Editing Turbojet (section)

== History ==

[[File:Ohain USAF He 178 page61.jpg|thumb|[[Heinkel He 178]], the world's first aircraft to fly purely on turbojet power, using an [[Heinkel HeS 3|HeS 3]] engine]]
The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman [[Maxime Guillaume]].<ref name= "Guillaume">{{cite patent|inventor=Maxime Guillaume |title=Propulseur par réaction sur l'air|country=FR|number=534801 |status=Patent|fdate=3 May 1921 |gdate=13 January 1922}}</ref> His engine was to be an axial-flow turbojet, but was never constructed, as it would have required considerable advances over the state of the art in compressors.<ref>{{Cite book|url= https://books.google.com/books?id=lxqtCwAAQBAJ&pg=PT7|title=Britain's Jet Age: From the Meteor to the Sea Vixen|last= Ellis|first=Guy|date=15 February 2016 |publisher=Amberley |isbn= 978-1-44564901-6}}</ref>

[[File:Whittle Jet Engine W2-700.JPG|thumb|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]]]]
In 1928, British [[RAF College Cranwell]] cadet<ref>{{cite web|url= https://www.pbs.org/kcet/chasingthesun/innovators/fwhittle.html |title=Chasing the Sun – Frank Whittle |publisher=PBS |access-date=26 March 2010}}</ref> [[Frank Whittle]] formally submitted his ideas for a turbojet to his superiors. In October 1929 he developed his ideas further.<ref>{{cite web|url= https://www.bbc.co.uk/history/historic_figures/whittle_frank.shtml |title= History – Frank Whittle (1907–1996) |publisher= BBC |access-date= 26 March 2010}}</ref> On 16 January 1930 in England, Whittle submitted his first patent (granted in 1932).<ref>{{cite patent |inventor=Frank Whittle|country=GB|number=347206 |status=Patent |title=Improvements relating to the propulsion of aircraft and other vehicles |fdate=16 January 1930 |gdate=1931-04-16}}</ref>  The patent showed a two-stage [[axial compressor]] feeding a single-sided [[centrifugal compressor]]. Practical axial compressors were made possible by ideas from [[Alan Arnold Griffith|A.A. Griffith]] in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Whittle later concentrated on the simpler centrifugal compressor only, for a variety of practical reasons. A Whittle engine was the first turbojet to run, the [[Power Jets WU]], on 12 April 1937. It was liquid-fuelled. Whittle's team experienced near-panic during the first start attempts when the engine accelerated out of control to a relatively high speed despite the fuel supply being cut off. It was subsequently found that fuel had leaked into the combustion chamber during pre-start motoring checks and accumulated in pools, so the engine would not stop accelerating until all the leaked fuel had burned off. Whittle was unable to interest the government in his invention, and development continued at a slow pace.

In Germany, [[Hans von Ohain]] patented a similar engine in 1935. His design, an axial-flow engine, as opposed to Whittle's centrifugal flow engine, was eventually adopted by most manufacturers by the 1950s.<ref>{{cite book | last1=Jenkins | first1=Dennis R. | last2=Landis | first2=Tony R. | title=Experimental & Prototype U.S. Air Force Jet Fighters | publisher=Specialty Press | date=2008 | isbn=978-1-58007-111-6}}</ref><ref>{{cite news | url=https://www.nytimes.com/1996/08/10/world/frank-whittle-89-dies-his-jet-engine-propelled-progress.html | title=Frank Whittle, 89, Dies; His Jet Engine Propelled Progress | work=The New York Times | date=10 August 1996 | last1=Foderaro | first1=Lisa W. }}</ref>

On 27 August 1939 the [[Heinkel He 178]], powered by von Ohain's design, became the world's first aircraft to fly using the thrust from a turbojet engine. It was flown by test pilot [[Erich Warsitz]].<ref>{{cite book |last=Warsitz |first=Lutz |year=2009 |url=http://www.pen-and-sword.co.uk/?product_id=1762 |title=The First Jet Pilot – The Story of German Test Pilot Erich Warsitz |publisher=Pen and Sword Books |location=England |isbn=978-1-84415-818-8 |page=125}}</ref> The [[Gloster E.28/39]], (also referred to as the "Gloster Whittle", "Gloster Pioneer", or "Gloster G.40") made the first British jet-engined flight in 1941. It was designed to test the Whittle jet engine in flight, and led to the development of the Gloster Meteor.<ref>{{cite book|url= https://books.google.com/books?id=DgakDAAAQBAJ&pg=PA3|title=The Gloster Meteor F.I & F.III|last=Listemann|first= Phil H.|date=6 September 2016|publisher= Philedition| page = 3 | isbn=978-2-918590-95-8 }}</ref>

The first two operational turbojet aircraft, the [[Messerschmitt Me 262]] and then the [[Gloster Meteor]], entered service in 1944, towards the end of [[World War II]], the Me 262 in April and the Gloster Meteor in July. Only about 15 Meteor saw WW2 action but up to 1400 Me 262s were produced, with 300 entering combat, delivering the first ground attacks and air combat victories of jet planes.<ref>{{Cite book|url= https://books.google.com/books?id=449Ob41RgZMC&pg=PT103|title=The Me 262 Stormbird: From the Pilots Who Flew, Fought, and Survived It|last1=Heaton |first1= Colin D.|last2=Lewis|first2= Anne-Marien|last3=Tillman|first3= Barrett |date= 15 May 2012|publisher= Voyageur Press |isbn=978-1-61058434-0}}</ref>{{Sfn | Listemann | 2016 | p = [https://books.google.com/books?id=DgakDAAAQBAJ&pg=PA5  5]}}<ref>{{cite web | url=https://www.smithsonianmag.com/smithsonian-institution/day-germanys-first-jet-fighter-soared-history-180978152/ | title=The Day Germany's First Jet Fighter Soared into History }}</ref>

Air is drawn into the rotating compressor via the intake and is compressed to a higher pressure before entering the combustion chamber. [[Fuel]] is mixed with the compressed air and burns in the combustor. The combustion products leave the combustor and expand through the [[turbine]] where [[Power (physics)|power]] is extracted to drive the compressor. The turbine exit gases still contain considerable energy that is converted in the propelling nozzle to a high speed jet.

The first turbojets, used either a [[centrifugal compressor]] (as in the [[Heinkel HeS 3]]), or an [[axial compressor]] (as in the [[Junkers Jumo 004]]) which gave a smaller diameter, although longer, engine. By replacing the propeller used on piston engines with a high speed jet of exhaust, higher aircraft speeds were attainable.

One of the last applications for a turbojet engine was [[Concorde]] which used the [[Olympus 593]] engine. However, joint studies by Rolls-Royce and Snecma for a second generation SST engine using the 593 core were done more than three years before Concorde entered service. They evaluated bypass engines with bypass ratios between 0.1 and 1.0 to give improved take-off and cruising performance.<ref>{{cite magazine |title=Power for the second-generation SST |author1=Young |author2=Devriese |department=Extracts from the 25th Louis Bleriot Lecture |magazine=Flight International |date=11 May 1972 |page=659}}</ref>  Nevertheless, the 593 met all the requirements of the Concorde programme.<ref>{{cite book |chapter=The Engine For TSR2 |author=J.D.Wragg |title=TSR2 with Hindsight |publisher=Royal Air Force Historical Society |isbn=0951982486 |page=120 | editor-last=Hunter | editor-first=Alexander Freeland Cairns |year=1998}}</ref> Estimates made in 1964 for the Concorde design at Mach 2.2 showed the penalty in range for the supersonic airliner, in terms of miles per gallon, compared to subsonic airliners at Mach 0.85 (Boeing 707, DC-8) was relatively small. This is because the large increase in drag is largely compensated by an increase in powerplant efficiency (the engine efficiency is increased by the ram pressure rise which adds to the compressor pressure rise, the higher aircraft speed approaches the exhaust jet speed increasing propulsive efficiency).<ref>{{cite journal | last=Hooker | first=S. G. | title=Power Plants for the Concord Supersonic Civil Airliner | journal=Proceedings of the Institution of Mechanical Engineers | volume=178 | issue=1 | date=1963 | issn=0020-3483 | doi=10.1177/0020348363178001159 | pages=1224–1237 | url=https://journals.sagepub.com/doi/10.1177/0020348363178001159 | url-access=subscription }}</ref>

Turbojet engines had a significant impact on [[commercial aviation]]. Aside from giving faster flight speeds turbojets had greater reliability than piston engines, with some models demonstrating dispatch reliability rating in excess of 99.9%. Pre-jet commercial aircraft were designed with as many as four engines in part because of concerns over in-flight failures. Overseas flight paths were plotted to keep planes within an hour of a landing field, lengthening flights. The increase in reliability that came with the turbojet enabled three- and two-engine designs, and more direct long-distance flights.<ref>{{cite magazine| last = Larson | first = George C. | title = Old Faithful | journal = Air & Space | volume = 25 | issue = 1 |date=April–May 2010 | page = 80 }}</ref>

High-temperature alloys were a [[reverse salient]], a key technology that dragged progress on jet engines. Non-UK jet engines built in the 1930s and 1940s had to be overhauled every 10 or 20 hours due to [[creep failure]] and other types of damage to blades. British engines, however, utilised [[Nimonic]] alloys which allowed extended use without overhaul, engines such as the [[Rolls-Royce Welland]] and [[Rolls-Royce Derwent]],<ref>{{cite book |title=World Encyclopedia of Aero Engines |edition=5th |author= [[Bill Gunston]] |publisher=Sutton Publishing |year= 2006 |page=192}}</ref> and by 1949 the [[de Havilland Goblin]], being [[Type certificate|type tested]] for 500 hours without maintenance.<ref>{{Cite web|url=https://www.flightglobal.com/pdfarchive/view/1949/1949%20-%200598.html|title=sir alec &#124; flame tubes &#124; marshal sir &#124; 1949 &#124; 0598 &#124; Flight Archive}}</ref> It was not until the 1950s that [[superalloy]] technology allowed other countries to produce economically practical engines.<ref>{{cite conference | last=Sims | first=C.T. | title=Superalloys 1984 (Fifth International Symposium) | chapter=A History of Superalloy Metallurgy for Superalloy Metallurgists | publisher=TMS | date=1984 | page= | doi=10.7449/1984/Superalloys_1984_399_419 | doi-access=free | pages=399–419}}</ref>