Problem 1: The engine
Germans lack engine power
No motor is powerful enough to lift the nearly 13-tonne rocket, so the Nazis have to make one themselves.
The enemy cities are hundreds of miles away and the rocket engines do not yet have the range and power to take the 1,000 kilos of explosives.
The Nazis are lucky that the physicist Robert H. Goddard already invented a rocket in 1926 that flies on liquid instead of solid fuel. That benefits the power, but it requires a more complex engine - especially in a large and heavy rocket like the V2.
And there are problems. The pressure in the engine is too low to create upward force, or the mixture of ethyl and liquid oxygen pops through the wall of the combustion chamber.
The Nazis experiment a great deal before they can make a strong, barrel-shaped combustion chamber with a double wall full of alcohol that has a cooling effect. They also get extra power from the engine with two turbo pumps, which inject fuel and oxygen into the combustion chamber at a whopping 125 liters per second.
All in all, the Nazis get 25 tons of thrust from the V2. That's 17 times as much as any other rocket of the time.
Thanks to a number of new techniques, the V2 rocket gets sufficient momentum:
- A new type of fuel
- Turbo pumps
- Another engine form
- A larger outlet
1. Fuel drives the drive
With liquid oxygen and ethyl, the rocket has more thrust per kilo of propellant than other solid fuel rockets of the time.Claus Lunau
2. Pump puts turbo on the engine
Two turbo pumps with steam increase the pressure at the fuel supply, so that much more enters the fuel chamber. The engine has ten times as much thrust.Claus Lunau
3. Form promotes combustion
The combustion chamber becomes barrel-shaped and therefore mixes the oxygen and the ethyl better. Furthermore, the shape makes the walls resistant to the 2600 ° C hot exhaust gases.Claus Lunau
4. Nozzle reduces friction
The exhaust does not slope 10 but 30 degrees. In this way the Germans reduce the friction between the steel and the exhaust gases, which makes the propulsion more efficient.Claus Lunau
Problem 2: Aerodynamics
Super speed breaks the hull
The V2 rocket is the first to fly faster than the sound, but with that speed the slightest deviation leads to disastrous swings in the air.
Before the V2, no large object had flown faster than the sound (around 1200 km / h). The German rocket even goes
4.5 times faster, which places high demands on aerodynamic stability.
The problem is mainly the descent to the destination: when the V2 rushes through the bottom layer of the atmosphere at 5700 km / h, the air density increases and the high air resistance pulls on the rocket. This allows it to break into pieces or even explode in the air.
READ THE WHOLE STORY - All about the men behind the Nazi Germany rocket program:
The Germans do everything in their power to build a strong, streamlined construction. The four rocket fins point backwards like the feathers of an arrow,
because experiments in some of the first wind tunnels have shown that this reduces turbulence and air resistance at supersonic speeds. The cover of the rocket is also designed according to new methods.
Wind tunnel tests with heat sensors show that the outside of the rocket becomes 805 ° C hot at those speeds, increasing friction. German aerodynamics cover the V2 with an ideal type of steel to prevent wear and tear while flying.
The Germans stabilize the V2 rocket with:
- Rocket Fins
- Low weight
- Reinforcements of cans
- A new projectile shape
1. Rocket fins provide stability
With fins, the pressure point shifts backwards, preventing the rocket from tipping forward at high speeds.Claus Lunau
2. Triplex distributes control rooms
The 'brain' of the rocket is a 1.4-meter-long control room with four plywood partitions. The wooden walls separate, among other things, control instruments, radio equipment and batteries and keep the weight of the rocket low.Claus Lunau
3. Tin can hold the point together
The tip of the rocket is reinforced with a thin sheet. This reinforcement must prevent the rocket from breaking into the air because the hull is overheated.Claus Lunau
4. Flight is stable thanks to the bullet shape
The rocket was formed after the "S" rifle bullet of the German infantry. The Nazis have discovered that the bullet flies stably without spinning, even at supersonic speeds.Claus Lunau
Problem 3: Precision
Rocket is blowing with the wind
Rockets fly in all directions. If the Nazis want to hit their enemy exactly, they must develop a brand new operating system.
Rocket control in the 1930s and 1940s means that you let a rocket point in one direction and hope for the best. The Nazis have little use of that if they have to hit cities like London and Paris from hundreds of kilometers away with their rockets.
They come up with an automatic control system, in which two gyroscopes keep the rocket on course, while an accelerometer monitors the speed. This allows the rocket to turn off the engine at exactly the right moment to reach the target.
The system allows the V2 rocket to hit a spot within 200 miles of the target after 200 kilometers in the air. However, due to errors in the settings and construction, the rocket is less reliable, and of the approximately 1,200 rockets that were fired at London, only 517 hit target.
The engineers are developing a very precise control system for that time, including:
- Rocket Fins
- Jet stirring
1. Stirring give a flying start
A rudder on each of the four rocket fins counteracts rolling and turning, especially just after the start. The rudders work two by two with the rudders at the outlet of the rocket.Claus Lunau
2. Jet rudders do the height work
At the outlet there are four graphite rudders that steer the rocket through the exhaust gases. That is conveniently high in the atmosphere, where the pressure drops and fins do not work well.Claus Lunau
3. Steering box keeps course
Gyroscopes detect deviations in the slope and course. Corrections are passed on to two electric motors, which they pass on to the tail rudders.Claus Lunau