Born: 1902. Died: 1968-01-01.
German rocket engineer who first worked for the Heylandt Company, then moved to Von Braun's rocket team, where he was involved in development of the V-2 rocket engine. Not to be confused with Walther Riedel, Director of the Karlshagen Development Works, who was involved with development of the sea-launched version of the V-2. Unrelated to his contemporary rocket engineer Klaus Riedel. Moved by the British to Saenger's facility in Trauen in early 1946 to conduct rocket engine tests there. Tests were completed on 16 June 1946.
The cause of early detonation of the warhead during the engine burn time is understood, but the crashes at the end of the trajectory are still a mystery. Dornberger is ordered to report to Hitler at Berchtesgaden. The call is received at 7 pm in the evening, following a bomb raid and ice storm. Dornberger is told that on the following morning Von Braun, Riedel II, and Groettrup are to be arrested for sabotage of the A4 program. Groettrup selects Dr Steinhoff as his representative. The men are accused of not putting all their energy in development of the A4 as a weapon - instead only using the financing of the Reich to support their private plans for manned spaceflight. Dornberger know he cannot complete the program without these men - Von Braun and Riedel were the key leaders, and Groettrup was head of the electrical systems section. Dornberger finally achieves their release by demonstrating to the SS that the biggest impediment to the program was Hitler's dream that the A4 would never reach London. After a few days in detention, Von Braun was moved to Schwedt, and then freed. The others were allowed out a bit later.