Aggregate-3 (A-3)

Germany


A-3

A-3 dimensions in mm


  • Development of the A3 can be traced at least to February 1935 when Major Ernst Ritter von Horstig sent General Karl Becker a budget of almost one half-million marks for the construction of two new test stands at Kummersdorf. Included were mobile test rigs, small locomotives, and office and storage space. The A3 plans called for a rocket with an inertial guidance system and a 3,300 pound (1500 kg) thrust engine.
  • In March 1936, Army General Werner von Fritsch witnessed a static firing of an A3 engine at Kummersdorf, and was sufficiently impressed to lend his support to the rocket program. Like the earlier A1 and A2 rockets, the A3 also used a pressure-fed propellant system, and the same liquid oxygen and 75% alcohol mixture as the earlier designs. It generated its 3,300 pounds of thrust (14.7 kN) for 45 seconds. It used a three-gyroscope system to deflect tungsten-alloy jet vanes. The design was finished and secretly patented in the spring of 1936 and further modifications that made the rocket stable at supersonic velocities were finalized in the autumn.
  • On Dec.4, 1937, the first A-3 lifted off from a new rocket research center at Peenemünde, on the Baltic coast as part of Operation Lighthouse. With a length of 6.7 meters, the A-3 was a large-scale experimental rocket to test liquid propulsion and a preliminary missile guidance system. The guidance system was ahead of its time: three gyroscopes and two integrating accelerometers controlled vanes directing the exhaust of the 14700 N thrust engine during its 45 second burn. A tail ring reinforced the fins at launch, but dropped away early in the flight.
  • Each rocket carried registering instruments to mesure either the heating of the skin through friction or atmospheric temperature and pressure during a parachute descent from a peak of 20 km.
    The first and second launches displayed problems with both premature parachute deployment and engine failure; both crashed close to their takeoff points. The parachute was disabled in the third and fourth rockets, but these, too, experienced engine failures, though the lack of parachute drag allowed them to crash further from the launch site.
    The A-3 may have been too much of an advance for the Peenemünde team, as none of the four test flights of the A-3 were completely successful.
  • After this unsuccessful series of launches, the A3 was abandoned and the A-5 program was added to give the rocket engineers a chance to learn the secrets of rocketry. In the meantime, work on the A4 continued.

Description:

Length: 6,74 m (22.1 ft)
Body Diameter: 0,68 m (2.2 ft)
Finspan: 0,93 m (3.1 ft)
Launch mass: 748 kg (1650 lb)
Propellant weight (kg): ??
Liftoff thrust: 14.7 kN
Total burn time: 45 sec
Guidance gyroscope
Propulsion ethanol and liquid oxygen.

Launch log:

DateAltitude
14 December 1937?? m
26 December 1937?? m
38 December 1937?? m
411 December 1937?? m

Notes:

1) For the first three seconds, during the first launch, the rocket ascended vertically, then suddenly the parachute popped out of the side, trailed behind the still accelerating vehicle, and was incinerated. The rocket turned into the wind, and the engine shut off automatically when it tipped over too far. After about twenty seconds it crashed back onto the island only about 300 meters from the launch site, exploding violently on impact.
2) When the second A-3 was launched two days later, virtually the same thing happened, with the vehicle crashing only 5 meters offshore.
3) The parachute was omitted for the third launch on December 8, and a signal flare was put in its place. The wind was stronger than on earlier attempts, and the rocket turned quickly into it, ejecting the flare after four seconds. Again the engine cut out automatically and the rocket crashed 2 kilometers out to sea.
4) The last attempt on December 11 was almost identical.

Ref.: #14, #98, #116, #117 - update: 15.06.12 Home