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{{Short description|Tailless fixed-wing aircraft that has no definite fuselage}}
{{Use dmy dates|date=May 2022}}
{{Use British English|date=May 2022}}
{{for|the Canadian football formation|Flying wing (football)}}

[[File:B-2 first flight 071201-F-9999J-034.jpg|thumb|upright=1.14|The [[Northrop B-2 Spirit]] stealth bomber]]
A '''flying wing''' is a [[tailless aircraft|tailless]] [[fixed-wing aircraft]] that has no definite [[fuselage]], with its crew, payload, fuel, and equipment housed inside the main wing structure. A flying wing may have various small protuberances such as pods, [[nacelle]]s, blisters, booms, or [[vertical stabilizer]]s.

Similar aircraft designs, that are not technically flying wings, are sometimes casually referred to as such. These types include [[blended wing body]] aircraft and [[lifting body]] aircraft, which have a fuselage and no definite wings.

A pure flying wing is theoretically the lowest [[Drag (aerodynamics)|drag]] design configuration for a fixed wing aircraft. However, because it lacks conventional stabilizing surfaces and the associated control surfaces, in its purest form the flying wing suffers from being unstable and difficult to control.

The basic flying wing configuration became an object of significant study during the 1920s, often in conjunction with other tailless designs. In the [[World War II|Second World War]], both [[Nazi Germany]] and the [[Allies of World War II|Allies]] made advances in developing flying wings. Military interest in the flying wing waned during the 1950s with the development of supersonic aircraft, but was renewed in the 1980s due to their potential for [[stealth technology]]. This approach eventually led to the [[Northrop Grumman B-2 Spirit]] [[Stealth aircraft|stealth]] bomber. There has been continual interest in using it in the large transport roles for cargo or passengers. [[Boeing]], [[McDonnell Douglas]], and [[Armstrong Whitworth]] have undertaken design studies on flying wing [[Airliner|airliners]]; however, no such airliners have yet been built.

The flying wing concept is mostly suited to [[subsonic aircraft]]. No supersonic flying wing has ever been built.

==Design==
{{More citations needed|section|date=May 2022}}

===Overview===
[[File:Northrop N-1M Udvar-Hazy.jpg|thumb|A [[Northrop N-1M]] on display at the [[National Air and Space Museum]]'s [[Steven F. Udvar-Hazy Center]] ]]

A flying wing is an [[aeroplane]] that has no definite [[fuselage]] or [[tailplane]], with its crew, payload, fuel, and equipment housed inside the main wing structure. A flying wing may have various small protuberances such as pods, [[nacelle]]s, blisters, booms, or [[vertical stabilizer]]s.
<ref name="Crane">Crane, Dale: ''Dictionary of Aeronautical Terms'', third edition, p. 224. Aviation Supplies & Academics, 1997. {{ISBN|1-56027-287-2}}.</ref>

A clean flying wing is sometimes presented as theoretically the most [[aerodynamics|aerodynamically]] efficient (lowest drag) design configuration for a fixed wing aircraft. It also would offer high structural efficiency for a given wing depth, leading to light weight and high [[fuel efficiency]].<ref>{{Cite journal |last=Weyl |first=A.R. |date=1945-03-01 |title=Stability of Tailless Aeroplanes |url=http://dx.doi.org/10.1108/eb031228 |journal=Aircraft Engineering and Aerospace Technology |volume=17 |issue=3 |pages=73–81 |doi=10.1108/eb031228 |issn=0002-2667}}</ref>

Because it lacks conventional stabilizing surfaces and the associated control surfaces, in its purest form the flying wing suffers from the inherent disadvantages of being unstable and difficult to control. These compromises are difficult to reconcile, and efforts to do so can reduce or even negate the expected advantages of the flying wing design, such as reductions in weight and [[Drag (physics)|drag]]. Moreover, solutions may produce a final design that is still too unsafe for certain uses, such as commercial aviation.

Further difficulties arise from the problem of fitting the pilot, engines, flight equipment, and payload all within the depth of the wing section. Other known problems with the flying wing design relate to [[Flight dynamics|pitch]] and [[Flight dynamics|yaw]]. Pitch issues are discussed in the article on [[tailless aircraft]]. The problems of yaw are discussed below.

===Engineering design===
A wing that is made deep enough to contain the pilot, engines, fuel, undercarriage and other necessary equipment will have an increased frontal area, when compared with a conventional wing and long-thin fuselage. This can actually result in higher drag and thus lower efficiency than a conventional design. Typically the solution adopted in this case is to keep the wing reasonably thin, and the aircraft is then fitted with an assortment of blisters, pods, nacelles, fins, and so forth to accommodate all the needs of a practical aircraft.

The problem becomes more acute at supersonic speeds, where the drag of a thick wing rises sharply and it is essential for the wing to be made thin. No supersonic flying wing has ever been built.

===Directional stability===
For any aircraft to fly without constant correction it must have [[directional stability]] in yaw.

Flying wings lack anywhere to attach an efficient vertical stabilizer or fin. Any fin must attach directly on to the rear part of the wing, giving a small moment arm from the aerodynamic centre, which in turn means that the fin is inefficient and to be effective the fin area must be large. Such a large fin has weight and drag penalties, and can negate the advantages of the flying wing. The problem can be minimized by increasing the wing sweepback and placing twin fins outboard near the tips, as for example in a low-aspect-ratio delta wing, but given the corresponding reduction in efficiency many flying wings have gentler sweepback and consequently have, at best, marginal stability.

The aspect ratio of a swept wing as seen in the direction of the airflow depends on the yaw angle relative to the airflow. Yaw increases the aspect ratio of the leading wing and reduces that of the trailing one. With sufficient sweep-back, differential induced drag resulting from the tip vortices and crossflow is sufficient to naturally re-align the aircraft.

A complementary approach uses twist or wash-out, reducing the angle of attack towards the wing tips, together with a swept-back wing planform. The [[Dunne D.5]] incorporated this principle and its designer [[J. W. Dunne]] published it in 1913.<ref name="dunne">Dunne, J.W.; "The Theory of the Dunne Aeroplane", ''The Aeronautical Journal'', April 1913, pp.83-102. Reprinted in ''Flight'', 16 Aug to 13 Sept 1913.</ref> The wash-out reduces lift at the tips to create a bell-shaped distribution curve across the span, described by [[Ludwig Prandtl]] in 1933, and this can be used to optimise weight and drag for a given amount of lift.

Another solution is to angle or crank the wing tip sections downward with significant [[Dihedral (aircraft)#Anhedral|anhedral]], increasing the area at the rear of the aircraft when viewed from the side. When combined with sweepback and washout, it can resolve another problem. With a conventional elliptical lift distribution the downgoing elevon causes increased induced drag that causes the aircraft to yaw out of the turn ("adverse yaw"). Washout angles the net aerodynamic vector (lift plus drag) forwards as the angle of attack reduces and, in the extreme, this can create a net forward thrust. The restoration of outer lift by the elevon creates a slight induced thrust for the rear (outer) section of the wing during the turn. This vector essentially pulls the trailing wing forward to cause "proverse yaw", creating a naturally coordinated turn. In his 1913 lecture to the Aeronautical Society of Great Britain, Dunne described the effect as "tangential gain".<ref name="dunne"/> The existence of proverse yaw was not proved until NASA flew its [[Prandtl-D]] tailless demonstrator.<ref>{{cite journal |last1=Bowers |first1=Albion, H |title=On Wings of the Minimum Induced Drag: Spanload Implications for Aircraft and Birds |journal=NASA STI Programme |date=1 March 2016 |pages=11–12 |url=https://ntrs.nasa.gov/citations/20160003578 |access-date=4 August 2021}}</ref>

===Yaw control===
In some flying wing designs, any stabilizing fins and associated control rudders would be too far forward to have much effect, thus alternative means for [[Yaw (rotation)|yaw]] control are sometimes provided.

One solution to the control problem is differential drag: the drag near one wing tip is artificially increased, causing the aircraft to yaw in the direction of that wing. Typical methods include:
* [[Deceleron|Split ailerons]]. The top surface moves up while the lower surface moves down. Splitting the aileron on one side induces yaw by creating a differential air brake effect.
* [[Spoiler (aeronautics)|Spoilers]]. A spoiler surface in the upper wing skin is raised, to disrupt the airflow and increase drag. This effect is generally accompanied by a loss of lift, which must be compensated for either by the pilot or by complex design features.
* [[Spoileron]]s. An upper surface spoiler that also acts to reduce lift (equivalent to deflecting an aileron upwards), so causing the aircraft to bank in the direction of the turn—the angle of roll causes the wing lift to act in the direction of turn, reducing the amount of drag required to turn the aircraft's longitudinal axis.

A consequence of the differential drag method is that if the aircraft maneuvers frequently then it will frequently create drag. So flying wings are at their best when cruising in still air: in turbulent air or when changing course, the aircraft may be less efficient than a conventional design.

===Related designs===
Some related aircraft that are not strictly flying wings have been described as such.

Some types, such as the [[Northrop X-216H|Northrop Flying Wing (NX-216H)]], still have a tail stabilizer mounted on tail booms, although they lack a fuselage.

Many hang gliders and microlight aircraft are tailless. Although sometimes referred to as flying wings, these types carry the pilot (and engine where fitted) below the wing structure rather than inside it, and so are not true flying wings.

An aircraft of sharply swept delta planform and deep centre section represents a borderline case between flying wing, [[blended wing body]], and/or [[lifting body]] configurations.

==History==
[[File:Horten H.IX line drawing.svg|thumb|The German [[Horten Ho 229]] flew during the last days of World War II and was the first jet powered flying wing.]]
===Early research===
[[File:XB-35.jpg|thumb|right|The [[Northrop YB-35]] bomber prototype began its development during World War II.]]

[[Tailless aircraft]] have been experimented with since the earliest attempts to fly. Britain's [[J. W. Dunne]] was an early pioneer, his swept-wing biplane and monoplane designs displayed inherent stability as early as 1910. His work directly influenced several other designers, including [[G. T. R. Hill]], who developed a series of experimental [[tailless aircraft]] designs, collectively known as the [[Westland-Hill Pterodactyl]]s, during the 1920s and early 1930s.{{sfnp|Sturtivant|1990|page= 45 }} Despite attempts to pursue orders from the [[Aviation Ministry]], the Pterodactyl programme was ultimately cancelled during the mid 1930s before any order for the Mk. VI was issued.{{sfnp|Mettam|1970}}

Germany's [[Hugo Junkers]] patented his own wing-only air transport concept in 1910, seeing it as a natural solution to the problem of building an [[airliner]] large enough to carry a reasonable passenger load and enough fuel to cross the [[Atlantic Ocean|Atlantic]] in regular service. He believed that the flying wing's potentially large internal volume and low drag made it an obvious design for this role. His deep-chord [[monoplane]] wing was incorporated in the otherwise conventional [[Junkers J 1]] in December 1915. In 1919 he started work on his "Giant" [[JG1]] design, intended to seat passengers within a thick wing, but two years later the Allied Aeronautical Commission of Control ordered the incomplete JG1 destroyed for exceeding postwar size limits on German aircraft. Junkers conceived futuristic flying wings for up to 1,000 passengers; the nearest this came to realization was in the 1931 [[Junkers G.38]] 34-seater ''Grossflugzeug'' airliner, which featured a large thick-chord wing providing space for fuel, engines, and two passenger cabins. However, it still required a short fuselage to house the crew and additional passengers.

The Soviet [[Boris Ivanovich Cheranovsky]] began testing tailless flying wing gliders in 1924. After the 1920s, Soviet designers such as Cheranovsky worked independently and in secret under [[Stalin]].<ref>{{cite web|url=http://www.century-of-flight.net/new%20site/frames/horten%20frame.htm |title=German flying wings |publisher=Century-of-flight.net|access-date=2012-03-30}}</ref> With significant breakthrough in materials and construction methods, aircraft such as the [[Chyeranovskii BICh-3|BICh-3]],<ref>"History of aircraft construction in the USSR" by V.B. Shavrov, Vol. 1 p. 431 (with images)</ref> [[Chyeranovskii BICh-14|BICh-14]], [[Chyeranovskii BICh-7|BICh-7A]] became possible. Men like Chizhevskij and Antonov also came into the spotlight of the Communist Party by designing aircraft like the tailless BOK-5<ref>[http://www.ctrl-c.liu.se/misc/RAM/bok-5.html BOK-5, V.A.Chizhevskij]</ref> (Chizhevskij) and OKA-33<ref>"History of aircraft construction in the USSR" by V.B. Shavrov, Vol.1 pp. 547–548.</ref> (the first ever built by Antonov) which were designated as "motorized gliders" due to their similarity to popular gliders of the time. The BICh-11, developed by Cheranovsky in 1932,<ref>"Rocket fighter" by William Green, p. 39-41.</ref> competed with the Horten brothers H1 and [[Adolf Galland]] at the Ninth Glider Competitions in 1933, but was not demonstrated in the 1936 summer Olympics in Berlin.

In [[Germany]], [[Alexander Lippisch]] worked first on tailless types before progressively moving to flying wings, while the [[Horten brothers]] developed a series of flying wing gliders through the 1930s. The H1 glider was flown with partial success in 1933, and the subsequent H2 flown successfully in both glider and powered variants.<ref name="CADOHORTTOPSECRET">{{cite web|title=Technical Report No. 76-45 on. Horten Tailless Aircraft|url=http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA800146|publisher=Central Air Documents Office|access-date=18 July 2010|author=U.S. Naval Technical Mission in Europe|page=5|format=PDF|quote=Hor ten. H-II Both glider and powered version - (see figures 19 and 20)}}</ref>

[[File:YB49-2 300.jpg|thumb|right|The [[Northrop YB-49]] was the YB-35 bomber converted to jet power.]]

In the [[United States]], from the 1930s [[Jack Northrop]] and [[Cheston L. Eshelman]] independently worked on their own designs. The [[Northrop N-1M]], a scale prototype for a long-range bomber, first flew in 1940.{{sfn|Gunston|1996|p=26}} The [[Eshelman FW-5]], which was commonly referred to as ''The Wing'', was an experimental cabin monoplane.{{sfn|Orbis|1985|p=1616}} Other 1930s examples of true flying wings include Frenchman [[Charles Fauvel]]'s AV3 glider of 1933 and the American [[Freel Flying Wing]] glider flown in 1937.{{sfn|Pelletier|p=15}} featuring a self-stabilizing airfoil on a straight wing.{{Citation needed|date=April 2009|reason=Freel not cited}}

===Second World War===
During the [[Second World War]], aerodynamic issues became sufficiently understood for work on a range of production-representative prototypes to commence. In [[Nazi Germany]], the [[Horten brothers]] were keen proponents of the flying wing configuration, developing their own designs around it - uniquely for the time using Prandtl's birdlike "bell-shaped lift distribution".<ref>{{cite journal |last1=Bowers |first1=Albion, H |title=Experimental Flight Validation of the Prandtl 1933 Bell Spanload |journal=NASA STI Programme |date=29 July 2021 |url=https://ntrs.nasa.gov/citations/20210014683 |access-date=4 August 2021}}</ref> One such aircraft they produced was the [[Horten H.IV]] glider, which was produced in low numbers between 1941 and 1943.<ref name="bbc 229">Dowling, Stephen. [http://www.bbc.com/future/story/20160201-the-wwii-flying-wing-decades-ahead-of-its-time "The Flying Wing Decades Ahead of its Time."] ''BBC News'', 2 February 2016.</ref> Several other late-war German military designs were based on the flying wing concept, or variations of it, as a proposed solution to extend the range of otherwise very short-range of aircraft powered by early [[jet engine]]s. [[File:Horten Ho 229 Smithsonian front.jpg|thumb|right|Part of a [[Horten Ho 229]] V3, unrestored as of 2007, at the Smithsonian's [[Paul E. Garber Preservation, Restoration, and Storage Facility|Paul Garber Facility]]]]
The [[Horten Ho 229]] jet fighter prototype first flew in 1944.<ref>{{Cite book |last=Green |first=William |url=https://www.worldcat.org/oclc/127356 |title=The warplanes of the Third Reich; |date=1970 |publisher=Macdonald & Co |isbn=0-356-02382-6 |location=London |oclc=127356}}</ref> It combined a flying wing, or ''Nurflügel'', design with a pair of [[Junkers Jumo 004]] jet engines in its second, or "V2" (V for ''Versuch'') prototype airframe; as such, it was the world's first pure flying wing to be powered by twin [[jet engine]]s, being first reportedly flown in March 1944. V2 was piloted by Erwin Ziller, who was killed when a flameout in one of its engines led to a crash. Plans were made to produce the type as the Gotha Go 229 during the closing stages of the conflict. Despite intentions to develop  the Go 229 and an improved [[Gotha Go P.60|Go P.60]] for several roles, including as a [[night fighter]], no Gotha-built Go 229s or P.60s were ever completed.<ref name=":0">{{Cite web |title=Gotha Go P.60A |url=http://www.luft46.com/gotha/gop60a.html |website=www.luft46.com |access-date=2 March 2017}}</ref> The unflown, nearly completed surviving "V3," or third prototype was captured by American forces and sent back for study; it has ended up in storage at the [[Smithsonian Institution]].<ref>{{cite web |url=http://www.airspacemag.com/need-to-know/Need-to-Know-Horten.html |title=Need to Know - The Luftwaffe's Flying Wing |last=Maksel |first=Rebecca |date=January 11, 2010 |website=Air & Space Smithsonian |publisher=Smithsonian Institution |access-date=June 11, 2013}}</ref><ref>{{Cite news |url=https://insider.si.edu/2018/04/desperate-for-victory-the-nazis-built-an-aircraft-that-was-all-wing-it-didnt-work/ |title=Desperate for victory, the Nazis built an aircraft that was all wing. It didn't work. |date=5 April 2018 |work=Smithsonian Insider |access-date=5 April 2018 |language=en-US}}</ref>

The Allies also made several relevant advances in the field using a conventional elliptical lift distribution with vertical tail surfaces. During December 1942, Northrop flew the [[Northrop N-9M|N-9M]], a one-third scale development aircraft for a proposed long-range bomber;{{sfn|O'Leary|2007|p=66}} several were produced, all but one were scrapped following the bomber programme's termination.{{sfn|O'Leary|2007|p=68}} In Britain, the [[Baynes Bat]] glider was flown during wartime; it was a one-third scale experimental aircraft intended to test out the configuration for potential [[winged tank|conversion of tanks into temporary gliders]].<ref name="Ellison">{{cite book |last=Ellison |first=Norman |title=British Gliders and Sailplanes 1922-1970 |publisher=Adam & Charles Black |location=London |date=1971 |isbn=0-7136-1189-8}}</ref>

The British [[Armstrong Whitworth A.W.52]]G of 1944 was a glider test bed for a proposed large flying wing airliner capable of serving [[transatlantic crossing|transatlantic]] routes.<ref>{{cite journal |title=The A.W. Flying Wing |url=http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%200902.html |journal=Flight |access-date=18 July 2010 |format=pdf |date=9 May 1946 |page=464 |archive-url=https://web.archive.org/web/20160305150726/http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%200902.html  |archive-date=5 March 2016|url-status=dead}}</ref><ref name="Tapper"/> The A.W.52G was later followed up by the [[Armstrong Whitworth A.W.52]], an all-metal jet-powered model capable of high speeds for the era; great attention was paid to [[laminar flow]].<ref name="Tapper"/><ref>{{cite journal |title=Twin-jet A.W.52 |url=http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%202270%20-%200296.html |journal=Flight |access-date=18 July 2010 |format=pdf |date=19 December 1946 |page=674 following}}</ref> First flown on 13 November 1947, the A.W.52 yielded disappointing results; the first prototype crashed without loss of life on 30 May 1949, the occasion being the first emergency use of an [[ejection seat]] by a British pilot. The second A.W.52 remained flying with the [[Royal Aircraft Establishment]] until 1954.<ref name="Tapper"/>

===Postwar===
Projects continued to examine the flying wing during the [[postwar]] era. The work on the [[Northrop N-1M]] led to the [[Northrop YB-35|YB-35]] long-range bomber, with pre-production machines flying in 1946. This was superseded the next year by conversion of the type to jet power as the [[Northrop YB-49|YB-49]] of 1947. The design did not offer a great advantage in range, presented a number of technical problems and did not enter production. In the Soviet Union, the [[Chyeranovskii BICh-26|BICh-26]], became one of the first attempts to produce a supersonic jet flying wing aircraft in 1948;<ref>"History of aircraft construction in the USSR" by V.B. Shavrov, Vol. 2. p. 114.</ref> aviation author [[Bill Gunston]] referred to the BICh-26 as being ahead of its time.<ref>Gunston, Bill. "The Osprey Encyclopaedia of Russian Aircraft 1875–1995". London, Osprey. 1995.</ref> However, the aeroplane was not accepted by the Soviet military and the design died with Cheranovsky.

Several other nations also opted to undertake flying wing projects. Turkey was one such country, the [[Turk Hava Kurumu Ucak Fabrikasi]] producing the [[THK-13]] tailless glider during 1948.<ref>Kılıç,M. 2009. Uçan Kanat, THK basımevi, Ankara, p. 5.</ref><ref>"Turkish Aeronautical Association (THK)", ''Turkish Aircraft Production'' (English-language page).[http://www.tuncay-deniz.com/ENGLISH/THK/thk.html] (retrieved 15 May 2014)</ref> Multiple British manufacturers also explored the concept at this time. Early proposals for the [[Avro Vulcan]], a [[nuclear weapon|nuclear-armed]] [[strategic bomber]] designed by [[Roy Chadwick]], also explored several flying wing arrangements, although the final design had a fuselage.<ref>[http://www.verdon-roe.co.uk/#/pictures--videos-avro-aircraft/postwar/698vulcan/avrovulcan/avrovulcansketch Alliott Verdon Roe official web site - Avro Vulcan sketch]</ref>

There has been continual interest in the flying wing for large transport roles for cargo or passengers. [[Boeing]], [[McDonnell Douglas]], and [[Armstrong Whitworth]] have undertaken design studies on flying wing [[Airliner|airliners]]; however, no such airliners have yet been built.<ref name="Tapper" />

Following the arrival of [[supersonic]] aircraft during the 1950s, military interest in the flying wing was quickly curtailed, as the concept of adopting a thick wing that accommodated the crew and equipment directly conflicted with the optimal thin wing for supersonic flight.

Interest in flying wings was renewed in the 1980s due to their potentially low [[radar]] reflection cross-sections. [[Stealth technology]] relies on shapes that reflect radar waves only in certain directions, thus making the aircraft hard to detect unless the radar receiver is at a specific position relative to the aircraft—a position that changes continuously as the aircraft moves.<ref>[http://www.centennialofflight.gov/essay/Evolution_of_Technology/Stealth_aircraft/Tech31.htm "Stealth Aircraft."] {{webarchive|url=https://web.archive.org/web/20110721035221/http://www.centennialofflight.gov/essay/Evolution_of_Technology/Stealth_aircraft/Tech31.htm |date=21 July 2011}} ''U.S. Centennial of Flight Commission'', 2003. Retrieved: 5 November 2012.</ref> This approach eventually led to the [[Northrop Grumman B-2 Spirit]], a flying wing [[Stealth aircraft|stealth]] bomber.<ref>{{Cite journal |last=Pelletier |first=Alan J |date=September–October 1996 |title=Towards the Ideal Aircraft: The Life and Times of the Flying Wing, Part Two |journal=[[Air Enthusiast]] |volume=65 |pages=8–19}}</ref><ref>{{Cite web |date=2003 |title=Stealth Aircraft |url=http://www.centennialofflight.gov/essay/Evolution_of_Technology/Stealth_aircraft/Tech31.htm |archive-url=https://web.archive.org/web/20110721035221/http://www.centennialofflight.gov/essay/Evolution_of_Technology/Stealth_aircraft/Tech31.htm |archive-date=21 July 2011 |website=U.S. Centennial of Flight Commission}}</ref> In this case, the aerodynamic advantages of the flying wing are not the primary reasons for the design's adoption. However, modern computer-controlled [[fly-by-wire]] systems allow for many of the aerodynamic drawbacks of the flying wing to be minimized, making for an efficient and effectively stable long-range bomber.<ref>{{harvnb|Moir|Seabridge|2008|p=397}}</ref><ref name = "sweetman 73">{{harvnb|Sweetman|2005|p=73}}</ref>

Due to the practical need for a deep wing, the flying wing concept is mostly adopted for [[subsonic aircraft]]. There has been continual interest in using it in the large transport role where the wing is deep enough to hold cargo or passengers. A number of companies, including [[Boeing]], [[McDonnell Douglas]], and [[Armstrong Whitworth]], have undertaken design studies on flying wing [[airliner]]s to date; however,<ref name="Tapper" >Tapper (1973)</ref> no such airliners have yet been built as of 2020.{{citation needed|date=December 2011}}

[[File:Wing bi-directional.svg|thumb|150px|Bi-directional flying wing, top-down view]]
The bi-directional flying wing is a variable-geometry concept comprising a long-span subsonic wing and a short-span supersonic wing, joined in the form of an unequal cross. Proposed in 2011, the low-speed wing would have a thick, rounded airfoil able to contain the payload and a long span for high efficiency, while the high-speed wing would have a thin, sharp-edged airfoil and a shorter span for low drag at supersonic speed. The craft would take off and land with the low-speed wing across the airflow, then rotate a quarter-turn so that the high-speed wing faces the airflow for supersonic travel.<ref>Zha, Im & Espinal, [http://www6.miami.edu/acfdlab/projects/AIAA2010-1013_slides_pdf.pdf Toward Zero Sonic-Boom and High Efficiency Supersonic Flight: A Novel Concept of Supersonic Bi-Directional Flying Wing]</ref> NASA has funded a study of the proposal.<ref>{{cite web |last1=Hall |first1=Loura |title=NIAC 2012 Phase I and Phase II Selections |url=https://www.nasa.gov/offices/oct/early_stage_innovation/niac/niac_2012_phaseIandII_awards.html |website=NASA |date=17 July 2017}}</ref> The design is claimed to offer low wave drag, high subsonic efficiency and reduced sonic boom.

Since the end of the [[Cold War]], numerous [[unmanned aerial vehicle]]s (UAVs) featuring the flying wing have been produced. Nations have typically used such platforms for [[aerial reconnaissance]]; such UAVs include the [[Lockheed Martin RQ-170 Sentinel]],<ref>{{cite news |first=David A. |last=Fulghum |title=RQ-170 Has Links to Intelligence Loss to China |url=http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a7544751e-3bdc-4e52-9be7-07000988da92&plckScript=blogScript&plckElementId=blogDest |work=[[Aviation Week & Space Technology]] |date=8 December 2009 |access-date=9 December 2009}}</ref><ref>{{cite news |title=Mystery UAV operation in Afghanistan |url=http://www.shephard.co.uk/news/2393/mystery-uav-operating-in-afghanistan/ |publisher=UV Online |date=10 April 2009 |access-date=9 December 2009 |archive-url=https://web.archive.org/web/20091206023713/http://www.shephard.co.uk/news/2393/mystery-uav-operating-in-afghanistan/ |archive-date=6 December 2009 |url-status=live |df=dmy-all }}</ref> the [[Northrop Grumman Tern]],<ref>{{Cite web|url=https://www.flightglobal.com/news/articles/northrop-grumman-wins-darpa-tern-programme-420385/|title=Northrop Grumman wins DARPA TERN programme|publisher=Flight Global}}</ref><ref>{{cite web |last1=Smith |first1=Rich |title=General Electric and Northrop Grumman Will Put a Drone on Every Boat |url=https://www.fool.com/investing/2018/03/23/general-electric-and-northrop-grumman-will-put-a-d.aspx |website=The Motley Fool |access-date=23 September 2020 |language=en |date=23 March 2018}}</ref> and the [[Nanning Huishi UAV|Nanning Huishi Flying wing]]. Civilian companies have also experimented with UAVs, such as the [[Facebook Aquila]], as [[atmospheric satellite]]s.<ref>{{Cite web |url=https://www.popularmechanics.com/flight/drones/g27419696/solar-aircraft-drones/ |title=Solar Drones Are Filling the Skies, But There's Still No Clear Winner |last=Hambling |first=David |date=9 May 2019 |website=Popular Mechanics |language=en-US |access-date=30 May 2019}}</ref><ref name="AT1">{{cite web |url=http://www.aviationtoday.com/2017/11/21/airbus-facebook-partner-haps-connectivity/ |title=Airbus, Facebook Partner on HAPS Connectivity |last=Bellamy III |first=Woodrow |date=21 November 2017 |website=[[Aviation Today]] |location=Rockville, MD |access-date=5 December 2017}}</ref> Various prototype [[unmanned combat aerial vehicle]]s (UCAVs) have been produced, including the [[Dassault nEUROn]],<ref>{{cite magazine| last=Broadbent |first=Mark |title= NEUROn Become's Europe's First Stealth Aircraft to Fly|magazine= [[Air International]] | date= January 2013 |volume= 84 |issue=1 |page=4|issn=0306-5634}}</ref> the [[Sukhoi S-70 Okhotnik-B]],<ref name="Flight testing">{{cite web |url=http://tass.com/defense/1012351 |title=Russia's attack drone prototype to start test flights this year |website=[[TASS]] |date=8 July 2018 |access-date=18 February 2019 |archive-url=https://web.archive.org/web/20190218082020/http://tass.com/defense/1012351 |archive-date=18 February 2019 |url-status=live |df=dmy-all}}</ref> and the [[BAE Systems Taranis]].<ref name="bbc">{{cite web |url=http://news.bbc.co.uk/1/hi/technology/10602105.stm |title=MoD lifts lid on unmanned combat plane prototype |first=Daniel |last=Emery |work=BBC News |date=12 July 2010 |access-date=12 July 2010| archive-url= https://web.archive.org/web/20100712191703/http://news.bbc.co.uk/1/hi/technology/10602105.stm| archive-date= 12 July 2010 | url-status= live}}</ref>

==See also==
* [[List of flying wings]]
* [[Delta wing]]
* [[Lifting body]]
* [[Oblique wing]]
* [[Vincent Burnelli]]
* ''[[Zanonia macrocarpa]]''

==References==
===Citations===
{{reflist|30em}}

===Bibliography===
* {{cite journal |last=Gunston |first=Bill |author-link=Bill Gunston|year=1996 |title=Beyond the Frontiers: Northrop's Flying Wings |journal=Wings of Fame |publisher=Aerospace Publishing|location=London |issue=Volume 2 |pages=24–37|isbn=1-874023-69-7|issn=1361-2034}}.
* {{citation |last=Mettam |first=H.A. |title=The Pterodactyl Story |journal=Flight International |date=26 March 1970 |pages=514–518 |volume=97  |number=3185 |url=http://www.flightglobal.com/pdfarchive/view/1970/1970%20-%200564.html }}
* {{citation |last1=Moir |first1= Ian |last2= Seabridge |first2=Allan G. |title=Aircraft Systems: Mechanical, Electrical and Avionics Subsystems Integration |location=Hoboken, New Jersey |publisher= John Wiley & Sons |year= 2008 |isbn=978-0-4700-5996-8}}.
* {{cite magazine|last=O'Leary |first=Michael|date=June 2007 |title=The Shape of Wings to Come |journal=[[Aeroplane (magazine)|Aeroplane]] |volume=35 |number=6, Issue 410|pages=65–68}}
* {{cite book |title= The [[Illustrated Encyclopedia of Aircraft]] (Part Work 1982-1985)|publisher= Orbis Publishing|ref={{SfnRef|Orbis|1985}} }}
* {{cite journal |last1=Pelletier |first1=Alain J |title=Towards the Ideal Aircraft? The Life and Times of the Flying Wing Part One: Beginnings to 1945|journal=[[Air Enthusiast]] |issue= 64, July–August 1994 |pages=2–17 |issn=0143-5450}}.
* {{Cite book |last=Sturtivant  |first=R. |title=British Research and Development Aircraft |publisher=G.T. Foulis |isbn=0854296972 |year=1990 |page=45}}.
* {{citation |last=Sweetman |first=Bill |title=Lockheed Stealth |location= North Branch, Minnesota |publisher= Zenith Imprint |year= 2005 |isbn= 978-0-7603-1940-6}}.
* {{cite book |last=Tapper |first=O. |title=Armstrong-Whitworth Aircraft since 1913 |pages=287–96 |year=1973 |location=London |publisher=Putnam |ref=Tapper, Armstrong-Whitworth Aircraft}}

==Further reading==
* {{cite book |last=Kohn |first=Leo J. |year=1974 |title=The Flying Wings of Northrop |location=Milwaukee, WI |publisher=Aviation Publications|isbn=0-87994-031-X}}
* {{Cite book |last=Laming |first=Tim|author-link=Tim McLelland|title=The Vulcan Story: 1952–2002|location=Enderby, Leicester, UK|publisher=Silverdale Books|year= 2002|isbn=1-85605-701-1}}.
* {{cite book |last=Maloney |first=Edward T.|year=1975 |title=Northrop Flying Wings |location=Buena Park, CA |publisher=Planes Of Fame Publishers |isbn=0-915464-00-4}}

==External links==
{{Commons category|Flying wing aircraft}}
* [http://www.century-of-flight.net/Aviation%20history/flying%20wings/Early%20Flying%20Wings.htm History of the Flying Wing] at Century of Flight.
* [http://www.nurflugel.com/Nurflugel/nurflugel.html The Nurflügel page]
* [https://web.archive.org/web/20040803121919/http://members.cox.net/rebid/bldwing.htm Flight to the Future] by Joe Mizrahi, ''Wings'', April 1999, Vol. 29, No. 2
* [http://www.warbirdforum.com/edwards.htm Glen Edwards and the Flying Wing]
* "[https://books.google.com/books?id=1dYDAAAAMBAJ&pg=PA14&dq=popular+Mechanics+1942&hl=en&ei=8m6hTMaUE8GdnAeJmPmJBA&sa=X&oi=book_result&ct=book-thumbnail&resnum=1&ved=0CC4Q6wEwAA#v=onepage&q=popular%20Mechanics%201942&f=true Flying Wings Are Coming]", ''Popular Mechanics'', '''77''', No. 3, March 1942. pp. 14-15, 190, 192-193.

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{{DEFAULTSORT:Flying Wing}}
[[Category:Flying wings| ]]
[[Category:Wing configurations]]
[[Category:Aircraft wing design]]