At that time, rocket pioneer and former SS major Wernher von Braun decided not to start their own rocket engine development, but to purchase an engine from North American Aviation (NAA) that was being developed by Dannenberg's former boss, Riedel, who had previously left the team to join NAA. Beaumont Hospital, and were eventually transferred to the Redstone Arsenal near Huntsville, Alabama, where development of the PGM-11 Redstone Missile was their first assignment. When the Korean War started, the group was required to leave their quarters in an Annex to the Wm. Goddard's idea of upper atmosphere research could now be conducted on a large scale. Due to range limitations, all rockets were launched vertically, to limit their range. Army and the support contractor General Electric to launch V-2s at the White Sands Proving Ground. Most members of the group performed calculations and designs of future advanced launch vehicles with longer ranges and greater payloads. He was interviewed for the documentary "The Hunt for Hitler's Scientists." Īfter the end of World War II, Dannenberg was brought to the United States with 117 other German specialists under Operation Paperclip to Fort Bliss, Texas. Dannenberg then became Walter Riedel's deputy and headed the crash effort to finalize production drawings of the V-2, the world's first ballistic missile, used by the Nazis to bomb London. After Thiel's death in an August 1943 bombing raid, a design freeze stopped all development efforts. Many improvements on which he worked could not be completed in time for production. This was the first man-made vehicle to reach space based on a then-current definition of 50 miles in altitude (see Kármán line for relevant background). He was at Peenemünde on 3 October 1942 to witness the launch of the first man-made object to reach outer space, a V-2 rocket. His main assignment was developing a rocket engine for the V-2 ballistic missile. Under Walter Thiel's guidance, he became a rocket propulsion specialist. In the spring of 1940, through the influence of Püllenberg, Dannenberg was discharged from the army and became a civilian employee at the Heeresversuchsanstalt Peenemünde ( Peenemünde Army Research Center). He took part in the initial stages of the Battle of France. When World War II began, Dannenberg, a member of the Nazi party since 1932, was drafted into the German Army in 1939, serving first with a horse-artillery unit acquired by the German Army in Czechoslovakia. Dannenberg studied mechanical engineering at the Technische Hochschule Hannover (current University of Hannover) with emphasis in diesel fuel injection, because he recognized that injectors would also be part of the process of moving propellants into a high-pressure rocket engine.
He witnessed two tests with a rocket-driven railroad car in Burgwedel near Hannover and then joined Albert Püllenberg's group of amateur rocketeers.
He became interested in space technology while attending a lecture by Max Valier, a German pioneer in that field. At the age of two, he and his family moved to Hannover, where he spent his youth. Dannenberg was born in Weißenfels, Province of Saxony (current Saxony-Anhalt).