Two men and one idea
The principle of the jet engine is simple. Air is drawn in and compressed, fuel is burned in it, and the hot gas expands through a turbine that drives the compressor and leaves at the back as a fast jet. The difficulty was to make materials that could take the heat and a compressor that would not stall.
Frank Whittle, a young officer of the Royal Air Force, patented a design in 1930. He found it hard to obtain support and the engine was built by a small private company he helped to found. In Germany Hans von Ohain, a physics student, developed a similar engine in the mid-1930s with the help of an aircraft maker, Ernst Heinkel, who was willing to pay for it.
First flights
Because Heinkel put money into it quickly, the German aircraft flew first. The Heinkel He 178 made the first flight of a jet aircraft on 27 August 1939, just before the war. The British Gloster E.28/39, with an engine by Whittle, followed on 15 May 1941.
The two men met after the war and became friends. Neither of them had known of the other's work at the time. The engines of today's airliners are much larger and more efficient, but their layout is recognisably that of the early designs.