V-2 rocket

The V-2 rocket, originally named Aggregat-4 (A4), was the world's first practical, modern ballistic missile. A ballistic missile is a rocket that follows a predetermined path, much like a thrown ball.

Developed by Nazi Germany during the Second World War, it was intended as a "vengeance weapon." The German military used these rockets to attack Allied cities, including London, Antwerp, and Liège. Because the rockets traveled at supersonic speeds, they moved faster than the speed of sound. This meant they impacted their targets without any audible warning.

The propulsion system of the A4 relied on a complex liquid-propellant rocket engine. The rocket used a mixture of 75% ethanol and 25% water, known as B-Stoff, as its fuel. To allow the fuel to burn in space, it also carried liquid oxygen (LOX), called A-Stoff, as an oxidizer.

A critical component was the turbopump, which rotated at 4,000 rpm. This pump was driven by a steam turbine powered by the decomposition of concentrated hydrogen peroxide. The turbopump forced the fuel and oxygen into the combustion chamber at a rate of 125 liters per second. During the initial stage, the engine produced 8 tons of thrust. As the turbopump pressurized the fuel, thrust increased to 25 tons to lift the 13.5 ton rocket.

Engineers used several specific methods to keep the engine from melting during flight. One method was regenerative cooling, where the fuel helped manage heat. They also used film cooling, which admitted alcohol through four rings of small perforations under slight pressure. This created a protective layer within the combustion chamber and exhaust nozzle. The water in the fuel mixture also played a vital role. It reduced the flame temperature and acted as a coolant by turning into steam. This helped reduce thermal stress on the engine parts.

To stay on course, the V-2 used a sophisticated guidance system. It featured four external rudders on the tail fins and four internal graphite vanes located in the jet stream.

These eight surfaces were controlled by an analog computer called the Siemens Vertikant LEV-3. This computer received electrical signals from gyroscopes, which are spinning tools used for stabilization. The system included two free gyroscopes to manage pitch and yaw. It also used a PIGA accelerometer to control the exact moment of engine cutoff. This ensured the rocket reached the correct velocity before entering its ballistic free-fall trajectory.

The development of the A4 was led by Wernher von Braun at the Peenemünde Army Research Center.

Von Braun had been interested in rockets since his youth, even building a homemade toy rocket car. He worked alongside other key figures like Walter Dornberger and Walter Riedel. The project was heavily influenced by the research of American physicist Robert H. Goddard. By late 1941, the Peenemünde center had mastered the essential technologies for the A4. These included large liquid-fuel engines, supersonic aerodynamics, and gyroscopic guidance.

However, the production of these weapons involved great human suffering. The rockets were constructed at the Mittelwerk site using forced labor. Approximately 12,000 laborers and concentration camp prisoners died during the production process.

Additionally, the attacks launched by the rockets resulted in the deaths of an estimated 9,000 civilians and military personnel. Despite the massive cost of the program, historical assessments show the V-2 had little strategic impact on the outcome of the war.

Even though the V-2 was a weapon of war, it holds a unique place in space history. On 20 June 1944, a V-2 rocket reached an altitude of 100 kilometers. Because 100km is the recognized edge of space, the V-2 became the first artificial object to travel into space.

After the war, the technology was highly sought after by the United States, the United Kingdom, France, and the Soviet Union. Through Operation Paperclip, captured hardware and scientists were moved to different countries. This technology directly influenced the development of later ballistic missiles and the beginning of modern spaceflight.