In 1937, aviation took a giant leap forward when British inventor and engineer Frank Whittle tested the world's first jet engine. It didn't work like the piston-engine prop planes of the day. Instead, Whittle's engine sucked air through forward-facing compressor blades. This air entered a combustion chamber, where it mixed with fuel and burned. A superheated stream of gases then rushed from the tailpipe, pushing the engine and the aircraft forward.
Hans Pabst van Ohain of Germany took Whittle's basic design and powered the first jet-aircraft flight in 1939. Two years later, the British government finally got a plane -- the Gloster E.28/39 -- off the ground using Whittle's innovative engine design. By the end of World War II, Gloster Meteor jets, which were successive models flown by Royal Air Force pilots, were chasing down German V-1 rockets and shooting them from the sky.
Today, turbojet engines are reserved primarily for military planes. Commercial airliners use turbofan engines, which still ingest air through a forward-facing compressor. Instead of burning all of the incoming air, turbofan engines allow some air to flow around the combustion chamber and mix with the jet of superheated gases exiting the tailpipe. As a result, turbofan engines are more efficient and produce far less noise.