Bachem Ba 349 Natter

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Y Ddraig Goch
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Bachem Ba 349 Natter

Post by Y Ddraig Goch » 30 Apr 2002 11:19

Bachem Ba 349 Natter

The Natter was born of necessity, to fill a requirement for a point defence fighter to attack Allied bombers, the Ba 349 was one of the most radical and desperate “fighters” ever built.

By spring 1944 it had become clear to the Luftwaffe high command that serious measures would have to be taken if it were to counter the increasing waves of Allied bombers penetrating the Reich. The Me 163 Komet was turning out to be ineffective against the Allies’ B-17 ‘combat box’ formations, and the Me 262 was not yet being used in its true role as a fighter. As a result, several unusual schemes were now looked at for a new ‘point-defence plan which had been designed to stop the rot.

The basic thinking behind the point-defence idea was that Germany should be divided up into geographical boxes or parcels of land. Each area would contain its own specifically assigned fighters, and as the Allied bombers passed over so these interceptors would rise up like a swarm of wasps to attack them. As the bombers flew on, so they would meet one such attack after another, passing from box to box. The bomber’s return home would meet equally stiff resistance as the fighters would have already refuelled and could be waiting for their return.

Essentially, the defence model needed a new kind of aircraft: one that would be cheap both to build and to operate; one that would be robust and reusable, and if possible have the speed to outmanoeuvre the Allied fighter escorts. If weight were to be kept low, then a short operating range and endurance would have to be accepted, but given the box system this wouldn’t be a problem provided that the aircraft had a short turn-around time.

Various manufacturers were invited to put proposals forward later that year, and among them Diplomeur Ingenieur Erich Bachem made his first appearance with his submission of the BP 20 ‘Natter’. He was in competition with the Heinkel P.1104 ‘Julia’, the Junkers EF 127 ‘Walli’ and Messerschmitt’s Project P.1104.

Heinkel won the contract. Bachem had submitted his proposal through influential but unofficial channels offered by his close associate Hans Jordanoff, and as Technical Director of the Fieseler-Werke, builders of the V-1 flying bomb, he also had close ties with Peenemunde. But his attempt to get in through the back door, as it were, cut no ice with the Air Ministry. There were other considerations. Heinkel was a preferred and established plane-maker and its Julia project had been in development since August so it was actually granted the point-defence commission on 8th September. The company won because Julia was easy and cheap to build and had low running costs. In addition, Heinkel already had its own dedicated woodworking shop in Vienna, which could be geared up too build the Julia very quickly. The Air Ministry could not have hoped for a more suitable contender.

As for Messerschmitt’s offering, it seems to have been an unusually half-hearted affair which never left the drawing board and was dropped as the company concentrated on the other pressures that the deteriorating situation in Germany was placing on all industry.

Although Heinkel duly placed the work with its woodworking plant at Vienna which, they felt, would be far enough away to be relatively safe from Allied raids unfortunately for the project, the woodworking plant was unexpectedly bombed by the Allies later in the autumn.

Undeterred at having lost the competition to Heinkel, Erich Bachem used his contacts and credentials to secure an interview with Himmler, who showed an immediate interest in his project, seeing it as a point-scoring exercise for the SS over the Luftwaffe and the regular army. Within twenty-four hours the Natter proposal was referred back to the Air Ministry for re-valuation.

Bachem had designed his fighter as a vertical-launch rocket-propelled, semi-reusable interceptor. The idea was neither unique nor new, but where the Natter score over its rivals was in its simple construction and its use of components that were not expensive or strategically important elsewhere. It was also versatile: its innovative launch rails could be fitted to a warship if necessary, endowing the remaining fleet with an aerial capability hitherto denied the ships, as the German navy had no aircraft carriers. Adopting a similar line of approach to that of Blohm und Voss, with their Bv 40 glider, could be built by unskilled and semi-skilled labour, with individual components assembled in any number of small carpentry shops dotted around the Black Forest region, and brought together as completed sub-assemblies at the Bachem finishing plant. This method of construction anticipated the system advocated as best practice by many manufacturers today.

The inventor had got hold of a modest undamaged factory at Waldsee, about forty kilometres from Lake Constance, which housed a small design office within its walls. He collected technicians from whatever he could find them, and a rocket expert from the Walter Werke, and begun development in earnest in August 1944 through the newly formed Bachem Company, just in time for the competition already mentioned. By the autumn, having bounced back, Bachem had over 60 skilled assembly workers who were framed out to various local-skilled sub-contractors working for the project. Because of Himmler’s patronage, the enterprise was taken into the Emergency Fighter Programme from September 1944 and received the official designation Ba 349, along with an order for fifteen prototypes.

As originally envisaged, the Natter, which was not designed with a landing capability, was to mount a two-stage attack. In phase one it would be blasted vertically off the ground, on autopilot. There after climbing almost vertically on an internal rocket the pilot, assuming manual control when positioned above the approaching bombers, would place the aircraft in a shallow dive, the Natter would jettison the nosecone to expose the battery of rockets. Nearing the bombers, the pilot would sight on one and fire his missiles. In phase two, having fired these unguided missiles, the pilot, using his remaining kinetic energy, would climb higher than the bombers and swoop back for a ramming attack. Just before impact he was to trigger a mechanism to separate his seat ( or front fuselage ) and the rear portion with rocket motor. But tests showed that no such simple ejection system could be incorporated, and the essence of the Natter was simplicity and this was eventually abandoned. Phase two was abandoned, and the plane was redesigned. Now, the aircraft was flown clear of the battlezone, and the pilot would then bale out. The entire nosecone was to be jettisoned by uncoupling the control column, moving it forward to release the safety catches, and then releasing mechanical catches to separate the nose from the rest of the fuselage. The pilot was effectively ejected by the deceleration of the rear section as it streamed a braking and recovery parachute. The rear fuselage, containing the valuable rocket engine, would parachute to the ground for recovery and reuse. Other detailed design improvements continued with wind-tunnel testing, which revealed little to desire in the Natter’s aerodynamics, until an overall final version was arrived at. In contrast to the Horten brothers, Bachem had access to every facility, even though the Horten’s Go 229 also fell within the Emergency Fighter programme; the brothers were denied such basics as wind-tunnel time too.

The launch tower was first designed as a steel latticework structure like a big piece of Meccano; it stood a little over twenty-three metres high. Towards the end of the war, as steel became ever scarcer, this was replaced with a simple nine-metre telegraph pole with a pair of shortened launch rails bolted to it. Common to both designs was the need for a solid concrete foundation into which the gantry could be secured, though the telegraph pole version could be quickly dismantled and removed from a mounting set into such a base. With dozens of these small foundations scattered around the launch area, ground crews could move their gantries from one to another fast, and Allied pilots would be lucky to trace them. We are familiar with the concept used by modern rockets such as the ‘Ariane’’ series used by the European Space Agency. The rocket is free-standing on the nozzles of its boosters, needing an adjacent gantry only to top up fuel tanks and give service access. Any in-flight course corrections can be made by adjusting the angles of the nozzles to redirect the thrust. The Natter, however, had fixed nozzles to redirect the thrust. The Natter, however, had fixed nozzles; and as the ‘g’ force on takeoff could be so powerful that the pilot might momentarily lose consciousness, it needed a degree of built-in control as it left the gantry to avoid any erratic manoeuvres. As a result, the Natter was ‘locked’ into the launch towers, its ailerons fixed to direct it, once free of the tower, until its pilot was conscience again and could override the built-in autopilot. A steel winch mounted at the top of the tower was used to haul the Natter into the vertical-launch position. Running the length of the tower was a pair of slotted rails, some four metres apart, into which the Natter’s reinforced wing tips were slid as it swayed on the winch cable. Once this was done, the lower sections of these rails were bolted into place, enclosing the tips securely. On launch, the fighter would run smoothly up these rails into the sky, by which time the pilot would have recovered and became acclimatised to the speed, ready to take the controls.

The chunky and inelegant airframe was made of wood, metal being used only for essential control linkages and so on. For its manned gliding tests only, a simple fixed tricycle undercarriage was fitted. The fuselage was a laminated monocoque with a single-spar wing that passed between two fuel tanks. The stubby wings had no aerodynamic control surfaces; it was left to the ailerons on the cruciform tail section to give the only control and generate most of the lift. The wing tips were sheathed in metal plating to reinforce them during lift-off. After giving consideration to several different armament types, Bachem opted for an arrangement of twenty-four hexagonal tubes in a honeycomb pattern, each holding a 73mm Fohn assault rocket. There was also provision for thirty-three 55mm R4M missiles, and both configurations were shrouded by a jettisonable plastic nose-cone. The look of the rockets gave rise to the nickname ‘Raketenwabe’ - ‘Rocket Honeycomb’. As the pilot only had to aim for Allied combat box formations, it was hoped that semi-skilled pilots would be able to fly the Natters, thus saving training time and fuel on conventional fighters, and life expectancy was under ten hours.

Importance was placed on providing a suitably armoured bulkhead for the cockpit in case anything should go wrong during the launch or firing of the weapons. Sandwich armour was placed around the monocoque sides and, as an aft bulkhead, an armoured plate was inserted between the pilot and the two fuel tanks behind him. Additional protection was provided by a sixty-millimetre-thick windscreen and ten-millimetre-thick side glazing. Instrumentation was, as usual, spartan, the weapons being aimed through a simple crosshair sight forward of the windscreen. The fuel tanks contained a 95-gallon supply of ‘T-Stoff’ fuel and a 45-gallon supply of ‘C-Stoff’ catalyst to power the Walter 509 rocket motor. The thrust-to-weight ratio was slightly less than required for vertical takeoff, so four jettisonable 500-kilgramme-thrust Schmiddling solid-fuel boosters were attached to the rear.

Initial acceleration wasn’t calculated to exceed a ‘g’ force of more then 2.2, but as we have said an attempt was made to protect the pilot as far as possible by presetting the ailerons while on the ground (a practice established within the V weapons programme at Peenemunde ) to give a consistent flight path so that the pilot could recover in time to complete his mission and release his rockets. The auxiliary boosters would be released at a height of between 170 and 190 metres via a radio link to an observer on the ground. At a range of around four kilometres from the Allied bombers, the recovered pilot would jettison the nose shrouding to expose the assault rockets before closing in for the attack. Once the attack was completed, the pilot would unbuckle his seat harness and uncouple the control column and the safety catches attaching the nose to the fuselage. The nose would then fall away from the airframe, taking with it the windscreen, forward bulkhead and instruments. Simultaneously, a parachute would open from the tail section, causing rapid deceleration. The pilot would then be thrown clear and return to the ground with his own parachute. This, at least was the theory, though from the sound of things the shocks sustained by the pilot during all this buffeting might have proved fatal.

The precious rocket in the rear section would meanwhile also float to earth on the main parachute attached to the tail section.

By November 1944 the first aircraft from the initial batch had already been built, such was the boost the authorities had given the Natter programme. And in running the project the SS were keen to demonstrate their much-vaunted ruthless efficiency, forcing manufacturers of components to get the job done despite the general collapse of German industry. The first gliding trials also took place in November, with an unpowered Natter being towed up by an He 111, on loan from the DFS, to an altitude of 6,000 metres. The Natter was ballasted to simulate the weight of the finished aircraft, and the pilot, Unteroffizier Zubert, reported excellent stability and general characteristics. In addition, the Natter was attached to the tow-line by two mountings, one on each upper surface of the wings, and for the most part flew below the He 111. This had two benefits: first, it minimised the problems involved in controlling the craft, as had the plane been attached by the nose the detachable shrouding there might have pulled away accidentally; secondly, because he wasn’t flying in the slipstream of the tug, Zubert could asses aerodynamics and general handling more accurately.

The project was forced through at such a pace that the first test firing came only a month later, at Heuberg, on 18 December. This was a disaster: the auxiliary rockets burned through cables controlling their fire-extinguishers and as a consequence overheated and burned out, wrecking the Natter. Luckily, the test was unmanned. The second attempt four days later met with success: the Natter left the ramp and disappeared into cloud at 750 metres.

Towed gliding tests had continued meanwhile, and the first flight was made on 28th february 1945, with Zubert at the controls. Prototypes were now being prefixed with the letter ‘M’ instead of ‘V’; this first Natter prototype to fly free was the M8.

Ten further unmanned launches followed the first, though most were to crash and explode following hard parachute landings, which mixed the unburned fuel residues with catastrophic effect. The launches also revealed the fact that even with the auxiliary boosters, the air speed wasn’t high enough to give full control to the pilot. This lead to a redesigning of the tail surfaces and the fitting of small control vanes in the rocket outlet, which had the effect of smoothing out the rocket thrust and gaining more lift and control. The improvements were introduced on the M16 and adopted for all subsequent models.

Progress was not without setbacks on the bureaucratic side. On 22nd December, the same day as the first successful test launch had taken place, the project’s controlling body, one of many weapons development commissions then operating, decided that both the Natter and the Julia held little promise and should be terminated. The final recommendation was that all work on the Julia be suspended ( its main manufacturing plant had already been destroyed by the Allies ) but that the Natter be given a stay of execution in the light of its ongoing trials. Even so, all plans for mass production were suspended as the commission felt that the scarce supply of Walter rockets would be better diverted to develop assisted versions of the Me 262.

The Natter was actually saved because Himmler was still interested in the project and allowed development to continue under the auspices of the SS. But other factors militated against the smooth progress of Bachem’s programme. The original brief had allowed only 250 man-hours of semi-skilled construction to complete one fighter; but problems with erratic autopilots and unpredictable Schmidding rocket boosters were causing that number to rise. The other main problem was that, probably as a result of the commission’s cancellation order, supplies of the Walter rockets had slumped even further than anticipated. These obstacles conspired to delay a launching of the first definitive Natter until 25th February 1945.

The Natter was launched with a dummy in the cockpit, and the test was a success: both the rocket section and the mannequin parachuted down without mishap. The SS were sufficiently impressed to order that further trials now be undertaken with actual pilots at the controls and so, against the better judgement of the Bachem team, Oberleutnant Lothar Siebert took off in the M23 a few days later. What went wrong precisely is unknown, but Siebert was killed, probably because he was knocked unconscious when the cockpit canopy unexpectedly broke away during the launch. The Natter took off as planned from its gantry and disappeared from sight into the clouds, only to crash violently to earth some fifty seconds later in a tremendous explosion close to the launch site. The SS dismissed this as a ‘technical hiccup’ and saw no reason to interrupt test-flights, calling for other volunteer pilots.

Bachem’s team had meanwhile decided to upgrade the rockets to more powerful Walter 509C units. These featured an auxiliary cruising chamber similar in principle to those fitted by Junkers to the Me 263 project it had developed. The four unreliable boosters were replaced with more a powerful pair of Schmidding rockets, each giving about a thousand kilograms of thrust. This new version of the Natter, designated Ba 349B, was planned to come onstream after the first fifty ‘A’ series aircraft had been literally used up. It offered nearly double the endurance of the original Natter, at 4.36 minutes, though there was a small performance deficit due to a weight increase of about 57 kilograms. Overall, however, the Natter had an impressive performance record: with forcers of 2.2 ‘g’ at launch, the climbing speed would have risen to over 1,000kph as it neared it operating height of 12,000 metres. With its boosters set at a hundred per cent thrust, a range of over eighty kilometres would have been in reach.

In the event, despite the auspices figures, only one “B” series model was built and actually flown, and even then it had to make use of the original kind of booster, as the better Schmidding rockets wern’t available. According to the author Renato Vesco, the only time a Natter flwe in anger was on 29 March 1945, when Feldwebel Ernst Hemmer piloted one of the first pre-production models against a formation of B-24 Liberators and succeeded in downing two and damaging a third. Research for this book has, however, uncovered no hard evidence to support the assertion.

Two months before the final surrender, the team was moved for its own safety to a base at Waldhausen, further from the reach of the advancing Allies. The move was to signal the effective end of testing, as there were now not enough lorries, and not enough fuel for them, to provide transport for the Natters and their equipment; and even the SS was unable to procure any supplies, so dire had the general situation become. As for the production target, even though it was now reduced to twenty examples a month, it was still a pipe dream: there was no rocket fuel to power the Natter machines even if there had been the materials and means to make them. Dornberger, now a general, cancelled the programme on 20th March, and Bachem prepared to move the remains of his operation to Bad Worrishofen in Schwabia, about ninety kilometres west of Munich.

On 24th April French troops entered Waldsee, but not before Bachem staff there had sunk the remaining rocket motors in the lake. As for Bad Worrishofen, it was only a temporary refuge, for the team moved again to what was to be their final destination, an alpine valley near St Leonard in Austria. By now all that remained of the project were five Natter machines, a few auxiliary boosters, and the blueprints for the design. All these, together, with the surviving team, US troops were to capture only a few days later.

Of the original fifty pre-production ‘A’-series fighters, only about twenty-two had been completed, and only fifteen ever flew. As late as April 1945 a group of Natter machines was apparently set up at Kirchheim near Stuttgart to attack bomber squadrons, but unconfirmed reports suggest that they were destroyed on their ramps to prevent them falling into enemy hands as US forces advanced on the site. A footnote to the storey concerns manufacturing blueprints and specifications for the fighter which were sold to the Imperial Japanese Army shortly before the end of the war, and smuggled out of Germany aboard one of the many cargo U-boats maintaining contact between the two remaining Axis powers. Only one partially built example is thought to have been discovered by advancing US troops as they entered Japanese held territory.

Conclusion
The Natter was so specialised in its role that the degrees of success would have depended on whether the pilot could have come within range of his targets in time to release his rockets. And even if he did, the question of his chances of survival once the plane broke into its component parts and he was supposed to parachute down is very open. Given time, the SS might have continued stubbornly with their pet project, but the Natter wasn’t really living up to expectations and it is likely that even if the war had gone on, the project would have soon reached its shut-off point anyway.

The definitive planned production model, the Ba 349C (BP 20C) was to have featured an improved wing and a further increase in fuel capacity.

Specification
Bachem Ba 349A Natter
Origin: Bachem-Werke BmbH.
Type: Part-expandable target-defence interceptor.
Powerplant: One 16.67kN ( 3,748lb ) thrust Walter
HWK 109-509 A-2 bi-fuel rocket motor and
boosted for vertical launch by four 1,102lb (500kg)
or two 2,205lb (1000kg solid motors).
Span: 11.9ft ( 3.60m ) .
Length: 20ft ( 6.10m ).
Height: 7.4ft ( 2.25m ).
Weights: Empty 1,940lb ( 880kg ); loaded
( with boost rockets ) 4,920lb ( 2,232kg );
maximum take-off 4,850lb ( 2,200kg ).
Maximum speed: Over 497mph ( 800km/h ) at
high altitude.
Initial rate of climb: 35,689ft/min ( 10,881m/min ).
Service ceiling: 45,920ft ( 14,000m ).
Range after climb: ( 39,360ft ( 12,000m ))
20-30 miles ( 32-48km ).
Armament: 24 Fohn ( Storm ) HS 217
73mm spin stabilised rockets, or 33 R4M
55mm spin-stabilised.

Bachem Ba 349B Natter
Origin: Bachem-Werke BmbH.
Type: Part-expandable target-defence interceptor.
Powerplant: One 19.61kN ( 4,409lb ) thrust Walter
HWK 109-509C bi-fuel rocket motor and
boosted for vertical launch by four 1,102lb ( 500kg )
or two 2,205lb (1,000kg solid motors).
Span: 13.1 1/2ft ( 4.00m ) .
Length: 19.9ft ( 6.02m ).
Height: 7.4ft ( 2.25m ).
Weights: Empty 2,414lb ( 1,095kg );
loaded ( with boost rockets ) 5,004lb ( 2,270kg );
maximum take-off 4,850lb ( 2,200kg ).
Maximum speed: Over 621mph ( 1,000km/h ) at
16,405ft ( 5,000m ).
Initial rate of climb: 35,689ft/min ( 11,368m/min ).
Service ceiling: 45,920ft ( 14,000m ).
Range after climb: ( 39,360ft ( 12,000m ))
35 miles ( 58km ).
Armament: 24 Fohn ( Storm ) HS 217
73mm spin stabilised rockets, or 33 R4M
55mm spin-stabilised rockets or ( proposed )
two 30mm MK 108 cannon each with 30 rounds.
/ Mike

"That which does not kill us makes us stronger"
Friedrich Nietzsche

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Erich
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Post by Erich » 01 May 2002 17:13

Interesting materials !
The only proof is that the a/c had one man flight in which the pilots neck was broken and the a/c crashed.
There are no victories as there is no confirming Abschussmeldung/Zerstörungsmeldung reports........the a/c had much testing to go before it ever could become operational.

E

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Post by Kurt_Steiner » 23 May 2004 15:53

As far as I know, the Ba 349 Natter only made some experimental flights: February 28th, 1945 was the first: the pilots (Olt. Lothar Siebert) neck was broken and the a/c crashed. It made 36 flights with 7 pilots before the allied troops made further testing impossible.
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Graham Clayton
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Re: Bachem Ba 349 Natter

Post by Graham Clayton » 19 Jul 2014 03:55

A couple of interesting photos of the Natter on the launch frame and taking-off can be seen here:

http://www.lonesentry.com/features/f36_ ... ba349.html
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Grzesio
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Re: Bachem Ba 349 Natter

Post by Grzesio » 21 Jul 2014 08:40

One correction...
The fuel tanks contained a 95-gallon supply of ‘T-Stoff’ fuel and a 45-gallon supply of ‘C-Stoff’ catalyst to power the Walter 509 rocket motor.
In this case C-Stoff is fuel, not catalyst, T-Stoff is oxidizer, not fuel. Walter 109-509 engine worked on basis of regular combustion, not just T-Stoff decomposition.

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Grzesio
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Re: Bachem Ba 349 Natter

Post by Grzesio » 22 Jul 2014 11:25

... and by the way...
24 Fohn ( Storm ) HS 217
73mm spin stabilised rockets, or 33 R4M 55mm spin-stabilised.
1. Do we have any proof, the Foehn rocket was designated as the HS 217?
2. R 4/M was fin stabilised, not spin stabilised.

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Re: Bachem Ba 349 Natter

Post by Edward L. Hsiao » 17 Jul 2019 03:12

This is a interesting a very detailed information about the Natter. It even managed to shoot some enemy planes out of the sky.

Edward L. Hsiao

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Re: Bachem Ba 349 Natter

Post by Edward L. Hsiao » 17 Jul 2019 03:53

Well, there is no confirmation of enemy planes ever shot down by the Natter.


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Kurt_Steiner
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Re: Bachem Ba 349 Natter

Post by Kurt_Steiner » 23 Jul 2019 09:43

As far as I know, the Natter only flew experimental sorties, no combat ones.

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Geoff Walden
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Re: Bachem Ba 349 Natter

Post by Geoff Walden » 01 Aug 2019 00:22

More period photos of Ba 349 Natter test launches, and remains of the launch sites, can be seen here:
http://thirdreichruins.com/misc_sites6.htm#natter
"Ordnung ist das halbe Leben" - I live in the other half.
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Re: Bachem Ba 349 Natter

Post by AllenM » 01 Aug 2019 01:18


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