V-2 rocket: Encyclopedia II - V-2 rocket - Technical Details

V-2 rocket - Technical Details

The V2 was an unmanned, internally guided, ballistic missile. At launch it would propel itself for a short time on own power, and its navigation system would direct it towards its target during this period. After engine shutdown it would continue on what is basically a free-fall trajectory (hence the term ballistic). The V-2 had an operational range of about 300 km (200 statute miles) carrying a 1000 kg (2200 lb) warhead. The V-2 had an accuracy circular error probable (CEP) of 11 miles (17 km). This means at a 200 mile (300 km) range, the V-2 would only have a 50% chance of being within 11 miles (17 km) of the target. With that kind of accuracy, it could be aimed to hit a city, but not a factory. Modern missiles, the Minuteman for example, have a CEP of 100 meters at a range of 10,000 km (330 ft at 6,200 mi). There was some experimentation with bigger fuel tanks for improved range before the war ended.

The V-2 was propelled by alcohol (ethanol and water) fuel, and the oxidizer was liquid oxygen. The fuel and oxidizer pumps were steam turbines, and the steam was produced by concentrated hydrogen peroxide with calcium permanganate catalyst. The water-alcohol fuel was kept in a tank of aluminium to save weight, which put a high pressure on German war economy, as this metal was rare and valuable. Ignition was by injecting two hypergolic substances into the combustion chamber, self-igniting upon mixing, basically creating the spark that would light the main thrust.

The combustion burner reached a temperature of 2500 to 2700 °C. The alcohol-water fuel was pumped along the double wall of the main combustion burner. This cooled the chamber and heated the fuel. The fuel was then pumped into the main burner chamber through 1224 nozzles, which assured the correct mixture of alcohol and oxygen at all times. Small holes also permitted some alcohol to escape directly into the combustion chamber, forming a boundary layer that further protected the wall of the chamber, especially at the neck where the chamber was narrowest. This boundary layer ignited in contact with the atmosphere, accounting for the long, diffuse exhaust plume of the V-2. (Later, post-V2 engine designs not employing the boundary layer show a translucent plume with shock diamonds.)

The V-2 was guided by an inertial gyroscopic navigation system controlling four external rudders on the tail fins, and four internal rudders, made of graphite, at the exit of the motor. Some later V-2s used "guide beams" (i.e. radio signals transmitted from the ground), to navigate the missile toward its target, but the first models used a simple analog computer that would adjust the azimuth for the rocket, and the flying distance was controlled by the moment of engine cut-off,"Brennschluss", ground controlled by a Doppler system or by different types of on-board integrating accelerometers. The rocket would stop accelerating and soon reach the top of the (approximately parabolic) flight curve.

The painting of the operational V-2s was mostly a camouflage ragged pattern with several variations, but in the end of the war a plain olive green rocket also appeared. During tests, the rocket was painted in a characteristic black/white chessboard pattern which aided in determining if the rocket was spinning around its own longitudinal axis.

In all over 6000 V-2's were built, of which approximately 3500 were launched against allied targets. At the end of the war literally hundreds fell into the hands of the allies as war booty.

Adapted from the Wikipedia article "Technical Details", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki