loan from the USA (although not in the same ballpark as the 1937 $30 million amount) and additional war supplies were being purchased whereever they were available. Among these purchases were a further 20 US Navy surplus Vindicators. These were well-used, but as second hand aircraft the cost was significantly reduced and they were shipped to Finland in summer 1939, along with a number of other second hand aircraft that had been purchased (these will be covered when we get to cover 1939 and the Emergency Procurement Program of that year, which was allocated some 45% of all Finnish State spending, significantly reducing funding for every other government program, albiet with some major but as it proved, short-lived, political fallout).

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In the event, the ex-US Navy Vindicators arrived in August 1939 and had not yet even been repainted as the Winter War broke out. Still with their US markings in many cases, they were pressed into service immediately – such was the tempo of operations that some of these aircraft were not reflagged until March 1940 – something which led to accusations from the USSR that US forces were assisting Finland.

Another and later source of supply were Vindicators that had been ordered for the French Air Force. The V156 (the export version of the Vindicator) was shown at the Paris Air Show in November 1938 and French interest had been aroused. The French Government decided in May 1938 to order ninety Vindicators as their own dive bomber program was falling apart. The first five were delivered to Orly in July 1939 and more were on the way as WW2 broke out. Some forty in all were delivered before Franch fell to the German onslaught. Circumventing the US Neutrality legislation, a further thirty Vindicators from the remaining French order, which had been already been repainted for sale to the UK, were reallocated to Finland and shipped to Petsamo in June 1940, entering service only in the final month of the Winter War where they saw little action.

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Vought Vindicators ordered for France, resold to the British and then side-tracked for urgent delivery to Finland in June 1940…..they entered service with the Merivoimat Air Arm in September 1940 and saw little or no action.

Northrop BT

The Northrop BT was a two seat, single engine, monoplane, dive bomber built by the Northrop Corporation for the United States Navy at a time when Northrop was a subsidiary of the Douglas Aircraft Company. The design of the initial version began in 1935. The Northrop XBT-1 had been entered in the competition as a combination dive bomber/scout aircraft and the Navy decided to develop the design as a dive bomber. The first prototype was powered by a 700 hp (522 kW) Pratt and Whitney XR-1535-66 Twin Wasp Jr. double row, radial air-cooled engine. The aircraft had slotted flaps and a landing gear that partially retracted. The next iteration of the BT, designated the XBT-1 was equipped with a 750 hp (559 kW) R-1535 engine. This aircraft was followed in 1936 by the BT-1 that was powered by an 825 hp Pratt and Whitney R-1535-94 engine. One of the BT-1 aircraft was modified with a fixed tricycle landing gear and was the first such aircraft to land on an aircraft carrier.

The Ilmavoimat/Merivoimat team evaluated the BT-1 in early 1937, but at this stage the prototype was undergoing a redesign to address issues indentified in testing.The aircraft was eliminated from consideration at this point, although it was agreed that it would be reevaluated following completion of the next version prototype. The final variant, the XBT-2, was a BT-1 aircraft modified to incorporate a fully retracting landing gear, wing slots, a redesigned canopy, and was powered by an 800 hp (597 kW) Wright XR-1820-32 radial air-cooled engine. The XBT-2 first flew on 25 April 1938 and after testing the US Navy placed an order for 144 aircraft. In 1939 the aircraft designation was changed to the Douglas SBD-1 with the last 87 on order completed as SBD-2s. The Northrop Corporation had become the El Segundo division of Douglas aircraft hence the change to Douglas. The U.S. Navy placed an order for 54 BT-1s in 1936 with the aircraft entering service during 1938. The BT-1s served on the USS Yorktown and Enterprise. The type was not a success in service due to poor handling characteristics, especially at low speeds, "a fatal flaw in a carrier based aircraft." It was also prone to unexpected rolls and a number of aircraft were lost in crashes.

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Northrop BT-1s over Miami in October 1939. With a crew of 2 (Pilot and Gunner), the BT-1 was powered by a single Pratt & Whitney R-1535-94 Twin Wasp Jr. double row radial air-cooled engine of 825 hp (615 kW), giving a maximum speed of 222mph with a range of 1,150 miles and a service ceiling of 25,300 feet. Armament consisted of one forward and one rear-facing machinegun and a 1,000lb bomb carried under the fuselage.

Curtiss SBC-3 Helldiver

The Curtiss SBC Helldiver was a two-place scout bomber built by the Curtiss-Wright Corporation. It was the last military biplane procured by the United States Navy. In 1932, the U.S. Navy gave Curtiss a contract to design a parasol two-seat monoplane with retractable undercarriage and powered by a Wright R-1510 Whirlwind, intended to be used as a carrier-based fighter. The resulting aircraft, designated the XF12C-1, flew in 1933. Its chosen role was changed first to a scout, and then to a scout-bomber (being redesignated XS4C-1 and XSBC-1 respectively), but the XSBC-1's parasol wing was unsuitable for dive bombing. A revised design was produced for a biplane, with the prototype, designated the XSBC-2, first flying on 9 December 1935.

The SBC-3 was the initial production model and was powered by a Pratt & Whitney R-1535 Twin Wasp Junior. The SBC-3 began operational service in 1938. A total of 83 SBC-3s were built. The SBC-4 was powered by a Wright R-1820 Cyclone. The SBC-4 entered service in 1939 with 174 SBC-4s in all being built. The US Navy took deliveries of the new aircraft in mid-1937 with the first batch of carrier-based aircraft going to the Yorktown, but time and technology caught up to the advanced biplane. The Finnish procurement team evaluated and tested a prototype aircraft in early 1937 but even at that stage, before it had enetered service, considered it an outdated design with inadequate performance. It was crossed off the list.

In US service, the SBC-4 was soon relegated to hack duties and service as an advanced trainer for training units in Florida. Within the US Navy, the SBC Helldiver was not destined to have a long U.S. service life, but its impact was felt as the type made a lasting contribution by serving as the key platform in developing dive bombing tactics and honing aircrew skills crucial to winning the war in the Pacific.The last aircraft was stricken from the Navy roster in October 1944. Aware of the use being made of the SBC-4 Helldivers in early 1939 on hack duties and service as an advanced trainer, the Finnish Procurement Team in Washington DC pressed the US to sell these to Finland as a matter of urgency, even going so far as to have the Finnish Ambassador in the US directly raise the matter with President Roosevelt. However, in this instance nothing successful was achieved and in the end some 50 SBC-4s were delivered to the French Navy. The 50 SBC-4s delivered to France were actually aircraft already in service with the United States Navy.

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The Curtiss SBC Helldiver Biplabe had a crew of 2 (Pilot and Gunner), was powered by a single Wright R-1820-34 radial engine of 850 hp (634 kW) with a maximum speed of 234mph, a range of 405 miles and a service ceiling of 24,000 feet. Armament consisted of two machineguns (one forward facing, one rear) and one 1,000lb bomb.

On 6 June 1940, Naval reservists received orders to immediately fly 50 SBC-4s to the Curtiss factory at Buffalo, New York. At Buffalo, a Bureau of Aeronautics inspector informed the pilots their aircraft were to be flown to Halifax, Nova Scotia to be loaded aboard the French aircraft carrier Béarn. From Buffalo to Halifax, the reserve pilots were officially employees of Curtiss. Curtiss paid each pilot $250 plus return rail fare from Halifax to Buffalo. All navy insignia were removed from their uniforms or taped over. Upon return to Buffalo, the pilots went back on Navy orders for return to their home bases. Curtiss employees worked overtime to remove and replace all gear and instruments marked BUAERO, BUSHIPS or BUORD. The Navy .30 in (7.62 mm) machine guns were replaced by .50 in (12.7 mm) guns and the aircraft were repainted in camouflage colors with the French tricolor on the rudders. The hasty conversion did not allow time for adequate checkout of replacement instruments. Weather deteriorated with rain and fog over most of the route from Buffalo to Halifax. The Bureau of Aeronautics inspector temporarily halted flights after one of the first pilots was killed in a crash between Buffalo and Albany.

When the weather improved, sections of three aircraft were dispatched from Buffalo Houlton, Maine. After landing at Houlton, the aircraft were towed down a road across the Canadian border for takeoff from a New Brunswick farm pasture to avoid legal implications of flying over the border. The surviving 49 aircraft flew over the Bay of Fundy and 44 of them were loaded aboard Béarn at Dartmouth, Nova Scotia together with 21 P-36 Hawk fighters and 25 Stinson 105s for the French Armée de l'Air and five Brewster Buffalos for Belgium. France surrendered while Béarn was crossing the Atlantic; she turned south to Martinique, where the SBC-4s corroded in the humid Caribbean climate while waiting on a hillside near Fort-de-France. The five SBC-4s remaining in Canada when France surrendered were taken over by the United Kingdom and were used as ground-instructional airframes. Nothing practical was gained, and Finland missed out on what could have been a reasonably adequate ground attack aircraft. Fortunately, other aircraft were available and it was not a critical loss.

Brewster SBA

The SBN was a United States three-place mid-wing monoplane scout bomber/torpedo aircraft designed by the Brewster Aeronautical Corporation and built under license by the Naval Aircraft Factory in Philadelphia, Pennsylvania. The United States Navy issued a specification for a scout-bomber in 1934 and the competition was won by Brewster. One prototype designated the XSBA-1 was ordered on October 15, 1934. The prototype first flew on April 15, 1936, and was delivered to the Navy for testing. Some minor problems were found during testing and the aircraft was given a more powerful engine.
The Ilmavoimat evaluation identified the production bottleneck issues with this aircraft and despite the promising performance of the prototype, it was eliminated from the shortlist as a result. Events proved this to be a correct decision.

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With a Crew of 3 (Pilot, Navigator, Gunner), a single Wright XR-1820-22 Cyclone radial engine of 950 hp (709 kW) giving a maximum speed of 254 mph, a range of 1015 miles, a service ceiling of 28,300 feet and armed with one rearward firing machinegun, the SBN carried up to 500lb of bombs.

Because of the pressures of producing and developing the Brewster F2A the company was unable to produce the aircraft and the Navy acquired a license to produce the aircraft itself at the Naval Aircraft Factory. In September 1938 the Navy placed an order for 30 production aircraft. Due to pressures of work at the NAF it did not deliver the first aircraft, now designated the SBN, until 1941 and the remaining aircraft were delivered between June 1941 and March 1942.

Grumman SBF

In late 1934, the U.S. Navy's Bureau of Aeronautics (BuAer) issued a specification for new scout and torpedo bomber designs. Eight companies submitted 10 designs in response, evenly split between monoplanes and biplanes. Grumman, having successfully provided the FF and F2F fighters to the Navy, along with the SF scout, submitted an advanced development of the SF-2 in response to the specification's request for a 5,000 lb (2,300 kg) aircraft capable of carrying a 500 lb (230 kg) bomb. Given the model number G-14 by Grumman, the aircraft received the official designation XSBF-1 by the Navy, and a contract for a single prototype was issued in March 1935.

The XSBF-1 was a two-seat biplane, featuring an enclosed cockpit, a fuselage of all-metal construction, and wings covered largely with fabric. Power was provided by a 650 hp (480 kW) Pratt & Whitney R-1535 Twin Wasp Junior air-cooled radial engine driving with a variable-pitch propeller. Armament was planned to be two .30 in (7.62 mm) forward-firing M1919 Browning machine guns, one of which could be replaced by a .50 in (12.7 mm) M2 Browning; the prototype carried only a single gun. A single .30 in weapon was fitted in the rear cockpit for defense, and one 500 lb (230 kg) bomb was to be carried in a launching cradle under the fuselage. The arrestor hook was carried in a fully enclosed position, while flotation bags were fitted in the wings in case the aircraft was forced to ditch. The landing gear of the XSBF-1 was similar to that of the F3F fighter.

The XSBF-1—piloted by test pilot Bud Gillies—flew for the first time on December 24, 1935. Following initial testing, which found the aircraft to be reasonably faultless, the XSBF-1 was delivered to the U.S. Navy for evaluation in competition with two other biplanes submitted to the 1934 specification, the Great Lakes XB2G and the Curtiss XSBC-3. Unusually for biplanes, all three types possessed retractable landing gear. The evaluation showed that the design from Curtiss was superior to the Grumman and Great Lakes designs, and an order was placed for the Curtiss type, designated SBC-3 Helldiver in service, in August 1936.

Given the US rejection of the aircraft, the Ilmavoimats evaluation of the prototype was cursory at best – it had been assigned to the Naval Air Station at Anacostia where it was being used for continued testing and as a hack aircraft.

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With a Crew of 2, the Grumman SBF had a maximum speed of 215mph, a range of 525 miles and a service ceiling of 26,000 feet. Amed with two machineguns (one forward-firing, one rear-facing, it could carry up to a 500lb bombload.

Blackburn Skua – evaluated 1937

The Blackburn B-24 Skua was a carrier-based low-wing, two-seater, single-radial engine aircraft operated by the British Fleet Air Arm which combined the functions of a dive bomber and fighter. Built to Air Ministry specification O.27/34, it was a low-wing monoplane of all-metal (duralumin) construction with a retractable undercarriage and enclosed cockpit. It was the Fleet Air Arm's first service monoplane, and was a radical departure for a service that was primarily equipped with open-cockpit biplanes such as the Fairey Swordfish. Performance for the fighter role was compromised by the aircraft's bulk and lack of power, resulting in a relatively low speed; the contemporary marks of Messerschmitt Bf 109 made 290 mph (467 km/h) at sea level over the Skua's 225 mph (362 km/h). However, the aircraft's armament of four fixed, forward-firing 0.303 in (7.7 mm) Browning machine guns in the wings and a single flexible, rearward-firing Lewis .303 in (7.7 mm) machine gun was effective for the time (although whenever possible the gunner would try to replace this with a Vickers "K" gun which was more reliable and had a higher rate of fire).

For the dive-bombing role, a single 250 lb (110 kg) or 500 lb (230 kg) bomb was carried on a special swinging crutch under the fuselage, which enabled the bomb to clear the propeller arc on release. Four 40 lb (20 kg) bombs or eight 20 lb (9 kg) Cooper bombs could also be carried in racks under each wing. The 500lb AP and SAP bomb was only used against armoured warships, for attacks on merchant ships and ground targets the normal bombload was a 250 lb bomb in the fuselage recess and either 20lb or 40lb bombs on the light series carriers. The 250 lb bomb had only a little less explosive content than the 500lb SAP and AP bombs (the extra weight of the latter was down to the casing, needed to punch through armour). If used against ground targets the SAP and AP bombs would often bury themselves deep before exploding, reducing the blast effect. The small and largely ineffective 100 lb anti-submarine (AS) bomb could also be carried in the fuselage recess.

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Powered by a Bristol Perseus XII nine cylinder, sleeve valve, air cooled radial engine rated at 815 hp, the Skua had a maximum speed of 225mph, a service ceiling of 20,500 ft (reached in 43 mins - the Skua had a very poor rate of climb) and maximum range of some 760 miles (an endurance of over 4 hours). It had large Zap-type air brakes/flaps which helped both in dive bombing and landing on aircraft carriers at sea.

The first prototype Skua had problems with stability and it and the second prototype (both known as Skua MK Is) had to be modified with a longer nose and upturned wingtips, features carried over to the production aircraft (known as Skua Mk IIs). The spin characteristics of the Skua were bad enough to prompt the fitting of an anti-spin parachute in the tail to aid recovery. Interestingly, the Skua was designed with a very specific task in mind, the sinking of enemy aircraft carriers, for which its single 500 lb bomb would have been more than adequate (only Britain developed and deployed aircraft carriers with armoured decks during World War II). The role of fighter was intended as secondary. In combat however the Skua was forced to be used as a fighter much more often than as a dive bomber. Its performance as a fighter was often better than might be imagined just by looking at its modest speed in level flight. Its long endurance also meant it could loiter at altitude (once it got there, it had a very poor rate of climb) and dive onto its victims. Where the Skua had the potential to be badly misused was in attacks against heavily armoured warships, where its 500 lb bomb would cause little damage.

Two prototypes were ordered in 1935 with the first prototype (K5178) flying nearly two years later on 9th Feb 1937. It was this first prototype that the Ilmavoimat evaluated in mid-1937. While the test pilots liked the Skua’s handling, the aircraft could only carry half the bombload of the Vindicator (which was the leading choice at this stage), was slower and had less range. The Ilmavoimat decided at this stage to eliminate the Skua from consideration but to revisit the aircraft after it entered production.

In the UK, in October of 1937 the first prototype went on to handling trials at A.&A.E.E. Martlesham. The second prototype (K5179) did not fly until 4th May 1938, and the first production Skua (L2867) flew on 28th August 1938. A total of 190 Skuas had been ordered as far back as July 1936, even before the first prototype had flown. Thus production was started a full two years after the order. However deliveries were prompt after that and over 150 had been delivered by the time WW2 started, with all but one being delivered by the end of 1939. This meant that the Skua was very much a "new" aircraft when it first went to war and its pilots were still finding their way in this big metal monoplane aircraft with its retractable undercarriage and enclosed cockpits, all a novelty to British carrier pilots of the time. It is interesting to speculate what might have happened if the original expected "in-service" date of 1937 had been kept to. Then the crews would have had two years to get to know their aircraft and the Navy would probably have had 4 or 5 fully equipped and trained Skua Squadrons "ready to go" at the outbreak of war.

One further weakness of the Skua was that, as delivered to the British Fleet Air Arm, the Skua’s only means of radio communication was by Morse code back to the carrier. There was no speach-based radio communication with the carrier and not even Morse code communication with other Skuas. This meant communication between aircraft was limited to hand-signals or Aldis-lamp. This must have severely limited the ability of the Skua crews to co-operate, particularly in the fighter role - No "Tally Ho Red Leader, bandits 9 o'clock low" for the poor Skua pilots!

Hawker Henley

The Hawker Henley was designed as a light bomber in response to British Air Ministry Specification P.4/34 of February 1934 for a light bomber and close support aircraft, with high performance and a low bomb load. It was however to be fully stressed for dive bombing and a speed of 300mph was mentioned. The resulting aircraft was very similar in appearance to the Hurricane, sharing most of the wing and the tail plane with that aircraft as well as many of the assembly jigs. The main difference between the two types was the cockpit, with the Henley designed to carry a two man crew – pilot and observer/ air gunner. Work on the Henley progressed slowly. The prototype took two years to complete, finally taking to the air on 10 March 1937. It could carry 4 x 500lb bombs on underwing racks. The Henley performed well in tests, but three years after issuing the initial specification the Air Ministry decided it no longer needed a new light bomber. However, rather than cancel the Henley, the Air Ministry decided to use the aircraft as a target tug. Somewhat ironically the Hawker Hurricane would later go on to perform a role very similar to that originally intended for the Henley, acting as a ground attack aircraft.

The Ilmavoimat/Meroivoimat Procurement Team evaluated and test flew the aircraft and considered it outstanding, placing it first in the overall rankings of the aircraft they evaluated. For financial reasons, the Vindicator was selected over the Henley for the Merivoimat’s first Dive Bomber Squadron. However, the Ilmavoimat would revisit the question of purchasing the Hawker Henley some two months later, in January 1938.

In RAF service, the Henley was not a great success as a target tug. The first modified Henley TT.III flew on 26 May 1938, and an order was placed for 200. In service it was discovered that the Merlin engine could not cope with high speed target towing. After a brief period towing large drogue targets, the Henley was retired in May 1942, in favour of the Boulton Paul Defiant, which was itself obsolescent as a front line aircraft. As a Target Tug, the Henley was powered by a 1,030hp Rolls Royce Merlin II or III with a maximum speed of 272 mph with an air-to-air target or 200mph with an air-to-ground target. It had a ceiling of 27,000 feet, a range of 950 miles and was unarmed.

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RAF Hawker Henley Target Tug

Loire-Nieuport LN 410

In late 1937, as has been mentioned in passing, the Finnish Government (Minister of Finance Risto Ryti) negotiated a loan with the French Government for some USD-equivalent-$8 million for the purchase of military equipment. As always, the bulk of the money went for equipment for the Maavoimat, but the Merivoimat were allocated enough of the loan to buy the old Russian naval guns in storage at Bizerte which were used to strengthen Finland’s coastal defences. And the Ilmavoimat were allocatred funds sufficient to buy a number of French aircraft. What the Ilmavoimat wanted was the Morane-Saulnier MS.406 – then perhaps the best of the French Fighters that were coming into service. With their rearmament program for the Armée de l'Air falling behind, the French declined to sell these but did offer to sell Finland the Arsenal VG-30, a cheap and lightweight fighter of wooden construction capable of being built quickly. The Finnish procurement team in France declined this offer, but became aware later in 1938 of the dive-bomber development program underway at the French company of Loire-Nieuport.

Between 1932 and 1936, Loire-Nieuport had been developing a two-seat dive bomber, the Nieuport 140, for the Aéronautique Navale, the aviation arm of the French Navy. It was renamed Loire-Nieuport LN.140 after the Nieuport company was absorbed into Loire-Nieuport in 1933. In 1936, the development of the LN.140 was abandoned after two fatal accidents. Development efforts were then concentrated on the LN.40 project which benefited from experience acquired with the LN.140, but was a new, and aerodynamically much more refined, design. In the second half of 1937 the LN.40 received government backing in the form of an order for a prototype, followed by orders for seven production aircraft destined for the aircraft carrier Béarn and three more for operational evaluation by the air force. The French Air Force also expressed interest in a land-based derivative of the LN.40, called LN.41. Initially it wanted to acquire 184 of these, enough to equip six dive bomber squadrons of 18 aircraft each, plus a reserve.

The prototype made its first flight on 6 July 1938, flown by Pierre Nadot and this was evaluated by an Ilmavoimat Test Team. The flight tests were not entirely successful. The original dive brake was found ineffective and during the Ilmavoimat tests was removed in favour of extending the landing gear to act as an aerodynamic brake. It was also found that the LN.40 could not fly dive bombing missions with full fuel tanks and the test team decided the aircraft was too slow, with a maximum speed of only 236mph.

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The LN.411 had a maximum speed of 236mph, a range of 745 miles and could carry a 500lb bomb. The Ilmavoimat at this stage declined to pursue the aircraft further but the Merivoimat remained interested and in August 1938 Loire-Nieuport agreed to work with the Merivoimat team on design improvements.A Hispano-Suiza 12Y engine was substituted for the LN.40’s older 690 hp Hispano-Suiza 12Xcrs engine, the tail surfaces wer eenlarged and the wing was extensively redesigned. A prototype for what was designated the LN.42 flew on 18 November 1938. Performance improvements however were disappointing and it was decided not to pursue the LN.42 further.

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The Loire-Nieuport LN42 had a maximum speed of 267mph, a service ceiling of 9800m and a range of 857 miles. Armament consisted of 500kg of bombs, 1x20mm HS Cannon and 2 machineguns.

However, in July 1939, Loire-Nieuport received orders for 36 LN.401 production dive bombers for the Fench Navy, and 36 LN.411 aircraft for the French Army. The LN.411 was almost identical to the LN.401, expect for the deletion of the arrestor hook, the wing folding mechanism and the emergency floatation devices. The first LN.411s were delivered in September 1939, in which month the French Air Force ordered 270 more. But in October 1939 General Vuillemin refused to accept these aircraft for the French Air Force. At this stage, with war with the USSR looking almost certain, Finland made a request that the 36 LN.411s completed for the Army and not wanted be sold to them. The French government agreed over the protests of the Navy and the aircraft were flown to Finland in November 1939 following the France-UK-Norwar-Sweden-Finland route.

They were used in combat during Winter War in dive-bombing attacks against Russian motorized columns and troop and artillery concentrations. Performance was adequate and losses were light as long as air superiority was maintained against enemy fighters. However, perhaps the greatest Ilmavoimat loss in the Wimter War occurred on 19 January 1940 when Soviet fighters broke through the Ilmavoimat fighter cover and attacked a squadron of LN.411’s, resulting in the loss of 10 out of 20 dive bombers committed, while seven of the survivors were sufficiently damaged to be no longer airworthy. However, as a dive-bomber, the remaining LN.411’s remained effective through to the end of the Winter War.

Junkers Ju87 (Stuka)

The Junkers Ju 87 or Stuka (from Sturzkampfflugzeug, "dive bomber") was a two-man (pilot and rear gunner) German ground-attack aircraft. Designed by Hermann Pohlmann, the Stuka first flew in 1935 and made its combat debut in 1936 as part of the Luftwaffe's Condor Legion during the Spanish Civil War. The Ju 87's principal designer, Hermann Pohlmann, held the opinion that any dive-bomber design needed to be simple and robust. This led to many technical innovations, like the retractable undercarriage being discarded in favour of one of the Stuka's distinctive features, its fixed and "spatted" undercarriage which, along with its inverted gull wings and its infamous Jericho-Trompete ("Jericho Trumpet") wailing siren, becoming the propaganda symbol of German air power.

The concept of dive-bombing was given a huge boost within the Luftwaffe when Ernst Udet took an immediate liking to the concept after flying the Curtiss Hawk II. When he invited Walther Wever and Robert Ritter von Greim to watch him perform a trial flight in May 1934 at the Jüterbog artillery range, it however raised doubts about the capability of the dive bomber. Udet began his dive at 1,000 m (3,800 ft) and released his 1 kg (2 lb) bombs at 100 m (330 ft), barely recovering and pulling out of the dive. The Chief of the Air Weapons Command Bureau, Walther Wever, and Secretary of State for Aviation, Erhard Milch, feared that such high-level nerves and skill could not be expected of "average pilots" in the Luftwaffe. Nevertheless, development continued at Junkers and Udet's "growing love affair" with the dive bomber pushed it to the forefront of German aviation development. Udet went so far as to advocate that all medium bombers have dive-bombing capabilities.

The design of the Ju 87 had begun in 1933 as part of the Sturzbomber-Programm. The Ju 87 was to be powered by the British Rolls-Royce Kestrel engine. Ten engines were ordered by Junkers on 19 April 1934 for £ 20,514, 2 shillings and sixpence. The first Ju 87 prototype was built by AB Flygindustri in Sweden and secretly brought to Germany in late 1934. It was to have been completed in April 1935, but, due to the inadequate strength of the airframe, construction was not completed until October 1935. However, the mostly complete Ju 87 V1 (less non-essential parts) took off for its maiden flight on 17 September 1935. The Ju 87 V1 which had a twin-tail, crashed on 24 January 1936 at Kleutsch near Dresden, killing Junkers' chief test pilot, Willy Neuenhofen, and his engineer, Heinrich Kreft. The square twin fins and rudders proved too weak; they collapsed and the aircraft crashed after it entered an inverted spin during the testing of the terminal dynamic pressure in a dive. The crash prompted a change to a single vertical stabilizer tail design. To withstand strong forces during a dive, heavy plating was fitted, along with brackets riveted to the frame and longeron, to the fuselage. Other early additions included the installation of hydraulic dive brakes that were fitted under the leading edge and could rotate 90°. The Stuka's design also included several other innovative features, including automatic pull-up dive brakes under both wings to ensure that the aircraft recovered from its attack dive even if the pilot blacked out from the high acceleration.

The RLM was still not interested in the Ju 87 and was not impressed that it relied on a British engine. In late 1935, Junkers suggested fitting a DB 600 in-line engine, with the final variant to be equipped with the Jumo 210. This was accepted by the RLM as an interim solution. The reworking of the design began on 1 January 1936. The test flight could not be carried out for over two months due to a lack of adequate aircraft. The 24 January crash had already destroyed one machine. The second prototype was also beset by design problems. It had its twin stabilizers removed and a single tail fin installed due to fears over stability. Due to a shortage of power plants, instead of a DB 600, a BMW "Hornet" engine was fitted. All these delays set back testing until 25 February 1936. By March 1936, the second prototype, the V2, was finally fitted with the Jumo 210Aa power plant, which a year later was replaced by a Jumo 210 G (W.Nr. 19310). Although the testing went well, and the pilot, Flight Captain Hesselbach, praised its performance, Wolfram von Richthofen told the Junkers representative and Construction Office chief engineer Ernst Zindel that the Ju 87 stood little chance of becoming the Luftwaffe's main dive bomber, as it was underpowered in his opinion. On 9 June 1936, the RLM ordered cessation of development in favour of the Heinkel He 118, a rival design. Apparently, Udet cancelled the RLM’s order the next day, and development continued.

On 27 July 1936, Udet crashed the He 118 prototype, He 118 V1 D-UKYM. That same day, Charles Lindbergh was visiting Ernst Heinkel, so Heinkel could only communicate with Udet by telephone. According to this version of the story, Heinkel warned Udet about the propeller's fragility. Udet failed to consider this, so in a dive, the engine oversped and the propeller broke away. Immediately after this incident, Udet announced the Stuka the winner of the development contest. Despite being chosen, the design was still lacking and drew frequent criticism from Wolfram von Richthofen. Testing of the V4 prototype (A Ju 87 A-0) in early 1937 revealed several problems. The Ju 87 could take off in just 250 m (820 ft) and climb to 1,875 m (6,000 ft) in just eight minutes with a 250 kg (550 lb) bomb load, and its cruising speed was 250 km/h (160 mph). However, Richthofen continued to push for a more powerful engine. According to the test pilots, the Heinkel He 50 had a better acceleration rate, and could climb away from the target area much more quickly, avoiding enemy ground and air defenses. Richthofen stated that any maximum speed below 350 km/h (217 mph) was unacceptable for those reasons. Pilots also complained that navigation and powerplant instruments were mixed together, and were not easy to read, especially in combat. Despite this, pilots praised the aircraft's handling qualities and strong airframe.

These problems were to be resolved by installing the Daimler-Benz DB 600 engine, but delays in development forced the installation of the Jumo 210 Da in-line engine. Flight testing began on 14 August 1936. Subsequent testing and progress fell short of Richthofen's hopes, although the machine's speed was increased to 280 km/h (173 mph) at ground level and 290 km/h (179 mph) at 1,250 m (4,000 ft), while maintaining its good handling ability. Despite teething problems with the Ju 87, the RLM ordered 216 Ju 87 A-1s into production and wanted to receive delivery of all machines between January 1936 and 1938. The Junkers production capacity was fully occupied and licensing to other production facilities became necessary. The first 35 Ju 87 A-1s were therefore produced by the Weserflug Aircraft Company Limited (WFG). By 1 September 1939, 360 Ju 87 As and Bs had been built by the Junkers factories at Dessau and Weserflug factory in Bremen.

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With a crew of 2 (Pilot and Rear Gunner), the Ju87 B-2 was powered by a Junkers Jumo 211D liquid-cooled inverted-vee V12 engine, of 1184 hp / 883 kW giving a maximum speed of 242mph with a ramge of 311 miles and a service ceiling of 26,903 feet with a maximum 1,103lb bombload. Armament consisted of 2× 7.92 mm (.312 in) MG 17 machine gun forward and 1× 7.92 mm (.312 in) MG 15 machine gun to the rear while a normal bombload consisted of a single 551lb bomb beneath the fuselage.

The Ilmavoimat Procurement Team evaluated the V4 prototype (A Ju 87 A-0) of the Ju87 in the second quarter of 1937. The overall assessment following completion of the series of test flights was that aircraft lacked manoeuvrability, was slow and with a limited range and the maximum practical bombload was only 500lbs, making its effectiveness against armored battleships questionable. In addition, armored protection for the engine and crew was lacking (as it was for almost all dive bombers of the period) and the aircrafts slow speed and poor manoeuvrability meant that a heavy fighter escort would be required in order to operate effectively (again, this applied to many of the dive bombers being evaluated). Furthermore, the aircraft was still, as of early 1937, in the prototype stage and their was no guarantees that it would actually move into production.

The Ilmavoimat decided to pursue the Ju87 no further for the 1937 procurement year.

Breda BA-65 ground attack fighter

The Breda Ba.65 was a single-engine ground attack aircraft designed by Antonio Parano and Giuseppe Panzeri and was a single-seat, all-metal, cantilever low-wing monoplane with aft-retracting main undercarriage intended to undertake multiple roles as a fighter, attack and reconnaissance aircraft. The prototype, which was first flown in September 1935, like the initial production aircraft, used the 522 kW (700 hp) Gnôme-Rhône K-14 produced under license by Isotta-Fraschini.

The Ba.65 sprang from the concept of a flying military jack-of-all-trades formulated by Colonel Amadeo Mecozzi as he set about procuring a modern ground-attack plane for the Regia Aeronautica in the early 1930s. For Mecozzi, the ideal military airplane was one that would be able to perform a wide variety of functions: fighter, light bomber, army cooperation and photo- reconnaissance. Of the several designs submitted to satisfy that specification that of the Societa Italiana Ernesto Breda was ultimately selected. Developed in 1932 from the Breda 27 single-seat fighter, the Breda 64 was completed early in 1933 as a cantilever monoplane. The Ba.64 prototype was powered by a Bristol Pegasus radial engine, license-built by Alfa Romeo, in a long-chord cowling, which was later replaced by an Alfa Romeo 125 RC35 engine rated at 650 hp. The Ba.64's undercarriage retracted rearward into the wings. The open cockpit was placed well forward on the fuselage in line with the wing roots to provide an excellent field of vision down as well as forward. The headrest behind the open cockpit was extended as a streamlined fairing all the way down the fuselage upper decking to the tail. It was constructed using a frame of chrome-molybdenum tubing skinned with metal, except for fabric over the rear fuselage and control surfaces. Armament consisted of four 7.7mm Breda-SAFAT guns in the wings and up to 880 pounds of bombs in racks under the wings.

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With a crew of 2, a maximum speed of 217mph, a range of 560 miles and a service ceiling of 22,965 feet, the Ba.64 was armed with 2 × 12.7 mm (.50 in) Breda-SAFAT machine guns and 3 × 7.7 mm (.303 in) Breda-SAFAT machine guns and could carry a 1200lb bombload.

The basic problem with the Ba.64 was its size in relation to its power plant. With a maximum speed of 220 mph, the new aircraft lacked the performance to be a very effective attack or reconnaissance plane, let alone a successful fighter. The first production Ba.64s were delivered in the summer of 1936 and were a profound disappointment. The Ba.64's mediocre speed and heavy handling characteristics were anything but fighter like. Pilots considered them ill-equipped to undertake missions as a bomber or fighter with faults including being underpowered, heavy handling characteristics and a tendency to enter high-speed stalls that led to a number of fatal crashes. In 1937, the Ba.64s took part in a series of well- publicized military maneuvers, but they were withdrawn from service the following year. Modified into two-seaters with a 7.7mm machine gun in the rear, only a small number of Ba.64s were built for the Regia Aeronautica, since Breda was already working on an improved model, the Ba.65. Two Ba.64s were purchased by the Soviet Union in 1938. One was delivered to General Francisco Franco's Nationalist forces in June 1937 and saw brief service during the Spanish Civil War. After limited use in front-line service, the Ba.64s were relegated to second-line duties.

Evolved from the Ba.64, the Ba.65 was a single-seater intended as an interceptor and attack-reconnaissance plane. It was armed with wing-mounted armament of two 12.7mm and two 7.7mm Breda-SAFAT machine guns together with an internal bombbay for a 440-pound bomb-load in addition to external ordnance that could total 2,200 pounds. The prototype was powered by a Fiat A80 RC41 18-cylinder, twin-row radial engine with a takeoff rating of 1,000 hp. The prototype was first test-flown by Ambrogio Colombo in September 1935 and production of the Ba.65 began in 1936, the initial model having a Gnôme-Rhône 14K 14-cylinder radial of 900 hp. The single-seat Gnôme- Rhône version of the Ba.65, of which 81 were built, attained a maximum speed of 258 mph at 16,400 feet and 217 mph at sea level. Maximum cruising speed was 223 mph at 13,125 feet, and range was 466 miles with a 440-pound bomb load (rather less at 342 miles when carrying a full bomb load). The service ceiling was 25,590 feet. Starting from the 82nd aircraft, the more powerful Fiat A.80 RC.41 18-cylinder, twin-row radial engine with a takeoff rating of 746 kW (1,000 hp) engine was adopted. Production ceased in July 1939 after 218 aircraft were built by Breda and Caproni.

During the late 1930s, Italian dictator Benito Mussolini was fond of putting on impressive shows to demonstrate his country’s martial capabilities. For displaying Italian air power, his weapon of choice was the Ba.65 – the large attack bomber its hefty fuselage had a look of blunt-nosed pugnacity thanks to its single radial engine. To foreign observers prior to World War II, the Ba.65 was the dominant symbol of Italian air power. In December 1936, Mussolini, stepping beyond his effort to instill a more martial spirit in his people with propaganda flyovers, decided to give his military personnel some experience in a real conflict–the Spanish Civil War. His program to assist Franco’s Nationalists included the establishment of a 250-plane aerial contingent, the Aviazione Legionaria. The first installment of that force consisted of four Ba.65s unloaded at Palma, Mallorca, on December 28 1936, to be joined by eight more on January 8, 1937. In March, the attack planes were transported to Cádiz, along with newly arrived Fiat C.R.32 fighters, on the steamship Aerienne. The last of the Ba.65s arrived on May 3 and were formed into the 65a Squadriglia Autonoma di Assalto under the command of Capitano Vittorio Desiderio.

Teething troubles were soon experienced with the new planes, and aircraft No. 16-29 was wrecked in a landing accident. Overall though, the Ba.65s proved effective in Spain, and were compared positively with the German Junkers Ju 87. In a unique engagement, on 24 August 1936 one of the Aviazione Legionaria pilots, a Sergente Dell’Aqua, scored an air-to-air victory when he encountered a lone twin-engine Tupolev SB-2 bomber over Soria and shot it down. Of the 23 Ba.65s sent to Spain, 12 were lost in the course of the civil war. The Ba.65s flew 1,921 sorties, including 368 ground-strafing and 59 dive-bombing attacks. During operations in northern Spain, several Ba.65s were converted to two-seaters, and one was experimentally fitted with an A360 two-way radio. At the end of the campaign in October, the squadron, now commanded by Capitano Duilio S. Fanali, was transferred to Tudela in Navarra, and in December the Bredas braved bitter winter weather conditions to participate in the battles for Teruel. After that city fell, the 65a Squadriglia, bolstered by the arrival of four more Ba.65s, took part in the Aragon offensive, which by April 15 had succeeded in cutting the Spanish Republic in two. During the Nationalist advance, the Ba.65s harassed retreating Republican troops, attacked artillery batteries and landing grounds, and bombed railway and road junctions.

During the Battle of the Ebro in July 1938, the 65a Squadriglia, now under the command of Capitano Antonio Miotto, used its Ba.65s as dive bombers for the first time, striking at pontoon bridges that the Republicans had thrown across the Ebro River. By September 1938, attrition had whittled the squadron’s complement of aircraft down to eight, but six more Ba.65s arrived, and in January 1939 the squadron–again under a new commander, Capitano Giorgio Grossi–was at Logroño and ready to take part in the final offensive against Catalonia. The Ba.65s’ final mission was flown from Olmedo on March 24. When the war ended five days later, the 65a Squadriglia had logged 1,921 sorties, including 368 ground-strafing and 59 dive-bombing attacks. Of the 23 Ba.65s sent to Spain, 12 had been lost–an acceptable enough record if one discounted the relative ineffectiveness of the aerial opposition they faced most of the time. When the airmen of the Aviazione Legionaria returned to Italy in May, they bequeathed their 11 surviving Ba.65s to the Spanish Ejercito del Aire.
While the Ba.65 was being blooded over Spain, a two-seat version, the Ba-65bis, had been developed, and export orders for the Breda assault monoplane had been solicited. Fifteen aircraft with 14K engines were ordered in 1937 by the Royal Iraqi Air Force (RIAF), 13 of which were Ba.65bis two-seaters equipped with a hydraulically operated Breda L dorsal turret mounting a 12.7mm Breda-SAFAT machine gun; the remaining two were dual-control trainers. Ten single-seat Ba.65s were delivered to the Soviet Union, and in 1938, 20 Ba.65s equipped with Piaggio P.XI C.40 engines–17 single-seat attack planes and three dual-control trainers–were delivered to Chile. In 1939, 12 Ba.65bis models with Fiat A80 engines and power turrets were ordered by Portugal for its Arma da Aeronautica. In June 1937, a Ba.65 was experimentally fitted with an American Pratt & Whitney R-1830 engine in anticipation of an export order from Nationalist China that was never placed.

The Ilmavoimat evaluated the aircraft but considered it unsuitable as a dive bomber – largely due to the design which had focused on a multi-role aircraft which was not stressed for dive bombing. Again, the aircraft was not considered further in 1937.

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The Breda Ba.65: impressively pugnacious looking but ungainly and vulnerable to enemy fighters

However, Breda Ba.65’s would be seen in Finland. In September 1939, 154 Ba.65s equipped the 101a and 102a Squadriglie of the 19o Gruppo of the 5o Stormo, the 159a and 160a Squadriglie of the 12o Gruppo, and 167a and 168a Squadriglie of the 16o Gruppo, both components of the 50o Stormo. When the Winter War broke out at the end of 1939, Italy and Mussolini were quick to express their support for Finland. And it was more than just words. While Italy sold aircraft, munitions and weapons to Finland, Mussolini was also quick to send aid above and beyond the Alpini Division that was in Finland conducting winter warfare exercises for the second year running. As was mentioned earlier, a small convoy of merchant ships accompanied the two Italian Light Cruisers sold to Finland and the merchant ships carried, among other cargo, two reinforced squadrons (12 aircraft each) of Regia Aeronautica volunteers - the 159a Squadriglia under Capitano Antonio Dell’Oro and the 160a Squadriglia under Capitano Duilio Fanali, both equipped with Breda Ba.65’s.

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Breda Ba.65 and Pilot of the 159a Squadriglia, 12o Gruppo, 50o Stormo preparing to take off on another combat mission – late January 1940

In combat from January 1940 and equipped with Finnish manufactured bombs, the Ba.65’s proved reasonably effective at first although vulnerable to Soviet fighters and AA fire. Steady attrition (some 50% were lost in action by the end of February 1940, primarily to AA fire), a shortage of spare parts and a realization by the Ilmavoimat that the large single-engined attack bomber was both ungainly and highly vulnerable AA fire and could only be used successfully where fighter cover and AA fire suppression was provided resulted in the phasing out of the Bredas in both the 160a and the 159a Squadriglia. The surviving aircraft were retained as ground attack trainers for a short period and were then stored for use only in an emergency situation. The heroic Italian airmen were amalgamated into a single squadron and reequipped with Blenheims from the UK that had been sold to Finland. Thus the strange situation came about where Italian Pilots flew British-supplied Blenheims while in the Middle East they fought against them.
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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CanKiwi2
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The last of the 1937 Fighter purchases – the Fokker G.1 Figh

Post by CanKiwi2 » 13 Jul 2011 21:26

And now, the last of the 1937 Fighter purchases – the Fokker G.1 Fighter

While the Ilmavoimat ordered 40 Curtiss Hawks for earlier in 1937, and the Merivoimat eventually confirmed an order for 20 Brewster Buffalos late in the same year, the Ilmavoimat was also looking for a heavy “Bomber destroyer” fighter and in early 1937 began initial discussions with Fokker regarding the Fokker G1 Fighter.

The G1 was designed and a first prototype was built in 1936 by Fokker head engineers Beeling and Schatzki; with the design and building of the prototype taking just 7 months. Work had actually started in March 1935 after receipt of a specification from the French Airforce for a two engined heavy fighter that was supposed to utilize French equipment: Hispano Suiza engines, instruments, and a landing gear to be delivered by OLA. French interest disappeared after several French designs subsequently appeared. Fokker however thought the design had potential and continued development on their own initiative as “Project 129”. The aircraft had a twin boom configuration, something which was not new, but which caused a great public sensation when first seen. In the fuselage there was room for both the crew and the aircrafts armament. The armament was in the nose: the prototype had 2x23mm Madsen cannon with 100 shells and 2x7.9mm machineguns with 550 cartridges, and was connected to the framework for the front of the central pod.

Like all Fokker aircraft of the period (and many aircraft constructed by other manufacturers at this time), the G1 was of mixed construction; the front of the central pod and the tail booms and tails were built around a frame of welded steel tubes covered with aluminium plating. The back of the central pod, however, as well as the wings, had a wooden frame, covered with triplex, a technique also used in Fokker's successful passenger aircraft at that time. The steel tubular frame was attached to the front wingspar. The many small windows in the rear part of the fuselage were made out of Perspex and hung in a Dural framework. The belly of the fuselage had two large doors with perspex windows, helpful for observation. There was also a bomb bay that could hold a 400 kg bombload. The rear part of the fuselage ended in a beautiful conical turret that could turn completely around its axis, giving the rear gunner a full 360 degree aim. The machine gun could be aimed by opening perspex panels running the full length of the turret. The wingspars went through the cockpit, right behind the pilot, and before the rear gunners compartment. 550 Liter fuel tanks with a reserve tank of of 150 liters were located in the wing, between the fuselage and the engine nacelles.

The wing edges, on both sides of the engine, contained the oil tanks. The outer parts of the wings were also made out of wood covered with triplex, glued together the same way Fokker used with their successful range of passenger planes and with plywood arches. All control flaps were made out of a Chromemolybdenum steel frame covered with linen. From the firewall on, the engine covers and struts were made out of aluminum. Directly behind the landing gear compartments the twin booms were again made of aluminum. The horizontal stabilizer, between the tail booms was also made out of aluminum and had the tail wheel in the middle, while the rudders were covered in canvas. The main landing gear was retractable into the engine nacelles.

Fokker decided to send the G1 to the Paris Air Show (which in those days did not have a flying display but only a static exhibition in the Grand Palais) even before its first flight, anticipating a lot of interest. His expectation was correct, with the G1 becoming the sensation of the show. The prototype was hung from the roof with steel cables between aircraft of the Polish and Russian manufacturers. The concept of a twin-boom twin-engined fighter, later adopted for the Lockheed P-38 Lightning, was quite revolutionary at the time, and the new aircraft was the centre of much critical appraisal. Interest was also generated as a result of the heavy armament of 8 machine guns in the nose. The G1 was given the nickname Le Faucheur (Mower) by the French and “Reaper” by the English, nicknames that pointed to the heavy armament in the nose. There is some doubt that the French came up with that name themselves; a lot of people think that Fokker made that name up himself. While the G1’s twin-engine, twin-boom design was also used for the Lockheed P-38 Lightning, conceived and designed around the same time, it is unlikely that the P-38 Lightning designed was derived from the slightly earlier Fokker G1 design.

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A truly remarkable similarity

After the Paris Air Show, the G1 was taken to Eindhoven/Welschap airfield, from where its first flight was made on 16 March 1937. A Czech pilot, Maresc, main test pilot for the Czechoslovakian government and senior pilot of the manufacturer Avia, made the maiden flight with the prototype (registration code X-2, and painted in green with medium blue belly). The flight went without flaws and after 20 minutes the pilot landed again. For the audience the G1 was a spectacularly promising plane that had minor problems. After 4 test flights this proved to be not quite so true. On the fifth test flight, problems occurred with one of the Hispano Suiza engines - due to overheating the engine broke down and threw several parts out through the exhaust pipes. Before this incident it was already well known that the Hispano engines were badly designed. One of the tail booms was also damaged.

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Fokker G1 Prototype X-2 in flight

The G1 was initially powered by two 559kW Hispano-Suiza 80-82 counter-rotating radial engines, but problems with these prototype units (they used too much oil) resulted in a change to similarly rated Pratt & Whitney SB4-G Twin Wasp Juniors during rebuilding (after the G1 suffered brake failure and rammed a hangar at Schiphol on 4 July 1937). A quick and dirty solution was to add extra oil coolers, placed underneath the engines. This solution was not very elegant and finally Fokker did choose another engine, the Pratt & Wittney Jr. SB4-G This engine produced less power but was much more reliable. For the Dutch Air Force, other engines were mounted; the more powerful Bristol Mercury VIII engines that where also used for the Fokker DXXI (this engine was specified as standard by the Dutch Air Force for all its aircraft). The aircraft design consequently had to be adjusted as the engines had a larger diameter and a different shape and the propellers were larger, meaning the engines had to be moved further away from the fuselage. The wider central wing meant that the fuel tank capacity could be increased.

The tail design was also slightly changed. The redesign incorprated higher landing gear to keep the propeller of the ground. These changes were incorporated in the X2 prototype which satisfied the LVA. Actually, the designers wished to replace the engines with Rolls-Royce Merlin engines (which would have made the G1 the fastest fighter in the air at the time), but those were not available for export from the UK. The design of the nose section of the G1 also caused problems. The armament chosen by the Dutch Air Force, 8 machine guns in the nose, caused the aircraft to become nose-heavy and made the plane difficult to manage during take-off and landing. Several G-1’s ground looped during landing and a good solution for this problem was not found although in 1939 there was a plan to give the G.1 a different setup. In this design modification, 4 of the machineguns were relocated to the bomb bay firing from underneath the pilot. In use with the Dutch, the machineguns also proved to be very unreliable, partly due to the low temperatures at high altitude. This sensitivity to subzero temperatures was partially resolved by using a different lubricant. Despite that the armament kept on causing problems; firing them on the ground was no problem, but in the air usually 2 or 3 of them jammed. This problem was not solved by the Dutch.

The Ilmavoimat Commander, Aarne Somervalo, expressed interest in buying one completed aircraft from Fokker together with a manufacturing license. It is not documented, but it is probable that Somervalo planned to perhaps switch the Bristol Blenheim manufacturing line over to the Fokker G1s. An Ilmavoimat team visited the Fokker factory in June 1937 and carried out a series of comprehensive test flights. Captain Gustaf Magnusson test flew the Fokker G1, reaching a speed of 650km/h (403.9mph), which attracted considerable attention in the local press. Ilmavoimat Captain Erkki Olavi Ehrnrooth also test flew the G1, although he damaged the booms and tail in an accident. The aircraft was repaired and Ehrnrooth flew more test flights. In his and Magnusson’s opinion, the G1 was a good aircraft, but would make a better fighter if the design was modified to focus on on this particular requirement and less on a multi-role fighter bomber.

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Fokker G1 being flown by Ilmavoimat Captain Erkki Olavi Ehrnrooth in June 1937 during the Ilmavoimat evaluation

Somervalo agreed – his major concern was the air defence of Finland against Soviet bombers and he saw the G1 meeting this need very effectively. He also saw the VL Wihuri filling this role, but at this stage the Wihuri was very much an unproven design – and by the time of these discussions the G1 was very much a real flying aircraft. Design modification discussions with Fokker took place in August 1937, resulting in a major redesign of the aircraft, the completion of an Ilmavoimat prototype in November 1937 followed by a further test series from which the results met or considerably exceeded all expectations. The Ilmavoimat placed an order for 15 Fokker G1’s in December 1937 and at the same time purchased an unlimited manufacturing license.

The modifications that the Ilmavoimat specified were that the Finnish G1’s were to be single-seaters, configured as a fighter-only, with no bomb bay (although inner-wing hard points for 22×500 lb or 4x250lb bombs were specified, giving the G1’s an effective ground attack capability), the fuselage size very considerably reduced as there would be no radio operator and no rear-gunner, with consequent substantial weight-savings. Also, the Finnish G1’s were to be powered by the more powerful Hispano Suiza 12Y engines (920 hp vs the 840hp Bristol Mercury or the 825hp Pratt & Whitney) engines which were starting to be built under license in Finland by the State Engine Factory (initially intended for the VL Wihuri) and were equipped with an additional fuel tank, increasing the range to some 1,300 miles. The considerably more powerful engines and the large weight reduction consequent on the aircraft being a single-seater with no bomb load and a substantially decreased fuselage pod increased the speed substantially, giving the aircraft a maximum speed of 340mph, making it one of the fastest fighters in the air at the time. The resultant aircraft looked very similar to the later Lockheed P-38 Lightning, indeed, the aircraft were almost indistinguishable when seen side by side. Finland specified that the aircraft would be shipped without the engines or armament– these would be installed in Finland with the assistance of Fokker technicians (the first aircraft completed was test flown from the factory with engines and armament shipped from Finland. Armament for the Finnish version consisted of 4x12.7mm forward-firing machine guns mounted in the nose together with 4x20mm Hispano Suiza cannon with 150 rounds each.

The reduction in size and weight of the fuselage, together with the massive nose-mounted armament, changed the centre of gravity of the aircraft to the extent that a nose-wheel was added to the Finnish aircraft. Clustering all the armament in the nose was also unlike most other Finnish fighter aircraft, which used wing-mounted guns with trajectories set up to crisscross at one or more points in a "convergence zone." Guns mounted in the nose did not suffer from having their useful ranges limited by pattern convergence, meaning good pilots could shoot much farther. A Fokker G1 could reliably hit targets at any range up to 1,000 yd (910 m), whereas other fighters had to pick a single convergence range between 100 and 250 yd (230 m). The clustered weapons had a "buzz saw" effect on any target at the receiving end, making the aircraft very effective for ground strafing as well.

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Ilmavoimat Fokker G1 – photo taken shortly after entering service with the Ilmavoimat in October 1938

The first six production G1s were received by the Ilmavoimat in October 1938 and, after fitting with the Finnish-license manufactured Hispano-Suiza engines and armament, were test flown in a series of exercises against other Finnish fighter aircraft. It was found that, while the Fokker G1 was not the most maneuverable fighter in the air, its sheer speed, particularly in a diving attack, combined with the devastating punch of its guns made it a fearsome foe when flown to maximize these advantages. While the G1 could not out-maneuver the Ilmavoimat’s single-engined fighters, its speed and rate of climb gave the pilots the option of choosing to fight or run, and in target shooting exercises, its focused firepower was found to be deadly. The concentrated, parallel stream of bullets allowed accurate shooting at much longer distances than fighters carrying wing guns. However, if faced by more agile fighters at low altitudes, G1s could suffer heavy losses and they could be avoided by opposing fighters because of the lack of dive flaps to counter compressibility in dives. Opposing fighter pilots not wishing to fight would perform the first half of a Split S and continue into steep dives because they knew the G1s would be reluctant to follow. On the positive side, having two engines was seen by the pilots as a built-in insurance policy, esecially after having an engine fail en route or in combat.

Two other problems were encounted in early exercises. The unique design feature of outwardly rotating counter-rotating propellers meant that losing one of the two engines on takeoff created a sudden drag, yawing the nose toward the dead engine and rolling the wingtip down on the side of the dead engine. Normal training in flying twin-engine aircraft when losing an engine on takeoff would be to push the remaining engine to full throttle; if a pilot did that in the G1, regardless of which engine had failed, the resulting engine torque and p-factor force produced a sudden uncontrollable yawing roll and the aircraft would flip over and slam into the ground (as happened with one early aircraft). Procedures were identified and taught to allow a pilot to deal with the situation by reducing power on the running engine, feathering the prop on the dead engine, and then increasing power gradually until the aircraft was in stable flight. Single-engine takeoffs were possible, though not with a maximum combat load. There were also early problems with cockpit temperature regulation: in the cold conditions of a Finnish winter and at high altitude, pilots were often too cold as the distance of the engines from the cockpit prevented easy heat transfer. VL made modifications to the heating system to try and solve this problem but it was never fully rectified.

However, despite these limitations and problems, the performance was seen as being exceptionally good, so good that the Ilmavoimat ordered a further 12 G1’s from Fokker in the first quarter of 1939 (after the initial shipment had been recieved) as it was taking time for the VL production line to switch over and come up to speed. All of the first batch of 15 G1s had all been shipped to Finland by December 1938. Finland had, as mentioned, also purchased a license to build the Ilmavoimat version of the Fokker G1 and, with a license for unlimited production and the designs in hand, had in early 1938 begun to switch the VL Blenheim production line over (it had been intended to construct the VL Wihuri’s, but the differences were so major that it made more sense to build a new assembly facility for the Wihuris and use the old Blenheim line for the Fokker G1s).

The first VL-built prototype flew in mid-1939 and the Finnish-built aircraft began entering service in late October 1939, with two per month initially rolling off the production line. Finnish built Hispano-Suiza engines, machine guns and cannon were fitted along with many fittings from the old Blenheim line (instrutments, wheel assemblies, etc) and the aircraft test flown. The first batch of 4 VL-built G1s were delivered to the Ilmavoimat in early January 1940, in the midst of the Winter War. These aircraft entered service, replacing combat losses and losses due to accidents (primarily due to engine-failure on takeoff and to ground-looping on landing, a problem which was never completely eliminated). A further batch of 6 aircraft was received in April 1940, entering service in time to replace further losses prior to the spring 1940 Offensive.

The second batch of 12 G1’s ordered from Fokker in March 1939 began to be shipped in July 1939. These later G1’s were fitted with the bubble canopy developed for the Ilmavoimat’s Miles M.20 Fighter and also with armour protection for the pilot as well as self-sealing fuel tanks. With the Soviet Union growing ever more threatening, the Molotov-Ribbentrop Pact of August 1939 (with the secret clauses relating to the Baltic States of which Finland was aware) and the invasion of Poland by both Germany and the Soviet Union in September 1939, the Ilmavoimat barely managed to have all 12 of the second batch ordered from Fokker in service before the Winter War broke out. At the same time, with the international situation growing more threatening and the Soviet Union putting more and more pressure on Finland in negotiations, the Ilmavoimat decided to purchase the earlier version of the Fokker G1’s that had been constructed for the Spanish Republican Air Force. These 12 Fokker G1’s were consequently shipped to Finland in July 1939. Performance was substantially less than the Hispano-Suizaienginned Fokker G1’s constructed for the Ilmavoimat, but the aircraft were delivered to AB Flygindustrie in Sweden, where they were substantially modified and re-engined into a similar configuration to the Finnish aircraft.

These 12 G1’s entered service in November 1939, along with the first two VL constructed G1 aircraft, meaning that the Ilmavoimat was able to field two squadrons (some 40 aircraft) of Fokker G1’s on the outbreak of the Winter War – and VL production, which started at 2 per month, had doubled to 4 per month by April 1940. By the end of the Winter War in September 1940, the Ilmavoimat fielded some 50 Fokker G1-I’s in total. The G1 continued to be built through WW2, with continuous improvements and modifications, including replacement of the Hispano-Suiza engines with newer and more powerful Merlins. Never receiving the publicity of the Lockheed P38 Lightning (and in fact often being mistaken for the P38 after Finland entered WW2 against Germany) it was as good a Fighter as its better known comrade and in the Winter War, was used with good effect to decimate both Soviet bombers and fighters.

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The Fokker G1 in ground-attack mode – with the ability to carry 2×500 lb or 4x250 lb bombs combined with its superlative nose-mounted battery of cannon and machineguns, the G1 was a lethal ground-attack fighter.

As delivered to the Ilmavoimat, the G1 Fighter flew with a single pilot and was powered by 2x1000hp Hispano-Suiza 12Y engines, had a maximum speed of 340 mph, a ceiling of 32,800 feet and a range of 1,300 miles. Armament consisted of 4xHispano 20mm cannon with 150 rounds each (2 AP, 2 tracer and 2 HE ammo belt composition) and 4x12.7mm Browning MG53-2 machineguns with 500rpg. The rate of fire was about 650 rounds per minute for the 20mm cannon round (130 g shell) at a muzzle velocity of about 2887 ft/s, and for the 12.7mm MGs (43–48 g), about 850 rpm at 2,756 ft/s velocity. The combined rate of fire was over 4,000 rpm with roughly every sixth projectile a 20 mm cannon shell. Time of firing for the 20 mm cannon and the 12.7mm machineguns were approximately 14 seconds and 35 seconds respectively. With more powerful engines, the Finnish G1’s could also carry an effective bombload when operating in a ground attack role. The Inner Hardpoints could carry 2×500 lb (227 kg) or 4x250 lb (113 kg) bombs.

OTL Note: The Fokker G1 Heavy Fighter is an interesting “might have been” that “almost was” as far as the Finnish Air Force was concerned. Finland actually ordered 26 of these aircraft, but construction was only partially completed before the outbreak of the Second World War. If they had been completed and delivered, they would have been a useful adjunct to the ilmavoimats front line fighter strength. The small number of Fokker G1’s that were in service with the Dutch Air Force (Luchtvaartafdeeling) certainly made an impact on the Luftwaffe in the limited air combat that took place after Germany invaded the Netherlands.

The Fokker G1 was a heavy twin-engined fighter plane comparable in size and role to the German Messerschmitt Bf 110 and the British Mosquito and somewhat similar in concept and appearance to the American Lockheed Lightning or Northrop Black Widow. Designed as an “air cruiser” (i.e. patrolling the air space and denying it to enemy planes, especially bombers; a role seen as important at the time by the followers of Giulio Douhet's theories on air power) the Fokker G.1 was a twin-boom, twin-engined fighter aircraft that could also be used for ground attack and light bombing missions (it could carry a bomb load of 400 kg). It was intended for a crew of two or three (a pilot, an optional bombardier/radio operator and a rear gunner).

With its heavy armament and clean lines, the G1 was the best aircraft the Netherlands Air Force had in May 1940. When Germany invaded the Netherlands on May 10, 1940, 23 of these G1’s were ready (12 with the 4th Fighter Group at Alkmaar and 11 with the 3rd Fighter Group at Rotterdam / Waalhaven), with four more R-1535-equipped aircraft originally intended for Spain also in services. The Germans were surprised by the ferocity of the supposedly docile Dutch. One advantage of small size is that the Belgian and Dutch aircrews tended to be of high quality - turnover of Air Force personnel was low, and as it was difficult to get into the air services, they developed into something of an elite. One enduring myth from the campaign is the destruction of the Dutch Air Force on the ground by the Luftwaffe at dawn on 10 May 1940. Only at Bergen airfield on the North Sea coast west and north of Amsterdam were the Dutch caught on the ground, where they lost a dozen of the new Fokker G1 fighters. This loss was bad enough, but at every other airfield, the Germans met a determined defence. The G1 squadron at Waalhaven got eight of its 11 aircraft into the air. The ensuing air battle proved to be one of the most lopsided of the whole battle of France. The Luftwaffe lost 13 aircraft shot down (eight bombers, three Messerschmitt fighters and two Ju52s). Just one G1 was lost (the tail gunner of this aircraft was killed by bomb splinters while running to his plane).

Noteworthy was the action of Lieutenant Bram van der Stok, based at De Kooy, during another of the largest dogfights of the first day. Eight Dutch Fokker D21s from De Kooy faced nine Messerschmitt Bf109Es from II(J)/TrGr186 (part of the air unit slated to serve on the never completed German aircraft carrier Graf Zeppelin). It was another surprise defeat for the ostensibly superior Germans. Although slower, the Dutch used the better manoeuvrability of the Fokker D21 to advantage. Five 109s were shot down, including the squadron leader’s machine, with another two damaged. The Dutch lost no aircraft. After May 1940, van der Stok escaped to Britain and flew Spitfires with the RAF until he was shot down and made a POW. He participated in the Great Escape from Stalag Luft III in March 1944, and became one of only three POWs to successfully get away. He eventually came to command No. 322 Squadron. In the film The Great Escape, his character was turned into an Aussie.

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Dutch Air Force (Luchtvaartafdeeling) Fokker G1 in action, WW2

Over the next five days, the Dutch Air Force fought a grim battle of attrition, heavily outnumbered and with only negligible aid from the French and British. Most action took place on 10 May, the first day, with more than 100 sorties. The Dutch faced alone the full onslaught of the whole of Luftflotte 2’s 600 combat aircraft (not counting the air transport fleet of 500 Ju52s). Managing only about 30 sorties on May 11, it looked as if the Dutch Air Force had collapsed, yet the next day close to 100 sorties were again mounted. The two single largest concentrations of Dutch aircraft, less than a dozen aircraft each, were seen on 12 May during the battle for the Grebbeberg, but this day proved to be the last gasp. Still, on the morning of 14 May, just before the capitulation of the Dutch Army, the Air Force was mounting defensive patrols, singly or in groups of two, three or four, with whatever could be scraped together, patched up and sent into the air: seven D.21s, four G.1s and a C.5

Of the Dutch Air Forces Fokker G1’s, one G1 squadron was almost completely destroyed on the ground, but the other scored thirteen confirmed kills. The Gls were successful in destroying several Junkers Ju 52/3ms during the early stages of the German invasion, but by the fifth day, when Dutch resistance ended, only one G1 was in fighting condition. Twelve were destroyed on the ground, nine were lost in battle and a Mercury and a Wasp were lost by accident. During attacks on German troops on the Grebbe-linie, several Fokker G1s successfully strafed the German lines while under very heavy anti aircraft fire. Dutch pilots had discovered they could evade the Luftwaffe fighters by flying very very low. This was called "HuBoBe" flying, which stands for Huisje Boompje Beestje, freely translated as: HouseTreeAnimal flying, because they would be so near the ground.

The Germans occupied the Fokker factory, ordering completion of 12 Gls that had been intended for Finland. These were used subsequently by the Luftwaffe as fighter trainers for Me-110 crews and for testing. There are no cases known of German G1’s participating in combat. Test flights from the factory were made under German supervision, but on 5 May 1941 two Dutch pilots (Leegstra and Vos) flying from Schipol on a test flight succeeded in evading an escorting German-flown G1 and escaped to England. Their G1B was taken to the Royal Aircraft Establishment, Farnborough, for examination, and used subsequently by Phillips and Powis (Miles Aircraft) at Reading for research into wooden construction, specifically to test the wooden wing for the English climate. A total of 62 G1’s are believed to have been built - none survived the war. Only a replica in the Dutch Air Force Museum in Soesterberg remains. There is no clear count of how many G1 's eventually fell into German hands. It can be assumed that several Dutch Mercury and many Wasp versions fell undamaged into German hands. It may also be assumed that a number of Danish aircraft were seized by the Germans as well as 20 of the aircraft that were to have been delivered to Finland. The Luftwaffe almost certainly had between twenty and thirty in service.

During the short development period of the test G1, a number of variations were explored. None of these came to fruition with the exception of the fitting of one G1 prototype with an observation dome under the fuselage. This was nicknamed the "Bathtub" and was not a success. However, Sweden, when they placed an order for the G1, ordered 12 of the aircraft with these observation domes. Besides the Netherlands Air Force, several foreign air forces also showed an interest in the G1. The aircraft was originally built to a French Air Force specification, but the French preferred French-built aircraft such as the Dewoitine D.520 or the Breguet 69 and did not, in the end, place orders for any G1’s. The Danish Air Force showed great interest in the aircraft as a dive bomber. To test this concept, the 302 prototype was equipped with dive brakes, similar to that of the Junkers Ju 87, and extensively tested. Denmark subsequently ordered 12 G1’s for use as dive bombers. These were to be built under license (a licence-production agreement was in negotiation when war broke out), and were not completed because of the German invasion, but were delivered in parts and subsequently captured by the Germans during Operation Weserübung before they could be assembled. (Just before the German invasion of Denmark, an order for a further 24 aircraft was placed. These additional aircraft were never delivered). The rest fell intact in German hands.

Overall, interested countries were: Spain (26 or 36 ordered, none delivered), Sweden (18 G1-A’s and a 77 machine manufacturing license ordered on 5 April 1940, none delivered and none built under the license), Estonia (9 ordered, none delivered), Finland (26 ordered, none delivered) as well as Belgium, Turkey, Hungary and Switzerland. Test Pilots from Finland, Sweden, Belgium and Turkey flew the aircraft. Licensing negotiations were also underway with Manfred Weiss in Hungary. Due to the German attack on the Netherlands, no aircraft were delivered to these countries. The Dutch embargo on weapons exports before World War II had killed the Spanish order (these aircraft were taken over by the LVA), but the Finnish batch was under construction when the Winter War broke out and a ban was then placed on its export. After lengthy negotiations a contract was drawn up to permit the G1B's export on 17 April 1940, by which time 12 had been completed, apart from armament. Swedish Air Force officer Bjorn Bjuggren wrote in his memoirs how he test-flew the aircraft in the late 1930s and found it tricky to use as a dive-bomber because of the difficulty in breaking out of the steep dive (the P-38 Lightning had similar problems breaking out of dives).

In the end, two versions were actually built: The first production G1’s were produced as a single-seat series for the Spanish Republican Air Force, who had ordered 26 or 36 aircraft (depending on the source). Construction of these aircraft began in the autumn of 1937, but the embargo on the sale of military equipment to Spain meant the delivery of the aircraft was halted before the aircraft left Fokker’s hands.After the final defeat of the Republicans in 1939, Estonia had decided to take over part of this order. Ten of the aircraft were assembled when Germany attacked the Netherlands and the Dutch Air Force took these over, although the Dutch had difficulties finding armament for these aircraft, eventually managing to arm only four of them where, from May 10 1940 on, they joined combat operations. Demonstrations had already been given to the Netherlands army air corps at Soesterberg, and considerable interest was shown, resulting at the end of 1937 in an order by the Dutch Luchtvaartafdeeling for 36 of the larger three-seat version G1s with Bristol Mercury VIII engines (the standard engine used by the Dutch air force), in order to equip two squadrons. This decision brought delays because although G1A production began immediately there was a hold-up in the supply of engines. Thus the first production aircraft to fly, actually the second of the batch, became airborne only on 11 April 1939. It remained with the makers for production testing and modifications, and the first aircraft was delivered to Soesterberg on 10 July 1939. Two versions were built: The G1A originally produced in series for Spain, and the larger G1B three-seat version for the Dutch airforce. In the end both types were used exclusively by the Dutch LVA. In total 62 were built.

Fokker offered Finland the G1-B machines which had been manufactured for the Spanish Air Force but Major General Lundqvist, commander of the Finnish Air Force, thought that the price was too high and delivery was suspended. After the Winter War broke out, the order was reinstituted. Fokker advised that they would be able to deliver 12 aircraft in a 4 to 5 month timeframe, with a further 6 aircraft in 6 months time. On the 2nd of February 1940, Lundqvist decided to abandon the order due to difficulty sourcing engines and propellors. The aircraft were instead sold to the Dutch Air Force.
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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A Medium Bomber for the Ilmavoimat in 1937……

Post by CanKiwi2 » 14 Jul 2011 16:49

A Medium Bomber for the Ilmavoimat in 1937…….

The plan for the 1937 procurement program made provision for the puchase of a single squadron of medium bombers for the Ilmavoimat (a further squadron was budgeted for in the 1939 program). As with other bomber purchases a strong emphasis was placed on low-altitude tactical bombing rather than “strategic” area bombing from high-altitude. Again and again Somervalo emphasised both to his “bomber” subordinates and to the General Staff that the Ilmavoimat did not have the resources to indulge in the fulfillment of unproven theories and such funding as was available should be concentrated on aircraft which could achieve accurate results, and to date that had only been achieved by low-level bombing strikes and by dive-bombing. As with other purchases over the last half of the 1930’s, the Ilmavoimat conducted a detailed evaluation and testing program – and again, this was for aircraft that were either in production or where prototypes had been completed and were undergoing testing.

As we have seen, in 1935 the Ilmavoimat had purchased 15 Savoia-Marchetti SM.81 bombers and prior to making the decision, had considered the Junkers Ju86, the designs for the Heinkel-111, the Dornier DO 13 and DO 23, the Bloch MB.200, the Potez 540, the Bristol Bombay, the Fairey Hendon, the designs for the Armstrong-Whitworth AW.23, the Handley Page Heyford, the Martin B-10 and the Caproni 122 bomber. In 1937, the Ilmavoimat was looking to purchase a further squadron of some 15-20 medium bombers and a number of the aircraft that had been only in the design stage in 1935 were looked at and evaluated as they were either available as prototypes or were actually beginning to enter production. Medium Bombers evaluated in 1937 included the Armstrong-Whitworth Whitley (UK), Bloch MB.210 (France), CANT Z.1007 (Italy), Fiat BR.20 Medium Bomber (Italy), Handley Page Hampden (UK), Heinkel He111 (Germany), Junkers Ju88 (Germany), Lioré-et-Olivier LeO 45 (France), PZL.37 Łoś (Poland), Savoia-Marchetti SM.79 (Italy) and the Vickers Wellington (UK).

Evaluation criteria heavily emphasized the ability to operate off rough airfields, good speed, manouverability and range, bombload and of course, cost and availability (with an emphasis on certainty of delivery). “Tactical” capability, as opposed to “strategic bombing” was emphasised heavily. The Ilmavoimat under the leadership of Major-General Somervalo had always emphasised support for the Maavoimat – and this was increasingly emphasised through the last half of the 1930s. Two distinct schools of aerial warfare had emerged after WW1 in the writings of air warfare theorists: tactical air warfare and strategic air warfare. Tactical air warfare was developed as part of a combined-arms attack which would be developed to a significant degree by Germany, and which contributed much to the success of the Wehrmacht during the first four years (1939–42) of World War II. The German Luftwaffe became a major element of the German blitzkrieg.

Three of the leading theorists of strategic bombing during this inter-war period were the Italian Giulio Douhet, the Trenchard school in Great Britain, and General Billy Mitchell in the USA. These theorists thought that aerial bombardment of an enemy's homeland would be an important part of future wars. Not only would such attacks weaken the enemy by destroying important military infrastructure, they would also break the morale of the civilian population, forcing their government to capitulate. Although area bombing theorists acknowledged that measures could be taken to defend against bombers – using fighter planes and antiaircraft artillery), the maxim of the times remained "the bomber will always get through". These theorists for strategic bombing argued that it would be necessary to develop a fleet of strategic bombers during peacetime, both to deter any potential enemy, and also in the case of a war, to be able to deliver devastating attacks on the enemy industries and cities while suffering from relatively few friendly casualties before victory was achieved.

Douhet's proposals were hugely influential amongst most airforce enthusiasts, arguing as they did that the bombing air arm was the most important, powerful and invulnerable part of any military. He envisaged future wars as lasting a matter of a few weeks. While each opposing Army and Navy fought an inglorious holding campaign, the respective Air Forces would dismantle their enemies' country, and if one side did not rapidly surrender, both would be so weak after the first few days that the war would effectively cease. Fighter aircraft would be relegated to spotting patrols, but would be essentially powerless to resist the mighty bombers. In support of this theory he argued for targeting of the civilian population as much as any military target, since a nation's morale was as important a resource as its weapons. Paradoxically, he suggested that this would actually reduce total casualties, since "The time would soon come when, to put an end to horror and suffering, the people themselves, driven by the instinct of self-preservation, would rise up and demand an end to the war..." As a result of Douhet's proposals many airforces allocated greater resources to their bomber squadrons than to their fighters, and the 'dashing young pilots' promoted in propaganda of the time were invariably bomber pilots.

Pre-war planners, on the whole, vastly overestimated the damage bombers could do, and underestimated the resilience of civilian populations. The speed and altitude of modern bombers, and the difficulty of hitting a target while under attack from improved ground fire and fighters which had yet to be built was not appreciated. Jingoistic national pride played a major role: for example, at a time when Germany was still disarmed and France was Britain's only European rival, Trenchard boasted, "the French in a bombing duel would probably squeal before we did". At the time, the expectation was any new war would be brief and very savage. A British Cabinet planning document in 1938 predicted that, if war with Germany broke out, 35% of British homes would be hit by bombs in the first three weeks. (This type of expectation should be kept in mind when considering the conduct of the European leaders who appeased Hitler in the late 1930s.). Douhet's theories were successfully put into action in Mesopotamia (modern-day Iraq) where RAF bombers used conventional bombs, gas bombs, and strafed forces identified as engaging in guerrilla uprisings. Arthur Harris, a young RAF squadron commander (later nicknamed "Bomber" Harris), reported after a mission in 1924, "The Arab and Kurd now know what real bombing means, in casualties and damage. They know that within 45 minutes a full-sized village can be practically wiped out and a third of its inhabitants killed or injured."

In Finland, the Ilmavoimat under Major-General Somervalo focused on practicalities, the first of which being that while “strategic” bombing was all very good in theory, the only enemy that Finland faced was the USSR and there was absolutely no possibility that the Ilmavoimat could ever, in its wildest daydreams, build a large enough bomber fleet to conduct an effective strategic bombing campaign against one of the largest and most powerful nations in the world. The second practicality was that ongoing Ilmavoimat trials with the SM.81’s had proven to (almost) everyone’s satisfaction that Douhet’s vision of strategic bombers pounding targets to rubble was incapable of being achieved – accuracy was minimal and from high altitude there was almost no chance of hitting a specific target – in trials, less that 7% of bombs dropped hit within 1,000 feet of their aiming point. In one series of bombing tests from 15,000 feet altitude in good visibility, it took 108 bomber missions dropping 650 bombs in total to achieve 2 hits inside a 400 by 500 ft area. Empiracally, the Ilmavoimat found that very low altitude bombing resulted in very significantly improved accuracy – and that the Curtiss Helldivers and Hawker Harts used as divebombers achieved the highest accuracy (this is something that we’ll explore in a lot more detail when we get to looking at Ilmavoimat doctrine and tactics).

Consequently, in 1937 when looking for a medium bomber, this was where the emphasis was very strongly put. The Ilmavoimat’s bomber force was small – resources could not afford to be wasted and what was wanted was, as has been mentioned above, the ability to operate off rough airfields, good speed, manouverability and range, bombload, cost and availability (with an emphasis on certainty of delivery) and a high level of “Tactical bombing” capability.
The initial shortlist for evaluation consisted of the following aircraft: Armstrong-Whitworth Whitley (UK), Bloch MB.210 (France), CANT Z.1007 (Italy), Fiat BR.20 Medium Bomber (Italy), Handley Page Hampden (UK), Heinkel He111 (Germany), Junkers Ju88 (Germany), Lioré-et-Olivier LeO 45 (France), PZL.37 Łoś (Poland), Savoia-Marchetti SM.79 (Italy) and the Vickers Wellington (UK).

Does anyone have any other suggestions on aircraft to be evaluated that aren’t listed here?
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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B-18 Bolo

Post by CanKiwi2 » 14 Jul 2011 17:28

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ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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A Medium Bomber for the Ilmavoimat - 1937

Post by CanKiwi2 » 15 Jul 2011 21:30

A Medium Bomber for the Ilmavoimat in 1937…….

The plan for the 1937 procurement program made provision for the puchase of a single squadron of medium bombers for the Ilmavoimat (a further squadron was budgeted for in the 1939 program). As with other bomber purchases a strong emphasis was placed on low-altitude tactical bombing rather than “strategic” area bombing from high-altitude. Again and again Somervalo emphasised both to his “bomber” subordinates and to the General Staff that the Ilmavoimat did not have the resources to indulge in the fulfillment of unproven theories and such funding as was available should be concentrated on aircraft which could achieve accurate results, and to date that had only been achieved by low-level bombing strikes and by dive-bombing. As with other purchases over the last half of the 1930’s, the Ilmavoimat conducted a detailed evaluation and testing program – and again, this was for aircraft that were either in production or where prototypes had been completed and were undergoing testing.

As we have seen, in 1935 the Ilmavoimat had purchased 15 Savoia-Marchetti SM.81 bombers and prior to making the decision, had considered the Junkers Ju86, the designs for the Heinkel-111, the Dornier DO 13 and DO 23, the Bloch MB.200, the Potez 540, the Bristol Bombay, the Fairey Hendon, the designs for the Armstrong-Whitworth AW.23, the Handley Page Heyford, the Martin B-10 and the Caproni 122 bomber. In 1937, the Ilmavoimat was looking to purchase a further squadron of some 15-20 medium bombers and a number of the aircraft that had been only in the design stage in 1935 were looked at and evaluated as they were either available as prototypes or were actually beginning to enter production. Medium Bombers evaluated in 1937 included the Armstrong-Whitworth Whitley (UK), Bloch MB.210 (France), CANT Z.1007 (Italy), Fiat BR.20 Medium Bomber (Italy), Handley Page Hampden (UK), Heinkel He111 (Germany), Junkers Ju88 (Germany), Lioré-et-Olivier LeO 45 (France), PZL.37 Łoś (Poland), Savoia-Marchetti SM.79 (Italy) and the Vickers Wellington (UK).

Evaluation criteria heavily emphasized the ability to operate off rough airfields, good speed, manouverability and range, bombload and of course, cost and availability (with an emphasis on certainty of delivery). “Tactical” capability, as opposed to “strategic bombing” was emphasised heavily. The Ilmavoimat under the leadership of Major-General Somervalo had always emphasised support for the Maavoimat – and this was increasingly emphasised through the last half of the 1930s. Two distinct schools of aerial warfare had emerged after WW1 in the writings of air warfare theorists: tactical air warfare and strategic air warfare. Tactical air warfare was developed as part of a combined-arms attack which would be developed to a significant degree by Germany, and which contributed much to the success of the Wehrmacht during the first four years (1939–42) of World War II. The German Luftwaffe became a major element of the German blitzkrieg.

Three of the leading theorists of strategic bombing during this inter-war period were the Italian Giulio Douhet, the Trenchard school in Great Britain, and General Billy Mitchell in the USA. These theorists thought that aerial bombardment of an enemy's homeland would be an important part of future wars. Not only would such attacks weaken the enemy by destroying important military infrastructure, they would also break the morale of the civilian population, forcing their government to capitulate. Although area bombing theorists acknowledged that measures could be taken to defend against bombers – using fighter planes and antiaircraft artillery), the maxim of the times remained "the bomber will always get through". These theorists for strategic bombing argued that it would be necessary to develop a fleet of strategic bombers during peacetime, both to deter any potential enemy, and also in the case of a war, to be able to deliver devastating attacks on the enemy industries and cities while suffering from relatively few friendly casualties before victory was achieved.

Douhet's proposals were hugely influential amongst most airforce enthusiasts, arguing as they did that the bombing air arm was the most important, powerful and invulnerable part of any military. He envisaged future wars as lasting a matter of a few weeks. While each opposing Army and Navy fought an inglorious holding campaign, the respective Air Forces would dismantle their enemies' country, and if one side did not rapidly surrender, both would be so weak after the first few days that the war would effectively cease. Fighter aircraft would be relegated to spotting patrols, but would be essentially powerless to resist the mighty bombers. In support of this theory he argued for targeting of the civilian population as much as any military target, since a nation's morale was as important a resource as its weapons. Paradoxically, he suggested that this would actually reduce total casualties, since "The time would soon come when, to put an end to horror and suffering, the people themselves, driven by the instinct of self-preservation, would rise up and demand an end to the war..." As a result of Douhet's proposals many airforces allocated greater resources to their bomber squadrons than to their fighters, and the 'dashing young pilots' promoted in propaganda of the time were invariably bomber pilots.

Pre-war planners, on the whole, vastly overestimated the damage bombers could do, and underestimated the resilience of civilian populations. The speed and altitude of modern bombers, and the difficulty of hitting a target while under attack from improved ground fire and fighters which had yet to be built was not appreciated. Jingoistic national pride played a major role: for example, at a time when Germany was still disarmed and France was Britain's only European rival, Trenchard boasted, "the French in a bombing duel would probably squeal before we did". At the time, the expectation was any new war would be brief and very savage. A British Cabinet planning document in 1938 predicted that, if war with Germany broke out, 35% of British homes would be hit by bombs in the first three weeks. (This type of expectation should be kept in mind when considering the conduct of the European leaders who appeased Hitler in the late 1930s.). Douhet's theories were successfully put into action in Mesopotamia (modern-day Iraq) where RAF bombers used conventional bombs, gas bombs, and strafed forces identified as engaging in guerrilla uprisings. Arthur Harris, a young RAF squadron commander (later nicknamed "Bomber" Harris), reported after a mission in 1924, "The Arab and Kurd now know what real bombing means, in casualties and damage. They know that within 45 minutes a full-sized village can be practically wiped out and a third of its inhabitants killed or injured."

In Finland, the Ilmavoimat under Major-General Somervalo focused on practicalities, the first of which being that while “strategic” bombing was all very good in theory, the only enemy that Finland faced was the USSR and there was absolutely no possibility that the Ilmavoimat could ever, in its wildest daydreams, build a large enough bomber fleet to conduct an effective strategic bombing campaign against one of the largest and most powerful nations in the world. The second practicality was that ongoing Ilmavoimat trials with the SM.81’s had proven to (almost) everyone’s satisfaction that Douhet’s vision of strategic bombers pounding targets to rubble was incapable of being achieved – accuracy was minimal and from high altitude there was almost no chance of hitting a specific target – in trials, less that 7% of bombs dropped hit within 1,000 feet of their aiming point. In one series of bombing tests from 15,000 feet altitude in good visibility, it took 108 bomber missions dropping 650 bombs in total to achieve 2 hits inside a 400 by 500 ft area. Empiracally, the Ilmavoimat found that very low altitude bombing resulted in very significantly improved accuracy – and that the Curtiss Helldivers and Hawker Harts used as divebombers achieved the highest accuracy (this is something that we’ll explore in a lot more detail when we get to looking at Ilmavoimat doctrine and tactics).

Consequently, in 1937 when looking for a medium bomber, this was where the emphasis was very strongly put. The Ilmavoimat’s bomber force was small – resources could not afford to be wasted and what was wanted was, as has been mentioned above, the ability to operate off rough airfields, good speed, manouverability and range, bombload, cost and availability (with an emphasis on certainty of delivery) and a high level of “Tactical bombing” capability.
The initial shortlist for evaluation consisted of the following aircraft: Armstrong-Whitworth Whitley (UK), Bloch MB.210 (France), CANT Z.1007 (Italy), Fiat BR.20 Medium Bomber (Italy), Handley Page Hampden (UK), Heinkel He111 (Germany), Junkers Ju88 (Germany), Lioré-et-Olivier LeO 45 (France), PZL.37 Łoś (Poland), Savoia-Marchetti SM.79 (Italy) and the Vickers Wellington (UK).

The Douglas B-18 Bolo, North American Aviation XB-21 Dragon and Vickers Wellesley were subsequently added to the evaluation and testing program.

The Armstrong-Whitworth Whitley (UK):

The Armstrong Whitworth A.W.38 Whitley was one of three British twin-engine, front line medium bomber types in service with the Royal Air Force at the outbreak of WW2 (the others were the Vickers Wellington and the Handley Page Hampden). The Whitley was designed by John Lloyd, the Chief Designer of Armstrong Whitworth Aircraft to meet Air Ministry Specification B.3/34 issued in 1934 for a heavy night bomber. The Whitley carried a crew of five and was the first aircraft serving with the RAF to have a (semi ) monocoque fuselage, utilizing a slab-sided structure which eased production. As Lloyd was unfamiliar with the use of flaps on a large heavy monoplane, they were initially omitted. To compensate, the mid-set wings were set at a high angle of incidence (8.5°) to confer good takeoff and landing performance. Although flaps were included late in the design stage, the wing remained unaltered. As a result, the Whitley flew with a pronounced nose-down attitude resulting in considerable drag.

The first prototype Whitley Mk I (K4586) flew on 17 March 1936, piloted by Armstrong Whitworth's Chief Test Pilot Alan Campbell-Orde and was powered by two 795 hp (593 kW) Armstrong Siddeley Tiger IX radial engines. The second prototype was powered by more powerful Tiger XI engines. Owing to the urgent need to replace the old and increasingly obsolete biplane heavy bombers still in service with the RAF, an order for 80 aircraft was placed in 1935, "off the drawing board," before the Whitley had first flown. These had medium-supercharged engines and manual operated drum magazine single machine guns fore and aft. After the first 34 aircraft had been built, the engines were replaced with more reliable two-stage supercharged Tiger VIIIs, resulting in the Whitley Mk II, completing the initial order. The replacement of the manually operated nose turret with a powered Nash & Thomson turret and a powered retractable two-gun ventral "dustbin" turret resulted in the Whitley Mk III. The turret was hydraulically powered but it was hard to operate and added considerable drag.

Early marks of the Whitley had bomb bay doors - the eight bays were in fuselage compartments and wing cells - that were kept closed by bungee cords and opened by the weight of the released bombs falling on them. Even the tiny random delay in time that it took for the doors to open led to highly inaccurate bombing performance. To aim bombs, the bombardier ("Bomb Aimer" in RAF terminology) opened a hatch in the nose of the aircraft which extended the bombsight out of the fuselage. The bombardiers position was in the nose with the front gun turret above. The pilot and second pilot/navigator sat by side by side in the cockpit. The navigator rotated so that he could use the chart table behind his seat. Behind the pilots was the wireless operator. The fuselage aft of the wireless operator was divided horizontally by the bomb bay. Aft of the bomb bay was the main entrance and aft of that the rear turret. The Whitley first entered service with No. 10 Squadron in March 1937 replacing Handley Page Heyford biplanes

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The Ilmavoimat evaluated the Whitley MkII in early 1937. The Whitley operatred with a Crew of 5 and was powered by 2 × two-stage supercharged Tiger VIII engines with a maximum speed of 230 mph, a range of 1,650 miles and a service ceiling of 26,000 feet. Armament consisted of machinegun in the nose and one in the tail. The Bomb load consisted of up to 7,000 lb (3,175 kg) of bombs in the fuselage and 14 individual cells in the wings, typically including 12 x 250lb bombs and 2 x500lb bombs. Individual bombs as heavy as 2,000lbs could be carried.

The Ilmavoimat evaluation team advised that the Whitley was designed from the start as a “night” bomber, and that it was hardly a modern looking aircraft with its slab-sided fuselage and prominent, jutting chin - and it also had a very distinctive nose-down flying attitude which added considerable drag and reduced performance. It was however, capable of carrying a very impressive bombload of 7,000lb. However, the Armstrong Siddeley Tiger engines were definitely unreliable and the defensive armament was poor. Performance was mediocre and it needed a considerable formed runway to take off. Flying the aircraft and performing tactical bombing missions at low altitude was assessed as being downright dangerous. Overall, the evaluation team rated the Whitley as completely unsuitable for use by the Ilmavoimat in the intended role.

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Armstrong Whitworth Whitley cutaway

The Bloch MB.210 (France):

The MB.210 derived from the Bloch MB.200 that the Ilmavoimat had evluated in 1935 and differed from its predecessor by its more deeply-set, cantilever wing and its retractable undercarriage. Developed as a private venture, the prototype MB.210 completed its first flight on 23 November 1934, powered by two 596 kW (800 hp) Gnome-Rhône 14Kdrs/grs air-cooled radial engines. This was followed by a second prototype, the MB.211 Verdun, powered by 641 kW (860 hp) Hispano-Suiza 12Y V-12 liquid-cooled inlines and fitted with a retractable undercarriage, this flying on 29 August 1935. Initial flight testing of this version was somewhat disappointing, so no further examples were built. Further progress with the MB.210, however, convinced the Armée de l'Air to order series production, the first example of which flew on 12 December 1936. The satisfaction did not last very long, however, since it was underpowered and the engines of production aircraft were inclined to overheating. The type was grounded until its engines could be replaced by the more powerful and reliable Gnome-Rhône 14N, these engines first being tested in summer 1937 and had to be replaced. Altogether, 257 units were manufactured amongst companies as diverse as Les Mureaux over Potez-CAMS, Breguet, Hanriot, and Renault.

The Ilmavoimat evaluated the MB.200 as well as the MB.210 and MB.211 prototypes, but considered them no improvement on the MB.200 evaluated in 1935 – indeed, they considred them even more obsolete and ineffective than they were in 1935. The fact that the French were equipping some 12 bomber units with 250 of these already obsolete (in the opinion of the team at least) aircraft caused the Ilmavoimat evaluation team to question whether they should even look at any further French aircraft.

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With a crew of 5, maximum speed of 200mph, a range of 1,056 miles, a service ceiling of 32,480 feet and a bombload of 3,520 lbs, the Bloch MB.210 was very much a design inspired by the Douhet doctrine of strategic bombing.

The Ilmavoimat evaluation team also expressed considerable concern about the ability of the French aircraft industry to delivery on any order placed. The French air force had begun a serious rearmament program in 1934 “Plan I”), which called for the production of 1,343 new aircraft. However, in the mid 1930s, the French aircraft industry was more one of scattered and disjointed complexes rather than a cohesive and capable structure. Up to forty organizations had input into nearly all aspects of aircraft design, development and production, while at the same time competing for the designated funding. As it existed in 1937, France’s aircraft industry was not structured to handle large orders and delays ere having a seriously adverse effect on the air force’s rearmament effort. Because of these organizational and structural issues, most of France’s military aircraft of the late 1930s emerged through a narrow technological window. It was a bottleneck which prevented the newly developed aircraft from achieving peak technological capability thus making them obsolete before they even reached operational status.

The problem was compounded by the type of airplanes the French government began to order. Plan I called for the construction of multirole air platforms capable of performing as bombers, fighters and reconnaissance aircraft. Instead of building dedicated platforms, the French government invested in various single type planes. Such aircraft were indeed able to carry out, on a pedestrian basis, each of the various types of missions they were called for, but they could not to distinguish themselves in any single one of them. The decision to develop such platforms was a painful compromise between the Army, the newly formed Air Force and the government. Many inside the air force believed with passion in Giulio Douhet’s strategic theory which called for the destruction of the enemy’s economic strength by destroying its infrastructure while on the other hand, the Army’s senior commanders desired that the new air force serve as a supporting force for the Army rather than as an independent force of its own.

In September 1936, France had developed a new strategic plan, Plan II. Plan II was different from its predecessor in one major area. The new Plan called for the production of up to 1,339 dedicated bombers with a complement of 756 fighters of all types. This shifting in priority towards the bomber had its roots in the new Air Minister Pierre Cot’s passion for Douhet’s strategic vision. Unfortunately for France, Plan II had no more chance of success than its predecessor. Chaos ruled in nearly all French aircraft factories. The problem was accentuated by the Popular Front’s nationalization effort of the mid to late 1930s. As a result of those two factors, France’s aircraft production actually fell during these years. In the spring of 1937, French factories were producing an average of forty units per month. This was five aircraft per month less than in 1936, the year the Germans overtook France in the total number of available airframes. Regardless of the suitability or not of the aircraft, the Ilmavoimat evaluation team expressed strong reservations about the ability of the French aircraft industry to deliver any aircraft ordered with any degree of certainty as to delivery timeframes.

The CANT Z.1007 Alcione (“Kingfisher”) (Italy):

In 1935, Filippo Zappata, the chief designer of the Cantieri Aeronautici e Navali Triestini, designed two medium bombers, the twin-engined CANT Z.1011 and the three-engined CANT Z.1007. Both were to be powered by 619 kW (830 hp) Isotta-Fraschini Asso XI.RC inline engines and were of wooden construction. The Z.1007 design was preferred by both Zappata and the Italian Aviation Ministry, with an order for 18 aircraft being placed on 9 January 1936. A further order for 16 more aircraft followed on 23 February 1937, even before a prototype had been built. It had a crew of five, consisting of two pilots, a flight engineer, a radio operatior and a bombadier/navigator.

The Cant Z.1007 was developed from the Cant Z.506 seaplane, an aircraft that had established many world records in the late 1930s. It was a land-based version and incorporated many improvements, especially on the powerplant. The Z.1007 was a mid-winged monoplane with a retractable tailwheel undercarriage. It had a totally wooden structure, and a very clean shape that was much more aerodynamic than the competing SM.79. The Z.1007 had three engines, with one engine in the nose and two in the wings. The trimotor design was a common feature of Italian aircraft at the time. The aircraft had a slim fuselage as the two pilots sat in tandem rather than side-by-side as in most bombers of the period. Visibility was good and the aircraft was almost a "three-engine fighter" with a very narrow fuselage. This reduced drag, but also worsened the task of the two pilots. The aft pilot had reduced instruments and visibility, and so had difficulty flying and landing the machine if needed; he was almost an 'emergency' pilot. Like most trimotor Italian aircraft of the period the Z.1007 suffered from poor defensive armament, poor engine reliability, and poor power to weight ratio due to low powered engines. The Z.1007 also suffered longitudinal stability problems that were partly rectified later by the adoption of a twin tail arrangement.

The Z.1007 had a defensive armament of four machine guns: two 12.7 mm (.5 in) and two 7.7 mm (.303 in). The main defensive weapon was a Caproni-Lanciani Delta manually-powered Isotta-Fraschini dorsal turret armed with a 12.7 mm (.5 in) Scotti or Breda-SAFAT machine gun. The turret had a good field of fire, although it had blind spot behind the tail. The 12.7 mm (.5 in) Breda was a standard weapon for Italian bombers and the field of fire was improved by the twin-tail configuration on later models. An electrically-powered Breda V turret carrying a similar armament was substituted in late production aircraft. Another 12.7 mm (.5 in) was in the ventral position behind the bomb bay, with a field of fire restricted to the lower rear quadrant of the aircraft. There were also two waist positions equipped with 7.7 mm (.303 in) Breda machine guns, with 500 rpg. Only one of the waist guns could be used at a time since the gunner for this position manned both guns.

The Z.1007 had a horizontal bomb bay which could carry a 1,200 kg (2,650 lb) bombload. Many other Italian aircraft had vertical bomb bays which not only limited accuracy, but also limited the size of bombs carried internally. There were also a pair of under-wing hard points which could carry up to 1,000 kg (2,200 lb) of bombs, giving the Z.1007 a potential 2,200 kg (4,900 lb) payload (to a maximum range of 640 km/400 mi), but the norm was 1,200 kg and 1,000 km range. The Z.1007's external hardpoints were a rarity in the bombers of the Regia Aereonautica. The Z.1007 could also carry two 454 mm (17.7 in), 800 kg (1,760 lb) torpedoes slung externally under the belly in an anti-shipping role, an option which was never used in Italian service. The bombardier's nacelle was near the wings, just below the pilot. This improved the layout compared to the SM.79, where the nacelle was almost in the tail section, with the double task of being a defence position with a machine gun mounted there.

The first prototype flew in March 1937, proving superior to the Z.1011, with its handling and manoeuvrability being praised. Its performance, however, was lower than predicted, and Zappata therefore started a major redesign of the Z.1007, production of the initial version being limited to the existing orders placed before the prototype flew. However, this was the aircraft that the Ilmavoimat evaluated. Major concerns were the poor power to weight ratio due to the low powered engines. The test pilots also expressed concerns about the longitudinal stability problems that had resulted in Zapatta beginning a redesign. These concerns were sufficient to ensure that the Ilmavoimat dropped the aircraft from further consideration.

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OTL Note: After much experimentation with the prototype, the production aircraft were fitted with annular radiators so their profile was similar to radial engines that would be fitted to the improved later versions. It had "excellent flying characteristics and good stability.” Delivery of production Asso powered Z.1007s started in February 1939, with production ending in October that year. The first Asso-powered Z.1007s were used to equip the 50° Gruppo of the 16° Stormo (i.e. the 50° Gruppo of the 16° Stormo) from May 1939. The Asso powered bombers were not considered suitable for operational use, however, owing to the unreliability of their and high maintenance requirements, while their defensive armament was considered inadequate. They were therefore used as trainers.

Zappata had, meanwhile, continued the development of a considerably changed version, the Z.1007bis , to resolve the problems with the original aircraft. While the new version was of similar layout, it was effectively a completely new design. Three Piaggio P.XI RC.40 radial engines, a derivative of the French Gnome-Rhône 14K) of 736 kW (986 hp) takeoff power replaced the less powerful and unreliable liquid cooled engines of the original version. The bis was longer with wings of greater span and area, while the aircraft was considerably heavier, weighing 580 kg (1,280 lb) more unladen, with a maximum takeoff weight 888 kg (1,960 lb) greater, while it carried heavier offensive and defensive armament. The prototype bis first flew in July 1939, with testing proving successful, with the Z.1007bis being ordered into large scale production, with deliveries of pre-production aircraft starting late that year.


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Cant Z.1007 “Alcione”s over Greece.

When Italy entered World War II on 10 June 1940, the Regia Aeronautica had two Stormi equipped with the "Alcione". One was the 16°, with 31 aircraft, equipped with the Isotta Fraschini engine and so declared "non bellici", "not suitable for war." The 47° Stormo had just received four CANT bis. The "Alcione" had its baptism of fire on 29 August 1940 when they began to be used for attacks on Malta, they were later involved in the attack on Greece, and then in the later stages of the Battle of Britain and after that, against Yugoslavia. Later in WW2 the Z.1007s were used mainly as night bombers and reconnaissance, they were also used for long range reconnaissance, with excellent results. Some, at least 20, were equipped with an auxiliary tank that gave 1,000 km (620 mi) extra endurance. Some were adapted for flare drops when day missions were too dangerous.

The Caproni Ca.135 (Italy)

General Valle (Chief of Staff of the Regia Aeronautica) initiated the "R-plan" - a program designed to modernize Italy's air force, and to give it a strength of 3,000 aircraft by 1940. In late 1934 a competition was held for a bomber with the following specifications: A speed of 210 mph) at 14,800 ft and 239 mph at 16,000 ft), a range: of 620 miles with a 2,600 lb bombload and a ceiling of 26,000 feet. The ceiling and range specifications were not met, but the speed was exceeded by almost all the machines entered. At the end of the competition, the "winners" were the Ca.135 (with 204 aircraft ordered), the Fiat BR.20 (204 aircraft ordered), the Piaggio P.32 (144 aircraft ordered), the Savoia-Marchetti SM.79 (96 ordered), the CANT Z.1007 (49 ordered), and the Piaggio P.32 (12 ordered). This array of aircraft was proof of the anarchy, clientelarism, and inefficiency that afflicted the Italian aviation industry. Worse was the continuous waste of resources by the Regia Aeronautica (Italian Royal Air Force). Orders were given for aircraft that were already obsolete. The winners of the competition were not always the best - the BR.20 was overlooked in favour of the SM.79, an aircraft which was not even entered in the competition.

The Caproni Ca.135 was an Italian medium bomber designed by Cesare Pallavicino of CAB (Caproni Aereonautica Bergamasca). The Ca.135 was to be built at Caproni's main Taliedo factory in Milan. However, the project was retained at Ponte San Pietro and the prototype, completed over 1934-35, (a long construction time for the period), was first flown on 1 April 1935. The new bomber resembled the Caproni Ca.310, with its rounded nose, two engines, low-slung fuselage and wings with a very long chord. Several versions were fitted with different engines and some had noticeable performance differences. The prototype was powered by two 623 kW (835 hp) (at 4,000 m/13,123 ft) Isotta-Fraschini Asso XI.RC radial engines initially fitted with two bladed wooden propellers. Structurally, it was built of mixed materials, with a stressed-skin forward fuselage and a wood and fabric-covered steel-tube rear section; the wings being of metal and wood, using fabric and wood as a covering. The wings were more than ⅓ of the total length, and had two spars of wooden construction, covered with plywood and metal. The tail surfaces were built of wood covered with metal and plywood. The fuel system, with two tanks in the inner wings, held a total of 2,200 L (581 US gal).

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Caproni Ca 135 Prototype

The Ca.135's fuselage shape was quite different from, for example, that of the Fiat BR.20. If the latter resembled the American B-25 Mitchell, the Ca.135, with its low fuselage more resembled the American B-26 Marauder. Its long nose accommodated the bomb-aimer (bombardier) and a front turret (similar to the Piaggio P.108 and later British bombers). The front part of the nose was detachable to allow a quick exit from the aircraft. It also had two doors in the cockpit roof, giving the pilots the chance to escape in an emergency. The right-hand seat could fold up to assist entry to the nose. A single 12.7 mm (0.5 in) machinegun in a turret in mid-fuselage, was manned by the co-pilot. A seat for the flight engineer was later fitted. The wireless operator's station, in the aft fuselage, was fitted with the AR350/AR5 (the standard for Italian bombers), a radiogoniometer (P63N), an OMI AGR.90 photographic-planimetric machine or the similar AGR 61. The aircraft was also equipped with an APR 3 camera which although not fixed, was normally operated through a small window. The wireless operator also had a 12.7 mm (0.5 in) machine gun in the ventral position. All this equipment made him very busy; as a result, an extra man was often carried. The aircraft had very wide glazed surfaces in the nose, cockpit, and the central and aft fuselage; much more than in other Italian aircraft.

Overall, the aircraft was fitted with three machine guns, of 12.7 mm (0.5 in) calibre in the turrets, and a 7.7 mm (0.303 in) calibre gun in the nose. All had 500 rounds, except the 7.7 mm (0.303 in) which had 350. Bombload, like most Italian bombers, was less than impressive in terms of total weight, but was relatively flexible, depending on the role - from anti-ship to close air support and a maximum 4,105lb bombload could be carried – or alternatively 2 × torpedoes (never used, but hardpoints were fitted). The aircraft was underpowered, with a maximum speed of 226 mph at 14,800 ft and a high minimum speed of 81 mph (there were no slats, and maybe not even flaps). The Service Ceiling was only 20,000 ft and the endurance, at 70% of throttle, was 990 miles. All-up weight was too high, with total of 819,240 lb, not the 16,260 lb expected.

The total payload was shared between the crew, weapons, radios and other equipment, fuel, oil, oxygen and bombs. There was almost no chance of carrying a full load of fuel with the maximum bombload. The lack of power made take-offs when over-loaded, impossible. Indeed, even with a normal load, take-offs were problematic. Take-off and landing distances were 418 m (1,371 ft) and 430 m (1,410 ft). The range was good enough to assure 2,200 km (1,400 mi) with 550 kg (1,210 lb) and 1,200 km (750 mi) with 1,200 kg (2,650 lb). The ear;y production version was fitted with two inline liquid-cooled Asso XI RC.40 engines, each giving 671 kW (900 hp) at 4,000 m (13,120 ft). Aerodynamic drag was reduced, with three-bladed metal propellers that were theoretically more efficient. These new engines gave the aircraft a maximum speed of 400 km/h (250 mph) at 4,000 m (13,120 ft). It could climb to 2,000 m (6,560 ft) in 5.5 minutes, 4,000 m (13,120 ft) in 12.1 minutes and 5,000 m (16,400 ft) in 16.9 minutes.

Despite this, the aircraft was still underpowered. The aircraft evaluated by the Ilmavoimat yawed to the right on take-off, had poor lateral stability; the engines (from comments made by the Italian pilots) were unreliable in service, and the bombers suffered a excessive number of oil and hydraulic leaks during testing. The Ca 135 was also assessed as being dangerously underpowered and lacking in defensive armament. As a result, the test team made strong recommendations against this aircraft.

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Caproni Ca 135

The Douglas B-18 Bolo (USA):

In 1934, the United States Army Air Corps put out a request for a bomber with double the bomb load and range of the Martin B-10, which was just entering service as the Army's standard bomber. In the evaluation at Wright Field the following year, Douglas showed its DB-1. It competed with the Boeing Model 299 (later the B-17 Flying Fortress) and Martin Model 146. While the Boeing design was clearly superior, the crash of the B-17 prototype (caused by taking off with the controls locked) removed it from consideration. During the depths of the Great Depression, the lower price of the DB-1 ($58,500 vs. $99,620 for the Model 299) also counted in its favor. The Douglas design was ordered into immediate production in January 1936 as the B-18. The initial contract called for 133 B-18s (including DB-1), using Wright R-1820 radial engines. The last B-18 of the run, designated DB-2 by the company, had a power-operated nose turret. This design did not become standard. An additional contract was placed in 1937 for a further 177 aircraft.

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The DB-1 design was essentially that of the DC-2, with several modifications. The wingspan was 4.5 ft (1.4 m) greater. The fuselage was deeper, to better accommodate bombs and the six-member crew; the wings were fixed in the middle of the cross-section rather than to the bottom, but this was due to the deeper fuselage. Added armament included nose, dorsal, and ventral gun turrets. Production B-18s, with full military equipment fitted, had a maximum speed of 217 mph, cruising speed of 167 mph, and combat range of 850 miles. The Bolo carried a 4,400lb bombload and was armed with 3 × .30 in (7.62 mm) machine guns.

The Ilmavoimat evaluation team considered the Bolo soundly designed and built but underpowered, carrying too small a bomb load and with limited defensive armament. The aircraft remained in consideration however.

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One thing that was evident to the Ilmavoimat Team was that Douglas would certainly be able to fulfill any orders placed. The manufacturing facilities were impressive!

The Fiat BR.20 Medium Bomber (Italy):

In 1934, Regia Aeronautica requested Italian aviation manufacturers to submit proposals for a new medium bomber; the specifications called for speeds of 330 km/h (205 mph) at 4,500 m (15,000 ft) and 385 km/h (239 mph) at 5,000 m (16,400 ft), a 1,000 km (620 mi) range and 1,200 kg (2,600 lb) bombload. Although Piaggio, Macchi, Breda, Caproni and Fiat offered aircraft that mainly exceeded the speed requirements (but not range), not all exhibited satisfactory flight characteristics or reliability. Accepted among the successful proposals, together with the trimotor Savoia-Marchetti SM.79 and Cant Z.1007, was the Fiat BR.20 Cicogna designed by Celestino Rosatelli, thus gaining the prefix BR, (for "Bombardiere Rosatelli"). The BR.20 was designed and developed quickly, with the design being finalised in 1935 and the first prototype (serial number M.M.274) flown at Turin on 10 February 1936. Production orders were quickly placed, initial deliveries being made to the Regia Aeronautica in September 1936. When it entered service in 1936 it was the first all-metal Italian bomber and it was regarded as one of the most modern medium bombers available anywhere.

The BR.20 was a twin-engine low-wing monoplane, with a twin tail and a nose separated into cockpit and navigator stations. Its robust main structure was of mixed-construction; with a slab-sided fuselage of welded steel tube structure having duralumin skinning of the forward and centre fuselage, and fabric covering the rear fuselage. The 74 m² (796 ft²) metal-skinned wings had two spars and 50 ribs (also made of duralumin), with fabric-covered control surfaces. The hydraulically actuated main undercarriage elements retracted into the engine's nacelles, and carried 106 x 375 x 406 mm wheels. The takeoff and landing distances were quite short due to the low wing loading, while the thickness of the wing did not compromise the aircraft's speed. The twin tail allowed a good field of fire from the dorsal gun turret.

The engines were two Fiat A.80 RC 41s, rated at 1,000 cv at 4,100 m (13,451 ft), driving three-blade Fiat-Hamilton metal variable-pitch propellers. Six self-sealing fuel tanks in the centre fuselage and inner wings held 3,622 Ls of fuel, with two oil tanks holding 112 L. This gave the fully-loaded bomber, (carrying a 7,900 lb payload) an endurance of 5½ hours at 350 km/h (220 mph), and 16,400 ft altitude. Takeoff and landing distances were 350 m (1,150 ft) and 380 m (1,250 ft) respectively. The theoretical ceiling was 24,930 ft. Crewed by four or five, the BR.20's two pilots sat side-by-side with the engineer/radio operator/gunner behind. The radio operator's equipment included an R.A. 350-I radio-transmitter, A.R.5 receiver and P.3N radio compass. The navigator/bomb-aimer had a station in the nose equipped with bombsights and a vertical camera. Another two or three crewmembers occupied the nose and the mid-fuselage, as radio-operator, navigator and gunners. The radio operator was also the ventral gunner while the last crew member was the dorsal gunner.

The aircraft was fitted with a Breda model H nose turret carrying a single 7.7 mm (.303 in) Breda-SAFAT machine gun, and was initially fitted with a Breda DR dorsal turret carrying one or two 7.7 mm (.303 in) machine guns. This turret was unusual because it was semi-retractable: the gunner's view was from a small cupola, and in case of danger, he could extend the turret. The aircraft was fitted with a further 7.7 mm (.303 in) machine gun in a ventral clamshell hatch that could be opened when required. The BR.20's payload was carried entirely in the bomb bay in any of the following possible combinations: 2 × 800 kg (1,760 lb) bombs as maximum load, 2 × 500 kg (1,100 lb), 4 × 250 kg (550 lb), 4 × 160 kg (350 lb), 12 × 100 kg (220 lb), 12 × 50 kg (110 lb), 12 × 20 kg (40 lb), or 12 × 15 kg (30 lb) bombs. Combinations of different types were also possible, including 1 × 800 kg (1,760 lb) and 6 × 100 kg (220 lb), 1 × 800 kg (1,760 lb) and 6 × 15 or 20 kg (30 or 40 lb), or 2 × 250 kg (550 lb) and 6 × 50 or 100 kg (110 or 220 lb) bombs. The BR.20 could also carry four dispensers, armed with up to 720 × 1 or 2 kg (2 or 4 lb) HE or incendiary bomblets. All the bombs were loaded and released horizontally, improving the accuracy of the launch.

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With a Crew of 5, the BR.20 was powered by 2 × Fiat A.80 RC.41 18-cylinder radial engines of 746 kW (1,000 hp) each giving a maximum speed of 273mph, a range of 1,709 miles and a service ceiling of 26,250 feet. Defensive armament consisted of 3× 12.7 mm (.5 in) Breda-SAFAT machine guns in nose, dorsal and ventral positions. A 3,530lb bombload could be carried.

The Ilmavoimat evaluation team considered the BR.20 a remarkably good aircraft that could be improved somewhat by increased engine power and heavier armament. They reommended that consideration be given to a gunship ground attack version fitted with nose-mounted cannon, a tricycle undercarriage and armour protection for the crew – and as with the Polish PZL 37, they considered that for Ilmavoimat use, 2 crew positions could be eliminated - the ventral gunner and the bombardier / nose gunner.

The Handley Page Hampden (UK):

The Handley Page HP.52 Hampden was a British twin-engine medium bomber designed or the RAF to the same specification as the Wellington (Air Ministry Specification B.9/32). The first production batch of 180 Mk I Hampdens was built to Specification 30/36. Conceived as a fast, manoeuvrable, "fighting bomber", the Hampden had a fixed .303 in (7.7 mm) Vickers K machine gun in the forward fuselage. To avoid the weight penalties of powered-turrets, the Hampden had a curved Perspex nose fitted with a manual .303 in (7.7 mm) Vickers K gun and two more single .303 in (7.7 mm) Vickers K installations in the rear upper and lower positions. The layout was similar to the all-guns-forward cockpits introduced about the same time in the Luftwaffe's medium bombers, notably the Dornier Do 17.

Construction was from sections prefabricated then joined. The fuselage was in three major sections - front, centre and rear. The centre and rear sections were themselves made of two halves. This meant the sections could be fitted out in part in better working conditions before assembly. In a similar way, the wings were made up of three large units - centre section, port outer wing and starboard outer wing - which were in turn sub-divided. The Hampden was a stressed skin design reinforced with a mixture of bent and extruded sections. The wing used a single main spar. The first prototype flew on 21 June 1936. Crewspace was cramped and there were a number of blindspots in the defense. Due to the short and narrow fuselage and long tail boom it was soon nicknamed “Flying Suitcase.”

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With a Crew of 4 (Pilot, navigator/bomb aimer, radio operator and rear gunner), the Hampden was powered by 2 × Bristol Pegasus XVIII 9-cylinder radial engines of 980 hp (730 kW) each giving a maximum speed of 265mph, a ramge of 1,095 miles and a service ceiling of 19,000 feet. Defensive armament consisted of 4-6 × .303 in (7.7 mm) Vickers K machine guns: one flexible and one fixed in the nose, one or two each in the dorsal and ventral positions. A maximum 4,000lb bombload or 1 Torpedo could be carried.

OTL Note: A total of 1,430 Hampdens were built: 500 by Handley Page, 770 by English Electric at Samlesbury in Lancashire; and in 1940–41, 160 in Canada by the Canadian Associated Aircraft consortium (although some were retained in Canada, 84 were shipped by sea to the United Kingdom). The Hampden wasn't good at daylight bombing as it had many blind spots for defense and the crew was very cramped in the narrow confines (3 feet wide at the widest point) of the fuselage. It proved to have a totally inadequate defensive armament. Heavy losses were suffered on day bomber missions. The Hampden was abandoned by RAF Bomber Command in 1942. Some were then converted to torpedo bombers.

The Heinkel He111 (Germany):

Tthe Heinkel He 111 had been designed earlier in the 1930s by Siegfried and Walter Günter. The first He 111 flew on 24 February 1935 and while the Ilmavoimat had rejected the civilian passenger aircraft as too small for the military transport they were then looking for, they were interested in the bomber version. In May 1935 evaluation flights of both the Junkers Ju86 and Heinkel He111 had been flown. Performance of the He111 was good – a speed of 255mph, a range of 1429 miles with maximum fuel and a bomb load of 2000kg internally (8 x 250kg bombs). However, the aircraft was still in development, delivery times could not be guaranteed and the cost as compared to the Italian SM.81 aircraft that in the end was selected as a bomber (in 1935) was on the high side. However the Ilmavoimat remained interested and in 1937 they re-evaluated the aircraft.

In 1935, when the Ilmavoimat had first evaluated the aircraft, the Heinkel was equipped with two BMW VI engines and the maximum speed was 311 km/h (193 mph). By early 1937, a number of prototypes with 9ncreasingly more powerful engines and better wing designs had been built – the Ilmavoimat at this stage tested a military bomber variant – the He111B-1. The bomb load was now 1,500 kg (3,300 lb), while there was also an increase in maximum speed and altitude to 215 mph (344 km/h) and 22,000 ft and the armament settled at three machine gun positions. Construction had begun at the Heinkel factory at Oranienburg and Heinkel assured the Finns that any order they placed could be met (mentioning also that the Turkish Air Force were negotiating to buy a number of the aircraft). The evaluation team rated the He111 highly.

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With a Crew of 4 (pilot, navigator/bombardier/nose gunner, ventral gunner, dorsal gunner/radio operator), the He111 had a maximum speed of 215mph, could carry a 3,300lb bombload with a range of 1,429 miles and had a service ceiling of 22,000 feet.

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Heinkel He111 of the Condor Legion in Spain. Ilmavoimat volunteers went on to fly the aircraft operationally in Spain and praised its performance highly. However, despite the 1935 amd 1937 evaluations which gave the aicraft high marks, it was never purchased by the Ilmavoimat

The Junkers Ju88 (Germany):

In August 1935, the Reichsluftfahrtministerium submitted its requirements for an unarmed, three-seat, high-speed bomber, with a payload of 800-1,000 kg (1,760-2,200 lb). Junkers presented their initial design in June 1936, and were given clearance to build two prototypes (Werknummer 4941 and 4942). The first two aircraft were to have a range of 2,000 km (1,240 mi) and were to be powered by two DB 600s. Three further aircraft, (Werknummer 4943, 4944 and 4945), were to be powered by Jumo 211 engines. The first two prototypes, Ju 88 V1 and V2, were different from the V3, V4 and V5 in that the latter three models were equipped with three defensive armament positions to the rear of the cockpit, and were able to carry two 1,000 kg (2,200 lb) bombs under the inner wing.

The first five prototypes had conventionally-operating dual-strut leg rearwards-retracting main gear, but starting with the V6 prototype, a main gear design that twisted the new, single-leg main gear strut through 90° during the retraction sequence debuted, much like the American Curtiss P-40 fighter design used. This feature allowed the main wheels to end up above the lower end of the strut when fully retracted [N 1] and was adopted as standard for all future production Ju 88s, and only minimally modified for the later Ju 188 and 388 developments of it. These single-leg landing gear struts also made use of stacks of conical Belleville washers inside them, as their main form of suspension for takeoffs and landings.

The aircraft's first flight was made by the prototype Ju 88 V1, which bore the civil registration D-AQEN, on 21 December 1936. When it first flew, it managed about 580 km/h (360 mph) and Hermann Göring, head of the Luftwaffe was ecstatic. It was an aircraft that could finally fulfill the promise of the Schnellbomber, a high-speed bomber. The streamlined fuselage was modeled after its contemporary, the Dornier Do 17, but with fewer defensive guns because the belief still held that a high speed bomber could outrun late 1930s-era fighters. However, production was delayed drastically with developmental problems and this was the situation when the Ilmavoimat assessed the prototype in early 1937.

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Junkers Ju88 V1 Prototype evaluated in early 1937

At this stage, the Ilmavoimat team liked the aircraft and could see its potential with its projected bombload of 6,600lb and a speed of 300mph+. However, with the problems still being worked on, a number of prototypes in development and production not yet in sight, the team recommended a “wait and see” approach with a further evaluation to be carried out in 1938.

...to be continued in the next post
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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A Medium Bomber for the Ilmavoimat - 1937 - continued

Post by CanKiwi2 » 15 Jul 2011 21:31

The Lioré-et-Olivier LeO 45 (France):

The Lioré-et-Olivier LeO 45 was a French medium bomber designed and built as a low-wing monoplane, all metal in construction, equipped with a retractable undercarriage and powered by two 1,100 hp Hispano-Suiza engines. It was conceived as a second-generation strategic bomber for the French Air Force. In contrast to its predecessors which relied on machine guns for protection, the emphasis was placed on a high-speed high-altitude bomber design. The expectation was that high speed would force enemy fighters into tail-chase attacks and to that effect the aircraft was designed with a rear-firing defensive cannon with an unobstructed rear arc of fire thanks to the twin rudders. The Service Technique Aéronautique released the initial requirements on 17 November 1934, specifying a 5-seat bomber with a top speed of 400 km/h (215 knots, 250 mph) at 4,000 m (13,125 ft), and a combat radius of 700 km (435 mi) carrying a payload of 1,200 kg (2,650 lb). In September 1936, the requirements were revised to account for development of 1,000 hp (746 kW)-class engines, with cruise speed raised to 470 km/h (255 knots, 290 mph) and crew reduced to four. The French Air Force's Plan II called for 984 of the resulting B4-class bombers.

Numerous manufacturers submitted a proposal, including Latécoère, Amiot with its Amiot 351, and Lioré et Olivier, which was to be soon nationalized as part of the SNCASE. Lioré et Olivier was a long-time purveyor to the Armée de l'air with its LeO 20 and other lesser-known biplane bombers that had earned a reputation for reliability, but were very traditional in design. The 1934 programme required modern solutions, and consequently the company management put a younger engineer, Pierre Mercier, who had expertise in cantilever airframes, at the helm of the design team. Mercier's work resulted in a design, christened the LeO 45, of a twin-engined aircraft of all-metal construction with a monocoque fuselage. Because of the speed requirements of the programme, a lot of effort was spent in reducing parasitic drag. Wings were equipped with slotted flaps and small bomb bays in the wing roots in addition to the main fuselage bomb bay, so as to limit the fuselage's cross-section. A new wing structure was designed and patented by Mercier, where the inner part used two spars, with enough room between them for a 200 kg-class bomb and large self-sealing fuel tanks. However the spars didn't go all the way to the wing-tip, but made way for a box-type structure at the tips.

Mercier also used his patented type of fairing for the LeO 45's radial engines. Unlike typical NACA cowlings, flow adjustment was not provided by flaps, but by a frontal ring that moved back and forth to respectively reduce or increase flow, without change in drag. Like many other French twin-engine planes of the era, propellers rotated in the opposite directions to eliminate the undesirable effects of propeller torque. The undercarriage was fully retractable, with an unusually complicated mechanism for the main wheels in order to reduce the size of the engine nacelles. The fuselage hosted the four-man crew in the following order: the bombardier, who was also the commander as per French tradition, sat in the glazed nose ahead of the pilot. Immediately behind the pilot, the radio operator could man a defensive 7.5 mm M.1934 (500 rounds) machine gun from an underbelly retractable "gondola". A corridor alongside the main bomb bay led to the rear gunner’s position which featured a powered mounting for the required 20 mm cannon. This was a really powerful cannon, the Hispano-Suiza HS.404, with 120 rounds, and excellent ballistic proprierties (over 800 m/s), well above MG FF and other Oerlikon guns. The turret was retraclable when not needed. The armament was completed with another 7.5 mm machine-gun M.1934/39, this time in the nose (300 rds).

Overall, the Leo's bombload was up to seven 200 kg bombs, or other combinations (up to a maximum of 1-2 500 kg bombs in the fuselage bomb bay, plus the two 200 kg bombs in the wings). The maximum bombload penalized fuel capacity, which was reduced to only 1,000 lts. The fuel tanks were: two 880 lts (inner wings), two 330 and two 410 lts (all in the external wings). The LeO 45-01 prototype, powered by a pair of Hispano-Suiza 14Aa 6/7 radial engines producing 1,120 hp (835 kW) each flew for the first time on 16 January 1937. Despite problems with longitudinal instability, and engine reliability and overheating, the aircraft demonstrated excellent performance, reaching 480 km/h (300 mph) at 4000 m, and attaining 624 km/h (337 knots, 388 mph) in a shallow dive. (Well after the Ilmavoimat evaluation, in July 1938, the prototype fitted with the new Mercier cowlings reached 500 km/h (270 knots, 311 mph). Subsequently, the troublesome Hispano-Suiza engines were replaced with Gnome-Rhone 14N 20/21 engines producing 1,030 hp (768 kW) each, and the aircraft was redesignated LeO 451-01.

The Ilmavoimat evaluation team liked the aircraft’s handling but expressed concerns regarding the limited range with a maximum bombload as well as the engine reliability issue. As with the Bloch MB.210, the team also expressed considerable concern about the ability of the French aircraft industry to delivery on any order placed (a well-founded concern as it turned out). This was especially frustrating as a large loan for purchases of military equipment had been made to Finland by the French government in 1937.

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The 16th Paris Air Show, in 1938, showed planes such as the prototype of the Lioré et Olivier LeO 45, shown here. With a Crew of 4, the prototype evaluated by the ilmavoimat was powered by two Hispano-Suiza 14Aa 6/7 radial engines producing 1,120 hp (835 kW) each and giving a maximum speed of 300mph, with a range of 1,800 miles and a service ceiling of 29,530 feet. Maximum bombload was 3,457lbs and defensive armament consisted of 1 cannon and 2 machineguns.

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OTL Note: As the international situation was worsening, the Armée de l'Air ordered the LeO 451, explicitly asking SNCASE not to delay production with further improvements, even though teething troubles were far from cleared. The first production LeO 451 was built in 1938. The decision to abandon Hispano-Suiza engines and a shortage of propellers resulted in production delays. The latter also caused most aircraft to be fitted with slower Ratier propellers which reduced the top speed from 500 to 480 km/h. As the result, although 749 LeO 451 had been ordered, only 22 were delivered by the start of World War II. Of these, only 10 were formally accepted by the Air Force. They were issued to a frontline unit tasked with experimenting the new type in the field, and flew a few reconnaissance flights over Germany, which resulted in the type's first combat loss. At the start of the Battle of France on 10 May 1940, only 54 of the 222 LeO 451 that had been delivered were considered ready for combat, the remainder being used for training, spares, undergoing modifications and repairs or having been lost.

The first combat sortie of the campaign was flown by 10 aircraft from GB I/12 and GB II/12 on 11 May. Flying at low altitude, the bombers suffered from heavy ground fire with one aircraft shot down and 8 heavily damaged. Within the next 8 days many of them were shot down, like the one piloted by sergent-chef Hervé Bougault near Floyon during a bombing mission over German troops. By the Armistice of 25 June 1940, LeO 451 of the Groupement 6 had flown approximately 400 combat missions, dropping 320 tons of bombs at the expense of 31 aircraft shot down by enemy fire, 40 written off due to damage, and 5 lost in accidents. It was an effective bomber, but it appeared too late to give any substantial contribution to the war effort. Although designed before World War II, it remained in service until September 1957.


The North American Aviation XB-21 Dragon (USA):

The North American XB-21, also known by the manufacturer's model designation NA-21, and sometimes referred to by the name "Dragon", was a prototype bomber aircraft developed by North American Aviation in the late 1930s, for evaluation by the United States Army Air Corps. North American Aviation's first twin-engined military aircraft, the NA-21 prototype was constructed at North American's factory in Inglewood, California, where work on the aircraft began in early 1936. The NA-21 was a mid-wing monoplane of all-metal construction, powered by two Pratt & Whitney R-2180 Twin Hornet radial engines, which were fitted with turbosuperchargers for increased high-altitude performance. Flown by a crew of six to eight men, the XB-21 featured a remarkably strong defensive armament for the time, including as many as five .30-calibre M1919 machine guns. These were planned to be fitted in hydraulically powered nose and dorsal turrets, in addition to manually operated weapons installed in waist and ventral positions. Up to 10,000 pounds (4,500 kg) of bombs could be carried in an internal bomb bay, with 2,200 pounds (1,000 kg) of bombs being able to be carried over a range of 1,900 miles (3,100 km).

The XB-21 flew for the first time on December 22 1936 at Mines Field, with company test flying indicated a number of minor problems. Modifications resolving these resulted in the aircraft being re-designated NA-39, and, accepted by the U.S. Army Air Corps as the XB-21. The aircraft, which had been assigned the serial number 38-485, was evaluated early in 1937 in competition against a similar design by Douglas Aircraft, an improved version of the company's successful B-18 Bolo. During the course of the fly-off, the gun turrets proved troublesome, their drive motors proving to be underpowered, and issues with wind blast through the gun slots were also encountered. As a result of these problems, the XB-21's nose turret was faired over, while the dorsal turret was removed. The XB-21 proved to have superior performance over its competitor, but price became the primary factor distinguishing the B-18 Bolo and the XB-21. On this account, the modified B-18 was declared the winner of the competition by the US Army Air Corps, Douglas quoting a price per aircraft of $64,000 USD, while North American's estimate was $122,000 USD per aircraft. The USAAAC placed an order for 177 of the Douglas aircraft, to be designated the B-18A. Despite this, the Army Air Corps found the performance of the XB-21 to have been favorable enough to order five pre-production aircraft, to be designated YB-21. However, soon after this contract was awarded, it was cancelled.

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With a crew of 6 to 8, the XB-21 was powered by 2 × Pratt & Whitney R-2180 Twin Hornet turbosupercharged radial engines of 1,200 hp (890 kW) each, giving a maximum speed of 220 mph, a range of 1,960 miles with 2,200lb of bombs and a combat radius of 600 miles with a 10,000lb bombload. The service ceiling was 25,000 feet and dfensive armament consisted of five .30-calibre machine guns, mounted in single turrets in the nose and dorsal positions, and single manually operated mounts in the waist and ventral positions.

The Ilmavoimat evaluation team tested both the B-18 Bolo and the XB-21 and considered both to be “reasonable” medium bombers but expressed reservations about their performance.

The Piaggio P.32 (Italy)

The Piaggio P.32 was an Italian medium bomber of the late 1930s, produced by Piaggio, and designed by Giovanni Pegna. The P.32 was a twin-engine monoplane with a crew of five or six. The main structure was of wood, with a glazed nose, low cockpit, twin tail-fins, and a distinct 'banana' shape in the fuselage. Utilizing their experience of designing experimental and record-breaking aircraft like the Piaggio P.16, Piaggio P.23M, and Piaggio P.23R, Piaggio designed the P.32 with very small wings for its size. This meant a high wing loading, which required Handley-Page leading edge slats and double trailing-edge flaps to provide enough lift at takeoff and landing.

The development of this aircraft began with the contest announced by the Regia Aeronautica (Italian Air Force) in 1934. The P.32 was one of many contenders, and certainly the most modern. The prototype first flew in 1936, and was tested at Guidonia, leading to an order for 12 aircraft, followed by a second order for five. These aircraft were fitted with the 615 kW (825 hp) Isotta-Fraschini Asso XI.RC inline V12 engine, and were designated the P.32 I. In early 1937 the P.32 Is were assigned to XXXVII Gruppo BT, 18 Stormo. The advanced wing design meant that they could only be flown by specially-trained crews. However, after entering service the aircraft was found to be fatally underpowered, with a maximum speed of only 386 km/h (240 mph), and then only with no bombs or defensive weapons carried. They were unable to fly on only one engine, and their handling qualities were markedly inferior to the SM.79 and BR.20.

The Ilmavoimat evaluation team test flew the aircraft but found it underpowered and with poor handling and manouverability. With a full load of bombs and fuel taking off ranged from problematical to impossible. The P.32 was quickly eliminated from consideration, not least because the Ilmavoimat test crews regarded the aircraft as a crash waiting to happen.

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The Piaggio P.32 had a crew of 5 or 6, a maximum speed of 240mph, a range of 1,212 miles and a service ceiling of 23,780 feet. It was armed with a dorsal turret with two 7.7 mm (.303 in) machine guns, a ventral turret and a single machine gun in the nose, and it could carry a 1,600 kg (3,500 lb) bombload.

The PZL.37 Łoś (Poland):

The PZL.37 was a twin-engine medium bomber designed in the mid 1930’s and built by PZL (Panstwowe Zaklady Lotnicze - National Aviation Establishment). It was the most modern aircraft in the inventory of the Polish Air Force and a symbol of Polish technological ingenuity. Thanks to several advanced technological designs (including a laminar-flow wing), and combining good performance and manoeuvrability with high bomb carrying capability, it was one of the best bombers in the world at the outbreak of World War II. In size it was slightly larger than the Lockheed L-10 Electra.

The PZL P.37 was developed in response to the specifications issued by the Departament Aeronautyki (Department of Aeronautics) in 1934 for a new twin engine bomber capable of carrying a bombload of 2000 kg (including 300 kg bombs) with speed in excess of 350 km/h and a range of 1200 km. The task of designing a new aircraft was given to a team of engineers led by Jerzy Dabrowski and Piotr Kubicki. The design was an aerodynamically “clean” fuselage with a small elliptical cross-section that enabled the plane to reach a speed of 400 km/h. This however, necessitated the inclusion of bomb bays in the wings. To accommodate the bomb bays Dabrowski designed a new wing profile of very good aerodynamic characteristics that was similar to the first laminar profiles, which become widely used in military aircraft later during the war. The wing also featured a caisson patented by Dr. Misztal and successfully used in the Polish challenge aircraft PZL.19 and PZL.26. The Departament Aeronautyki accepted Dabrowski’s project with a few minor modifications such as a reduction of the aircraft’s defensive armament in favour of achieving higher speed.

Construction of prototypes commenced in 1935, with the first PZL.37/I prototype, fitted with a single vertical stabilizer and powered by Bristol Pegasus XIIB engines, flying on December 13 1936. This revealed several problems with the fuel system, main undercarriage shock absorbents, rudder etc. These were fixed by PZL and in 1937 the aircraft was transferred to ITL (Aviation Technology Institute) for further testing. The second prototype (P.37/II, 72.2) was completed in 1937. The second prototype PZL.37/II, with twin vertical stabilizers in place of a single one to improve the rear field of fire and other improvements such as a redesigned cockpit and a revolutionary new undercarriage (designed and patented by Piotr Kubicki) with sway beam and twin wheels replacing the heavy main undercarriage unit with a single wheel, and this was accepted for production. During testing of the prototypes P.37/I was lost due to inadequate riveting of the main wing that caused the wing to break off during flight. In the same year (1937) PZL received an order for 10 production PZL P.37A’s which was soon increased to 30 aircraft. The first 10 serial aircraft were produced in 1938 and were powered by the Bristol Pegasus XII B radial engines produced in Poland under licence. The main production variant, the PZL.37B, was fitted with the twin tail and newer Pegasus XX engines. Production of PZL.37B for the Polish Air Force by Panstwowe Zaklady Lotnicze (PZL) started in autumn 1938.

Two aircraft of the second order were converted to demonstrator aircraft and were used to test Gnome-Rhone (GR) 14N engines – this became a prototype for the export variant. The aircraft was demonstrated in Greece, Turkey, Romania, Bulgaria, and Yugoslavia where it was shown in Belgrade during the International Aviation Show in 1938. During the same year this aircraft was also shown in Paris. The Łoś was very well received by international aviation experts and was considered to be one of the best bombers at the time due to its high speed and bombload. It was able to carry a heavier bombload than similar aircraft such as the Vickers Wellington, though the size of the bombs was limited. Smaller than most contemporary medium bombers, it was relatively fast and easy to handle. Thanks to the new landing gear with double wheels it could also easily operate from rough fields or meadows.

Typically for the late 1930s, its defensive armament as designed consisted of only 3 machine guns, which proved too weak against enemy fighters. For export purposes, new variants were developed: the PZL.37C with Gnome-Rhone 14N-0/1 engines of 985 cv (971 BHP, 724 kW), and a maximum speed 445 km/h and the PZL.37D with 14N-20/21 of 1,065 cv (1,050 BHP, 783 kW) and a maximum speed 460 km/h. The crew consisted of four: a pilot, commander-bombardier, radio operator and a rear gunner. The bombardier was accommodated in the glazed nose. The radio operator sat inside the fuselage, above the bomb bay, and also operated an underbelly rear machine gun. The main undercarriage retracted into the engine nacelles. The undercarriage was double-wheeled, with an independent suspension for each wheel - thanks to this landing gear it could easily operate from rough fields or meadows. It was also able to carry a heavier bombload than similar aircraft, for example the Vickers Wellington though the size of the bombs was limited. The bombs were carried in a two-section bomb bay in the fuselage and 8 bomb bays in the central section of the wings. The maximum load was 5,690lb of bombs (2 × 600lb and 18 × 250lb). Apart from two 600lb bombs, it could not carry bombs larger than 250lbs.

Starting with a presentation at an Air Show in Belgrade in June 1938 and in Paris in November, the PZL.37 met with a huge interest. For export purposes, new variants were developed: the PZL.37C with Gnome-Rhô:ne 14N-0/1 engines of 985 cv (971 BHP, 724 kW), maximum speed 445 km/h and the PZL.37D with 14N-20/21 of 1,065 cv (1,050 BHP, 783 kW), maximum speed 460 km/h. In 1939, 20 PZL.37Cs were ordered by Yugoslavia, 12 by Bulgaria, 30 PZL.37Ds and a production license by Romania and 10, raw materials and parts for another 25 and a production license by Turkey and, finally, 12 aircraft for Greece. The Belgian company Renard received permission for the license production of 20-50 aircraft for Republican Spain but cancelled this in 1939. Also Denmark, Estonia and Iran were negotiating. Deliveries to the Polish Air Force were very slow due to delays in deliveries of radio equipment, guns, bomb racks and propellers. However, by 31 August 1939 the Polish Air Force had a total of 86 PZL P.37s in service: An additional 31 airframes were at different stages of assembly in Okecie and Mielec.

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With a crew of 4, powered by Bristol Pegasus XX radial engines of 723 kW (970 hp) each, the PZL.37B had a maximum speed of 256mph, a combat radius of 630 miles, a service ceiling of 23,000 feet and could carry up to 5,690lb of bombs. Defensive armament consisted of 3 machineguns, one in the nose, 1 in the rear upper station and 1 in the underbelly station.

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The Ilmavoimat evaluation team rated the PZL 37 highly. It was small and higjly maneuverable, had excellent rough-field capability and could carry a significant bombload. Combat radius was somewhat limited however and defensive armament was on the light side. Maximum speed was considered acceptable.

However, a number of modifications were recommended in the event a decision was made to purchase the aircraft. The most significant of these was a recommendation to replace the glazed nose with a solid nose fitted with four Hispano-Suiza 20mm cannon has had been done with the Ilmavoimats Bristol Blenheims and armour protection for the Pilot. As a result, the Commander-Bombardier position would be eliminated and the Pilot would function as Pilot, Bomb-aimer and Radio-operator combined. It was also recommended that the Radio Operator / Ventral Gunner position be eliminated and the ventral gun removed completely while the rear upper station be upgraded to two machineguns. The fitting of more powerful engines was also recommended – the Rolls Royce Merlin II (rated at 1,030-horsepower 770 kW) and with production starting in Finland. It was however expected that this engine would soon see a major increase in performance. With the Finnish Oil Refinery online, Neste had been experimenting with the production of 100 octane fuel for the Ilmavoimat and the adapatation of the Merlin engine to run on this was being trialled, with initial results indicating the result would be an increase in power to some 1,265 horsepower. With these or similarly upgraded Hispano-Suiza 12Y engines fitted, an increase in speed to some 280mph was projected.

(For comparison, the slightly later B-25 Mitchell had a maxium speed of 275mph, a combat radius of 1,350 miles and a bombload of 6,000lbs). It was also significantly larger and was powered by 2 × Wright R-2600 "Cyclone 14" radials of 1,850 hp (1,380 kW) each).

OTL Note: German air superiority, dispersal of Polish bomber units and inadequately equipped field airstrips prevented the effective use of Poland’s aircraft in the September 1939 Campaign. The Łoś was mainly used for missions that included reconnaissance and bombardment of German mobile forces, a task for which the Łoś was not intended. Moreover, none of the sorties included a large enough number of aircraft to inflict any real damage. Repairs of damaged aircraft were not possible since the ground crews did not have all the essential equipment and battle worthiness was further affected by the fact that most of the aircraft were not fully equipped (radio, compass, etc.). A shortage of fuel and an inability to coordinate operations with Polish fighters (it should be noted that PZL P.37 was much faster than any of the contemporary Polish fighters) made the situation even worse. Most of the bombing missions involved attacks on randomly chosen mobile German forces and a total of 119 tonnes of bombs were dropped.

27 aircraft were lost during the hostilities: 11 were destroyed by enemy fighters, 5 by enemy AA fire, 1 by friendly AA fire, 2 were destroyed on the ground by enemy bombers, 3 were abandoned by crews due to technical difficulties, 3 were damaged on the ground and lost due to the pilot error, 2 crash landed due to lack of fuel. German forces captured a total of 41 PZL 37s in Warsaw and Mielec. Those aircraft were at different stages of assembly although several were completed. Polish workers used by the Germans to clear airfields destroyed the majority of them, which resulted in only two PZL P.37B’s being airworthy. German war booty also included 50 brand new PZL Pegasus XX engines that were sold to Sweden. Polish crews evacuated 27 P.37s to Romania. These aircraft were seized by the Romanian government and despite Polish government's diplomatic efforts backed up by France and Great Britain the aircraft were never returned to Polish Air Force, which new squadrons were being formed in France. Later on the aircraft equipped 76 and 77 Squadron of Fortele Aeriene Regale Romane (Royal Romanian Air Force) and took part in the attack on Soviet Union in 1941.


Polish Air Force PZL 37s in Finland

On September 1, 1939, Poland had about 86 PZL.37s in service. With Poland on the verge of defeat and under attack from both Germany and the Soviet Union, twenty-seven PZL.37s (17 from the Bomber Brigade and ten training aircraft) loaded as many of their squadron personnel as was possible into the aircraft and flew to Finland. The Ilmavoimat incorporated these aircraft and personnel immediately and they went on to fly as a Polish Volunteer Squadron in the Winter War. Polish flying skills were well-developed and the Polish pilots and aircrew flying for Finland in the Winter War were regarded as fearless bordering on reckless. Success rates were very high, on a par with the Ilmavoimat pilots in point of fact. German war booty from Poland also included 50 brand new PZL Pegasus XX engines that were sold to Sweden – these were promptly resold by Sweden to Finland for use by the Ilmavoimat as spares.

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Polish Air Force PZL 37 Łoś aircraft on a bombing mission during the Winter War. The Polish aircraft retained the Polish insignia and fought as a “Polish Air Force unit attached to the Ilmavoimat” during the Winter War, considering themselves at war with the USSR. A considerable number of Polish Air Force personnel managed to find their way to Finland over the course of the Winter War, as eager to continue the fight against the USSR as they were to also fight Germany.

The Savoia-Marchetti SM.79 (Italy):

The SM.79 project began in Italy in 1934, where the aircraft was first conceived as a fast, eight-passenger transport capable of being used in air-racing (the London-Melbourne competition). Piloted by Adriano Bacula, the prototype flew for the first time on 28 September 1934. Originally planned with the 800 hp Isotta-Fraschini Asso XI Ri as a powerplant, the aircraft reverted to the less powerful 590 hp Piaggio P.IX RC.40 Stella (a license-produced Bristol Jupiter and the basis of many Piaggio engines). The engines were subsequently replaced by Alfa Romeo 125 RC.35s (license-produced Bristol Pegasus). This prototype was completed too late to enter the London-Melbourne race, but flew from Milan to Rome in just one hour and ten minutes, at a 410 km/h average speed. Soon after, on 2 August 1935, the prototype set a record by flying from Rome to Massawa in Eritrea in 12 flying hours (with a refuelling stop at Cairo).

The SM.79 had three engines, with a retractable tailwheel undercarriage and featured a mixed-material construction, with a box-section rear fuselage and semi-elliptical tail. Like many Italian aircraft of the time, the fuselage of the SM.79 was made of a welded tubular steel frame and covered with duralumin forward, duralumin and plywood over the top, and fabric on all other surfaces. As with most cantilevered low-wing monoplanes, the wings were of all-wood construction, with the trailing edge flaps and leading edge slats (Handley-Page type) to offset its relatively small size. The internal structure was made of three spars, linked with cantilevers and a skin of plywood. The wing had a dihedral of 2° 15'. Ailerons were capable of rotating through +13/-26°, and were used together with the flaps in low-speed flight and in takeoff. The grouping of engines, the slim fuselage, coupled with a low and wide cockpit and the "hump" gave this aircraft an aggressive and powerful appearance. Its capabilities were significant with over 2,300 hp available and a high wing loading that gave it characteristics not dissimilar to a large fighter.

The engines fitted to the main bomber version were three 582 kW (780 hp) Alfa Romeo 126 RC.34 radials, equipped with variable pitch, all-metal three-blade propellers. Speeds attained were around 260mph at 12,000 feet, with a relatively low practical ceiling of 23,400 feet m. The best cruise speed was at 60% of power. The landing was characterized by a 125 mph final approach with the slats extended, slowing to 90mph with extension of flaps, and finally the run over the field with only 600 feet needed to land. With full power available and flaps set for takeoff, the SM.79 could be airborne within 900 feet then climb to 12,000 feet in 13 minutes 2 seconds. The bomber version had ten fuel tanks (3,460 l).The endurance at full load averaging 200mph was 4 hr 30 min. In every case, the range (not endurance) with a 1,000 kg payload was around 5-600 miles.

The aircraft crew complement was either five or six in the bomber version with cockpit accommodation for two pilots, sitting side-by-side. Instrumentation in the central panel included oil and fuel gauges, altimeter for low and high altitude (1,000 m and 8,000 m), clock, airspeed and vertical speed indicator, gyroscope, compass, artificial horizon, turn and bank indicator, rev counters and throttles for all three engines. Cockpit equipment also included the flight controls, fire extinguishers, and control mechanisms for the brakes and other systems. The SM.79's defensive armament consisted of four, and later five machineguns. Three were 12.7 mm (0.5 inch) calibre guns, two of which were in the "hump," with the forward one (with 300 cartridges) fixed with an elevation of 15°, and the other manoeuvrable with 60° pivotal movement in the horizontal, and 0-70° in the vertical planes. The amount of ammunition was 500 cartridges (in two metal boxes), as was the third 12.7 mm machine gun, located ventrally. There was also a 7.7 mm (0.303 inch) machinegun fitted laterally, with a mount that allowed a rapid change of side for the weapon. This Lewis gun was later replaced by two 7.7 mm Bredas, which were more reliable and faster firing (900 rounds/min instead of 500), even though there was only sufficient room in the fuselage for one man to operate them. Despite the low overall power (Rate of Fire and energy of the projectile) of the SM.79's machine guns, it was heavily-armed by 1930s standards (for bombers, essentially three light machine guns), the armament being more than a match for the lightly-protected fighter aircraft of the time, not usually fitted with any armour. By the time of World War II however, the Sparviero's vulnerability to newer fighters was significant, and in Italian use in WW2 it lost its reputation of "invulnerability" that it had initially gained in use in Spain.

The internal bomb bay was configured to carry bombs vertically, preventing larger bombs being accommodated internally. The aircraft could hold two x 500 kg, five x 250 kg, 12 x 100 kg or 50 kg bombs, or hundreds of bomblets. The bombardier, with an 85° forward field of view, had a "Jozza-2" aiming system and a series of bomb-release mechanisms. The machine gun to the rear of the gondola prevented the bombardier from lying in a prone position, and as a result, the bombardier was provided with gambali, retractable structures to support his legs while being seated. Torpedoes were carried externally, as were larger bombs. This was only standardized from 1939, when two hardpoints were fitted under the inner wing. Theoretically two torpedoes could be carried, but the performance and the manoeuvrability of the aircraft were so reduced that usually only one was used in action. In addition, the SM.79's overall payload of 3,800 kg prevented it carrying 1,600-1,860 kg of bombs without a noticeable reduction of the fuel load (approximately 2,400 kg, when full).
The introduction of the aircraft in operational service was made with 12° Stormo (Wing), starting in early 1936. 12° Stormo was involved in the initial evaluation of the bomber, which continued throughout 1936. Its capabilities were still being explored when the Spanish Civil War broke out, and a number of SM.79s were dispatched to support the Nationalists. By 4 November 1936 there were six SM.79s with crew to fly them operating in Spain and serving with the Aviazione Legionaria, an Italian unit sent to assist Franco's Nationalist forces during the Spanish Civil War. By the beginning of 1937 there were 15 SM.79s in total, and they went on to be used in Spain throughout the conflict, with very few losses.

Evaluation by the Ilmavoimat was carried out in early 1937 and overall, with a speed of 260mph, a range of 1,615 miles amd abombload of 2,645lbs, the evluation team on the whole consider the Fiat BR.20 better overall.

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Italian SM.79’s…..

The Vickers Wellesley (UK)

The Vickers Wellesley was a British 1930s light bomber built by Vickers-Armstrong at Brooklands near Weybridge, Surrey, for the Royal Air Force. The design originated from the Air Ministry Specification G.4/31 which called for a general purpose aircraft, capable of carrying out level bombing, army co-operation, dive bombing, reconnaissance, casualty evacuation and torpedo bombing. The Vickers Type 253, which used a radical geodesic airframe construction that was derived from that used by Barnes Wallis in the airship R100, was tested against the specification along with the Fairey G.4/31, Westland PV-7, Handley Page HP.47, Armstrong Whitworth A.W.19, Blackburn B-7, Hawker P.V.4 and the Parnall G.4/31. The Type 253 was declared the winner, with 150 being ordered for the RAF. The Vickers Type 246 monoplane, which used the same geodetic design principles for both the fuselage and wings, was then built as a private venture, first flown at Brooklands by Chief Test Pilot J "Mutt" Summers, on 19 June 1935.

The Wellesley was a single-engine monoplane with a very high aspect ratio wing, and a manually-operated, retractable undercarriage. As it was not known how the geodetic structure could cope with being disrupted by a bomb bay, the Wellesley's bomb load was carried in two streamlined panniers under the wings. The Wellesley Mk I had two separate cockpits, one each for the pilot and navigator positions. The geodetic structure evolved from Wallis’s work on airships. The fuselage and wings were built with conventional longerons (running horizontally along the full length of the structure). Light alloy members were then wrapping in two spirals – clockwise and anti-clockwise – around the longerons, producing a lattice structure. The geodetic frame would then be covered with fabric. For maximum strength the spiral members needed to follow the shortest possible path around the fuselage (in the geographical discipline of geodetics the ‘great circle’ is the shortest route between two points on a sphere). At any point on the fuselage the stresses in the opposing spiral members would be balanced against each other, producing a very strong structure at lighter weights than was possible with the standard metal frame construction in use at the start of the 1930s.

The Vickers Type 246 was offered to the RAF. This had superior performance, but did not attempt to meet the multi-role requirements of the specification, being designed as a bomber only. An initial order for 96 Type 246s was then substituted for the Type 253 order. The RAF ultimately ordered a total of 176 as the Wellesley, to a newly written specification 22/35, with a 14-month production run starting in March 1937. The RAF received its first Wellesleys in April 1937, serving with No.76 Squadron at Finningley, and eventually equipped six RAF Bomber Command squadrons in the UK. It was a production Wellesley just entering service with the RAF that the Ilmavoimat evaluated and flew at the same time as they looked at the Vickers Wellington. While the British offocially designated the Wellesley as a medium bomber, the Ilmavoimat team considered that it carried an insufficient bombload to qualify for the medium bomber designation. They also considered the defensive armament inadequate and, given the recent experience of the Finnish volunteers in the Spanish Civil War, information on which was rapidly percolating back into the Ilmavoimat, the maximum speed was inadequate. The Ilmavoimat evaluation team recommended that the Wellesley not be considered further.

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With a Crew of 2, the Wellesley was powered by a single Bristol Pegasus XX radial piston engine of 925 hp (690 kW) giving a maximum speed of 228mph, a range of 1,220miles and a service ceiling of 25,500 feet. Armament consisted of 1 × .303 in (7.7 mm) Vickers machine gun in right wing and 1 × .rear-facing 303 in (7.7 mm) Vickers K machine gun in the rear cockpit. A 2,000lb bombload could be carried.

The Vickers Wellington (UK):

The Vickers Wellington was a British twin-engine, long range medium bomber designed in 1932 to meet the requirements of Air Ministry specification B.9/32 by Vickers-Armstrongs' Chief Designer, R. K. Pierson. The prototype first flew in June 1936 and was, for a short time, known as the Vickers Crecy (and appeared at the 1932 Hendon Air Display as such) before the name Wellington was adopted. The prototype differed from production aircraft in carrying no defensive armament, a smaller tail (from the Stranraer flying boat), and was slightly smaller and more streamlined overall. The Wellington used a geodesic construction method, which had been devised by Barnes Wallis inspired by his work on airships, and had previously been used to build the single-engine Wellesley light bomber. The fuselage was built up from 1650 elements, consisting of aluminium alloy (duralumin) W-beams that were formed into a large framework.
Wooden battens were screwed onto the aluminium, and these were covered with Irish linen, which, once treated with many layers of dope, formed the outer skin of the aircraft. The metal lattice gave the structure tremendous strength, because any one of the stringers could support some of the weight from even the opposite side of the aircraft. Blowing out one side's beams would still leave the aircraft as a whole intact; as a result, Wellingtons with huge areas of framework missing continued to return home when other types would not have survived; the dramatic effect was enhanced by the doped fabric skin burning off, leaving the naked frames exposed. However, the construction system also had a distinct disadvantage in that it took considerably longer to build a Wellington than other designs using monocoque construction techniques. Also, it was difficult to cut holes into the fuselage to provide additional access or equipment fixtures.

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The Vickers Wellington Prototype K4049: Twin-engined day bomber designed to meet Operational Requirement OR.5 and conforming to Specification B.9/32, designed under Rex Pierson and Barnes Wallis. Initial studies (as Vickers Type 249) with R-R Goshawk or Bristol Perseus engines, but definitive prototype (Type 271) as ordered in September 1933 powered by 980 hp Bristol Pegasus X engines.

Geodetic construction, gross weight of 21,000 Ib (9,526 kg) and defensive armament of single 0.303-in (7.7-mm) guns in nose, tail and dorsal positions. The unarmed prototype K4049 first flown at Weybridge on June 15, 1936; provisionally known as Crecy until name Vickers Wellington confirmed in September. Lost on April 19, 1937, during A&AEE trials at Martlesham Heath, by which time first production contract placed.


In the first quarter of 1937, when the Ilmavoimat evaluated the early prototype, a new prototype was being designed and built in response to revised Air Ministry Specification B29/35 which had been drawn up around the Vickers design. The new prototype was not built at this stage, and the Ilmavoimat team recommended postponing a detailed evaluation and test flight series until this had been completed and was available to test fly. The team’s assessment was that the Wellington was an excellent medium bomber and should be further assessed when the new prototype was available. In the event, while the Wellington was indeed evaluated in 1938, financial considerations led to an American aircraft being selected and the Wellington would not be purchased. This did not however mean that the Vickers Wellington did not see combat in the Winter War.

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Royal New Zealand Air Force Vickers Wellington Mark I Bombers (with the original Vickers turrets) at RAF Stradishall on the 10th of July 1939.

The most modern aircraft of the RNZAF in mid-1939 were 30 recently purchased Vickers Wellington bombers. The New Zealand government had ordered 30 Vickers Wellington Mk1C bombers in 1938. RNZAF aircrew were sent to England to train on the new aircraft based at RAF Marham. It was intended that the crews fly the aircraft to New Zealand in batches of six. RAF official records name this group of airman as "The New Zealand Squadron.” In August 1939, anticipating war with Germany, the New Zealand government loaned these aircraft and their (New Zealand) aircrews to the RAF. Shortly after the arrival of the ANZAC Battalion in Finland in early January 1940, the New Zealand Government dispatched the Squadron to Finland where they served with the Ilmavoimat, flying combat missions for the duration of the Winter War.

As flown by the New Zealand Squadron, the Wellington had a Crew of 6, was powered by 2 × Bristol Pegasus Mark XVIII radial engines of 1,050 hp (783 kW) each with a maximum speed of 235mph, a ramge of 2,550 miles and a service ceiling of 18,000 feet. Defensive armament consisted of 6 to 8 .303 Browning machineguns (2x in nose turret, 2 x in tail turret and 2x in waist positions. A bombload of 4,500lb could be carried.

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The New Zealand Squadron’s motto was “Ake Ake Kia Kaha” ("For ever and ever be strong") and this, and the squadron badge, were painted on all aircraft.

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Two No.75 (New Zealand) Squadron Wellingtons returning to their forward base in Eastern Karelia from a mission, late January 1940.

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The Survivors: Personnel of No.75 (New Zealand) Squadron in front of one of their 18 remaining Vickers Wellington Bombers. Photo taken at Immola Airfield, Finland, late August 1940.

And the recommendation is…….Yours!

Based on the evaluation criteria which heavily emphasize the ability to operate off rough airfields, good speed, manouverability and range, bombload (and ability to deliver this from a low level with reasonable accuracy) and of course, cost and availability (with an emphasis on certainty of delivery and ability of the supplier to complete manufacturing within a reasonable timeframe) – what are your recommendations? And feel free to add any aircraft I haven’t listed above.

Based on any feedback, I’ll write up the “decision” (which may or may not reflect a consensus, but then, military decisions are rarely democratic!
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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CanKiwi2
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And without waiting for any response....

Post by CanKiwi2 » 15 Jul 2011 22:15

The 1938 Ilmavoimat and Merivoimat Air Arm Procurement Program

Projects underway with VL through 1938

The VL Viima Manufacturing Program

As you may recall, the Ministry of Defense had ordered 60 Viima IIs on 27 June, 1936. They were delivered over December 1936 with the final aircraft completed and delivered in July 1938. The Viima production line was then converted over to the production of the VL Pyry Advanced Trainers which were ordered in early 1938 (detailed below).

The VL Fokker D.XXI Manufacturing Program

An initial order with VL for 20 Fokker D.XXI (in addition to the 20 purchased outright from Fokker) was increased by another 20 in mid-1936 and VL went on to build and deliver forty Fokker D.XXI’s over the period late-1936 to early 1938, with one per week rolling of the construction line by mid-1937 (at which time, 60 Fokker D.XXI’s were in service, equipping three fighter squadrons). Production ceased in early 1938 and the Fokker production line was converted over to the newly ordered Miles M.20 Fighter (detailed below).

The VL Bristol Blenheim Manufacturing Program

By the end of 1937, 22 locally built Blenheims had been completed. Construction continued with a further 20 completed up to October 1938, bringing the total delivered by VL to some 42, in addition to the 20 that had been delivered from Britain. Production of Bristol Blenheims by VL was discontinued in October 1938 in order to concentrate on setting up the production line for the new VL Wihuri fighter-bomber.

The VL Wihuri Manufacturing Program

Significant issues were experienced getting the VL Wihuri program underway. A following Post will go into this while project and the difficulties and challenges experienced and how they were overcome.

VL Pyry Advanced Trainer – 40 ordered in early 1938

In 1936 it had been decided that in light of the rapid advances in aircraft technology and designs and the decision to purchase monoplane fighter aircraft for the first time, a newer monoplane Advanced Trainer was needed. In 1936 the Ilmavoimat had commissioned a design and a prototype from the State Aircraft Factory and in mid 1937 a prototype for the new advanced fighter trainer, the VL Pyry, was delivered. The first flight of the Pyry prototype was on 29 August 1937. The test program was completed by November 1937, with the aircraft proving to meet all the requirements.
The Ilmavoimat ordered a first series of 40 aircraft on 3 May 1938 and in August 1938, work began to convert the Viima production line over to produce the Pyry. Preparations had been underway since the order had been placed and the conversion was swift. Construction of the first Pyry started in October 1938 and the 40 aircraft ordered were delivered between December 1938 and June 1939.

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The VL Pyry remained in use as an Advanced Trainer for the Ilmavoimat until 1962.

Miles M.20 Fighter - ordered June 1938

While the De Havilland VL Wihuri bomber project that was underway from l937 replaced the Blenheim construction program in late 1938, the Ilmavoimat was searching for a more modern fighter aircraft that VL could build as Fokker D.XXI production ended. With the rearmament programs of all the major european powers underway, sourcing fighter aircraft from suppliers in these countries (and the leading european fighters were all either German, French, British or Italian) was now increasingly problematical and the implementation of more modern aircraft construction technology was also a challenge. Thus, VL looked in two directions at once. The first was for a fighter that could be be constructed in Finland using as close toexisting methods as possibletoreduce the leadtime, would be relatively cheap and would have performance on a par with the Hurricanes or Curtiss Hawks. The second was to acquire the industrial machinery and expertise to allow VL to move to more modern construction methods and to license a fighter to build locally.
The de HavillandWihuri project was proving that the first was possible, but that project was behind schedule and something that couldenter service in a shorter timeframe – and would be a pure fighter – was desired. TheIlmavoimat Procurement Team spent the first few months of 1938 exploring options with different aircraft manufacturers – and narrowed the options down to two by early May. The French in particular were already working on designs to meet a 1936 specification for "light fighter" of wooden construction that could be built rapidly in large numbers. Three design projects were underway in mid-1937, the Arsenal VG-30, the Caudron C.714 and the Bloch MB-700.

The Arsenal VG-30 was a conventional, a low-wing monoplane that was all wooden in construction, using plywood over stringers in a semi-monocoque construction and which was to be powered by the Potez 12Dc flat-12 air-cooled inline engine, (which was running into development problems). The VG-30 was to be armed with a 20 mm Hispano-Suiza HS.404 cannon firing through the propeller hub, and four 7.5 mm MAC 1934 M39 drum-fed machine guns, two in each wing. The VG-33 was to match theMe109 in in speed (347mph) and manoeuvrability and the prototype was scheduled to fly in October 1938.

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The Arsenal VG-33 as it entered production: The VG-33 was a modified version of the VG-31 using the Hispano-Suiza 12Y-31 engine, and first flew on April 25, 1939. It had a surprisingly good performance of 347mph, and was ordered into production with a contract for 220 aircraft in September 1939, later raised to 1,000. Production didn't take long to start, but most of the airframes never received engines and were sitting at the factory when it fell to the Germans. In larger quantities, this plane could have shown the Luftwaffe a rough time, but as was the case for most French planes, production problems plagued the VG-33 such that only 160 aircraft were close to completion before the Armistice, with just 19 of 40 produced actually taken on by the Armée de l'Air. Just two machines flew in an active group, the piecemeal GC 1/55 which began life on June 18 1940 and conducted missions for just a week.

In early 1938, the Arsenal VG-30 was still in the design stages and a prototype was not available for evaluation. The Ilmavoimat Procurement Team looked at the designs but given the experience with the Loire-Nieuport LN-419 Dive-Bomber, decided to wait until a prototype was completed and flying before a further evaluation. In the event, a prototype was available in May 1939, and the Ilmavoimat did look further at this aircraft.

The Caudron C.714 was based on the C.710 model, which was an angular design developed from an earlier series of air racers. One common feature of the Caudron line was an extremely long nose that set the cockpit far back on the fuselage. The profile was the result of using the 336 kW (450 hp) Renault 12R-01 12-cylinder inline engine, which had a small cross section and was fairly easy to streamline, but very long. The landing gear was fixed and spatted, and the vertical stabilizer was a seemingly World War I-era semicircle instead of a more common trapezoidal or triangular design. Armament consisted of a 20 mm Hispano-Suiza HS.9 cannon under each wing in a small pod.
The C.710 prototype first flew on 18 July 1936. Despite its small size, it showed good potential and was able to reach a level speed of 470 km/h (292 mph) during flight testing. Further development continued with the C.711 and C.712 with more powerful engines, while the C.713 which flew on 15 December 1937 introduced retractable landing gear and a more conventional triangular vertical stabilizer. The final evolution of the 710 series was the C.714 Cyclone, a variation on the C.713 which first flew in April 1938 as the C.714.01 prototype. The primary changes were a new wing airfoil profile, a strengthened fuselage, and instead of two cannons, the fighter had four 7.5 mm MAC 1934 machine guns in the wing gondolas. It was powered by the newer 12R-03 version of the engine, which introduced a new carburettor that could operate in negative g. The Armée de l'Air ordered 20 C.714s on 5 November 1938, with options for a further 180. Production started at a Renault factory in the Paris suburbs in summer 1939

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Armée de l'Air Caudron C.714.

The Ilmavoimat Procurement Team conducted an evaluation and completed a series of test flights with the prototype C.714 Cyclone in June 1938, but considered the climb rate poor and the aircrafts maneuverability to be well below par. A decision was made at this stage to eliminate this design from consideration..

In France, deliveries to the Armée de l'Air did not start until January 1940. After a series of tests with the first production examples, it became apparent that the design was seriously flawed. Although light and fast, its wooden construction did not permit a more powerful engine to be fitted. The original engine seriously limited its climb rate and maneuverability with the result that the Caudron was withdrawn from active service in February 1940. In March, the initial production order was reduced to 90, as the performance was not considered good enough to warrant further production contracts. On 18 May 1940, 35 Caudrons were delivered to the Polish Warsaw Squadron, the Groupe de Chasse polonais I/145, stationed at the Mions airfield. After just 23 sorties, adverse opinion of the fighter was confirmed by front line pilots who expressed concerns that it was seriously underpowered and was no match for contemporary German fighters.

On 25 May 1940, only a week after it was introduced, French Minister of War Guy la Chambre ordered all C.714s to be withdrawn from active service. While the Ilmavoimat did not order any Caudron C.714’s, a number ended up with the Ilmavoimat. Eighty were diverted to Finland to fight in the Winter War. These were meant to be flown by French pilots but with the war in France going badly, the French instead released the Polish Warsaw Squadron, the Groupe de Chasse polonais I/145 from the fighting and dispatched them to Finland. The Poles flew their remaining 30 Caudrons to Britain and then to Sweden before continuing to Norway. There, they flew the Caudrons through the remainder of the Winter War, losing nine in combat and nine in accidents on landing and takeoff. Of the eighty additional C.714’s that were to be shipped to Finland events in France resulted in only six aircraft being delivered, and an additional 10 were waiting in the harbour when deliveries were stopped. The six aircraft that arrived were assembled, tested and given registrations CA-551 to CA-556. Finnish pilots found the aircraft were too unreliable and dangerous to use in Finnish conditions, but they were release to the Polish Squadron as replacements. Two of the aircraft were damaged during a transport flight to Pori. Further, the Finnish pilots found that it was difficult to start and land the aircraft from the air bases at the front. Following the end of the Winter War, the Finnish CR.714 aircraft were permanently grounded on 10 September 1940, and taken out of service in 1941.

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Ilmavoimat Caudron C.714 flown by Polish Pilots of the Warsaw Squadron

The Bloch MB-700: As mentioned above, in the last few years before the war, the French Air Ministry began to consider using non-strategic materials such as tropical woods for warplane construction to avoid running short of steel or light alloys in the event of a conflict. On 12 January 1937, the Ministry’s STAé Aeronautical Department issued technical specification A23, calling for light C1 single-seat fighters of wooden construction using less-powerful engines than the 900/1,000hp units in the basic fighter programme. To meet this requirement, André Herbemont, who had designed all the SPAD fighters since 1918, produced the MB 700. It was designed and built in the former Blériot Aéronautique factories in Suresnes, which had been incorporated into SNCASO when the French aviation industry was nationalised in 1936. The MB 700 featured an all-wood, stressed-skin structure; the fuselage was covered with formed plywood in the forward section, canvas in the rear. The engine was a Gnome-Rhône 14 M6 delivering 700hp at takeoff. As designed, the MB-700 was to be equipped with two Hispano Suiza HS 404 cannons and two wing-mounted MAC 1934 M 39 machine guns or four wing-mounted 7.5mm M 39 machine guns

In early 1938, the Bloch MB-700 was still in the design stages and a prototype was not available for evaluation. The Ilmavoimat Procurement Team looked at the designs but as with the Arsenal VG, given the experience with the Loire-Nieuport LN-419 Dive-Bomber, decided to wait until a prototype was completed and flying before a further evaluation. In the event, a prototype was not available until April 1940, and the Ilmavoimat did not look further at this aircraft.

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The Bloch MB 700-01

The MB 700-01 made its first flight on 19 April 1940, with Daniel Rastel at the controls. It lasted 16 minutes and reached an altitude of 1,800 metres. The second flight was not completed until 13 May 1940, again with Daniel Rastel. During this 50 minute flight, the aircraft reached 4,000 metres. The prototype had not been fitted with weapons. It reached a speed of 550km/h (342mph) and had a range of 685 miles, which was a remarkable performance considering the available power. The prototype had only completed about 10 flying hours when the Buc airfield was occupied by German forces who burned the plane. Construction of a second prototype was started but never finished. It featured a number of modifications in relation to the 01: larger propeller, modified radiator, etc. A naval version, baptised MB 720, was also designed, but never got off the drawing board.

Falling back on the British – the Miles M.20 Fighter

With work on the de Havilland Wihuri well underway in early 1938, the Ilmavoimat Procurement Team approached de Havilland for ideas. Geoffrey de Havilland in turn referred them to Frederick George Miles, the designer of the recently purchased Miles Kestrel Trainer. Miles was an outstanding aircraft designer and the aircraft he came up with were often technologically and aerodynamically advanced for their time. Peripherally aware of Miles’ growing reputation but largely influenced by de Havilland’s recommendation, the Ilmavoimat approached him in July 1938 and asked for ideas for a fighter aircraft that could be constructed in Finland cheaply and with regard to Finland’s resource and strategic limitations. Miles came up with an initial design within two weeks and the Ilmavoimat promptly commissioned a prototype. To reduce production times the aircraft was to be as close as possible to all-wood construction and would use as many parts as possible from the Fokker D.XXI construction program,. The engine was to be either the Finnish produced or Hispano-Suiza.

The first prototype flew 65 days after the commission was placed, in late October 1938. Almost all wood, it lacked hydraulics, and had streamlined fixed spatted landing gearand was powered by a Rolls Royce Merlin engine. The prototype also featured a bubble canopy for improved pilot visibility, one of the first fighters to do so and a feature that the Ilmavoimat would on to include in (and retrofit to) their fighter aircraft wherever possible. The prototype was armed with eight wing-mounted machineguns and was actually faster than the Hawker Hurricane (but slower than the Spitfire) – and could carry more ammunition than either. With a maxiumum speed of 333mph, a service ceiling of 32,800 feet and and a range of 920 miles, it was the fighter the Ilmavoimat had been looking for.

The Ilmavoimat conducted test flights through November and December 1938 and after the conclusion of these, ordered an initial batch of 20 from Miles Aircraft (these were built by Philips and Powis Aircraft at Woodley airfield in Reading and delivered in May 1939), purchased an unlimited license to manufactire the aircraft and with the assistance of engineers from Philips and Powis converted the Fokker D.XXI production line at VL (the State Aircraft Factory) over to construction of the new fighter aircraft over January-March 1939. Initial production was slow, the first 2 Finnish prototypes were only completed in May 1939, but thereafter some 4 aircraft a month were completed through to November 1939 (26 Miles M.20 fighters had been delivered by VL by the end of November 1939 – 46 were in service at the start of the Winter War). VL construction continued throughout the Winter War, with an average of 6 aircraft per month being completed from January 1940 on as production was stepped up.

In addition, in late August 1939, the secret addenda within the Molotov-Ribbentrop Pact concerning Poland, Finland and the Baltic States became known to Finland through both Germany and the USA. Under the circumstances, money became no object and the emphasis was placed on the urgent acquisition of more arms, munitions and aircraft – and an urgent order for a further 60 Miles M.20 Fighters was placed with Philips and Powis Aircraft immediately. Construction was rapid as the order specified that the Finns would supply their own engines and armament, thus bypassing the bottleneck that existed in Britain, where any war-related maunfacturing was dedicated to meeting the surging demands of the UK military. A first shipment of 25 of the aircraft was received in late December 1939 via Lyngefjiord, these were transported to Tampere where engines and machineguns were fitted and they entered service in late March 1940, replacing losses and allowing (together with VL-manufactured aircraft) for a third squadron to be equipped with the Miles M.20 fighters. The remaining aircraft were not delivered as the UK cancelled the order and moved Philips and Powis Aircraft over to construction of Miles Magister target tugs and Miles Master trainers for the RAF. Finland protested that the aircraft were desperately needed, but to no avail.

In service with the Ilmavoimat, the Miles M.20 proved to be a fast, strong and highly manoueverable aircraft, highly effective in combat and cheap and fast to build, albeit without any armor for the pilots. Pilots loved the visibility afforded by the bubble canopy as well as the fire power, speed and maneouverability which made the fighter an excellent dogfighter, able to easily mix it with the agile and maneouverable Soviet fighters. Construction was straightforward and after war broke out, VL managed to step up production to 6 aircraft per month in January 1940. By May 1940, VL through superhuman efforts had raised output to some 10 per month, whereupon the limitation became the production of aircraft engines. The Finnish Government had earlier set up the State Aircraft Engine Factory, which in 1938 had begun producing the Rolls-Royce Merlin under license as well as the Bristol Mercury, also under license. By mid-1939, with the threat of war with the Soviet Union looming ever larger, engine production was stepped up with work running 24/7 around the clock and output doubling over the period July-October 1939. With Finnish construction of the de Havilland Wihuris (each of which required two Merlins) as well as the Miles M.20 Fighters, engine manufacturing became, if not quite a bottleneck, at least very tight as replacement engines were also needed for aircraft already in service.

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Prototype Miles M.20

OTL Note: During the Battle of Britain, the Royal Air Force was faced with a potential shortage of fighters. To meet the Luftwaffe threat, the Air Ministry commissioned Miles Aircraft to design the M.20. Designed and built as a simple and cheap alternative to the Spitfire and Hurricane, the first prototype flew 65 days after the design was commissioned (15 September 1940) and tested out in compliance with Specification F.19/40., the engine used was the Rolls Royce Merlin, identical to those used on the Avro Lancaster and some Bristol Beaufighter marks. Armed with the same eight .303 Browning machine guns as the RAF’s Hawker Hurricane, the M.20 prototype was actually faster than the Hurricane but slower than the Spitfire types then in production, while carrying more ammunition, and with a greater range than either. As the Luftwaffe was defeated over Britain, the need for the M.20 Fighter vanished and the design was abandoned without entering production. The first prototype was later scrapped at Woodley.

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Second Prototype of the Miles M.20

Hawker Henley Ground Attack Aircraft – 20 ordered January 1938

As mentioned for the 1937 Procurement Program, the Hawker Henley had been designed as a light bomber in response to British Air Ministry Specification P.4/34 of February 1934 for a light bomber and close support aircraft, with high performance and a low bomb load. Fairey, Gloster and Hawker all rushed to complete a design that met this need, with intense competition to achieve the highest possible performance. Hawker’s entry, the Henley, was in design and appearance closely related to the Hawker Hurricane. This was a result of the aircraft being required to carry only a modest bomb load and with performance being paramount. As the Hurricane itself was then in an advanced design stage, the Hawker design team chose to focus its efforts on developing an aircraft similar in size to the Hurricane fighter, especially as it was benefical both economically and production-wise if assemblies were common to both aircraft.

This resulted in the Henley, as it was to become known, sharing identical outer wing panel and tailplane jigs with the Hurricane. Both were also equipped with the Rolls-Royce Merlin engine as it offered the best power/weight ratio as well as a minimal frontal area.The main difference between the two types was the cockpit, designed to carry a two man crew – pilot and observer/ air gunner. The Henley’s cantilever fabric-covered monoplane wing was mid-set, retractable tailwheel type landing gear was selected. It was also fully stressed for dive bombing and very similar in appearance to the Hurricane and able to carry 4 x 500lb bombs on underwing racks. The main difference between the two types was the cockpit, with the Henley designed to carry a two man crew – pilot and observer/ air gunner.

Although construction of a Henley prototype began as early as mid-1935, with all priorities going to Hurricane development, work on the Henley progressed slowly. The prototype took two years to complete, finally taking to the air on 10 March 1937, shortly after the competing Fairey P.4/34. Subsequently the aircraft was refitted with light alloy stressed-skin wings and a Merlin I engine, and further test flights confirmed the excellence of its overall performance. The Ilmavoimat/Meroivoimat Procurement Team valuated and test flew the aircraft in mid-1937 - and had considered it outstanding, placing it first in the overall rankings of the aircraft they evaluated although for financial reasons, the Vindicator was selected. In January 1938, with a large increase in budget for the 1938 financial year, the Ilmavoimat revisited the Henley and placed an immediate order for 20 with a number of modifications. In early 1938 Hawker had still not received the RAF / Air Ministry order and work to meet the Ilmavoimat order commenced immediately, particularly as the Finnish order specified that they would fit their own engines and propellers (thus avoiding the bottlenecks that were occurring in the UK with Merlin and Totol production.

The most significant modifications made by the Ilmavoimat were the elimination of the Gunner / Observer and all associated equipment together with a return to a Hurricane-like single seater cockpit /canopy, saving a considerable amount of weight – which was promptly restored by the addition of some 350 lb (159 kg) of armour plating added to the radiator housing, cockpit and fuel tanks (the Ilmavoimat had not forgotten their Junkers J1 with its “steel bathtub.” The second major modification was the fitting of two VL / Tampere / Hispano Suiza designed pods containing a British Vickers “S” 40mm cannon with 12 rounds each under each wing, together with a single machinegun in each wing loaded with tracers for aiming purposes.

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Ilmavoimat Hawker Henley in RAF insignia prior to modifications and delivery

The Ilmavoimat had been working on a “tank buster” project since early 1937 in an effort to come up with an effective air-based counter to Soviet armor. The 20mm Hispano-Suiza cannons had been trialled and found to be ineffective on anything except motor vehicles and light armour. The next stage had been to look at heavier guns that could be mounted in an aircraft. The Bofors 37mm had been experimented with but an auto-feeder hadproved difficult to design and develop – and in looking for an alternative solution that was more ready-made, Suomen Hispano-Suiza Oy had tracked down the Vickers “S”. Essentially, this gun was a 40 mm (1.57 in) developed in the late 1930s as an aircraft weapon and was a long-recoil design derived from the 37 mm 1½pdr "COW gun" from Coventry Ordnance Works. The ammunition was based on the 40x158R cartridge case of the naval 2 pdr Anti-Aircraft gun (the "Pom-pom"). The gun was originally intended as a bomber defensive weapon and had been tested as such in a turret fitted to a modified Vickers Wellington II. It had not adopted for service by the British, but Vickers were more than happy to sell a small number for testing.
After tests showed a high level of accuracy with an average of 25% of shots fired at tanks striking the target and achieving “kills”, the Ilmavoimat went ahead and placed an order with Vickers, as well as asking Hawker to install the guns in all the production aircraft. Attacks with HE were twice as accurate as with AP, possibly because the ballistics were a closer match to the .machineguns used for sighting (the HE shell was lighter and was fired at a higher velocity).

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The Vickers “S” 40mm mounted on a Hawker Henley
The Henleys were delivered in August 1938 and exceeded expectations considerably. Fitted with the Finnish builtHispano-Suiza 12Yengines, they had a maximum speed of 300mph and were configured to carry 2x500lb bombs together with the two 40mm cannon pods, making them a lethal ground attack aircraft. So enthused was the Ilmavoimat with the performance of the aircraft that a further 20 were ordered in early 1939. These were produced at the tail-end of the British order for their “target tugs”and were delivered in late summer 1939.

Meanwhile, in RAF service, the Henley was not proving to be a great success as a target tug. With some 200 in service, it was discovered that the Merlin engine could not cope with high speed target towing. It was soon discovered that unless the aircraft were restricted to an unrealistically low tow speed of 220 mph (355 km/h), the rate of engine failures was unacceptably high. This resulted in Henleys being withdrawn from this role and relegated to towing larger drogue targets with anti-aircraft co-operation units. Predictably, the Henley proved to be even more unsuited to this role, and the number of engine failures increased. Several Henleys were lost after the engine cut-out and the drogue could not be released quickly enough. In September 1939, with war with the USSR looming unmistabably closer, the Finnish government made an urgent request to the British government to purchase a large number of the Henley “target tugs” – and undertook to pay for replacement Miles Master target tugs similar to those that had been built for them for glider towing by Phillips and Powis Aircraft Limited.

The Finns already had assurances in hand that Phillips and Powis Aircraft Limited were able to produce the Miles Master tugs rapidly (the Finns also undertook to take the Henleys minus their engines – they would fit their own) and this taken together with the obvious unsuitability of the Henley for use as a target tug, resulted in the British agreeing to trade 80 Hawker Henley’s to Finland. Approximately half were crated and shipped in early November 1939 and arrived in Tampere some three weeks later, just prior to the attack on Finland by the USSR on the 30th of November 1939. A small stockpile of Hispano-Suiza 12Y engines had been built up and these were fitted after the shipment arrived. The other half of the order were flown to Finland “as is” in mid-December 1939 (after the Winter War had borken out) by Ilmavoimat Ferry Pilots, some of whom, to the amazement of the RAF and the delight of British newspapers, were women.

Image“She climbed out of the cockpit of her Hawker Henley Dive Bomber and became instantly famous. Wearing a summer uniform of white shirt, dark tie and sleeves rolled above the elbow, she slung a parachute over her shoulder and shook out her long blonde hair. Back-lit by the afternoon sun, Ilmavoimat Ferry Pilot Maureen Dunlop looked unbelievably gamorous.”

One of the more memorable photos of the Winter War was a shot taken of a female Ilmavoimat Ferry Pilot taken just after a familiarisation flight in one of the Hawker Henley’s that was to be transferred to Finland. The photo achieved widespread publication in the UK, the USA and France as well as in Italy and did much to boost the image of Finland as a courageous democracy fighting an all-out war against the Bolsheviks. The pilot was actually an Anglo-Argentinian volunteer, Maureen Dunlop, who had travelled from Buenos Aires to the UK where she had approached the Finnish Embassy and volunteered as a pilot. Desperately short of trained pilots and themselves already using women pilots for non-combat flights, the Finnish embassy accepted her after a flight test. Her first assignment was flying a Hawker Henley to Finland. She went on to fly for the Ilmavoimat for the duration of the Winter War before returning to the UK, where she flew as a ferry pilot for the British Air Transport Auxilary.

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Well after WW2, a novel came out that was very loosely based on Maureen Dunlop’s adventures during the Winter War and WW2.

OTL Note: It’s not. The author used the picture for the cover and it’s about female pilots with the ATA in WW2 but that’s about the sum total of the connection. It’s a great photo tho – it made the covers of Life and the UK’s “Picture Post” magazines. If you want to know more, read “The Spitfire Women of World War II” by Giles Whittell.
A number of additional Vickers “S”guns had been purchased earlier in the year – and Vickers had supplied these quickly. In Finland, the 40mm cannon pods were added and the bomb racks restored. The second seat was removed, if there was time the canopy was replaced, Ilmavoimat radios were installed and lastly, additional armour was retrofitted where available (which was only for about half the aircraft received, which was reason in part for the heavy losses these squadrons suffered over the Winter War).

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An Ilmavoimat Hawker Henley ground attack aircraft in action – January 1940 – Karelian Isthmus. Henleys so equipped were nicknamed “Lentäminen-purkinavaaja” by the Ilmavoimat Pilots who flew them ("Flying Can Opener"). With their 40mm cannon with only 12 rounds per gun, they were incapable of being used as fighters but their speed of around 300mph generally proved sufficient to get them out of trouble and the additional armour helped, although it didn’t stop them taking losses from Soviet AA guns where these existed and were used effectively (in the early months of the Winter War, this was not often).
The first of the ex-RAF Henleys had modifications completed and began entering service in February 1940, at first replacing losses in the existing two Henley-equiped squadrons that had served so well over the first three months of the Winter War- by late February 1940 almost half of the 40 Henley’s in service at the start of the war had been shot down. Being the pilot of a “Lentäminen-purkinavaaja” was a high-risk occupation with a low rate of survival. However, they were devastating ground attack aircraft, decimating attacking Soviet armor on any number of occasions as the Russians attacked and equally as dangerous to the enemy when the Finnish forces attacked. They saw service through to the end of WW2.

The Ilmavoimat Henley “Lentäminen-purkinavaaja” later influenced the design of the A-10 Thunderbolt II, with Unto Oksala's book, “Purkinavaaja Pilot” being required reading for all members of the A-X project, along with Hans Rudel’s “Stuka Pilot.”

Torpedo Bomber Purchase - 1938

The Soviet Baltic Fleet was a threat that was always in the minds of the Finnish General Staff – the existence of a strong Soviet Baltic Fleet opened up the possibility of an amphibious movement to outflank the defences of the Karelian Isthmus and hence the ever-present emphasis the Finns put on the Coastal Defence Batteries and the Coastal Defence Divisions as well as on the Marine Division and the Torpedo Boat and Fast Minelater flotillas. Bottling up the Soviet Navy in Krondstadt was one of the primary missions of the Merivoimat and also for the nacent Merivoimat Air Arm.
At the end of 1937, the Merivoimat Air Arm’s torpedo bomber forces consisted of a small number of now-obsolete Blackburn Ripons. The existing Blackburn Ripon’s were considered to be getting long in the tooth and short of performance and a more modern aircraft was planned to be acquired – not to replace the Ripons as these could still be used for patrolling areas such as the Gulf of Bothnia - but to augment them. In 1938, the Merivoimat Budget made provision for the purchase of a Squadron of new Torpedo Bombers as well as an additional squadron of Dive Bombers. Accordingly, the Ilmavoimat Procurement Team searched for such an aircraft and, as with all their purchases, evaluated a number of types before maing a decision.

In early to mid-1938, there were a number of Torpedo Bombers already in service, but some of them were either obsolete, or nearly so. However, the procurement team went ahead and evaluated many of these on the off-chance that a good aircraft might be missed. And, as always, there was the dual question of both cost and availability to be assessed – and aircraft manufacturers, particularly those in Britain, France and Germany, were often overruled by their respective Governments when it came down to actual delivery. The following aircraft were evaluated over the first six months of 1938.

The Douglas TBD Devastator (USA):
The Blackburn Baffin (UK):
The Fairey Swordfish (UK):
The Fairey Albacore (UK):
Latécoère 298 (France):
Heinkel He111 (Germany):
Heinkel He115 (Germany):
Dornier D022 (Germany):
Blohm and Voss Ha140 (Germany):
Junkers Ju88 (Germany):
Fieseler Fi167 (Germany):
Savoia-Marchetti SM.79 Sparviero ("Sparrowhawk") (Italy)
ex Ngāti Tumatauenga ("Tribe of the Maori War God") aka the New Zealand Army

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