Editing Turbojet (section)

{{short description|Airbreathing jet engine which is typically used in aircraft}}
{{for|the Hong Kong based ferry company|TurboJET}}
{{More citations needed|date=April 2008}}
{{Seriesbox aircraft propulsion}}
[[Image:Jumo 004.jpg|thumb|[[Junkers Jumo 004]], the first production turbojet in operational use. Note the starter pull-start handle housed in the center of the intake nose bullet.]]
[[File:JetEngineGraph2.PNG|thumb|Diagram of a typical gas turbine jet engine]]
[[File:Frank Whittle CH 011867.jpg|thumb|Frank Whittle]]
[[File:Ohain.jpg|thumb|Hans von Ohain]]
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]] (that drives the compressor). 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.<ref>{{cite web|title=Turbojet Engine|publisher=NASA Glenn Research Center|url=http://www.grc.nasa.gov/WWW/K-12/airplane/aturbj.html|access-date=6 May 2009}}</ref> 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.

Turbojets have poor efficiency at low vehicle speeds, which limits their usefulness in vehicles other than aircraft. Turbojet engines have been used in isolated cases to power vehicles other than aircraft, typically for attempts on [[land speed record]]s. 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. These are common in helicopters and hovercraft.

Turbojets were widely used for early supersonic [[Fighter aircraft|fighters]], up to and including many [[Jet_fighter_generations#Third|third generation fighters]], with the [[MiG-25]] being the latest turbojet-powered fighter developed. As most fighters spend little time traveling supersonically, [[Fourth-generation_fighter|fourth-generation fighters]] (as well as some late third-generation fighters like the [[F-111]] and [[Hawker Siddeley Harrier]]) and subsequent designs are powered by the more efficient [[Turbofan#Low-bypass_turbofan|low-bypass turbofans]] and use [[Turbofan#Afterburning_turbofan|afterburners]] to raise exhaust speed for bursts of supersonic travel. Turbojets were used on the [[Concorde]] and the longer-range versions of the [[TU-144|Tu-144]] which were required to spend a long period travelling supersonically. Turbojets are still common in medium range [[cruise missile]]s, due to their high exhaust speed, small frontal area, and relative simplicity.