Editing Tiltrotor (section)

==History==
[[File:Original Tiltrotor Patent.gif|thumb|Original Patent filed May 28, 1929]]
[[File:Trascendental_Model_1-G.jpg|thumb|[[Transcendental Model 1-G]] hovering]]
[[File:X-22a onground bw.jpg|thumb|[[Bell X-22]]]]<!--expand until separate TiltFan article-->
[[File:XV-15 N703NA USCG.jpg|thumb|A [[Bell XV-15]] prepares to land]]

The first work in the direction of a tilt-rotor (French "Convertible") seems to have originated ca. 1902 by the French-Swiss brothers Henri and Armand Dufaux, for which they got a patent in February 1904, and made their work public in April 1905.<ref>[http://www.pionnair-ge.com/spip1/spip.php?article7 Le premier vol d’un hélicoptère à moteur à explosion, produit des frères Dufaux (1905)]</ref>{{Unreliable source?|date=February 2020}}

Concrete ideas of constructing [[VTOL|vertical take-off and landing]] (VTOL) aircraft using helicopter-like rotors were pushed further in the 1930s. The first design resembling modern tiltrotors was patented by George Lehberger in May 1930, but he did not further develop the concept. In [[World War II]], Weserflug in Germany came  up with the concept of their P.1003/1 around 1938, which was tilting to the top with part of the wings but not the full wings, so it may be in between tilt-rotor and tilt-planes. Shortly after a [[Germany|German]] [[prototype]], the [[Focke-Achgelis Fa 269]], was developed starting in 1942, which was tilting to the ground, but never flew.<ref>{{cite book|last=Springmann|first=Enno |author2=Gottfried Hilscher |title=Focke: Flugzeuge und Hubschrauber von Heinrich Focke 1912-1961|publisher=Aviatic-Verlag GmbH|year=1997|isbn=3-925505-36-9}}</ref><ref>{{cite book|last=Nowarra|first=Heinz|author-link=Heinz Nowarra|title=Die Deutsche Luftrüstung 1933-1945|publisher=Bernard & Graefe|date=1985–1988|isbn=3-7637-5464-4}}</ref><ref>{{cite book |last=Maisel |first=M.D |author-link=M.D Maisel |url=https://history.nasa.gov/monograph17.pdf |title=The History of the XV-15 Tilt Rotor Research Aircraft: From Concept to Flight |publisher=National Aeronautics and Space Administration, Office of Policy and Plans, NASA History Division |date=2000}}</ref> [[Platt-LePage Aircraft Company|Platt and LePage]] patented the PL-16, the first American tiltrotor aircraft.  However, the company shut down in August 1946 due to lack of capital.<ref>{{cite web|url=http://www.helis.com/types/tiltrotor.php|title=Tiltrotors|website=helis.com|access-date=1 April 2018}}</ref>

Two prototypes which made it to flight were the one-seat [[Transcendental Model 1-G]] and two seat Transcendental Model 2, each powered by a single reciprocating engine. Development started on the Model 1-G in 1947, though it did not fly until 1954. The Model 1-G flew for about a year until a crash in [[Chesapeake Bay]] on July 20, 1955, destroying the prototype aircraft but not seriously injuring the pilot. The Model 2 was developed and flew shortly afterwards, but the [[US Air Force]] withdrew funding in favor of the Bell XV-3 and it did not fly much beyond hover tests. The Transcendental 1-G is the first tiltrotor aircraft to have flown and accomplished most of a helicopter to aircraft transition in flight (to within 10 degrees of true horizontal aircraft flight).

Built in 1953, the experimental [[Bell XV-3]] flew until 1966, proving the fundamental soundness of the tiltrotor concept and gathering data about technical improvements needed for future designs.

[[File:VTOL DiscLoad-LiftEfficiency.svg|thumb|right|VTOL disc loading lift efficiency]]
A related technology development is the [[tiltwing]]. Although two designs, the [[Canadair CL-84 Dynavert]] and the [[LTV XC-142]], were technical successes, neither entered production due to other issues. Tiltrotors generally have better hover efficiency than tiltwings, but less than helicopters.<ref>Warwick, Graham. [http://www.flightglobal.com/pdfarchive/view/1992/1992%20-%200262.html "Tilting at targets"] page 44 ''[[Flight International]]'', Number 4304, Volume 141, 5–11 February 1992. Accessed: 4 January 2014.</ref>

In 1968, Westland Aircraft displayed their own designs—a small experimental craft (We 01C) and a 68-seater transport We 028—at the [[Society of British Aerospace Companies|SBAC]] [[Farnborough Airshow]].<ref>[http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%202034.html "twenty Sixth SBAC Show"] ''Flight International'', 19 September 1968 p446</ref>

In 1972, with funding from [[NASA]] and the [[U.S. Army]], [[Bell Helicopter Textron]] started development of the [[XV-15]], a twin-engine tiltrotor research aircraft. Two aircraft were built to prove the tiltrotor design and explore the operational flight envelope for military and civil applications.<ref name="ames1">[http://www.simlabs.arc.nasa.gov/library/tiltrotor/ctr20th.html#History "History of tiltrotor technology", NASA Ames Research Center] {{webarchive|url=https://web.archive.org/web/20080705115900/http://www.simlabs.arc.nasa.gov/library/tiltrotor/ctr20th.html |date=2008-07-05 }}</ref><ref name="nasaXv15">{{cite book |url=https://history.nasa.gov/monograph17.pdf |title=The History of the XV-15 Tilt Rotor Research Aircraft |publisher=NASA |first1=Martin D. |last1=Maisel |first2=Demo J. |last2=Giulianetti |first3=Daniel C. |last3=Dugan |series=Monographs in Aerospace History No. 17 |year=2000 |isbn=0-16-050276-4 |id=NASA SP-2000-4517}}</ref>

In 1981, using experience gained from the XV-3 and XV-15, Bell and [[Boeing]] Helicopters began developing the [[V-22 Osprey]], a twin-turboshaft military tiltrotor aircraft for the [[U.S. Air Force]] and the [[U.S. Marine Corps]].<ref name="ames1"/>

Bell teamed with Boeing in developing a commercial tiltrotor, but Boeing went out in 1998 and Agusta came in for the [[AgustaWestland AW609|Bell/Agusta BA609]].<ref name="nasaXv15"/><ref name=cs2tech/> This aircraft was redesignated as the [[AW609]] following the transfer of full ownership to [[AgustaWestland]] in 2011.<ref name=Wynbrandt>{{cite news |url=http://www.ainonline.com/aviation-news/hai-convention-news/2012-02-11/aw609-finally-ready-its-close |title=AW609 Finally Ready for its Close-up |work=AINonline.com |first=James |last=Wynbrandt |date=11 February 2012 |access-date=14 February 2012 |archive-date=February 14, 2012 |archive-url=https://web.archive.org/web/20120214172623/http://www.ainonline.com/aviation-news/hai-convention-news/2012-02-11/aw609-finally-ready-its-close |url-status=dead }}</ref> Bell has also developed a tiltrotor [[unmanned aerial vehicle]] (UAV), the TR918 [[Bell Eagle Eye|Eagle Eye]].

Russia has had a few tiltrotor projects, mostly unmanned such as the [[Mil Mi-30]], and has started another in 2015.<ref>{{cite web|url=http://www.flightglobal.com/news/articles/maks-russian-helicopters-launches-unmanned-tiltrotor-416138/|title=MAKS: Russian Helicopters launches unmanned tiltrotor concept|date=27 August 2015|website=flightglobal.com|access-date=1 April 2018}}</ref>

Around 2005<ref name="boeing1">[http://boeing.com/news/releases/2005/photorelease/q3/pr_050923p-1.html "Bell-Boeing's QTR selected for Heavy Lift study"] {{webarchive|url=https://web.archive.org/web/20060830203438/http://boeing.com/news/releases/2005/photorelease/q3/pr_050923p-1.html |date=2006-08-30 }}. Boeing, 22 September 2005.</ref>–2010,<ref>Brannen, Kate. [https://archive.today/20130121104039/http://www.defensenews.com/story.php?i=4710186&c=AME&s=LAN "Pentagon Sheds Some Light on JFTL Effort"]. ''Defense News'', 15 July 2010.</ref> Bell and Boeing teamed up again to perform a conceptual study of a larger [[Bell Boeing Quad TiltRotor|Quad TiltRotor]] (QTR) for the US Army's Joint Heavy Lift (JHL) program. The QTR is a larger, four rotor version of the V-22 with two [[tandem wing]]s sets of fixed wings and four tilting rotors.

In January 2013, the [[Federal Aviation Administration|FAA]] defined US tiltrotor noise rules to comply with [[International Civil Aviation Organization|ICAO]] rules. A noise certification will cost $588,000, same as for a large helicopter.<ref name=tiltnoise>{{cite web|title=Noise Certification Standards for Tiltrotors|url=https://www.federalregister.gov/articles/2013/01/08/2013-00111/noise-certification-standards-for-tiltrotors|publisher=[[Federal Aviation Administration]]|access-date=13 January 2013|date=8 January 2013}}</ref><ref>{{cite web|title=FAA Publishes Modified Noise Rules For Tiltrotors|url=http://www.aero-news.net/subscribe.cfm?do=main.textpost&id=98a33b6f-df48-4348-88bd-c66db2d8a24a|publisher=Aero-News|access-date=13 January 2013|date=11 January 2013}}</ref>

AgustaWestland says they have free-flown a manned electric tiltrotor in 2013 called [[AgustaWestland Project Zero|Project Zero]], with its rotors inside the wingspan.<ref>{{cite magazine|last=Paur|first=Jason|title=Meet Project Zero, the World's First Electric Tilt-Rotor Aircraft|url=https://www.wired.com/autopia/2013/03/agustawestland-electric-tilt-rotor/|magazine=[[Wired (website)|Wired]]|access-date=6 March 2013|date=6 March 2013}}</ref><ref>{{cite web|title=AgustaWestland Unveils Revolutionary ''Project Zero'' Tilt Rotor Technology Demonstrator|url=http://www.asdnews.com/mobile/news/47974/AgustaWestland_Unveils_Revolutionary___Project_Zero___Tilt_Rotor_Technology_Demonstrator.htm|publisher=ASDNews|access-date=6 March 2013|archive-date=5 July 2013|archive-url=https://web.archive.org/web/20130705214242/http://www.asdnews.com/mobile/news/47974/AgustaWestland_Unveils_Revolutionary___Project_Zero___Tilt_Rotor_Technology_Demonstrator.htm|url-status=dead}}</ref><ref>"[http://www.agustawestland.com/about-us/driving-innovation/advanced-concepts/project-zero Project Zero] {{Webarchive|url=https://web.archive.org/web/20151203225623/http://www.agustawestland.com/about-us/driving-innovation/advanced-concepts/project-zero |date=December 3, 2015 }}" ''[[AgustaWestland]]''</ref>

In 2013, Bell Helicopter CEO John Garrison responded to Boeing's taking a different airframe partner for the US Army's [[Future Vertical Lift|future lift requirements]] by indicating that Bell would take the lead itself in developing the [[Bell V-280 Valor]],<ref>{{cite web|url=http://www.aviationtoday.com/rw/products/airframes/Bell-to-Take-V-22-Development-Forward-Alone-Without-Boeing_78676.html|title=Bell to Take Tiltrotor Technology Forward Without Boeing - Rotor & Wing International|date=5 March 2013|website=aviationtoday.com|access-date=1 April 2018|archive-date=October 6, 2014|archive-url=https://web.archive.org/web/20141006101540/http://www.aviationtoday.com/rw/products/airframes/Bell-to-Take-V-22-Development-Forward-Alone-Without-Boeing_78676.html|url-status=dead}}</ref> with Lockheed Martin.

In 2014, the [[Clean Sky]] 2 program (by the [[European Union]] and industry) awarded AgustaWestland and its partners $328 million to develop a "next-generation civil tiltrotor"<ref>"[http://www.agustawestland.com/about-us/driving-innovation/advanced-concepts/ngctr?WT.ac=Next%20Generation%20Civil%20TiltRotor Next Generation Civil Tiltrotor] {{Webarchive|url=https://web.archive.org/web/20150922072105/http://www.agustawestland.com/about-us/driving-innovation/advanced-concepts/ngctr?WT.ac=Next%20Generation%20Civil%20TiltRotor |date=September 22, 2015 }}" ''[[AgustaWestland]]''</ref><ref name=vert2014-09>{{cite news |first=Mike |last=Hirschberg |url=http://www.agustawestland.com/documents/17633750/23356203/body_AHS_vertiflite_NextGenCTR_Vertiflite_Sep_Oct_2014.pdf |title=The shape of things to come, part 2 |work=Vertical Magazine |date=September 2014 |access-date=13 April 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150414020029/http://www.agustawestland.com/documents/17633750/23356203/body_AHS_vertiflite_NextGenCTR_Vertiflite_Sep_Oct_2014.pdf |archive-date=14 April 2015 }}</ref><ref>Pierobon, Mario. "[https://archive.today/20150413222942/http://www.propilotmag.com/archives/2015/Feb%2015/A3_AW_p1.html AW aims to be civil tiltrotor leader]" [https://archive.today/20150413222943/http://www.propilotmag.com/archives/2015/Feb%2015/A3_AW_p2.html Page 2] [https://archive.today/20150413222942/http://www.propilotmag.com/archives/2015/Feb%2015/A3_AW_p3.html Page 3] ''ProPilotMag''.</ref> design for the offshore market, with [[Critical Design Review]] near the end of 2016. The goals are tilting wing sections, 11 metric tons [[Maximum takeoff weight]], seating for 19 to 22 passengers, first flight in 2021, a cruise speed of 300 knots,<ref>{{cite web|url=http://www.ainonline.com/aviation-news/business-aviation/2015-10-12/agustawestland-plans-fly-next-gen-tiltrotor-2021 |title=AgustaWestland Plans To Fly Next-gen Tiltrotor in 2021 |work=Aviation International News}}</ref> a top speed of 330 knots, a ceiling of 25,000 feet, and a range of 500 nautical miles.<ref name=cs2tech>"[http://ec.europa.eu/research/participants/data/ref/h2020/other/guide-appl/jti/h2020-guide-techprog-cleansky-ju_en.pdf 8.6 Next Generation Civil Tiltrotor (NextGenCTR) Project – WP1]" pages 254-301. Size: 747 pages, 23 MB. ''[[Clean Sky]] 2'', 27 June 2014. Accessed: 7 October 2014.</ref><ref>Huber, Mark. "[http://www.ainonline.com/aviation-news/aviation-international-news/2014-10-05/agustawestland-pushes-ahead-larger-tiltrotor AgustaWestland Pushes Ahead with Larger Tiltrotor]" ''AINonline'', 5 October 2014. Accessed: 7 October 2014. [https://web.archive.org/web/20141007180847/http://www.ainonline.com/aviation-news/aviation-international-news/2014-10-05/agustawestland-pushes-ahead-larger-tiltrotor Archived] on 7 October 2014</ref><ref>"[http://www.cleansky.eu/sites/default/files/documents/events/20141609/6b-_frc_tiltrotor.pdf AgustaWestland civil tiltrotor]" ''AgustaWestland''</ref>