Credit: © Mark Wade
Status: Retired 1942. First Launch: 1939-10-01. Last Launch: 1939-10-01. Number: 1 . Thrust: 15.00 kN (3,372 lbf). Gross mass: 900 kg (1,980 lb). Height: 5.82 m (19.09 ft). Diameter: 0.78 m (2.55 ft).
The recovery system consisted of a drogue and main parachute. Many others with no propulsion system or using a monopropellant system were built for air-drop tests. The A5 was flown from 1938 to 1942, and was essential in refining the aerodynamics and other technology for the A4. Propellants Lox/75% alcohol.
The first A5 drop test model is delivered to Peenemuende just weeks after the third A3 test. Production is planned at a rate of 10 per month to define the A4 aerodynamic configuration. Objective of the first tests is to break the sound barrier - in the wind tunnel no configuration of fins had managed to go through the barrier without disintegrating. The only test possibility was to drop the model from a great height, and let gravity accelerate it to supersonic speeds. The model weighs 250 kg and is 1.6 m long and 20 cm in diameter.
In the summer of 1938 the decision is made to go ahead with four A5 tests from Greifswalder Oie without the stabilising system or a parachute. The first missile ascended into a low wind, and reached 8 km altitude, nearing but not exceeding the sound barrier. Maximum altitude reached in the test series is 12 km.
In order to test the A4's stabilisation system, Walter, Kiel, is subcontracted to build a large number of model A5's. Like the drop test models, these are 20 cm and 1.6 m long. However they weigh only 47 kg gross lift-off mass, with a 27 kg empty mass. The rocket engine burns 85% hydrogen peroxide monopropellant using a calcium permanganate catalyst. The engine produces 120 kgf for 15 seconds, and has an exhaust velocity of 1000 m/s. The design objective is a low cost, reliable, and simple rocket, which will allow a large number of trail-and-error test launches to be made within a tight budget. The fins developed for the A4 as a result of these tests were shorter and wider than those of the A3. They owed nothing to aircraft wing designs of the times, which couldn't withstand supersonic speeds. But they were still too affected by the wind, tending to set the rocket on a rotation around its long axis during ascent.
The model is dropped from a He-111 bomber from 7000 m. It breaks through the sound barrier at 1000 m altitude at a speed of 360 m/s. The stabilising fins keep the maximum oscillation of the model to within 5 degrees from vertical. The drogue ring parachute then deployed to decelerate the model to 100 m/s, followed by the main parachute which slows it to 5 m/s when it impacts in the ocean.
New test series at Greifswalder Oie. The island had changed a lot, with massive new concrete installations. Three A3's were flown with a new Siemens control system. The first was launched vertically, reaching 7 km at 45 seconds into the flight at the time of engine cut-off. Both the drogue and main parachutes functioned correctly, and the rocket splashed down in the harbour and was recovered a half hour later by a motor boat (the rocket could float for up to two hours before water entering the empty propellant tanks would sink it).
This was the first test of the pitch-over manoeuvre required for the operational A4. The test went perfectly - the rocket pitched over 4 seconds after lift-off, reaching 4 km altitude, and was 6 km downrange from the launch point when the drogue parachute deployed. The rocket was recovered from the ocean successfully. This was finally a complete success after seven years of developmental effort. But the rocket had not broken the sound barrier.