THE 456th FIGHTER INTERCEPTOR SQUADRON

THE PROTECTORS OF  S. A. C.

 

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The Bachem Ba-349 "Natter"

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  Possibly the oddest plane to ever fly, the Bachem Ba 349 Natter (Viper) is more properly thought   of as a manned surface-to-air missile (SAM).

 

 


 

 
Erich Klöckner was tasked with developing the 'Natter' towards the end of 1944, when experienced combat pilots were in short supply and ways were being sought of maintaining the offensive against the Allied bombers.

This aircraft was a manned, rocket-propelled single-flight projectile which could be flown by a pilot with only limited training in how to aim it at the enemy. It was to be launched vertically from a gantry and fire its nose-mounted load of 34 3-inch rockets into a bomber stream in a single salvo lasting 0.4 seconds. The pilot would then bale out, as the aircraft was simple, cheap and disposable. However, it was calculated that the average acceleration during the climb would be 2.2g, the highest projected altitude 52,000 feet, the average climb speed 420 mph and the horizontal speed while accelerating away from the fighter escort would be 620 mph! Exactly how the pilot was going to abandon the aircraft safely when his 7 minute fuel supply ran out was left to him!

 

Klöckner put in a less than enthusiastic assessment of the project and refused to fly it until a number of requirements had been met. He was then visited by two high-ranking SS officers, who did their best to persuade him that there was no time, the Führer needed the weapon and that nobody should shrink from his duty to defend the Fatherland in the hour of its greatest need. The word 'Ritterkreutz' (Knight's Cross) was mentioned, but when that failed there was something muttered about a pistol as they paced up and down the floor!

A
volunteer was eventually found and strapped in, but shortly after lift-off the plexiglass canopy blew off and at the speeds reached by the rocket it is likely that the pilot lost consciousness almost immediately. The engine of the 'Natter' ran all the way to the ceiling altitude, then the aircraft went into a steep dive and disappeared, crashing into the Danube valley.


At least one Foo-fighter sighting appears to have been of a Bachem Ba349 'Natter' - The case in which in which pilot Lt. David L. McFalls and his radar-observer, Lt. Ned Baker, saw ‘[a] glowing red object shooting straight up, which suddenly changed to a view of an aircraft doing a wing-over, going into a dive and disappearing.’

 

Upon launch, the Natter would be guided, by ground-based radio-control, to a point above and in front of the target bombers. At this point the pilot would assume control of the aircraft and ‘push over’ for a gliding attack. Both in its appearance and its manoeuvres, this seems to agree with the Foo-fighter reported by McFalls and Baker.

However, no flights were known to be made during nighttime with the Bachem Ba349 'Natter'.

 

With the Allies decimating the Luftwaffe in 1944, desperate measures were thought up to address the issue. Although most of the Luftwaffe commanders pressed for more jet fighters like the Me 262, all sorts of crazy ideas were given the green light for development, typically at the behest of some high-ranking Nazi official.

The problems were many. Jet engines of the era had serious problems throttling up during takeoff and landing, so airbases were death traps. Once in the air things got much better, but attempting to target a plane travelling 200 or more miles an hour slower was tremendously difficult. This wasn't too much of a problem for the Luftwaffe's cadre of expert pilots, but as the allies thinned their ranks the jets were being flown by "green" pilots who were completely ineffective. No amount of Me 262s would solve this problem, so some other solution was needed.

 

Various efforts had been underway to develop missiles for this purpose, but invariably problems with the guidance systems prevented these from seeing widespread use. Fitting a pilot to the top seemed like the only solution, which the Luftwaffe requested in early 1944. A number of simple designs were proposed, most using a prone pilot to reduce frontal area. The front runner for the design was initially the Heinkel P.1077 that took off from a rail and landed on a skid like the Messerschmitt Me 163 Komet.

 

Erich Bachem's BP20 was a warmed-over design from when he worked at Fieseler, but considerably more radical than the other offerings. It was built using glued and screwed wooden parts with an armoured cockpit, powered by a Walter HWK 509A-2 rocket, similar to the one in the Me 163. Four strap-on Schmidding rockets were used for launch, providing a combined thrust of 47 kN (10,582 lb) for 10 seconds before they were jettisoned. The plane rode up a rail for about 25 metres, by which time it was going fast enough for the flight controls to keep it flying straight.

 

The plane took off and was guided almost to the bomber's altitude using radio control from the ground, with the pilot taking control right at the end to point the nose in the right direction, jettison the plastic nosecone and pull the trigger. This fired a salvo of rockets (either 33 R4Ms or 24 Hs 217s), at which point the plane flew up and over the bombers. After running out of fuel the plane would then be used to ram the tail of a bomber, with the pilot ejecting just before impact to parachute to the ground.

 

Needless to say many thought the idea was crazy and rejected it out of hand. The design was in fact much more reasonable than any of the others in one aspect — they all required the non-existent pilots to actually fly the plane into a landing. After some political wrangling Bachem's design caught the eye of Heinrich Himmler at the SS. Suddenly, one day later, it was the winner of the design contest. The Luftwaffe nevertheless managed to include some minor redesigns to try to save as much of the plane as possible, as well as eliminating the ramming attack.

 

The resulting tiny plane was fired up a 50 foot wooden pole with the help of four solid fuel rockets, at the end of which it was already going fast enough for its control surfaces to work. The solids burned out after 12 seconds, at which point the main engine was long up to full thrust. The mission now had the plane guided to a point in front and above the bombers, where the pilot would turn off the autopilot, and push over for a gliding attack. After firing its armament of rockets it continued gliding down at high speed to about 3,000 m, at which point the plane "broke" when a large parachute opened at the rear of the plane, popping off the nose section and the pilot with it. Both would land under their separate parachutes, and only the cockpit and wooden wings went to waste.

 

Perhaps even more amazing than the design itself was the fact that it was actually built and tested. This was no small feat due to the incredible secrecy the SS placed on the project. After building wind-tunnel models early in the program, they were shipped off for testing and the only results returned to the Bachem designers were that it would be "satisfactory" up to speeds of about 685mph.

 

Full sized models were then completed and started flight testing in November 1944. The initial versions didn't include an engine, and were towed in the air by a Heinkel He 111 bomber for glide testing. Other test articles were equipped with extra solid motors for launch and autopilot tests. All of these went well, but during testing it was shown that any attempt to re-use the engine was hopeless, the landing speed was simply too high.

 

Construction of the production Ba 349A models had already started in October, and fifteen were launched over the next few months. Each launch resulted in some small modification to the design, and eventually these were collected into the definitive production version, the Ba 349B which started testing in January.

 

In February 1945 the SS funders decided that the program was not going fast enough, and demanded a manned launch later that month. The first, and possibly the only, time that the aircraft was tested in this way was on February 28, when Lothar Siebert flew a Ba 349A. Things went well at first, but at 500 m (1,600 ft) the cockpit canopy pulled off. The plane suddenly turned over and flew directly into the ground. Siebert was killed in the accident, and the cause was never explained. It was suspected that the canopy may simply have not been properly latched before launch.

 

US forces overran the factory at Waldsee in April, but small numbers of Bachem staff had moved and taken the remaining ten B models with them. Soon the US had caught up with them again, and six of the ten were burnt.

 

Several sources claim that an operational unit of Natters was set up by volunteers in Kirchheim but didn't carry out any operations, but the evidence for this not conclusive.

 

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The "Natter" was launched from a frame in the manner of a projectile from a gun. The pilot assumed control after the missile was airborne. The "Natter" represented a cross between a fighter and a suicide-type a

Bachem Ba 349 Natter



Bachem Ba 349 Natter (colubrid) was a World War II era German  experimental point-defense rocket-powered interceptor aircraft which was to be used in a very similar way as unmanned surface-to-air missiles. After vertical takeoff which eliminated the need for airfields, the majority of the flight to the bombers was radio controlled from the ground. The primary mission of the (inexperienced) pilot was to aim the aircraft at its target bomber and fire its armament of rockets. The pilot and the main rocket engine should then land under separate parachutes, while the wooden fuselage was disposable. The only manned test flight, on 1 March 1945, ended with test-pilot Lothar Sieber being killed.

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 Launching of the "Natter" was impressive. The blast of its rocket gives an idea of the power used in attaining a climbing speed of 435 miles per hour—about 38,000 feet a minute. This speed was attained climbing almost straight up.




Development
 


With Luftwaffe air superiority being challenged by the Allies even over the Reich in 1943, radical innovations were required to overcome the crisis. Surface-to-air missiles appeared to be a very promising approach to counter the Allied bombing offensive and various projects were started, but invariably problems with the guidance systems and fusing prevented these from seeing widespread use. Providing the missile with a pilot who could control the weapon during the critical terminal approach phase offered a solution and was requested by the Luftwaffe in early 1944.

 

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A number of simple designs were proposed, most using a prone pilot to reduce frontal area. The front runner for the design was initially the Heinkel P.1077 "Julia" that took off from a rail and landed on a skid like the Messerschmitt Me 163 Komet.

 

 

 

Bachem proposal

 

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Erich Bachem's BP20 was a development from a design he worked on at Fieseler, but considerably more radical than the other offerings. It was built using glued and screwed wooden parts with an armored cockpit, powered by a Walter HWK 509A-2 rocket, similar to the one in the Me 163. Four jettisonable Schmidding rocket boosters were used for launch, providing a combined thrust of 4,800 kgf (47 kN or 10,600 lbf) for 10 seconds before they were jettisoned. The aircraft rode up a rail for about 25 metres, by which time it was going fast enough for the aerodynamic flight controls to keep it flying straight.

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The aircraft took off and was guided almost to the bomber's altitude using radio control from the ground, with the pilot taking control right at the end to point the nose in the right direction, jettison the plastic nosecone and pull the trigger. This fired a salvo of rockets (either 33 R4M or 24 Henschel Hs 217), at which point the aircraft flew up and over the bombers. After running out of fuel the aircraft would then be used to ram the tail of a bomber, with the pilot ejecting just before impact to parachute to the ground.

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Despite its apparent complexity, the design had one decisive advantage over the competitors — it eliminated the necessity to land an extremely fast rocket aircraft at an airbase that, as the history of the Me 163 demonstrated, was extremely vulnerable against air raids.

 


Modifications


After Bachem's design caught the eye of Heinrich Himmler at the SS, it emerged as the winner of the design contest. The Luftwaffe nevertheless managed to include some minor redesigns to try to save as much of the aircraft as possible, as well as eliminating the ramming attack.

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At first complacent in the face of the strategic bombing threat, the Germans in 1943 became fearful, then frantic. They were willing to try out any possibly effective counterweapon. One of these trial weapons was the piloted rocket called the "Natter," a test model of which is shown here.

The resulting tiny aircraft was fired up a 50 foot (15 meter) wooden pole with the help of four solid fuel rockets (Schmidding), at the end of which it was already going fast enough for its control surfaces to work. The RATO boosters burned out after 12 seconds, at which point the main engine was long up to full thrust. Mission control now had the aircraft guided by radio to a point in front and above the bombers, where the pilot would turn off the autopilot, and push over for a gliding attack. After firing its armament of rockets it continued gliding down at high speed to about 3,000 m (10,000 ft), at which point the aircraft "broke" when a large parachute opened at the rear of the aircraft, popping off the nose section and the pilot with it. The pilot and the tail with the engine would land under their separate parachutes, and only the nose and the fuselage with the wooden wings were disposable.

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A cross-section of the "Natter" illustrates its component parts. The rocket fuel is a liquid, as in the V–2 type of rocket. The chute was used to prevent wrecking the main motor, which, like the pilot, was jettisoned.

At Schloss Ummendorf near Biberach an der Riß scientists of Technische Hochschule Aachen under Professor Wilhelm Fucks calculated the Natter's aerodynamics with a large Analog computer while RATO engines were tested at Bachem-Werke factory in Waldsee. The Deutsche Versuchsanstalt für Luftfahrt (DVL) in Braunschweig provided Wind-tunnel test of models which were built early in the program. The results returned to the Bachem designers were that it would be "satisfactory" up to speeds of about Mach 0.95 or 685 mph, i. e. close to the sound barrier.

 

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A Bachem Ba349 displays its rocket armament at Farnborough (England) in 1946. The swastikas are not authentic.


Testing


Full sized models were then completed and started flight testing on 3 November 1944 in Neuburg an der Donau. The initial prototype BP-20 M1 did not include an engine, and was towed up to 3000 meter by a Heinkel He 111 bomber for glide testing by Erich Klöckner. Klöckner managed to bail out as planned, and stated that it handled well over 200 km/h. Only the center of gravity and the fixing of pulling wires caused concerns..

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Other test articles were equipped with extra solid motors for launch and autopilot tests. All of these went well, but during testing it was shown that any attempt to re-use the engine was hopeless; the impact speed was simply too high

 

Until 27 January 1945 several manned and unmanned gliding flights after having been towed or released from a Mistel were conducted. Also, the unmanned vertical takeoff starts powered by rockets, which started on 18 December 1944 on Truppenübungsplatz Lager Heuberg near Stetten am kalten Markt were completed, as well as tests of the weapons. The distance from the Bachem factory in Waldsee to Heuberg was only 50 kilometers.

 

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First manned test flight


Construction of the production Ba 349A models had already started in October, and fifteen were launched over the next few months. Each launch resulted in some small modification to the design, and eventually these were collected into the definitive production version, the Ba 349B which started testing in January.

 

In February 1945 the SS funders decided that the program was not going fast enough, and demanded a manned launch later that month. The first and only time that the aircraft was tested in this way was on March 1, when Lothar Sieber flew Ba 349A M23, which was launched from the Lager Heuberg military training area near Stetten am kalten Markt. Things went well at first, but one of the jettisonable Schmidding boosters failed to release and the Natter got out of control. At 500 m (1,600 ft) the cockpit canopy pulled off as Sieber intended to bail out. He was instructed by radio to keep trying to shake off the booster, but inside the clouds he lost orientation. Also, the parachute did not open due to the stuck booster. Eventually, the aircraft turned over and slammed into the ground, killing Sieber. It is suspected that Sieber may have broken the sound barrier on the way down.

24 x 77mm rocket tubes mounted in the nose formed the armament of the "Natter", alternatively it would be 33 x 55mm rocket tubes.

The cause was explained as a failure of the canopy which may simply not have been properly latched before launch. Photos were altered to hide the fact that a FuG16 radio was in the cockpit, used to order Sieber not to bail out. Excavations in 1998 found remains of the booster.

 

 

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 Interior cockpit detail

Of the 36 Natter that had been built, 18 were used in unmanned tests, and two crashed with pilots, one during a glide and one with Sieber. Of the remaining 16, ten were burned at the end of the war while four were captured by Americans, one went to Britain and one ended up with the Russians. Of the four American aircraft one is reported to have been fired aloft -pilotless- at Muroc Army Air Base in 1946. It would have crash landed somewhere near Las Vegas.

 


Legacy

US forces overran the factory at Waldsee in April, but small numbers of Bachem staff had moved and taken the remaining ten B models with them. Soon the US had caught up with them again and captured four, as six of the ten were burnt.

Interior cockpit detail

Interior cockpit detail

Several sources claim that an operational unit of Natters was set up by volunteers in Kirchheim unter Teck but didn't carry out any operations, but the evidence for this is inconclusive.

Coincidentally, in Japan during the last days of the Pacific War, the Mizuno aircraft company under orders from the Imperial Japanese Navy developed an aircraft similar to the Natter. The Mizuno Shinryu[4] suicide-interceptor rocket aircraft was the result. It would have been armed with air-to-air unguided rockets mounted under its wings and used, like the Natter, for interception of enemy aircraft, as well as a nose mounted warhead to be used for a suicide attack.

 

 

Natter launch pads at Kirchheim (Teck)

 

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Remnants of a Natter launch pad near Kirchheim

There are three launch pads for the Bachem Ba 349 in the Hasenholz forest near Kirchheim/Teck at 48°37′42.2″N, 9°29′57.4″E, 48°37′42″N, 9°29′53.5″E and 48°37′39.8″N, 9°29′54″E. They are all that remain from the active launch site constructed in 1945. The three launchpads are arranged in the form of an equilateral triangle, whose sides point toward the east and the south. The distance between the launchpads is approximately 50 meters. The circular concrete pads on which the Bachem Ba 349's and their launch towers once stood still exist. In the center of each of the three concrete plates is a square hole approximately 50 centimeters deep, which once served as the foundation for the launch tower. Beside each hole is a pipe, cut off at ground level, which was probably once a cable pit. The Natter launchpads at Kirchheim (Teck) might be the only remnants of these rocket launch pads still on publicly accessible terrain. The former test site for the Natter in Baden-Württemberg on the Heuberg near Stetten am kalten Markt is in an active military area, and therefore not accessible to tourists.


 

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Natter launch pad in the Hasenholz woods.

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A Bachem Ba349 at the Smithsonian Institute's Paul E. Garber Preservation, Restoration, and Storage Facility in Suitland, MD

Survivors



Three Ba 349As survive today. Two can be found in the USA:

A restored Ba 349A is on display at the Smithsonian Institution's Steven F. Udvar-Hazy Center near Washington, D.C. This aircraft was captured at the war's end and transferred to Freeman Field, Indiana for evaluation. It was given the foreign captured equipment number T2-1.

 

 

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A replica of Bachem Ba349 at the Deutsches Museum in Munich, Germany

The U.S. Air Force transferred the aircraft to the The National Air Museum (now the National Air & Space Museum) on May 1, 1949. The aircraft was stored for many years at the museum's Paul E. Garber Preservation, Restoration, and Storage Facility in Suitland, Maryland before undergoing a full restoration. It was one of the first aircraft moved to the new center in 2004.

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An additional unrestored Ba 349A remains at the Garber facility and restoration plans are unknown.

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"Natter" model undergoing windtunnel tests.



Ba 349 Natter
Type rocket interceptor
Manufacturer Bachem
Designed by Erich Bachem
Maiden flight March 1 1945
Introduced n/a
Number built 11 production aircraft (Ba 349B)

 

Specification

 

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Walter HWK 509A liquid-fuel rocket

General characteristics

Crew: 1
Length: 6.02 m (19 ft 9 in)
Wingspan: 3.60 m (11 ft 10 in)
Height: ()
Wing area: 4.8 m² (51.7 ft²)
Empty weight: 800 kg (1,940 lb)
Loaded weight: 2,232 kg (4,920 lb)
Powerplant:
1× Walter HWK 509A liquid-fuel rocket, 16.7 kN (10,600 lbf)
4× Schmidding 109-533 (1.200 kp, 11,768 kN, 10 seconds) solid fuel rocket boosters, () each


 

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Performance

Maximum speed: 1,000 km/h (620 mph)
Service ceiling 14,000 m (46,000 ft)
Endurance: 6 minutes of flight
Armament

24 × 73 mm Hs 217 Föhn rockets or 33 × 55 mm R4M rockets


 

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American GI's examine one of a pair of captured "Natter's"

 

A "Natter" floats back to the ground by parachute after the pilot has bailed out.

 

33 x 55mm roket tubes, alternative armament to the 24 x 77mm rocket tubes.

 

 

 


 

 

Bachem Ba 349

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Bachem Ba 349A

 

Development - Construction - Armament - Engine - Mission Profile

By the Spring of 1944, it had become evident to the German High Command that the steadily escalating daylight offensive against the industry of the Third Reich being mounted by the U.S.A.A.F. could no longer be countered by orthodox means alone. so serious was the situation that careful consideration had to be given to the unorthodox, and there was no shortage of highly ingenious schemes for intercepting and destroying the intruding bomber formations, but few withstood more than cursory examination of their practicability, One radical proposal which did appear to offer some possibility of success, however, was that submitted by Dipl,-Ing. Erich Bachem who suggested an inexpensive vertically-launched semi-expendable rocket-propelled target-defense interceptor.


 

DEVELOPMENT HISTORY
In 1944 the RLM issued a requirement for a small and inexpensive target-defense interceptor, Bachem, who had maintained close contact with Dr. von Braun and bi-fuel rocket motor development, submitted a proposal which he designated the BP 20 Natter (Adder).

Numerous projects were submitted to the RLM to meet the demands of the new requirement, and in the final evaluation during the early Summer of 1944 a Heinkel proposal, the Project 1077 Julia, was selected.

 

Bachem's proposal was rejected out of hand mainly because it called for the aircraft to be semi-deposable and the RLM's requirement for consideration did not envision the partial lose of the interceptor after each mission. The RLM also looked at the fact that the design had been uninvited and submitted for consideration through abnormal channels. Being passed to on to the RLM for consideration with the aid of the Luftwaffe's General of Fighters, Adolf Galland.

Bachem, however was convinced of the feasibility of this project and applied for and was granted an interview with no lesser personage than Henrich Himmler, who headed of the dreaded SS.

Himmler displayed immediate interest in the Natter project, promising his full personal support. Within 24 hours, Bachem had been informed that the RLM had reconsidered its earlier rejection and was now granting the Natter project its highest developmental priority. So much can be said for the fear and intimidation that Himmler and the SS carried in getting the RLM to reconsider.

The definitive Natter differed in some respects to that originally proposed by Bachem. The first design envisioned an initial attack on the bomber formation during which the Natter would expend its battery of rockets, the pilot then using the remaining kinetic energy to gain sufficient height to perform a ramming attack in a dive. Immediately before impact the pilot was to eject himself from the cockpit of the Natter, activation of the ejector seat triggering explosive bolt which would detach the aft fuselage housing the rocket motor, a parachute being automatically deployed to lower this to the ground for retrieval and re-use. Later it was concluded that the cockpit of the Natter was to small to permit the installation of an effective ejection seat. Furthermore, its provision would only serve to complicate a design which was intended to provide the essence of simplicity, and it was decided, therefore, to dispense with the ramming attack, the pilot jettisoning the forward fuselage complete with windscreen after discharging his rockets, this action releasing the parachute housing cover and deploying the parachute

CONSTRUCTION

 

Three versions of
the Natter were Built:

BA-20 (V)- Experimental models

A-Series - Pre-production models of which 36 examples were built.

B-Series - Final production version of the Natter, This re-design featured slightly better aerodynamics and a cruise chamber for longer endurance (4.36 min. compared with 2.23 min. on the A-series). Only three example were completed and of those, only one tested before the war ended .

C-Series Design study that featured a "T" configuration rather then the "cross" configuration used on the A & B series designs. The version C was foreseen which could be launched from its own transport trailer, able to house two Ba-349 C's. This trailer could easily transform into a ramp of 12 m with an 80 degree inclination (See below)

During the weeks that followed detailed design was pursued in parallel with wind tunnel trails at Braunschweig. During tunnel testing speeds in excess of Mach 0.95 were simulated without the appearance of any adverse stability or compressibility effects. The entire airframe was of wooden construction, metal being used only for control push-rods, hinges and load-supporting attachment points. The fuselage was of semi-monocoque construction with laminated skin, stringers and formers, and the wing possessed a single laminated wooden spar which was continuous from wingtip to wingtip and passed between the fuselage fuel tanks. The wing incorporated no movable surfaces, rolling control being obtained by differential operation of the elevons which formed part of the horizontal tail surfaces. The tail assembly might be described as of asymmetrical cruciform design in that the tailplane was mounted above the fuselage and the vertical surfaces were extended below the fuselage. large by comparison with the wing, the tail contributed an important proportion of the total lift, both wing and tailplane being of rectangular design without dihedral, taper or sweep.

 

ARMAMENT

Alternative forms of armament considered during the initial development stage included a Rohrbatterie of 49 30-mm SG 119 rocket shells, and the cylindrical semi-automatic Trommelgerat with 40 30-mm shells, but eventually a Bienenwabe (Honeycomb) arrangement of hexagonal tubes for 73-mm Hs 217 Fohn (Storm) missiles or quadrangular tubes for 55-mm R4M missiles was adopted. Whereas the Bienenwabe for the smaller missiles comprised 33 tubes, that for the larger missile consisted of 24 tubes, an earlier arrangement of 28 Fohn tubes being discarded owing to the inadequacy of exhaust gas venting which resulted in an explosion during test firing. A jettisonable plastic faring enclosed the forward end of the Bienenwabe prior to firing. Sighting of the missile battery was accomplished through a simple steel wire ring mounted on the nose. The pilot firing the missiles all at once when that attacked aircrafts shape filled the site ring.

 

A Bachem Ba349 displays its rocket armament

POWER PLANTThe Bachem pre-production BA-20 and Ba-349A models were powered by the liquid fuel Walter HWK 509A engine. Fuel was 750 kg of 80% hydrogen peroxide and 20% of a 30/70 mixture of hydrazine/ methanol. Thrust was 1700 kg for five minutes. As this was too low for take off, four Schmidling solid fuel boosters with a total thrust of 2000 kg were added. They weighed 495 kg in all, and burned for 10 seconds, then discarded.

In spite of being launched from a tower with launch rails, speed at take off was too low for effective control, so from vehicle V16 on, thrust vectoring was added in the form of hollow water filled steel rudders in the rocket exhaust. The water took 30 s to boil away, then they melted.

The later Ba-349B series incorporated the Walter HWK 509C-1 liquid fuel rocket motor possessing thrust of 4,410 lb. 93,750 lb. from the main chamber and 660 lb. trust from the auxiliary chamber. This motor provided for twice the endurance in flight time.

 

Bachem Ba 349A Data

 

Power Plant Walther 509A engine w/ 4 solid fuel boosters*
Maximum Speed  11,000 m per 60 seconds (Vert) 1000 km/h (Horiz)
Take-off Weight 2230 kg loaded w boosters (880 kg empty)
Span 4 meters
Endurance 130 s at 800 km/h at 3000 m
Range 20-80 km depending on altitude
Length 6.02 m
Weapons 24 x 73 mm Fohn rockets or 33 x 55 mm R4M
Internal Fuel 750 kg
*Ba 349B had a Walther 509c engine, which also had a cruise setting, doubling the endurance.

 

MISSION PROFILE


For launching the Ba 349 was to be mounted on a near-vertical 80-ft. ramp, the wingtips and the tip of the lower tail fin being strengthened to run in the three guide rails. The ramp itself was pivoted at its base to enable the aircraft to be loaded in the horizontal position. (Later a simplified ramp was developed that used a simple wood spar with a pulley on the top that allowed the Natter to be pulled up into firing position. This ramp did not require rail guides for the wing tips and provided a simple gantry that avoided the need of a permanent launch point and to ensure a totally mobile system that required very little time to set up).

The Natter wasn't supposed to be flown by "real" pilots, but pilots with very little training. During launch, it was to have enough stability that control inputs weren't needed. It was calculated that the initial acceleration would not exceed 2.2 g but the possibility of the pilot blacking out was safeguarded against by pre-setting the elevons for the required flight path while the Natter was still on the ramp. After that, radio control from the ground took over and gave commands to a three axis autopilot assuming guidance of the interceptor to an altitude of 550-600 ft., at which point the booster rockets would be jettisoned.

At a range of 1-2 miles from the target formation it was intended that the pilot would override the autopilot control, jettison the plastic nose cone to expose the missiles, aim at the part of the sky were the bombers were densest, fire the entire complement of missiles in one salvo, turn away from the formation and bale out. The sole purpose of the pilot was to direct the aircraft during the final phase of the attack. This meant that the Natter could employ personal withy out any training other than that which could be provided on a rudimentary ground trainer. After completing his attack the pilot was to release his seat harness, uncouple the control column, and release the safety catches and mechanical connections holding the nose section. This would fall away from the aircraft, complete with windscreen, instrument panel, forward bulkhead and rudder pedals, simultaneously releasing a parachute housing in the rear fuselage. The sudden deployment of he parachute would throw the pilot forward and clear of the aircraft, and he would descend by parachute in the normal way. The rear compartment housing the Walter engine, which also fell by parachute, would be recovered for another usage.

It probably would have worked well, as it was small, fast and armored aircraft armed with powerful rockets. The risks to the pilots were probably quality control during construction and the many steps required for a successful mission.

2 examples of the Natter exist today. One is at the Smithsonian Air & Space Museum Gerber Storage Facility and the other in the Deusche Museum in Germany.

 

Information sources from:

"Natter" Bachem Ba 349 by Joachim Dressel Publ. by Schaffer Military History 1994

Warplanes of the Third Reich by William Green Publ. Galahad Books 1990

Holman Projector - Urban-Fredriksson 27 June 1993, Swedish Aviation Home Page

 

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Natter Propulsion Systems

 

Drawing of the Walter Rocket Motor HWK 109-509 C with cruise burners. The Walter engine was used as propulsion for most of the rocket fighter projects because it was the most advanced engine available.

 

 

View of he HWK 109-509 A without afterburner

 

 

Natter's in assembly plant. Note the Walter rocket motor installation on the first plane, which has the tail assembly detached.

 

A Natter being readied for engine test firing. Note the harnesses and blocks on wings used to anchor the Natter during rocket firings on the ground.

 

Test burn of the Natter's soild fuel boosterss

 

 

 

 

Construction of the Natter

It had been planned that the construction of the airframe demanded only 250 manhours, and the Natter could be built for the most part by semi-skilled and unskilled labor. A small number of wood-working shops in and around the Schwarzwald were set-up and producing laminated wooden components for the Ba 349 by February of 1945.

 

Looking forward at the fuselage of the Bachem Ba 349 on a jig. The beams and lower shells are assembled.

 

The wings of the Ba 349 took advantage of simple wooden construction and provided the advantage of avoiding vital war materials and ease of construction

 

The wing halves of the Ba 349 could be produced with relatively simple tools.

 

 

The fuselage skin was scrap wood and attached to the spans by glue, 

 

 

 

 

Finished rear fuselage components.

 

 

 

Fuselage completion of a Ba 349. Women were used more and more as the war progressed.

 

Mock-up of the fuselage with rotatable pilot seat.

 

 

 

Production Ba 349s at the Bachem factory in Bad Waldsee.

 

 

Final assembly of the Bachem Ba 349. The engine is recognizable in the aircraft on the left.

 

Prototype Launch-Part 1

The first vertical launching of a pilotless Natter occurred on December 18, 1944, the empty airframe being fitted with four Schidding booster rockets. This test proved a complete failure, the Natter failing to leave the ground as a result of the booster rockets burning through the release cables. As second attempt was made four days later, and on this occasion the Natter left the ramp as planned and disappeared into the cloud base at an altitude of 2,460 ft.

Ten more unmanned Ba-349s were launched successfully, although it was ascertained that climbing speed attained by the time the boosters were jettisoned was insufficient to result in full control surfaces effectiveness. To remedy this defect the vertical tail surfaces were substantially redesigned , both upper and lower rudder portions being almost doubled in cord, the lower portion also being substantially reduced in depth as was also the elongated ventral fin. The chord of the elevons was also increased, and small water-cooled control vanes were introduced in the rocket orifice, these having a life of approximately 30 seconds by which time sufficient speed had been attained to render the normal control surfaces fully effective. These changes were introduced on the Ba 349A V16 and all subsequent Natters built.

Early Natter painted yellow with black strip for greater visibility for ground controllers during unmanned flight test.

Inscription on tail reads:
If found, report to the Commander of Troop Exercise Ground Heuberg.Telephone Stetten am Kalten Markt 222.  Reward!

 

 This unmanned Bachem Ba 349 is ready for take-off. The markings on the wings were to help technical personal monitor the flight profile, e.g. spinning on the longitudinal axis. Aircraft is painted overall gloss dark gray

The second picture shows the fueling of the Walter rocket motor. Note the clamps around the wing base. These were attached to cables and used to pull the Natter up into its vertical launch position and removed prior to flight.

The first picture shows the complete clamp/pulley system.

 

Additional photos showing unmanned Natters prior to launch. The photos show the stationary launch platform that required the Natter's wing tips to be guided along channeled tracks.


Prototype Launch Part 2

The original idea of using the first 50 airframes for gliding trials and pilotless launching had by this time been abandoned owing to the time factor, and something of the impetus placed behind the Natter programmed as a result of Himmler's support had diminished. In fact, on December 22, 1944, the day on which the first successful pilotless launching was made, a meeting in Berlin of the Chief Development Commission for aircraft concluded that neither the Ba-349 or Project 1077 Julia held promise. It was recommended that all work on the Julia be suspended, and that development of the Ba-349, although opposed on technical and tactical grounds, should be continued in view of the imminence of powered trials, but that all preparations for series production be discontinued.

Further testing showed that the behavior of the Schmidding booster rockets were proving to be less than reliable, burning time and thrust varying and several units exploding under test. The Patin three-axis autopilot tended to be erratic and was proving difficult to synchronize, and the Walter rocket motors continued to be in very shot supply.

Bachem, dissatisfied with the powered endurance of the Natter, had adapted the interceptor to take the Walter 509C featuring an auxiliary cruising chamber. this necessitated some revision of the aft fuselage to take the vertically-disposed rocket pipes of the new power plant, and for aerodynamic reasons, the lower contours of the fuselage were deepened marginally, this having the incidental advantage of providing space for the installation of two 30-mm MK cannon which had been proposed as an alternative armament to the rocket batteries. No attempt was made to increase fuel capacity, but for c.g. reasons the attachment points of the booster rockets were moved further back. Provisions were also made to replace the 1,102 lb booster units with two Schmidding 533 solid-fuel boosters each providing 2,205 lb. thrust.

This development, was designated the Bachem Ba 329B, and was to supplement the initial run of Ba 349A, with the 51st aircraft.. The B series offered a powered endurance of 4.36 minutes compared with only 2.23 minutes with the A series. in any event only three B series interceptors were completed before work came to a standstill at Waldsee, one of these actually being flown, although non-availability of the improved booster rockets necessitated the retention of the 1,102 lb. booster

 

 A powered machine is brought to the launch gantry. Left of center is a container (milk can) for fuel          (T-Stoff).


 The Natter is set up with a tow cable. in the foreground are pumps for fueling. Note that the horizontal tail structure is different from production models. Testing on this aircraft featured the increased size of the tail to provide greater control during launch.

 

Standard three-rail launch gantry used in test flight of the Natter. This system proved to very cumbersome to set-up and impractical for field operation. Later a more mobile system was devised that did away with the rails. To provide simplicity and quick set-up a simple pole and pulley system was devised for actual operational usage.

 

Grosse Rohrbatterie 108 Launcher

The following photos show the installation of the "Grosse Rohrbatterie 108" weapon package in the nose of the Natter.

The "Grosse Rohrbatterie 108" with 32 R4M 55mm rockets was to replace the "Fohn" rocket launcher in later models.

Technical drawing of the installation for the rocket weapon "Grosse Rohrbatterie 108".

 

 

Test stand assembly for live firing testing with the "Rohrbatterie 108". This was to replace the "Fohn" rocket launcher.

 

 

An unidentified variant of the Bachem "Natter" separated with the entire nose section from the fuselage.

 

Taken from Natter Bachem Ba 349 by Joachim Dressel

 

 

Hs 217 Fohn 73mm Rocket

The below photos show the installation of the Fohn rocket weapon package in the nose of the Natter. The battery consisted of 24 Hs 217 "Fohn 73 mm rockets.

Because of its appearance, it was nicknamed the "rocket honeycomb" (Raketenwabe).

Detail from the Smithsonian's sole surviving example at the Silver Hill, MD storage facility.
Note the remaining missile still in one of the sleeves.

 

  Detail of the installation plans for a variant of the "Fohn. 

 

 

 

Installation Study for the rocket weapon Fohn in the nose of the BP-20. because of its appearance, it was nicknamed the 'rocket honeycomb" (Raketenwabe)

Note simple ring aiming site.

Fohn weapons package attached to a Natter.

 

 

 

Taken from Natter Bachem Ba 349 by Joachim Dressel Publ. by Schaffer Military History 1994

 

 

Towing & Glide Testing

Such was the impetus placed behind the Ba 349 program that the first of an initial series of 50 Versuchs models were to be completed at Waldsee within three months of the launching of the Natter project. At this stage it was proposed to use all 50 of the first batch aircraft on the "unpowered" test phase, and the first gliding trials were performed near Heuberg in November 1944, the test Ba 349's were fitted with a fixed under carriage and ballasted to weight of 3,748 lb. The test aircraft was then towed to an altitude of approximately 18,000 ft. behind an Heinkel He-111. The test pilot, Zupert, subsequently reported that stability was excellent and the controls light and effective at all speeds between 125 and 425 m.p.h.

The following are photos of the first test aircraft used in stability and glide testing.

Construction detail of the towed glider prototype with tricycle landing gear attached.

 

Completed prototype with fixed tricycle landing gear.

 

 

 

 

The BP-20 prototype in tow under a Heinkel He-111. The tow cable was installed in this instance on the upper wing. Certain cable motions which were a danger to pilots and machines could thus be minimized.
Unidentified Bachem staff, (possibly Unteroffizer Hans Zubert on the right) with the BP-20 M8 .
This aircraft was used in free flight test in February 1945. Note the Messerschmitt Me-262 jet fighter in the background.

 

 

Recovery Testing

 

The promised deliveries of the Walter 509A rocket motor failed to materialize. In fact, the first Walter 509A power plant did not reach Bachem until February 1945. Thus, the first complete Natter could not be launched until the 25th of that month.

For the initial test with the Walter 509A installed a dummy pilot was seated in the cockpit. The Ba 349 was launched successfully and at a predetermined altitude the nose section and power plant section broke away, both the dummy pilot and power plant descended safely by parachute. The RLM, impressed by the results of the test, demanded that piloted trials with the Walter 509A installed should commence immediately. Bachem voiced his opinion that such tests were still premature, and in in this he was supported by Professor Ruff of the DVL, but all objections were dismissed, and on February 28 the first manned launch was made.

 


Test of the recovery mechanism on the Bachem Ba 349 Natter in February 1945.

As the parachute deploys the dummy is thrown clear of the aircraft.

 

Manned Flight Testing

Oberleutnant Lothar Siebert's Fatal Flight,
February 28, 1945

The success of previous unmanned test cleared the way for the first manned test flight. Three days after the last successful unmanned flight, Oberleutnant Lothar Siebert volunteered for the first manned test, and boarded the tiny interceptor mounted vertically on the launching rails. The initial part of the launch was normal. Trailing black smoke from he booster rockets, the aircraft lifted off the launcher and climbed away gaining speed. At the end of the initial phase, the boosters fell clear and the interceptor continued its vertical climb. Then, at a height of about 1,600 ft, the cockpit was seen to fall away. To the horror of those watching, the nose tilted away from the vertical and the aircraft described a wide arc across the sky. Seemingly there was no attempt to effect a recovery and it dived straight into the ground with Siebert still in the cockpit.

The cause of the accident was never determined satisfactorily. One possibility was that the canopy had not been locked in place before launch and when it tore away it might have knocked the pilot unconscious. But that did not explain why the Natter deviated from its intended vertical flight path, at a time when it should have been controlled by the auto pilot.

Despite this tragic accident there was no shortage of volunteers willing to fly the novel interceptor.

Early in April a Natter battery was set up at Kircheim near Stuttgart, with ten "A" series launchers. The diminutive rocket fighters and their pilots stood to during the daylight hours, ready to engage the next force of enemy bombers to come within range. They were still waiting when American ground forces approached the site, and to prevent their capture, the rocket fighters and their launchers were blown up.

Copyright - Air International, July 1996 , Erich Bachem's Snake in the Sky, By Dr. Alfred Price

  The pilot, Oberleutnant Lother Siebert discussing the flight with Erich Bachem.

 

BP-23 M23 sits ready for its pilot

 

 

 

 

 

 

 

Ground crew readies the M-23 for flight testing.

 

 

 

 

 

 

 

 

Siebert going through the precarious proceedure of boarding the aircraft.

 

 

 

 

 

The Natter with Siebert clears he tower.

 

 

 

 

 

Raising a cloud of dust, Siebert's Natter gains altitude.

 

 

 

 

 

 

Shortly afterwards the canopy brakes away and the aircraft tilted on its back, before arcing into the ground with the pilot still on board.

 

 

 

 

Natter's Captured By the Allies After May 1945

This series of photos shows several armed Natters as found by American troops in St. Leonhard. The American found complete aircraft, spare parts and undamaged documentation.

It is also reported that at least one Natter feel into Soviet hands. This machine was found in Thuringen where the Ba 349 was to be made under license as fast as possible.

 

 

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Last Updated

02/10/2014

 

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