A-9 & A-10

A-9 / A-10

Comparison of A9/A10

• The A9/A10 was the world’s first practical design for a transatlantic ballistic missile.
• It was proposed to use an advanced version of the A9 to attack targets on the US mainland from launch sites in Europe, for which it would need to be launched atop a booster stage, the A10.
• Design work on the A10 began in 1940, for a projected first flight to take place in 1946. The initial design was carried out by Ludwig Roth und Graupe and was completed on 29 June 1940. Hermann Oberth worked on the design during 1941, and in December 1941 Walter Thiel proposed that the A10 use an engine composed of six bundled A4 engines, which it was thought would give a total thrust of 180 tonnes.
• Work on the A10 was resumed in late 1944 under the Projekt Amerika codename, and the A10's design was amended to incorporate a cluster of 6 A4 combustion chambers feeding into a single expansion nozzle. This was later altered to a massive single chamber and single nozzle. Test stands were constructed at Peenemunde for firings of the 200 tonne thrust motor.
• It was considered that existing guidance systems would not be accurate enough over a distance of 5,000 km, and it was decided to make the A9 piloted. The pilot was to be guided on his terminal glide towards the target by radio beacons on U-boats and by automatic weather stations landed in Greenland and Labrador.
• The final design of the A10 booster was approximately 65 ft (20 m) in height. Powered by a 375,000 lbf (1,670 kN) thrust rocket burning Diesel oil and nitric acid, during its 50 second burn it would have propelled its A9 second stage to a speed of about 2,700 mph (4,300 km/h) and an altitude of 15 mi (24 km).
• The original second stage A9 design was a refined A4 with swept wings. A later version had two fuselage strakes instead of wings. Wind tunnel tests showed that these provided better supersonic lift and solved the problem of transonic shift of centre of lift. A secondary benefit was better packaging of the A9 into the forward interstage of the A10.
• Guidance systems of the time were hopelessly inaccurate at the 5000 km range planned for the A9/A10. Therefore it was decided that the A9 would have to be piloted. After cut-off of its engine at 390 km altitude and 3,400 m/s, the A9 would re-enter and begin a long glide to extend the range. The pilot was to be guided by radio beacons on surfaced German submarines in the Atlantic Ocean. After reaching the target the pilot would lock in the target in an optical sight, then eject. Death or internment as a prisoner of war would follow.

Description:

• Stage Number: 1. 1 x A-10 Gross Mass: 69,043 kg. Empty Mass: 16,993 kg. Thrust (vac): 235,238 kgf. Isp: 247 sec. Burn time: 55 sec. Isp(sl): 210 sec. Diameter: 4.1 m. Span: 9.0 m. Length: 20.0 m. Propellants: Lox/Alcohol No Engines: 1.

  A9 Stage Separation - Credit: Gary Webster.

• Stage Number: 2. 1 x A-9 Gross Mass: 16,259 kg. Empty Mass: 3,000 kg. Thrust (vac): 29,437 kgf. Isp: 255 sec. Burn time: 115 sec. Isp(sl): 220 sec. Diameter: 1.7 m. Span: 3.2 m. Length: 14.2 m. Propellants: Lox/Alcohol No Engines: 1.