The Gloster E.28/39, was the first British turbojet-engined aircraft first flying in 1941. It was the fourth turbojet aircraft to fly after the German Heinkel He 178 (1939), the Italian Caproni Campini N.1 (1940) And the Heinkel He 280 (1941).

The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine. The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through the turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently into practical engines during the late 1930s.