http://www.spaceline.org/history/4.html
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Each V-2 was 46 feet long, had a diameter of 5 feet, 6 inches and finspan of 12 feet. The entire rocket weighed about 27,000 pounds at launch. The top six feet of the V-2 was a warhead containing up to 2,000 pounds of conventional explosives.
Below the warhead was a 5-foot section containing instrumentation, a 20-foot section containing the fuel tanks and a 15-foot section containing the engine.
The instrumentation section contained an automatic pilot, accelerometer and radio equipment. The automatic pilot was made up of two electric gyroscopes that stabilized the rocket's pitch, roll and yaw motions.
As the rocket moved about the axes of the gyroscopes, the movement was measured by electronic potentiometers. This caused electric command signals to be sent to a series of steering vanes at the base of the rocket.
The V-2 employed two sets of steering vanes. An external set of four steering vanes was made up of one steering vane at the base of each of the four V-2 fins. An internal set of four steering vanes was located at the base of the engine.
Both sets of steering vanes were designed to work together to deflect the engine exhaust and steer the rocket. Movement of the steering vanes was intended to cause the potentiometers in the instrumentation section to read zero voltage, thus keeping the rocket on a predetermined path.
Whenever the potentiometers read any voltage, an electric command would be sent to corresponding steering vanes to correct the motion of the rocket until the voltage again read zero. The steering vanes were controlled by electrohydraulic mechanisms.
The accelerometer was used to measure the velocity of the rocket, while the radio equipment was used for a variety of purposes. In some instances, the radio equipment was used merely to receive commands from the ground to shut off fuel flow to the engine.
In more complex applications, a radio transmitter and second receiver were employed to measure the rocket's velocity through the Doppler principle. In some cases, radio equipment allowed the V-2 to be radio-guided from the ground.
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Once the control officer believed the rocket was ready for launch, an electric command was sent to start the fuel pumps. After about three seconds, the fuel pump steam turbine reached full speed, the fuel flow reached its full value of 275 pounds-per-second and the engine thrust reached about 69,000 pounds.
The V-2 was then launched, and began to rise slowly. It continued in a vertical rise for about four seconds, then was pitched to its programmed launch angle by the gyroscopic guidance system. The maximum pitch angle was typically about 45 degrees, which produced the greatest range.
After about 70 seconds, the V-2 fuel flow was stopped, and the engine shut down. By this time, the rocket had achieved a speed of 5,000 to 6,000 feet-per-second. The rocket would then complete an unpowered ballistic trajectory, reaching its target just five minutes after being launched.
Achieving a maximum altitude of 50 to 55 miles, the V-2 could impact a target within an operational design range of 180 to 190 miles, although some are believed to have flown as many as 220 miles. Because the V-2 flew so high and so fast, there was no defense against it. The missiles could not be detected until they exploded on the ground.
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