Info: Early Japanese Army Air Force Aircraft

[Robert Hurst]

Hi

Mitsubishi Ki-18

In a new fighter competition organised by the Army in 1934, in which Mitsubishi was not initially involved, Nakajima submitted the Ki-11, a low-wing monoplane with a non-retractable fixed undercarriage, which looked very similar to the Boeing P-26. Kawasaki's entry was a sesquiplane biplane, the Ki-10. The Ki-11 was slightly superior to the Ki-10 in speed, yet the Ki-10 was more manoeuvrable. The latter plane, however, was accepted by the Army as the Type 95 Fighter, but without much enthusiasm.

At this time Mitsubishi's Ka-14 9-Shi Navy Fighter protototype was showing outstanding performance and not only captured the respect of the Navy, but of the Army as well. With the Navy's consent, the Army placed a contract with Mitsubishi for a modified version of the 9-Shi Fighter for evaluation, this became the Ki-18. The main differences between this and the original Navy model revolved around various equipment and systems changes dictated by the Army. Changes from the Navy model included reversing the direction of the throttle movement (in the Army forward was idle) and substituting standard Army machine-guns. This reversing of the throttle movement probably resulted from earlier French influence.

The Ki-18 was a low-wing monoplane of all-metal construction with fabric-covered control surfaces. It was powered by a Kotobuki 5 nine-cylinder radial, rated at 550 hp fro take-off, and 600 hp at 3,100 m (9,185 ft), driving a two-blade fixed-pitch wooden propeller, the Ki-18 introduced a long-chord engine cowling, an enlarged rudder and larger mainwheels and spats.

The new aircraft was completed in August 1935, and was tested at the Air Technical Research Institute at Tachikawa and later at the Akeno Army Flying School throughout the autumn and winter of 1935. In the early part of 1936 the Kotobuki 5 was changed to the Kotobuki 3, rated at 640 hp for take-off and 715 hp at 2,800 m ( 11,485 ft) at the suggestion of Capt. Oujira Matsumura, an instructor at Akeno. The direct-drive Kotobuki 3 seemed to be an Army preference. During these tests, flown primarily by Capt. Akita, a maximum speed of 444 km/h (276 mph) at 3,050 m (10,000 ft) was recorded, and the aircraft was able to climb to 5,000 m (16,404 ft) in 6 min 25.8 sec - an exceptional rate. These remarkable tests continued until the Ki-18 was badly damaged in alanding accident.

Opinions by those who flew the aircraft were that stability and control could be improved but no changes were made. However, while the Ki-18 was being evaluated at the Akeno Flying School, it gained excellent marks in every respect and it was requested that further models be produced. The Akeno recomendations were countered by the Air Technical Research Institute expressing dissatisfaction with the engine which it termed unreliable. Supporting this claim, the senior organisation, Army Air Headquarters, concluded that the Ki-18 had insufficient performance for acceptance as an Army fighter. Therefore, a new competition would be staged, inviting three aircraft companies to participate. Thus, the Ki-18 ended with only one aircraft, to the astonishment of Mitsubishi, because of the dissatisfaction expressewd by the Air Headquarters, while this same aircraft was considered a revolutionary fighter for the Japanese Navy.

Technical Data

Manufacturer: Mitsubishi Jukogyo KK (Mitsubishi Heavy Industries Co Ltd).
Type: Single-engine fighter.
Crew (1): Pilot in open cockpit.
Powerplant: One 600 hp Nakajima Kotobuki 5 nine-cylinder air-cooled radial engine, driving a two-blade fixed-pitch wooden propeller.
Armament: Two fixed forward-firing 7.7 mm Type 89 machine-guns.
Dimensions: Span 11 m (36 ft 1 3/16 in); length 7.655 m (25 ft 1 1/4 in); height 3.15 m (10 ft 4 in); wing area 17.8 sq m (191.603 sq ft).
Weights: Empty 1,110 kg (2,447 lb); loaded 1,422 kg ( 3,135 lb); wing loading 79.9 kg/sq m (16.3 lb/sq ft); power loading 2.6 kg/hp (5.2 lb/hp).
Performance: Maximum speed 444 kh/h (276 mph) at 3,050 m (10,000 ft); landing speed 112 km/h (70 mph); climb to 5,000 m (16,404 ft) in 6 min 26 sec.
Production: A single Ki-18 prototype was built by Mitsubishi Jukogyo KK in 1935.

The photo was taken from Japanese Aircraft 1910-1941, by Robert C Mikesh & Shorzoe Abe.

Regards

Bob

[Robert Hurst]

Hi

Nakajima Ki-19

Acknowledging the experience that both Nakajima and Mitsubishi had accumulated with designing twin-engined aircraft, the Army contracted with both companies in 1935 to develop a modern heavy bomber to replace the Mitsubishi Ki-1 Army Type 93 Heavy Bomber of 1933 vintage. With this order came a chnage whereby the military issued pre-contractual specifications that were to be met in creating new designs.

Among the requirements issued in February 1936 were: maximum speed 399 km/h (248 mph) at 3,000 m (9,842 ft); climb to that altitude in less than 8 minutes; take-off in less than 300 m (984 ft); normal operating altitude from 2,000 m (6,561 ft) to 4,000 m (13,123 ft); and endurance of more than five hours at 299 km/h (186 mph) at 3,000 m (9,842 ft). Structural strength was specified as well, including a load factor of 6 while at high angle of attack, and 4 while in a glide. Minimum bomb load for short-range missions was to be 1,000 kg (2,205 lb) with a variety of load configurations. Loaded, the bomber was to have a weight of less than 6,400 kg (14,109 lb). Other specified requirements were a crew of from four to six; engines to be either the Nakajima Ha-5 or Mitsubishi Ha-6; and three gun positions (nose, dorsal and ventral, each with one flexible 7.7 mm (0.303 in) Type 89 machine-gun). The Hi-2 (Type 94) or Hi-5 radio, and other details were also specified.

Rightfully selected for the design team were Ken-ichi Matsumura as chief designer, assisted by Setsuro Nishimura and Toshio Matsuda, all of whom had previous twin-engined design experience on the Nakajima-Douglas DC-2 commercial airliner project, and the short-lived LB-2 long-range attack bomber project for the Navy.

The Ki-19, two prototypes of which were built by Nakajima, was a mid-wing cantilever monoplane of all-metal construction with fabric-covered control surfaces. Embodying the latest innovations in bomber design, this aircraft had a bomb-bay within a very streamlined fuselage as opposed to carrying the bombs externally. Its cantilever wing was mounted at mid-level on the fuselage, and a Douglas-type hydraulically-operated retractable undercarriageand split-flaps were used.

Performance testing by the Army Air Technical Research Institute with the competing Mitsubishi Ki-21 entries lasted from March to May 1937 at Tachikawa. From there, the evaluation process moved to the Army's main bomber base at Hamamatsu for bombing and other operational testing which began in June that year. The evaluators closely studied the engines as well as the airframe and performance. Not completely satisfied with the combinations of airframe and engines, although the Mitsubishi Ki-21 airframe and Nakajima engines had been selected, the Army ordered two additional Ki-19 prototypes from Nakajima to be powered by the Mitsubishi Ha-6, and two prototypes of the Mitsubishi Ki-21 to be powered by Nakajima Ha-5 engines.

Prototypes from the two companies were almost identical in performance, but the Army officially selected the Mitsubishi Ki-21 as the Army Type 97 heavy Bomber considering that the Nakajima Ha-5 was the more reliable engine in spite of its poor reputation for reliability. Nakajima havin glost the Army contract, converted the fourth prototype, one of those powered by the Mitsubishi Ha-6, into a civil aircraft and in April 1939 gave it the new designation N-19. It was commonly refreed to as the N-19 Long-Range Communications Aircraft and sold to the Dmei Tsushin-sha (Domei Press Co), registered J-BACN and named Domei No.2.

Technical Data

Manufacturer: Nakajima Hikoki KK (Nakajima Aeroplane Co Ltd).
Type: Twin-engine heavy bomber.
Crew (5): Pilot, co-pilot, navigator/bombardier, radio-operator/gunner and gunner.
Powerplant: Two 890 hp Nakajima Ha-5 fourteen-cylinder double-row air-cooled radial engine, driving Hamilton Standard controllable-pitch metal propellers.
Armament: Three flexible 7.7 mm (0.303 in) Type 89 machine-guns in nose, dorsal and ventral positions. Bombload of 1,000 kg (2,205 lb) for short-range missions.
Dimensions: Span 22 m (72 ft 2 in); length 15 m (49 ft 2 1/2 in); height 3.65 m (11 ft 11 3/4 in); wing area 62.694 sq m (674.854 sq ft).
Weights:* Empty 4,750 kg (10,472 lb); loaded 7,150 kg (15,763 lb); wing loading 113.5 kg/sq m (23.3 lb/sq ft); power loading 4.1 kg/hp (9.1 lb/hp).
Performance:* Maximum speed 351.9 km/h (218.6 mph); cruising speed 300 km/h (186.42 mph); range 4,000 km (2,845 miles).
Production: A total of four prototypes were built by Nakajima Hikoki KK between 1937-1938.

* Note: Weights and performance are for N-19 with Ha-6 engines.

The photo was taken from Japanese Aircraft 1910-1941, by Robert C Mikesh & Shorzoe Abe.

Regards

Bob

[Robert Hurst]

Hi

Mitsubishi Ki-20

In order to meet an Army order to manufacture a bomber version of the, then, very large Junkers G.38 passenger aircraft, Mitsubishi entered into a contract with Junkers in September 1928 to obtain design data, working drawings, manufacturing techniques and production rights. Germany at that time was forbidden to build military aircraft, but, as the K.51, the G.38 could be converted into a bomber for export. Features could be designed into the basic aircraft for the purchaser, such as armament and internal systems to meet Japanese Army requirements. Accordingly, the Junkers K.51 design became in Japan the Ki-20, a retroactive designation made long after its existence. The intended, but very secret, purpose was for the bomber to be capable of attacking the fortified Island of Corregidor at the emtrance to Manila Bay from the Japanese airfield at Pintung in Formosa (Taiwan), a need that did not materialise until thirteen years later. This Junkers technology introduced Mitsubishi to entirely new design and manufacturing methods.

Nobushiro Nakara, soon to be the chief designer for this project, and Kyonosuke Ohki were sent by Mitsubishi to Germany in 1928 to study the design and prepare for its manufacture in Japan. In December of that year, engineer Yonezo Mitsunawa and chief mechanic Tsunetaro Ishihama went to Junkers to study manufacturing techniques, while engineer Keisuke Ohtsuka purchased the necessary machines, tools, jigs and materials in Germany in April 1930. From Germany came a team of engineers led by Eugene Harbard Schade to assist with manufacture. Representitives of the Japanese Army, included Col. Kozumi as chief, with engineers Kuranishi, Ando, Lt. Matsumura and others to assist.

The Ki-20 was a large four-engined mid-wing monoplane with a non-retractable undercarriage with tandem wheels and a biplane tail with triple fins. Construction was of all-metal corrugated stressed-skin structure. When production began, the first and second aircraft were built with components imported from Germany, the third included only a proportion of imported components, but the remaining aircraft were of all-Japanese manufacture.

The Ki-20's defensive armament, formidable for the period comprised a total of eight 7.7 mm (0.303 in) machine guns and one 20 mm (0.79 in) cannon. The layout of this formidable array was as follows: Two 7.7 mm (0.303 in) machine-guns in an open bow-gunner's cockpit, one dorsal mounted 20 mm (0.79 in) cannon on top of the fuselage, two underwing turrets each with a single 7.7 mm (0.303 in) machine-gun and two upper wing turrets each with two 7.7 mm (0.303 in) machine-guns, these blending into the rear portions of the two outboard engine nacelles. Bombs were carried under the fuselage on external racks. The standard bomb load was 2,000 kg (4,409 lb) with a claimed maximum of 5,000 kg (11,023 lb).

The first aircraft was completed in 1931 and flown from Kagamigahara under conditions of extreme secrecy which prevailed for nearly the entire life of the aircraft. The first four aircraft were powered by four 800 hp Junkers L-88 petrol engines, and the last two by 720 hp Junkers Jumo 204 diesels. Power arrangements varied from time to time, such as installing two Junkers L-88s inboard and two Junkers Jumo 204s outboard. Later Kawasaki Ha-9 were installed for trials to further develop the aircraft for long-range bomber missions. But by the time these tests were concluded the Army realised that the performance of these heavy, slow, ungainly aircraft with their chronic engine problems, fell far short of expectations for a long-range strategic bomber capable of attacking targets as far away as the Philippines.

These were enormous aircraft for their day, with a huge bat-like wing which spanned nearly one-metre more than the Boeing B-29 Superfortress. In terms of wing area (which was almost double that of the B-29) the Ki-20 was the largest aircraft ever built in Japan. It was one of the largest landplanes at that time, and because of this caused considerable problems especially if assigned to operational units in unprepared forward areas. Although the aircraft was flown both in Japan and Manchuria, they were never used in combat; instead they were used for research and domestic propaganda purposes. Their first public demonstration was not until January 1940, when three appeared during a formation fly-past over Tokyo, having taken-off from Tachikawa Airfield. When taken out of service soon after, they were displayed at various defence exhibitions and amusement parks. The last was stored in the Aviation Memorial Hall at Tokorozawa where it survived with other rare types until the end of the Pacific War.

Technical Data

Manufacturer: Mitsubishi Kokuki KK (Mitsubishi Aircraft Co Ltd).
Type: Four-engine long-range heavy bomber.
Crew (10): Capt, two pilots, bombardier/nose gunner, flight engineer/top gunner, radio operator/top gunner and four wing gunners.
Powerplant: Four 800 hp Junkers L-88 twelve-cylinder vee liquid-cooled engines, or four 750 hp Type Ju (Ju 204) twelve-cylinder vertically-opposed liquid-cooled diesel engines, driving four-blade wood propellers.
Armament: See text.
Dimensions: Span 44 m (144 ft 4 1/4 in); length 23.20 m ( 76 ft 1 1/2 in); height 7 m (22 ft 11 3/4 in); wing area 294 sq m (3,164.693 sq ft).
Weights: Empty 14,912 kg (32,875 lb); loaded 25,448 kg (56,103 lb); wing loading 86.6 kg/sq m (17.7 lb/sq ft); power loading 7.96 kg/hp (17.5 lb/hp).
Performance: Maximum speed 200 km/h (124 mph).
Production: A total of six Ki-20s were built by Mitsubishi Kokuki KK as follows: No.1 April 1931-March 1932, Nos.2 and 3 April 1932-March 1933, No.4 April 1933-March 1934 and Nos. 5 and 6 April 1934-March 1935.

The photos were taken from Japanese Aircraft 1910 to 1941, by Robert C Mikesh & Shorzoe Abe.

Regards

Bob

[Robert Hurst]

Hi

Mitsubishi Ki-21 - Pt 1

The Ki-21 was designed by Mitsubishi in answer to a specification asking for a twin-engined heavy bomber to replace the Army Type 92 Heavy Bomber (Mitsubishi Ki-20) and the Army Type 93 Heavy Bomber (Mitsubishi Ki-1) which had been issued on 15 February, 1936, by the Koku Hombu. Requirements included: (1) operating altitude, 2,000 to 4,000 m (6,560 to 13,125 ft); (2) endurance, over five hours at 300 km/h (186 mph); (3) maximum speed, 400 km/h (248.5 mph) at 3,000 m (9,845 ft); (4) climb to 3,000 m (9,845 ft) in 8 min; (5) take-off run, less than 300 m (985 ft); and (6) engines, two 850 hp Nakajima Ha-5 or two 825 hp Mitsubishi Ha-6 radials. The aircraft was required to be operated by a normal crew of four, with two extra seats made available for additional gunners as required. Defensive armament was to consist of no less than three flexible machine-guns in nose, dorsal and ventral positions, and with full fuel load, bomb-load was to equal 750 kg (1,653 lb) while maximum bomb-load for short range missions was to be 1,000 kg (2,205 lb).

Credited to a team led by engineers Nakata and Ozawa, the two Ki-21 prototypes were completed at Mitsubishi's 5th Airframe Works at Nagoya in December 1936. Powered by two 825 hp Mitsubishi Ha-6 radials driving variable-pitch propellers, the two aircraft were all-metal cantilever monoplanes with wings set at mid-fuselage above the ventral bomb-bay and were characterised by an angular glazed nose housing the bomb-aimer's position and a 7.7 mm (0.303 in) Type 89 machine-gun movable only in the vertical axis. The second Ki-21 prototype differed from the first in the design of its dorsal turret, a long greenhouse replacing the semi-hemispherical turret which generated excessive drag. A third flexible 7.7 mm (0.303 in) Type 89 machine-gun firing towards the rear was mounted in the ventral step. Commencing on 18 December, 1936, when the first Ki-21 made its maiden flight, the two aircraft were used in the manufacturer's flight test programme until March 1937 when both aircraft were pitted against the first two Ha-5 powered Nakajima Ki-19s. A third competitive design, the Kawasaki Ki-22 had been submitted in answer to the specification of 15 February, 1936, but had not been approved for prototype construction. The competitive evaluation of the Ki-21 and Ki-19 culminated in June 1937 with bombing trials held at Hamamatsu. The Ki-21 was credited with superior performance and lighter wing loading but the Ki-19 had more reliable engines, better flight characteristics and offered a more suitable bombing platform. Consequently, the Koku Hombu ordered additional prototypes of both types and Mitsubishi were instructed to use the 850 hp Nakajima Ha-5 engines, rated at 950 hp for take-off, and 1,080 hp at 4,000 m (13,125 ft), and to improve the flight characteristics of their Ki-21.

The photos were taken from Japanese Aircraft of the Pacific War, by Rene J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Mitsubishi Ki-21 - Pt 2

The third Ki-21, the first to be powered by a pair of 850 hp Nakajima Ha-5s, featured a hemispherical nose housing a 7.7 mm (0.303 in) Type 89 machine-gun on a ball-and-socket mounting and had a redesigned rear fuselage without ventral step. Directional stability, particularly important during the bombing run, was improved with the fitting of redesigned vertical tail surfaces. When a new series of competitive trials against the Ki-19 were held at Tachikawa, the Ki-21 so modified easily won a production order, and the last five Ki-21 prototypes actually became Service trials aircraft, and were used for testing operational equipment. The initial production model, the Ki-21-Ia, ordered in 1937 as the Army Type 97 Heavy Bomber Model IA was externally identical to the Ha-5 powered prototypes but featured an increase in fuel tank capacity from 1,840 litres (405 Imp gal) to 2,635 litres (580 Imp gal). Beginning in the spring of 1938 Mitsubishi built 143 aircraft of this type ( Ki-21 c/ns 9 to 151). A produciton order for the Ki-21 had also been awarded to Nakajima Hikoki KK which, between August 1938 and February 1941, built a total of 315 Ki-21-Ia, Ki-21-Ib and Ki-21-Ic aircraft. These last two versions of the Ki-21 were developed by Mitsubishi to overcome the weakness of the aircraft's defensive armament and lack of fuel tank protection which had become painfully clear when the 60th and 61st Sentais had been sent to China with their Ki-21-Ias in the summer of 1938.

The Ki-21-Ib retained the same three flexible Type 89 machine-guns in the nose, dorsal and ventral positions, and was also armed with a similar machine-gun firing through lateral openings on either side of the rear fuselage. A fifth 7.7 mm (0.303 in) Type 89 machine-gun was mounted as a 'stinger' in the extreme tail of the aircraft, this remotely-controlled gun installation having previously been tested on the fifth prototype. The 120 Mitsubishi-built (Ki-21 c/ns 152 to 271) Army Type 97 Heavy Bomber Model IB, like the Nakajima-built Ki-21-Ibs, had their fuel tanks partially protected by laminated rubber sheets. Other modifications incorporated in the Ki-21-Ib included an enlarged bomb-bay, larger landing flaps, and new horizontal tail surfaces with a total area increased from 10.82 sq m (116.465 sq ft) to 11.32 sq m (121.847 sq ft). The Ki-21-Ic, of which Mitsubishi built 160 (Ki-21 c/ns 272 to 431), received an additional lateral machine-gun, and an auxiliary fuel tank with a capacity of 500 litres (110 Imp gal) could be fitted in the rear bpmb-bay. When this tank was installed four 50 kg (110 lb) bombs were carried externally. Since the Ki-21 had been designed its weight had steadily increased and larger main wheels had to be installed on the Ki-21-Ic. In service the Ki-21-Ib and -Ic replaced the earlier version in front-line units operating in northern China and Manchuria, and the Ki-21-Ias were assigned to training units and bomber sentais retained in Japan.

The photos were taken from Japanese Aircraft of the Pacific War, by Rene J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Mitsubishi Ki-21 - Pt 3

Fighting a war in China, the Japanese Army found themselves critically short of transport aircraft, and pending delivery of the Ki-57, it was decided to modify some of the Ki-21-Ias taken out of front-line bomber units as freight transports for service with Dai Nippon Koku KK (Greater Japan Air Lines Co Ltd) on their military contract routes between Japan, Manchuria and China. Designated MC-21, these aircraft had all armament and military equipment removed but, initially at least, retained the bomber's glazed nose and dorsal greenhouse. Although primarily used as a freighter, the MC-21 could be fitted if necessary with nine troop seats in a primitive cabin. Starting in February 1940 with J-BFOA Hiei, a small number of MC-21s were delivered to Dai Nippon Koku KK. Later these aircraft were further modified by replacing the glazed nose with a metal fairing. Other Ki-21-Is were similarly modified in the field to serve as communication and hack aircraft with various Army commands.

The photos were taken from Japanese Aircraft of the Pacific War, by Rene J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Mitsubishi Ki-21 - Pt 4

In the light of negligible Chinese Air Force opposition, the Ki-21-Ib and -Ic were quite effective but, preparing themselves for a bigger conflict, in November 1939 the Japanese Army instructed Mitsubishi to increase the aircraft's speed and ceiling. The first Ki-21-Ic (Ki-21-I c/n 272) was chosen as development aircraft for the advanced version of the Army Type 97 Heavy Bomber, and was powered by two 1,450 hp Mitsubishi Ha-101 fourteen-cylinder air-cooled radials, rated at 1,500 hp at take-off and 1,340 hp at 4,600 m (15,090 ft). A complete redesign of the engine nacelles was necessary to house the Ha-101, which had larger diameter propellers than the Ha-5, and fully enclose the undercarriage. The armament, fuel tank arrangement and other systems remained unchanged but the area of the horizontal tail surfaces was further increased from 11.32 sq m (121.847 sq ft) to 13.16 sq m (141.653 sq ft). Flight trials of the modified aircraft, the Ki-21-II, began in March 1940, and led to a produciton order as the Army Type 97 Heavy Bomber Model 2A (Ki-21-IIa). Commencing in December 1940 with the delivery of four Service trials machines, the Ki-21-IIa supplemented the earlier versions in front-line units and at the start of the Pacific War most Army jubaku sentais (heavy bomber groups) had converted to this variant.

When the war against the Allies started, the Japanese Army air units were assigned the primary task of supporting the invasion of Thailand, Burma (Myanmar)and Malaya (Malaysia) while maintaining constant pressure against the Chinese. On the first day of the war the 3rd Hikoshidan (Air Division) operating from bases in French Indo-China (Vietnam, Cambodia & Laos) had three Jubaku Sentais with 87 of the Army Type 97 Heavy Bombers on strength and some of these aircraft were first deployed in support of the landings at Kota Bharu. During the following seven months the Ki-21-IIs supported Army ground operations in Southeast Asia and the Netherlands East Indies (Indonesia), and played an important part in the fall of Hong Kong and Rangoon. Initiallly facing obsolete Allied aircraft the Ki-21-IIs proved quite successful but, when pitted against RAF Hurricanes and P-40s of the American Voluteer Group over Burma and China, losses increased sharply.

To remedy the chronic weakness of the defensive armament, the long dorsal greenhouse, offering only a limited field of fire to the dorsal machine-gun, was eliminated starting with the Ki-21 c/n 1026. To replace this hand-held machine-gun Mitsubishi designed a large conical turret housing a 12.7 mm (0.5 in) Type I machine-gun. With the installation of this turret - operated by bicycle pedals with chain-drive for gun traverse - the aircraft was redesignated Army Type 97 Heavy Bomber Model 2B or Ki-21-IIb, and late production aircraft of this variant were characterised by the replacement of the exhaust collector ring with individual exhaust stacks offering some thrust augmentation. Mitsubishi delivered 688 Ki-21-IIbs bringing total produciton of all Ki-21s, including prototypes and Nakajima-built aircraft to 2,064.

During the early war years the Ki-21 was one of the best-known Japanse aircraft and it received one of the original code names: 'Jane' after General MacArthur's wife. As the famous general did not appreciate this form of compliment the code name was quickly changed to 'Sally'. Later, the absence of the long dorsal greenhouse - one of 'Sally's' main recognition features - led Allied intelligence to identify the Ki-21-IIb as a new type of Japanese bomber which accordingly received the code name 'Gwen'. When the aircraft was properly identified as being merely a version of the Ki-21 it was renamed 'Sally 3', 'Sally 1' referring to the Ha-5 powered models and 'Sally 2' to the Ha-101 powered Ki-21-IIa. Whether known as 'Gwen' or 'Sally 3', the Ki-21-IIb was met by Allied forces from New Guinea to India and China. By 1943, the Ki-21-II equipped jubaku sentais outnumbered two-to-one the Ki-49 equipped units and the Army Type 97 Heavy Bomber carried the brunt of the Japanese offensive air actions against Calcutta. Other Ki-21-II Sentais fought gallantly to slow down the Allied advance from New Guinea to the Philippines but, with their fighter escort being outnumbered and being hunted on the ground by Allied fighter sweeps, their losses were very high. Fortunately for the Army, at long last a replacement for the Ki-21 was becoming available and the Army Type 97 Heavy Bombers began to be phased-out of operations during the last year of the war. At the time of the Japanese surrender only the 58th Sentai still operated the Ki-21 in its original role and most remaining aircraft were being used as communication or headquarters aircraft or for special missions. One such mission was the commando attack on Yontan airfield, Okinawa, on which one out of nine Ki-21-IIbs despatched by the 3rd Dokuritsu Hikotai (Independent Wing) managed to crash-land near parked US aircraft and suppy dumps, considerable damage being inflicted by the fanatical commandos.

The Mitsubishi Ki-21 had contributed more than any other aircraft to bringing the air branch of the Army to parity of equipment with other air forces. However, the inability of the Japanese aircraft industry to provide in time an adequate successor to the Ki-21 forced the use of the aircraft beyond its planned operational career. During the latter part of the war, despite its obsolescence, the Ki-21 was still liked by its crews for its pleasant handling characteristics and ease of maintenance and was preferred to the more modern Nakajima Ki-49.

Photos were taken from Japanese Aircraft of the Pacific War, Rener J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Mitsubishi Ki-21 - Pt 5

Units Allocated

7th, 12th, 14th, 58th, 60th, 61st, 62nd, 92nd, 94th, 95th and 98th Sentais. 3rd Dokuritsu Hikotai. 22nd Hikodan. 1st, 5th and 8th Hikoshidan Shireibu Hikodan. Hamamatsu Army Bomber Flying School.

Technical Data.

Manufacturer: Mitsubishi Jukogyo KK (Mitsubishi Heavy Industries Co Ltd).
Type: Twin-engine heavy bomber.
Crew (5+2): Pilot, co-pilot, navigator/bombardier, radio-operator/gunner and gunner. Two additional gunners could be carried when required.
Powerplant: (1st & 2nd Ki-21 prototypes) Two 825 hp Mitsubishi Ha-6 fourteen-cylinder air-cooled radials, driving three-blade variable-pitch metal propellers; (3rd-8th Ki-21 prototypes, Ki-21-I and MC-21) Two 850 hp Army Type 97 (Nakajima Ha-5 KAI) fourteen-cylinder air-cooled radials, driving three-blade variable-pitch metal propellers; (Ki-21-II) Two 1,450 hp Army Type 100 (Mitsubisji Ha-101) fourteen-cylinder air-cooled radials, driving thre-blade constant speed metal propellers.
Armament: (Prototypes and Ki-21-Ia) One flexible 7.7 mm (0.303 in) Type 89 machine-gun in each of nose, ventral and dorsal positions; (Ki-21-Ib) One flexible 7.7 mm Type 89 machine-gun in each of nose, ventral and dorsal positions. One flexible 7.7 mm (0.303 in) Type 89 machine-gun in a tail stinger and one flexible 7.7 mm (0.303 in) Type 89 machine-gun firing from either side of the fuselage; (Ki-21-Ic and Ki-21-IIa) One flexible 7.7 mm (0.303 in) Type 89 machine-guns in each of nose, ventral, dorsal, tail and port and starboard beam positions; (Ki-21-IIb) One flexible 7.7 mm (0.303 in) Type 89 machine-guns in each of nose, ventral, tail and port and starboard beam positions and one 12.7 mm (0.5 in) Type 1 machine-gun in dorsal turret. Bomb-load - normal 750 kg (1,653 lb); maximum 1,000 kg (2,205 lb).
Dimensions: (Ki-21-Ia) Span 22.5 m (73 ft 9 13/16 in); length 16 m (52 ft 5 29/32 in); height 4.35 m (14 ft 3 13/32 in); wing area 69.6 sq m (749.165 sq ft). (Ki-21-IIb) Span 22.5 m (73 ft 9 13/16 in); length 16 m (52 ft 5 29/32 in); height 4.85 m (15 ft 10 15/16 in); wing area 69.6 sq m (749.165 sq ft).
Weights: (Ki-21-Ia) Empty 4,691 kg (10,342 lb); loaded 7,492 kg (16,517 lb); maximum 7,916 kg (17,452 lb); wing loading 107.6 kg/sq m (22 lb/sq ft); power loading3.9 kg/hp (8.7 lb/hp). (Ki-21-IIb) Empty 6,070 kg (13,382 lb); loaded 9,710 kg (21,407 lb); maximum 10,610 kg (23,391 lb); wing loading 139.5 kg/sq m (28.6 lb/sq ft); power loading 3.2 kg/hp (7.1 lb/hp).
Performance: (Ki-21-Ia) Maximum speed 432 km/h (268 mph) at 4,000 m (13,125 ft); climb to 5,000 m (16,405 ft) in 13 min 55 sec; service ceiling 8,600 m (28,215 ft); range - normal 1,500 km (932 miles) maximum 2,700 km (1,680 miles). (Ki-21-IIb) Maximum speed 486 km/h (302 mph) at 4,720 m (15,485 ft); cruising speed 380 km/h (236 mph) at 5,000 m (16,405 ft); climb to 6,000 m (19,685 ft) in 13 min 13 sec; service ceiling 10,000 m (32,810 ft); range - maximum 2,700 km (1,680 miles).
Production: A total of 2,064 Ki-21s were built by Mitsubishi Jukogyo KK at Nagoya and Nakajima Hikoki KK at Ota as follows:

Mitsubishi Jukogyo KK:

8 prototypes and Service trials aircraft - November 1936-March 1938
143 Ki-21-Ia production aircraft - March 1938-1939
120 Ki-21-Ib production aircraft - 1939-1940
160 Ki-21-Ic production aircraft - 1940
4 Ki-21-II Service trials aircraft - December 1940
590 Ki-21-IIa production aircraft - December 1940-1942
688 Ki-21-IIb production aircraft - 1942-September 1944

Total

1,713

Nakajima Hikoki KK

351 Ki-21-Ia,-Ib and -Ic production aircraft - August 1938-February 1941

An unknown number of Ki-21-Is were modified as transport aircraft under the designation MC-21.

The photo was taken from Japanese Aircraft of the Pacific War, by Rene J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Nakajima Ki-27 - Pt 1

In 1934, the Army had issued a specification calling for a replacement type for the Army Type 92 (Kawasaki KDA-5) Fighter, then standard equipment for the fighter units. In answer to this specification Kawasaki submitted the Ki-10, a refinement of their older biplane, and Nakajima entered the Ki-11, wire-braced low-wing monoplane inspired by the Boeing P-26. Although powered by a Nakajima Ha-8 with a maximum rating of only 640 hp versus the 800 hp rating of the Kawasaki Ha-9-II of the Ki-10, the Ki-11 was considerably faster. However, the Service pilots were not yet ready for such novelties as low-wing monoplanes and enclosed cockpits, and the Ki-10, more manouevrable and faster climbing than the Ki-11, was selected for production as the Army Type 95 Fighter and became the JAAF's last combat biplane.

Nakajima, despite their failure to obtain a production contract for the Ki-11, had acquired enough test data with this aircraft and the Ki-12, an experimental low-wing monoplane powered by a liquid-cooled Hispano-Suiza 12Ycrs with hub-mounted cannon, to be satisfied with the potential of the monoplane fighter configuration and to embark on their own on the design of a more advanced machine, the Type PE. The PE design was still in its early phase when, in June 1935, the Koku Hombu instructed Mitsubishi, Kawasaki and Nakajima each to build two prototypes of advanced fighter aircraft.

Nakajima's wisdom in pursuing the development of the monoplane fighter was vindicated when Kawasaki submitted their Ki-28 low-wing cantilever monoplane powered by an 800 hp Kawasaki Ha-9-IIa liquid-cooled engine, while Mitsubishi submitted the Ki-33, a version of their A5M monoplane then being manufactured for the JNAF as the Navy Type 96 Carrier Fighter. In the meantime, Nakajima had decided as a private venture to carry on with the design of the Type PE and to enter in the forthcoming competition a development of this machine which received the military designation Ki-27.

The single Type PE produced was completed in July 1936 and was followed in October 1936 by the first prototype Ki-27. Both machines, designed by T Koyama, were low-wing cantilever monoplanes each powered by a 650 hp Nakajima Ha-1a radial, rated at 710 hp for take-off and 650 hp at 2,000 m (6,560 ft), and fitted with fixed spatted undercarriages; they differed in minor details affecting the design of the cowling, canopy, vertical tail surfaces and wheel spats. The Type PE was retained by Nakajima and provided useful information which was incorporated in the prototype Ki-27 during its construction.

Before its retirement, the Type PE was also used to flight test the 'butterfly' combat flaps which Nakajima used with considerable success to improve the manoeuvrability of their wartime fighters. In designing the Type PE and the Ki-27, T Koyama had selected an extremely light structure and made use of a new aerofoil section developed by Nakajima which gave the aircraft its remarkable manoeuvrability.

The top photo was taken from The Complete Book of Fighters, by William Green & Gordon Swanborough, the centre photo was taken from Japanese Aircraft of the Pacific War, by Rene J Francillon, and the bottom photo was taken from Warplanes of the Second World War Fighters Vol 3, by William Green.

Regards

Bob

[Marcus Wendel]

Thanks again, very good info.

/Marcus

[Caldric]

As always I find your post very educational and above par Robert, thanks for your work and great post.

[Robert Hurst]

Hi

Nakajima Ki-27 - Pt 2

The first prototype Ki-27, flying from Ojima Airfield on 15 October 1936, had a wing area of 16.4 sq m (176.527 sq ft) and was joined in December 1936 by a second machine on which the wing area was increased to 17.6 sq m (189.444 sq ft). Following manufacturer's trials, the two aircraft were handed over to the Rikugun Kokugijutsu Kenkyujo (Army Aerotechnical Research Institute) at Tachikawa where they were pitted against the Mitsubishi Ki-33 and Kawasaki Ki-28.

During competitive trials, the second Ki-27 reached a maximum speed of 468 km/h (291 mph) at 4,000 m (13,125 ft) versus the Ki-28's speed of 485 km/h (301 mph) at the same altitude and the Ki-33's 474 km/h (295 mph) at 3,000 m (9,845 ft). An altitude of 5,000 m (16,405 ft) was reached in 5 min 10 sec by the Ki-28, in 5 min 38 sec by the Ki-27 and in 5 min 56 sec by the Ki-33.

Despite its slightly inferior performance the Ki-27 was found the best of the three because of its superlative manoeuvrability, and ten pre-production aircraft , built between June and December 1927, were ordered. During the competitive trials, the incidence of the wings of the second Ki-27 had been increased by 1.5 degrees to improve handling characterstics and, despite its larger wing area , the aircraft was only 7 km/h (4.35 mph) slower than the less manoeuvrable first prototype.

To improve manoeuvrability further it was decided to increase the wing span of the pre-production aircraft from 10.4 m (34 ft 1 7/16 in) to 11.31 m (37 ft 1 1/4 in) and the wing area from 17.6 sq m (189.444 sq ft) to 18.56 sq m (199.777 sq ft). Although retaining the long streamlined forward section housing the telescopic gunsight, the pre-production aircraft's canopy was modified by replacing the metal headrest by a fixed clear vision section and by fitting rearward sliding panels over the cockpit. Tests were completed late in 1937 and the aircraft was placed in production as the Army type 97 Fighter Model A (Ki-27a).

The top photo was taken from Warplanes of the Second World War: Fighters Vol 3, by William Green, the middle photo was taken from The Concise Guide to Axis Aircraft of World War II, by Dasvid Mondey, and the bottom photo was taken from The Complete Book of Fighters, by William Green & Gordon Swanborough.

Regards

Bob

[Robert Hurst]

Hi

Nakajima Ki-27 - Pt 3

Like the pre-production aircraft, the production Ki-27a was fitted with the larger wings, but the canopy was once again modified by adopting a more conventional windshield and using a metal-covered rear section, while the more powerful Nakajima Ha-1b rated at 780 hp at 2,900 m (9,515 ft) was fitted. The aircraft carried a pair of synchronised 7.7 mm (0.303 in) Type 89 machine-guns mounted in the upper fuselage forward decking.

In March 1938 the aircraft saw operation over Northern China where they quickly wrested control of the sky away from the hard-pressed Chinese forces. Shortly thereafter, the Imperial Japanese Army reorganised their air units by replacing the mixed units made up of fighter, bomber and reconnaissance aircraft with specialised sentais made up of only one type
of aircraft, and the 59th Fighter Sentai activated at Kagamigahara, Gifu Prefecture, on 1 July, 1938, was the first unit to be equipped exclusively with Army Type 97 Fighters. As fast as deliveries allowed, Ki-27s were delivered to the 64th, 13th, 5th and 11th Sentais in that order before September 1938.

As production gained tempo the Ki-27a gave place to the Ki-27b characterised by the clear vision panels of the canopy's rear section, modified oil cooler, and provision under the wing centre-section for four 25 kg (55 lb) bombs. These bombs could be replaced by two 130 litre (28.6 Imp gal) slipper drop tanks lying flat under the wings on both sides of the fuselage. For gunnery training a cine-gun could be attached on the port-wing near the root. Production of the Ki-27b was also entrusted to Mansyu Hikoki Seizo KK (Manchurian Aeroplane Manufacturing Co Ltd) at Harbin, Manchukuo.

The photos were taken from Japanese Aircraft of the Pacific War, by Rene J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Nakajima Ki-27 - Pt 4

When on 4 May, 1939, fighting began on the Manchukuo/Outer Mongolia border in the Nomnhan area between Japanese and Russian forces, the Japanese Army committed, along with other air units, five Ki-27 equipped Fighter Sentais - the 1st, 11th, 24th, 59th and 64th - mustering some 80 machines. At the peak of the fighting, Japanese forces had increased to 200 fighters, mostly Ki-27s but including some Ki-10s.

When hostilities ceased, the Japanese claimed to have shot down no fewer than 1,340 Russian aeroplanes and destroyed a further 50 machines on the ground, and they reported that the Russians had committed up to 3,000 aircraft during the five month Nomonhan Incident. The Russian counter-claim of committing only 450 aircraft suggests that the Japanese overstated their claims to hide what was actually a defeat, as they admitted losing 120 aircraft against the Russian reports that 215 Nipponese planes had been destroyed.

The photos were taken from Japanese Aircraft of the Pacific War, by Rene J Francillon.

Regards

Bob

[Robert Hurst]

Hi

Nakajima Ki-27 - Pt 5

The Nomonhan Incident was settled without either side gaining a decisive advantage, but the loss of at least 120 aircraft and their experienced crews was disastrous for the Japanese; however, the fighting had given them an opportunity to test their aircraft against a determined adversary and the Ki-27 had proved itself to be superior to the Russian Polikarpov I-15 fighter biplanes but hard pressed against the faster Polikarpov I-16 fighter monoplanes.

In December 1941, when the Japanese began operations against the Allies, the 1st, 11th, 50th, 54th and 77th Sentais flying Army Type 97 Fighters were deployed in support of the invasion of the Philippines, Burma, Malaya and the Netherland East Indies, while other Ki-27 equipped Sentais were operating on the Chinese mainland, in Manchukuo and in Japan.

Although obsolescent the aircraft obtained some remarkable successes against the overwhelmed Allied forces. The Ki-27 was assigned the Allied code names 'Abdul' (China-Burma-India theatre) and 'Nate' South-west Pacific Area theatre), the latter being exclusively used from 1943 onwards. As the JAAF expanded, the Ki-27 was delivered to many new units in Japan, but most of these re-equipped with modern machines before deployment overseas while the remainder of the Ki-27s provided air defence for the Japanese homeland until 1943. However, throughout the war Ki-27s served as front-line fighters with the Manchurian Air Force.

As the aircraft were replaced by Ki-43, Ki-44 and Ki-61 fighters, the Ki-27s were increasingly used as advanced trainers. To suit the Ki-27 to its new duty, the wheel spats were removed, a tailwheel replaced the skid previously used, and so modified, the aircraft was redesignated Army Type 97 Fighter Trainer. In the last months of the war some Ki-27 trainers were used in suicide attacks carrying a 500 kg (1.102 lb) bomb-load.

The photos were taken from Warplanes of the Second World War Fighters Vol 3, by William Green.

Regards

Bob