Whittle's team experienced near-panic when the engine would not stop, accelerating even after the fuel was switched off. It was liquid-fuelled, and included a self-contained fuel pump. Whittle had the first turbojet to run, the Power Jets WU, on 12 April 1937. Whittle would later concentrate on the simpler centrifugal compressor only, for a variety of practical reasons. Griffith in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Practical axial compressors were made possible by ideas from A.A. The patent showed a two-stage axial compressor feeding a single-sided centrifugal compressor. On 16 January 1930 in England, Whittle submitted his first patent (granted in 1932). In October 1929 he developed his ideas further. In 1928, British RAF College Cranwell cadet Frank Whittle formally submitted his ideas for a turbojet to his superiors. The Whittle W.2/700 engine flew in the Gloster E.28/39, the first British aircraft to fly with a turbojet engine, and the Gloster Meteor They are also still used on some supersonic fighters such as the MiG-25, but most spend little time travelling supersonically, and so employ turbofans and use afterburners to raise exhaust speed for supersonic sprints. Turbojets are still common in medium range cruise missiles, due to their high exhaust speed, small frontal area, and relative simplicity. Turbojets were used on Concorde and the longer-range versions of the TU-144 which were required to spend a long period travelling supersonically.
These are common in helicopters and hovercraft. Where vehicles are "turbine-powered", this is more commonly by use of a turboshaft engine, a development of the gas turbine engine where an additional turbine is used to drive a rotating output shaft. Turbojet engines have been used in isolated cases to power vehicles other than aircraft, typically for attempts on land speed records.
Turbojets have poor efficiency at low vehicle speeds, which limits their usefulness in vehicles other than aircraft. Turbojets can be highly efficient for supersonic aircraft. At these transonic speeds, the turbofan is quieter and has better range-specific fuel consumption than the turbojet. At medium to high speeds, where the propeller is no longer efficient, turboprops have been replaced by turbofans. Turbojets have been replaced in slower aircraft by turboprops because they have better specific fuel consumption. In operation, turbojets typically generate thrust by accelerating a relatively small amount of air to very high supersonic speeds, whereas turbofans accelerate a larger amount of air to lower transonic speeds.
While the turbojet was the first form of gas turbine power plant for aviation, it has largely been replaced in use by other developments of the original concept. 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. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust.
The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through the turbine. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine (that drives the compressor). It consists of a gas turbine with a propelling nozzle. The turbojet is an airbreathing jet engine, typically used in aircraft.