Aircraft

Until the 1940s, the only system available for powering aircraft was the piston-driven propeller engine. In order to increase the speed and lifting power of an airplane, the only option that aeronautical engineers had was to try to increase the efficiency of the engine or to add more engines to the airplane. During World War II, the largest power plants consisted of as many as 28 cylinders, capable of developing 3,500 horsepower.

At the very end of World War II, German scientists produced an entirely new type of power system, the jet engine. As "new" as the jet airplane was in 1944, the scientific principles on which it is based had been around for more than 2,000 years. You can think of a jet engine as a very large tin can, somewhat fatter in the middle and more narrow at both ends. Both ends of the tin can have been removed so that air can pass in the front of the can (the engine) and out the back.

The center of the engine contains the elements necessary for its operation. Compressed air is mixed with a flow of fuel and ignited. As combustion gases are formed, they push out of the rear of the engine. As the gases leave the engine, they also turn a turbine which compresses the air used in the middle of the engine.

The principle on which the jet engine operates was first enunciated by Sir Isaac Newton in the seventeenth century. According to Newton's second law, for every action, there is an equal and opposite reaction. In the jet engine, the action is the surge of burned gases flowing The first supersonic transport to fly, the Soviet Union's Tupolev-144. It flew on December 31, 1968, two months before the Concorde's inaugural flight. U.S. National Aeronautics and Space Administration (NASA). out of the back of the engine. The reaction to that stream of hot gases is a forward push that moves the engine—and the wing and airplane to which it is attached—in a forward direction.

Because the exiting gases turn a turbine as well as powering the engine, a jet of this kind is also known as a turbojet. The first airplanes of this kind—the German Messerschmitt 262 and the British Gloster Meteor—were available for flight in the spring of 1944, only months before the end of the war. The first turbojet planes were capable of speeds of about 540 MPH (865 km/h), about 20 MPH (33 km/h) faster than any piston-driven aircraft then in flight.