A few air-breathing engines made for high-speed applications (ramjets and scramjets) use the ram effect of the vehicle's speed instead of a mechanical compressor.

A rudimentary demonstration of jet power dates back to the aeolipile, a device described by Hero of Alexandria in 1st-century Egypt.

Historians have further traced the theoretical origin of the principles of jet engines to traditional Chinese firework and rocket propulsion systems.

The Italian Caproni Campini N.1, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II were unsuccessful.

Alan Arnold Griffith published An Aerodynamic Theory of Turbine Design in 1926 leading to experimental work at the RAE.

Practical axial compressors were made possible by ideas from A.A.Griffith in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design").

Republican president Manuel Azaña arranged for initial construction at the Hispano-Suiza aircraft factory in Madrid in 1936, but Leret was executed months later by Francoist Moroccan troops after unsuccessfully defending his seaplane base on the first days of the Spanish Civil War.

His plans, hidden from Francoists, were secretly given to the British embassy in Madrid a few years later by his wife, Carlota O'Neill, upon her release from prison.

[12] Von Ohain's first device was strictly experimental and could run only under external power, but he was able to demonstrate the basic concept.

Their subsequent designs culminated in the gasoline-fuelled HeS 3 of 5 kN (1,100 lbf), which was fitted to Heinkel's simple and compact He 178 airframe and flown by Erich Warsitz in the early morning of August 27, 1939, from Rostock-Marienehe aerodrome, an impressively short time for development.

By this point, some of the British designs were already cleared for civilian use, and had appeared on early models like the de Havilland Comet and Avro Canada Jetliner.

By the 1960s, all large civilian aircraft were also jet powered, leaving the piston engine in low-cost niche roles such as cargo flights.

Jet engine designs are frequently modified for non-aircraft applications, as industrial gas turbines or marine powerplants.

[21] Therefore, in supersonic flight, and in military and other aircraft where other considerations have a higher priority than fuel efficiency, fans tend to be smaller or absent.

However, due to low fuel costs and high cabin noise, early propfan projects were abandoned.

The true advanced technology engine has a triple spool, meaning that instead of having a single drive shaft, there are three, in order that the three sets of blades may revolve at different speeds.

To reach high flight speeds, even greater exhaust velocities are required, and so a convergent-divergent nozzle is needed on high-speed aircraft.

[33] The engine thrust is highest if the static pressure of the gas reaches the ambient value as it leaves the nozzle.

Also at supersonic speeds the divergent area is less than required to give complete internal expansion to ambient pressure as a trade-off with external body drag.

[35] This overview highlights where energy losses occur in complete jet aircraft powerplants or engine installations.

How well the individual components contribute to turning fuel into thrust is quantified by measures like efficiencies for the compressors, turbines and combustor and pressure losses for the ducts.

It is used to preserve the mechanical integrity of the engine, to stop parts overheating and to prevent oil escaping from bearings for example.

The North American XB-70 Valkyrie and Lockheed SR-71 Blackbird at Mach 3 each had pressure recoveries of about 0.8,[41][42] due to relatively low losses during the compression process, i.e. through systems of multiple shocks.

The propelling nozzle at speeds above about Mach 2 usually has extra internal thrust losses because the exit area is not big enough as a trade-off with external afterbody drag.

For example, composite materials, combining metals with ceramics, have been developed for HP turbine blades, which run at the maximum cycle temperature.

If the increasing air mass flow reduces the fuel ratio below certain value, flame extinction occurs.

On the other hand, turbojets accelerate a much smaller mass flow of intake air and burned fuel, but they then reject it at very high speed.

Turbofans have a mixed exhaust consisting of the bypass air and the hot combustion product gas from the core engine.

[82] With the exception of scramjets, jet engines, deprived of their inlet systems can only accept air at around half the speed of sound.

The exception to this is scramjets which may be able to achieve about Mach 15 or more,[citation needed] as they avoid slowing the air, and rockets again have no particular speed limit.