In 1928, a 21-year-old RAF cadet named Frank Whittle wrote a thesis at Cranwell proposing that a gas turbine could propel an aircraft at speeds no piston engine could reach. He patented the concept in 1930. The British Air Ministry was skeptical; they allowed the patent to lapse into the public domain. In Germany, development was largely independent in engineering terms, but von Ohain was aware of Whittle's published patent before filing his own; he sketched a similar concept in 1933 and took it to Ernst Heinkel. On August 27, 1939—just days before World War II began—von Ohain's Heinkel He 178 made the first jet-powered flight in history. Whittle's engine, the W.1, did not fly until May 15, 1941. By then, Germany had already fielded the Me 262, the world's first operational jet fighter. Whittle's engine was superior pound-for-pound, but British bureaucracy cost him two years. After the war, von Ohain was brought to the United States under Operation Paperclip and worked at Wright-Patterson AFB. The two men met in 1948, became friends, and gave joint lectures. Both died knowing they had changed aviation forever.