The successful development of the gas turbine for aircraft propulsion stimulated much thought, some serious and a great deal speculative, on the possibilities of even more advanced forms of propulsion. The ramjet and the rocket immediately sprang to mind. The former was a natural development of the turbo–jet. It could extend the useful field of the turbo–jet but the bounds of that extension could be clearly seen. On the other hand, the rocket was not restricted by the same fundamental limitations and its eventual, although still somewhat remote, exploitation in wider spheres could be prophesied with some confidence. Before the 1939—45 War, the stage of development of the rocket motor was comparable with that of the internal combustion engine a century ago. Pioneers like Tsiolkovski in Russia, Esnault–Pelterie in France, Oberth in Austria and Goddard in America had laid down the basic theory and made some small scale experiments in support, but the first major practical steps came from the Germans during the war.

Before the 1939-45 War, the stage of development of the rocket motor was comparable with that of the internal combustion engine a century ago. Pioneers like Tsiolkovski in Russia, Esnault-Pelterie in France, Oberth in Austria and Goddard in America had laid down the basic theory and made some small scale experiments in support, but the first major practical steps came from the Germans during the war.