Born: 1907. Died: 1944-08-09.
Winkler had resigned as president. Oberth is back in Berlin, and a meeting is held, with Nebel, Wurm, Oberth, Klaus Riedel, Winkler, and Willy Ley in attendance. It was decided to try and get the Oberth rocket materials back from Ufa and press on to demonstrate flight of a liquid propellant rocket. For this purpose the Oberth rocket was much too ambitious and probably wouldn't work anyway. Nebel proposes building a new 'Minimum Rakete' or 'Mirak' to demonstrate that it could be done. Work begins to obtain funds to ground test and perfect Oberth's 'Kegelduese' conical rocket motor.
The VfR fires its 'Kegelduese' liquid oxygen and gasoline-fueled rocket motor in a demonstration for the Director of the Chemisch-Technische Reichsanstalt in an attempt to secure financial support. Nebel had arranged the demonstration and runs the Kegelduese for 90 seconds. It generates 7 kgf and consumes 6 kg of liquid oxygen and 1 kg of gasoline in that time (specific impulse 90 seconds). Participating are Oberth, Nebel, Riedel, Ley, and Von Braun. Nebel's Mirak is not yet ready to test.
Nebel and Riedel conduct a series of tests of the Mirak rocket at the farm of Riedel's grandparents near Bernstadt, Saxony. They slowly perfect the motor, finally achieving significant net thrust by September, when the motor explodes, ending the test series.
Riedel improvises a rocket, using the thrust chamber developed for the Mirak, fed by two long tanks containing liquid oxygen and gasoline, which would form guiding sticks for the forward-mounted engine. The lashed-together rocket rises to 20 m on its first 'static' test.
The perfected Repulsor has the propellant tanks close together at the centreline, to form a guide stick in the manner of Congreve's war rockets. It reaches an altitude of 1000 m, and the parachute recovery system functioned perfectly at apogee. Subsequent such 'one stick' Repulsors' will reach 1500 m altitude and 3000 m range - in fact, they are normally launched only partially-fuelled to prevent them landing outside the perimeter of the Raketenflugplatz.
As the influence of Nazism in German Society increases, the VfR disintegrates in political disputes and withdrawal of funding by its wealthiest backers. In this period it occurs to Riedel that alcohol may prove a better fuel than gasoline - primarily because as a fuel it needs much less of the expensive and difficult-to-handle cryogenic liquid oxygen. Experiments determine that 60% alcohol to water is the best fuel mixture, and for the first time use the fuel to cool the combustion chamber before leading it into the chamber - regenerative cooling.
Nebel is presented with a water bill of 1600 Marks for 1930-1933. He and the VfR are unable to pay, so the government cancels the lease and takes the property back. Klaus Riedel manages to arrange employment for himself and several of the VfR technicians with Siemens, which also agrees to allow them to store the Raketenflugplatz rockets and technical materials in a company warehouse. After Riedel and the others are recruited by the Army and leave for Peenemuende, Nebel allegedly sells of these materials. In any case they disappear.
Talented German engineer, instrumental in developing the first liquid propellant rocket engines in Germany at VfR and in design and debugging of the V-2's engine. Unrelated to contemporary rocket engineers Walter Riedel and Walther Riedel. Killed in an automobile crash near Karlshagen, Germany.