Editing Swept wing (section)

===Early history===
The first successful aeroplanes adhered to the basic design of rectangular wings at right angles to the body of the machine. Such a layout is inherently unstable; if the weight distribution of the aircraft changes even slightly, the wing will want to rotate so its front moves up (weight moving rearward) or down (forward) and this rotation will change the development of lift and cause it to move further in that direction. To make an aircraft stable, the normal solution is to place the weight at one end and offset this with an opposite downward force at the other - this leads to the classic layout with the engine in front and the control surfaces at the end of a long boom with the wing in the middle. This layout has long been known to be inefficient. The downward force of the control surfaces needs further lift from the wing to offset. The amount of force can be decreased by increasing the length of the boom, but this leads to more [[skin friction]] and weight of the boom itself.

This problem led to many experiments with different layouts that eliminates the need for the downward force. One such wing geometry appeared before [[World War I]], which led to early swept wing designs. In this layout, the wing is swept so that portions lie far in front and in back of the [[center of gravity]] (CoG), with the control surfaces behind it. The result is a weight distribution similar to the classic layout, but the offsetting control force is no longer a separate surface but part of the wing, which would have existed anyway. This eliminates the need for separate structure, making the aircraft have less drag and require less total lift for the same level of performance. These layouts inspired several flying wing gliders and some powered aircraft during the interwar years.<ref name="Hallion">{{cite web |last=Hallion |first=Richard, P |title=The NACA, NASA, and the Supersonic-Hypersonic Frontie r|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100025896_2010028361.pdf |work=NASA |publisher=NASA Technical Reports Server |access-date=7 September 2011}}</ref>

[[File:Burgess-Dunne ExCC.jpg|thumb|A [[Burgess-Dunne]] tailless biplane: the angle of sweep is exaggerated by the sideways view, with washout also present at the wingtips.]]
The first to achieve stability was British designer [[J. W. Dunne]] who was obsessed with achieving inherent stability in flight. He successfully employed swept wings in his tailless aircraft (which, crucially, used [[Washout (aeronautics)|washout]]) as a means of creating positive [[longitudinal static stability]].<ref>Poulsen, C. M. [http://www.flightglobal.com/pdfarchive/view/1943/1943%20-%201376.html "Tailless Trials."] ''[[Flight International|Flight]],'' 27 May 1943, pp. 556–558. Retrieved: 1 August 2014.</ref> For a low-speed aircraft, swept wings may be used to resolve problems with the [[Center of gravity of an aircraft|center of gravity]], to move the wing spar into a more convenient location, or to improve the sideways view from the pilot's position.<ref name="Hallion" /> By 1905, Dunne had already built a model glider with swept wings followed by the powered [[Dunne D.5]], and by 1913 he had constructed successful powered variants that were able to cross the [[English Channel]]. The Dunne D.5 was exceptionally aerodynamically stable for the time,<ref>{{cite journal |last= Poulsen |first= C. M. |date=27 May 1943 |title=Tailless Trials |journal=[[Flight International|Flight]] |pages=556–58 |url=http://www.flightglobal.com/PDFArchive/View/1943/1943%20-%201376.html |access-date=27 February 2008 }}</ref> and the [[Dunne D.8|D.8]] was sold to the [[Royal Flying Corps]]; it was also manufactured under licence by [[Starling Burgess]] to the [[United States Navy]] amongst other customers.<ref name="Lewis">{{harvnb|Lewis|1962|pages=228–229}}</ref>

Dunne's work ceased with the onset of war in 1914, but afterwards the idea was taken up by [[G. T. R. Hill]] in England who designed a series of gliders and aircraft to Dunne's guidelines, notably the [[Westland-Hill Pterodactyl]] series.<ref>Sturtivant 1990, p. 45.</ref> However, Dunne's theories met with little acceptance amongst the leading aircraft designers and aviation companies at the time.<ref>{{cite web |url=http://www.aviationclassics.co.uk/news/swept-wing-technology |title=Issue 9 - North American F-86 Sabre: Swept wing technology |publisher=Aviation Classics |url-status=dead |archive-url=https://web.archive.org/web/20131203010821/http://www.aviationclassics.co.uk/news/swept-wing-technology |archive-date=3 December 2013 }}</ref>