Editing STOVL (section)

==History==
[[File:LiftThrust1.PNG|thumb|Comparison of lift and thrust for various aircraft]]
In 1951, the [[Lockheed XFV]] and the [[Convair XFY Pogo]] [[tailsitter]]s were both designed around the [[Allison YT40]] [[turboprop]] engine driving [[contra-rotating propellers]].

The British [[Hawker P.1127]] took off vertically in 1960, and demonstrated conventional take-off in 1961. It was developed into the [[Hawker Siddeley Harrier]] which flew in 1967.

In 1962, Lockheed built the [[Lockheed XV-4 Hummingbird|XV-4 Hummingbird]] for the [[U.S. Army]]. It sought to "augment" available thrust by injecting the engine exhaust into an ejector pump in the fuselage. First flying vertically in 1963, it suffered a fatal crash in 1964. It was converted into the XV-4B Hummingbird for the [[U.S. Air Force]] as a testbed for separate, vertically mounted lift engines, similar to those used in the [[Yakovlev Yak-38]] 'Forger'. That plane flew and later crashed in 1969.<ref name="x-planes">Jim Winchester, ''X-Planes and Prototypes'', Barnes and Noble Books</ref> The [[Ryan XV-5 Vertifan]], which was also built for the U.S. Army at the same time as the Hummingbird, experimented with gas-driven lift fans. That plane used fans in the nose and each wing, covered by doors which resembled half garbage can lids when raised. However, it crashed twice, and proved to generate a disappointing amount of lift, and was difficult to transition to horizontal flight.

Of dozens of [[VTOL]] and [[V/STOL]] designs tried from the 1950s to 1980s, only the subsonic Hawker Siddeley Harrier and Yak-38 Forger reached operational status, with the Forger being withdrawn after the fall of the [[Soviet Union]].

[[Rockwell International]] built, and then abandoned, the [[Rockwell XFV-12]] supersonic fighter which had an unusual wing which opened up like [[window blind]]s to create an ejector pump for vertical flight. It never generated enough lift to get off the ground despite developing 20,000 [[pound-force|lbf]] of thrust. The French had a nominally Mach 2 [[Dassault Mirage IIIV]] fitted with no less than 8 lift engines that flew (and crashed), but did not have enough space for fuel or payload for combat missions. The German [[EWR VJ 101]] used swiveling engines mounted on the wingtips with fuselage mounted lift engines, and the VJ 101C X1 reached supersonic flight (Mach 1.08) on 29 July 1964. The supersonic [[Hawker Siddeley P.1154]], which competed with the Mirage IIIV for use in NATO, was cancelled even as the aircraft were being built.

In 1983, the Defense Advanced Research Projects Agency ([[DARPA]]) initiated the Advanced STOVL (ASTOVL) program to develop a supersonic STOVL fighter (SSF) to replace the Harrier for the U.S. Marine Corps and the U.K. Royal Navy. Several propulsion methods were explored under ASTOVL and assigned to different contractors for research and development. These include the Shaft-Driven Lift Fan (SDLF) by [[Lockheed Corporation|Lockheed]] which had a forward [[lift fan]] powered by a shaft connected to the main engine's low-pressure spool and engaged by a clutch, the Lift-Plus-Lift/Cruise (LPLC) by [[Northrop Corporation|Northrop]] (later [[Northrop Grumman]]) which had a separate dedicated lift engine alongside the main engine, and the Gas-Driven Lift Fan (GDLF) by [[McDonnell Douglas]] that used the main engine bleed air to power a lift fan; all methods had an aft vectoring nozzle for the main engine.<ref>{{cite web |url=https://www.flightglobal.com/as-mcdonnell-douglas-revises-jast-design/11174.article |last= |first= |title=As McDonnell Douglas revises JAST design |work=Flight International |date=20 February 1996}}</ref>

ASTOVL would continue under the [[Common Affordable Lightweight Fighter]] (CALF) program, which eventually became part of the [[Joint Strike Fighter program]]; the [[Lockheed Martin X-35|Lockheed Martin X-35B]] with the SDLF was eventually selected for full-scale development in 2001, with the production aircraft for operational service becoming the F-35B with the [[Pratt & Whitney F135|F135-PW-600]] engine. [[NASA]] uses the [[abbreviation]] SSTOVL for Supersonic Short Take-Off / Vertical Landing,<ref>{{cite book |publisher = NASA |location = [Washington, D.C.] |title = Performance characteristics of a one-third-scale, vectorable ventral nozzle for SSTOVL aircraft |author = Barbara S. Esker |date = 1990 |isbn = 9780760770917 |oclc = 24990569 |ol = 17630526M}}</ref> and as of 2012, the X-35B/F-35B are the only aircraft to conform with this combination within one flight.<ref>[https://www.pbs.org/wgbh/nova/transcripts/3004_xplanes.html "X-planes".] ''PBS: Nova transcript''. Retrieved 9 January 2010.</ref><ref name="f-35b supersonic">Cavas, Christopher P. [http://www.marinecorpstimes.com/news/2010/06/dn_jsf_supersonic_061410/ "F-35B STOVL fighter goes supersonic."] {{webarchive|url=https://web.archive.org/web/20110714034433/http://www.marinecorpstimes.com/news/2010/06/dn_jsf_supersonic_061410/ |date=14 July 2011 }} ''[[Marine Corps Times]]'', 15 June 2010. Retrieved 15 June 2010.</ref>

The experimental Mach 1.7 [[Yakovlev Yak-141]] did not find an operational customer, but similar rotating rear nozzle technology is used on the F-35B which entered service on 31 July 2015.<ref>{{cite web|url=https://www.f35.com/news/detail/u.s.-marine-corps-declares-the-f-35b-operational|title=U.S. Marine Corps Declares the F-35B Operational - F-35 Lightning II|website=F-35 Lightning II|access-date=11 January 2017|archive-date=31 July 2015|archive-url=https://web.archive.org/web/20150731222239/https://www.f35.com/news/detail/u.s.-marine-corps-declares-the-f-35b-operational|url-status=dead}}</ref>

Larger STOVL designs were considered, the [[Armstrong Whitworth AW.681]] cargo aircraft was under development when cancelled in 1965. The [[Dornier Do 31]] got as far as three experimental aircraft before cancellation in 1970.

Although mostly a VTOL design, the [[Bell Boeing V-22 Osprey]] has increased payload when taking off from a short runway.<ref>[http://www.bellhelicopter.com/en/aircraft/military/pdf/V-22_64214_pGuide.pdf V-22 Osprey Pocket Guide] {{webarchive|url=https://web.archive.org/web/20101229211428/http://www.bellhelicopter.com/en/aircraft/military/pdf/V-22_64214_pGuide.pdf |date=29 December 2010 }}. Bell Boeing, 2007. Retrieved 17 April 2010.</ref>