Bachem Ba 349 Natter

A captured Bachem Ba 349 Natter on display. (Note markings were added)

The Bachem Ba 349 (BP 20) Natter was a semi expendable rocket powered interceptor developed by Germany during the latter years of World War 2.

Design History

In the early days of 1944, the Luftwaffe’s urgent need for a weapon with which to comb at Allied bomber streams more effectively led the German Air Ministry to issue a requirement to Heinkel, Junkers, Messerschmitt and Bachem for what was, in effect, a cheap and semi expendable piloted missile. The Bachem BP20 Natter (Adder) project was selected for development as the Ba 349 on 1 August 1944. Bachem’s design office – headed by Erich Bachem and H. Bethbeder – evolved a comparatively crude airframe which emphasised ease of manufacture by unskilled woodworkers without using complex jigs, allowing the type to be mass-produced in small woodworking factories. Lateral control was exercised via differential use of the elevators, due to lack of ailerons. The fuselage, with its small cockpit, housed a Walter 109-509A-2 sustainer rocket capable of producing 3,748 lb (16.67 kN) for 70 seconds at full power, which could run at a minimum output of331lb (1.47 kN). The aircraft would be launched vertically using the lift off power of four Schmidding 109-533 solid fuel rocket motors attached in pairs to the rear fuselage, with each producing 2,646 lb (11.77 kN) thrust for 10 seconds before release.

Testing

The first of 15 machines for the test programme became available in October 1944, being towed aloft by a Heinkel He-111 for unpowered handling trials, for which the aircraft was fitted with a fixed tricycle undercarriage. Further piloted glide tests in December 1944 were followed by unmanned flights using only the booster rockets. The first vertical launch with boosters and sustainer – but no pilot – took place on 23 February 1945, a few days before Lother Siebert made the first – and likely only – manned vertical launch, which ended with Siebert’s death when the aircraft dived from 5,000 ft (1,525m) into the ground, after the cockpit canopy became detached in flight.

Operational use

The tactics evolved for the Natter would have involved a vertical launch on autopilot, with the pilot assuming manual control when in position above the approaching bomber stream. The pilot would then initiate a shallow dive and jettison the nose cone, thus exposing the armament, consisting of either 24 Henschel Hs 217 Fohn 2.87in (73mm) or 33 R4M 2.17in (55mm) unguided rockets in the nose. After firing these rockets, the Natter would be flown clear of the combat zone, when the pilot would prepare to bale out by releasing his straps, after which the entire nose section would be jettisoned by uncoupling of the control column, thus moving the nose forward to release the safety catches, before releasing mechanical catches to separate the nose. This would cause the removal of the forward fuselage by the airflow, effectively ejecting the pilot via the deceleration of the rear section by streaming a breaking and recovery parachute, allowing the pilot to descend under his own parachute, and the rear section to be salvaged to permit reuse of the rocket motor. An initial plan - which was eventually abandoned - called for the pilot to use the Natter’s remaining kinetic energy to climb above the bombers after the rockets had been exhausted, in order to carry out a ramming attack.

Variants

• Ba349A – Initial production version. 200 were ordered (50 for the Luftwaffe and 150 for the SS). About 20 examples were completed, but never used operationally.
• Ba349B – Proposed improved version with increased wing/tail areas, the more powerful 4,409 lb st (19.61 kN) Walter 109-509C, which could be throttled down to 441 lb st (1.96 kN), extra fuel and a pair of 30mm cannon in addition to the rockets.

Specification

• (Performance Figures are estimated)
  • Ba349A - Maximum speed of 497 mph (800 km/h) at sea level, initial climb rate of 36,415 ft (11,100m) per minute, service ceiling of 45,920 ft (14,000m) and radius of action of 24.8 miles (40 km) at 39,380 ft (12,000m). The max loaded weight was 4,850 lb (2,200 kg). Wingspan was 11 ft 9 1/2in (3.60m), length was 20 ft (6.10m) and wing area was 29.60sq ft (2.75 sq m).
  • Ba 349B – Maximum speed of 621 mph (1,000 km/h) at 16,405 ft (5,000 km). Range 36 miles (58 km) at 9,840 ft (3,000m), 24 miles (39 km) at 32,810 ft (10,000m). Empty weight 2,414 lb (1,095 kg), loaded weight 5,004 lb (2,270 kg). Wingspan was 13 ft 1 1/2in (4.00m), Length was 19 ft 9in (6.02m), Height from fin base to fin top was 7 ft 4 1/2in (2.25m) and wing area was 50.59 sq ft (4.70 sq m).