Bachem Ba 349 Natter (Adder/Viper)
Vertically-Launched, Rocket-Powered Interceptor
The Bachem Ba 349 Natter was designed to quickly intercept inbound Allied bomber formations, attacking with high-explosive rockets buried in the nose.
Authored By: Dan Alex | Last Edited:
The Bachem Ba 349 Natter (translated to "Adder" though also known as the "Viper") was one of the late-war German aircraft initiatives intended to shift the balance of the Allied air campaign in favor of the Reich. The Natter was developed throughout the final years of the war, initially rejected by the German Air Ministry, and eventually constructed in over 20 to 30 usable examples. However, even before a single unit could carry out a mission in anger, Natter launch positions were overrun by advancing American Army personnel, formally tying yet another German Luftwaffe "secret weapon" to the pages of history and nothing more. By its very design, the Natter was nothing more than a piloted rocket of sorts though its launch and cockpit facilities were reusable after recovery - its rocket armament payload having been spent in the attack phase.
Luftwaffe air superiority, which had largely controlled the skies of World War 2 prior to 1943, was now challenged to the point that the German Air Ministry sought to curtail the damaging results incurred by the relentless Allied bombing campaign. The campaign centered primarily around use of American heavy bombers during the day and British heavy bombers during the night, creating a potent, non-stop, "one-two" punch against German installations of value. The Allied bombers proved such a detrimental component on the German military that it began to prioritize fighter production and development for the sheer purpose of self-defense to protect its airfields, oil reserves, factories, supply depots, bridges and strategic cities and towns. By 1944, the situation was growing ever dimmer as targets within Germany herself were being targeted with regularity. As such, a certain level of unspoken desperation began to sink in and the German Air Ministry began entertaining many different approaches to solve the Allied bombing campaign problem.
Up to now, rocket propulsion was in its relatively infancy concerning aircraft of war. The Messerschmitt Me 163 "Komet" and its volatile fuel mixture first flew on September 1st of 1941 but would not enter feasible production and subsequent operational service until 1944 with only 370 built in all. German Erich Bachem, a one-time engineer at the Fieseler aircraft concern, struck out on his own in 1943 and began his Bachemwerke GmbH facility based out of Waldsee. Bachem held a substantial claim to fame during his time at Fieseler for he was responsible for the design of the world-renowned Fieseler Fi 156 Storch ("Stork"), an excellent light liaison aircraft built around a robust and flexible airframe with superb short take-off and landing (STOL) qualities. As such, Bachem was no stranger to rather unconventional aircraft developments and, from his newly established Waldsee location, contributed various flight control surfaces to a variety of Luftwaffe projects from then on.
However, with losses across the German-held territories beginning to mount, the Luftwaffe developed an all-new requirement based around a low-cost, quick production interceptor intended to combat the Allied bomber formations directly. Bachem, always the observer, could study the incoming waves of enemy bombers over his own town and noted general tactics and overall implementation used when traversing German airspace. As such, he began to develop an interceptor that could reach attack altitude quickly and unleash a potent payload directly into the enemy aircraft formations. To reach the required altitude, the design would be launched vertically to avoid unnecessary time-consuming take-off procedures with help from rocket thrust propulsion. Construction would be primarily of plywood wood (held mainly by glue and screws) save for the nose assembly for German wartime materials such as metal were required elsewhere in the war effort. Bachem nicknamed his development the "Natter" to coincide with the deadly nature of the Adder viper.
In early 1944, the Luftwaffe requirement was officially fleshed out and revealed to interested parties. Bachem enrolled his initial plan - assigned the designation of "Ba P.20" - into the endeavor while other submissions were delivered from German aviation stalwarts Heinkel, Junkers and Messerschmitt. After the first line of reviews had concluded, the Bachem submission was pushed aside as being too far-fetched, more of a comical gesture than a serious design submission. The German Air Ministry sought a more conventional aircraft for its interceptor requirement and the Bachem submission came off more as a manned rocket than anything else. The Air Ministry also sought a reusable flight system to help keep production costs down and the Bachem design was seemingly centered around a disposable airframe. To keep his efforts alive, Bachem then teamed with famed German aviator Adolf Galland to help push through his interceptor design but even venture this fell to naught, leaving the Natter initiative in limbo for the time being.
Bachem's next option was to tap Heinrich Himmler - Adolf Hitler's right-hand man - and was granted an interview. Himmler, always interested in the unorthodox and exotic, took to the Bachem design and agreed to further the Viper program by whatever means necessary. Himmler's power within the German hierarchy was such - sometimes usurping that of Hitler himself - that Bachem received a call from the German Air Ministry in less than a day to speak of his once-rejected Natter. At one point Himmler even suggested the opening of a new concentration camp to provide the "skill laborers" the Natter development would require but Bachem politely turned down this despicable notion. Himmler instead committed hundreds of his Waffen SS troops to the program - a valuable waste of critical manpower to say the least.
In August of 1944, no fewer than three Natters were available for early flight testing. Its design was rather utilitarian in appearance and consisted of a basic tubular airframe fuselage with an integrated cockpit, empennage section and nose cone. The nose cone was the bread-and-butter of the Natter for it fielded the necessary 24 x Fohn RZ-73 series 2.87" (73mm) high-velocity, high-explosive rocket payload to be used against the enemy bombers. The nose was "cut-off" at its end to reveal the rockets. In flight, the rockets would be covered over in a jettisonable plastic cap to maintain the aircraft's aerodynamic principles. The cockpit was fitted immediately aft of the nose assembly with seating for one and heavily framed with limited viewing. Additionally, the fuselage spine blocked nearly all rearward visibility but this was negligible for the Natter was in no way a "fighter" aircraft of any sort - simple a single-minded short-ranged, short-term interceptor. The fuselage tapered off at the rear to which a HWK 509C-1 series bi-fuel rocket motor was installed. This had the output of 4,400lbs of thrust and would be augmented by 4 x Schmidding-brand solid-fuel jettisonable boosters at launch (two held externally at each empennage side), providing the Natter with the necessary lift and altitude reach within a short amount of time. The boosters provided a further 1,100lbs of thrust each and could burn for up to 6 seconds, jettisoned after use. Wings were short, stubby and straight installations with clipped tips, providing the basic flight controls. There were both a dorsal and ventral vertical tail fin while the dorsal fin also held a pair of smaller horizontal planes.
All told, the Natter weighed in at nearly 5,000lbs. The aircraft's wingspan measured in at just over 13 feet with a running fuselage length of nearly 20 feet. When in profile, the Natter measured a height of 7.5 feet. At the time of launch, the airframe could hit speeds of approximately 620 miles per hour and climb an astounding 37,400 feet per minute. Its operational radius was a limited 12 miles while its service ceiling was 33,300 feet - well within the operational altitude of Allied bombers. The Natter could clock that altitude in just 60 seconds. Total endurance in a typical flight was just 4.6 minutes to 30,000 feet which made every second, literally, count for the Natter pilot. Beyond the 24 x 2.87" rocket armament, the Natter was - at one point - considered for 2 x 30mm MK 108 series heavy autocannons as well.
To maintain the vertical nature of the launch phase the aircraft would be rested on its tail and set up against an 80 foot vertically-set launching ramp. Initial flight control would be accomplished by autopilot via a radio-radar linkage arrangement to which the pilot would then be given control of the aircraft once it was within 5,000 feet of the intended targets. From there, the pilot could guide his aircraft via traditional flight controls at an enemy bomber (large targets by their very nature) and avoid enemy machine gun fire with his relatively small aircraft. Upon initiating the "attack" phase, the nose assembly would jettison its plastic cover cap and expose the 24 x 2.87" Fohn unguided rockets within. At this point, the pilot would fire all 24 rockets in a single ferocious salvo. The next step involved manually disengaging the empennage and its valuable booster rocket section. The canopy was then jettisoned and the pilot bailed out (under 150 miles per hour) in a conventional manner. Both the remaining rear fuselage section and pilot glided back to earth under deployed parachutes to be recovered/reused another day. If the rocket launching facilities failed at some point, the pilot could also consider ramming the aircraft nose into the enemy, of course he bailing out before the moment of impact.
The Natter undertook gliding trials in October of 1944 and the controls proved adequate for the task. In December of 1944, the Natter project had evolved to the point that a new model version - the Ba 349-M - was unveiled with a fixed undercarriage. This was primarily utilized to formally evaluate the in-flight controls of the Natter when tethered to a "mothership" host - in this case, the ubiquitous Heinkel He 111 medium bomber - as the Natter could now be landed "safely" behind the aircraft in controlled tests. In March of 1945, the situation across the German Reich was dire. Nevertheless, attention was still being paid to unorthodox developments of many kinds including jet-powered aircraft, flying wings, rocket fighters, guided missiles and mega- tanks.
March also marked the first manned test flight of a Ba 349 with pilot Lothar Siebert at the controls. The Natter rose from its vertical launch rail as intended but, under 1,700 feet, the canopy was lost. The aircraft then went into a pseudo-loop and ultimately drove straight into the ground, resulting in a total loss of both aircraft and pilot. The cause of the crash was believed to be a faulty canopy fitting and the program resumed nonetheless. The Natter was, however, successfully tested in later weeks under manned control - at least three such instances were recorded. The German Air Ministry was "satisfied enough" with the results of the Natter development program that it deemed the aircraft cleared for formal operations. The series would be produced in two distinct forms, each differentiated by their main rocket propulsion - the Ba 349A was to be completed with the single-chambered HWK 509A-1 series whilst the Ba 349B would have the dual-chambered HWK 509C-1 installed - the latter affording the Natter more flight time.
In April of 1945, Bachemwerkes had produced approximately 20 to 36 Natters for operational service (sources vary on the total). However, April also proved a dismal month for the German Reich for, aside from mounting losses across every major front, leader Adolf Hitler had committed suicide in his underground bunker in Berlin as Soviet Army forces approached. Several German leaders were clearly clamoring for a favorable cease fire with the British and Americans while these enemy forces made steady - sometimes unmolested gains - into German territory. In the German town of Kirchheim, at least ten Natters were setup and presumably poised to strike. However, American Army forces spread through the area and captured these positions in full before their German caretakers could destroy them - bringing an end to the "wrath" of the mighty German Viper.
Amazingly, two complete Natters are known to exist total. One is showcased at the Deutsches Museum in Munich, Germany while the other is a part of the collection at the National Air & Space Museum at Silver Hill, Maryland.