For their independent development of the turbojet engine.
Frank Whittle was an English aviation pioneer who helped invent the jet engine.
As a young man, Whittle attempted to join the Royal Air Force, but failed due to a lack of height. However, he was able to join on his third attempt and became an apprentice in 1923. He later qualified as a pilot officer in 1928.
In 1930, Whittle, then a a 22 year old Royal Air Force officer, conceived the idea of a jet engine and he was later granted a patent in 1932. However, Whittle initially struggled to interest the Air Ministry or industry in the concept.
In June 1939, the Air Ministry finally began taking an interest in Whittle's invention -- it directed that a flight engine be built and the Gloster Aircraft company started building an experimental plane, the E28/39, to demonstrate the concept. The aircraft was succesfully tested in May 1941. The United States took notice and quickly applied the design to the war effort. By October 1942, the first American turbojet-driven fighter, the XP-59A Aircomet, had been built. The British Meteor, another beneficiary of Whittle's designs, followed in 1944.
In recognition of his contributions, Whittle was knighted by King George VI in 1948. He retired from the Royal Air Force that same year, with the rank of air commodore. He later went to work in the US, becoming a research professor at the US Naval Academy.
Hans von Ohain was one of the fathers of jet propulsion. His HeS 1 design was the first self-contained jet engine to run, and a later design, HeS 3, was the first to power an all-jet aircraft. While these designs did not enter production, von Ohain's contributions were invaluable in advancing aviation.
Von Ohain began development of the turbojet engine in the 1930s while pursuing his doctoral studies at Goettinger University in Germany. He and Frank Whittle worked independently of one another, their designs serving as yet another example of simultaneous invention. At the conclusion of World War II, he and Whittle met and the two became friends.
Following World War II, von Ohain was brought to the US to work for the United States Air Force at Wright-Patterson Air Force Base. In 1956 he became the Director of the Air Force Aeronautical Research Laboratory and in 1975 he was appointed Chief Scientist of the Aero Propulsion Laboratory.
In the early 1960s, von Ohain worked on the design of gas core reactor rockets which would retain nuclear fuel while allowing working mass to be used as exhaust. The mass-flow technique of these designs was later used to create a jet engine with no moving parts, in which airflow through the engine created a stable vortex that acted as the compressor and turbine.
In addition to the Draper Prize, von Ohain won many other engineering and management awards, including the American Institute of Aeronautics and Astronautics' Goddard Award, and the US Air Force Exceptional Civilian Service Award.
Very few inventions have had a greater impact on human society than the jet engine. By compressing air, heating it to high temperatures, and then forcing it out the back at great speeds, jets generate far more thrust than propellers and can work at much higher altitudes. As a result, jet airplanes fly faster, farther, and more efficiently than their propeller-driven ancestors. In turn, jet airplanes have revolutionized travel, connecting the far corners of the world and transporting people and goods at speeds that would have been unimaginable just decades before.