Editing Variable-sweep wing (section)

===Production===
During the 1960s, the first programmes to produce mass production variable-sweep aircraft commenced. In the United States, such a configuration for the TFX (Tactical Fighter Experimental) program, which resulted in the development of the [[General Dynamics F-111]], a sizable twin-engined aircraft intended to perform multiple roles.<ref>Eden 2004 pp. 196–197.</ref><ref name=erg66colls>{{cite news |url=https://news.google.com/newspapers?id=o-VVAAAAIBAJ&sjid=EuEDAAAAIBAJ&pg=6856%2C3575947<!--https://news.google.com/newspapers?id=b5ghAAAAIBAJ&sjid=MpoFAAAAIBAJ&pg=3595%2C773184-->|work=Eugene Register-Guard |location=(Oregon) |agency=Associated Press |last=Price |first=Bem |title=Capital still buzzing whether TFX a colossal blunder |date=18 September 1966 |page=5A}}</ref> The F-111 is the first production aircraft to feature a variable-geometry wing and it, along with other systems such as [[terrain following radar]] and [[turbofan]] engines outfitted with [[afterburner]]s, were innovative technologies for the era.<ref name=Logan_p14>Logan 1998, p. 14.</ref><ref name= Miller_p17_9>Miller 1982, pp. 17, 19.</ref>

Despite this head start in the field, development of the F-111 was protracted; flight testing of the F-111A model only ended in 1973.<ref name=Logan_p32>Logan 1998, p. 32.</ref> During 1968, cracks were discovered in the F-111's [[wingbox|wing attach points]], the issue also has been attributed with the loss of an F-111 in the following year.<ref name=retplg>{{cite news |url=https://news.google.com/newspapers?id=StoxAAAAIBAJ&pg=2650%2C6893340 |work=Reading Eagle |location=(Pennsylvania) |agency=Associated Press |title=F-111 problems return to plague President |date=13 January 1970 |page=8}}</ref> Accordingly, the attach points were structurally redesigned and subject to intensive testing of both the design and manufacturing quality.<ref name=Miller_p31_47>Miller 1982, pp. 31, 47.</ref> The F-111B, intended for the [[US Navy]], was cancelled in 1968 due the aircraft's weight and performance issues, as well as its inadequacies for the service's fighter requirements.<ref>Boyne 2002, p. 252.</ref><ref>Thomason 1998, pp. 52–53.</ref> Several variants, such as the FB-111A [[strategic bomber]] model, featured elongated wings to give a greater range and load-carrying capability.<ref name=Miller_p38-43>Miller 1982, pp. 38–43.</ref> The F-111's wing featured pivoting [[hardpoint|pylon]]s (two under each wing) which automatically adjusted to the sweep angle. Subsequent swing-wing aircraft, such as the [[Panavia Tornado]] and [[Sukhoi Su-24]], would also be similarly equipped.{{Citation needed|date=November 2020}}
[[File:Sukhoi Su-24 inflight Mishin-2.jpg|thumb|left|A [[Sukhoi Su-24]] ]]

In the [[Soviet Union]], military planners had also formulated similar requirements, which led to [[TsAGI]], the Soviet aerodynamics bureau, performing extensive studies into variable geometry wings. TsAGI evolved two distinct designs, differing mainly in the distance (expressed as a percentage of total [[wingspan]]) between the wing pivots. By adopting a wider spacing, this not only reduced the negative aerodynamic effects of changing wing sweep, but also provided a larger fixed wing section which could be used for [[landing gear]] or stores [[Aircraft pylon|pylons]]. This could, in fact, be adapted to more-or-less existing airframes, which the Soviets accordingly did, such as with the [[Sukhoi Su-17]] (based on the earlier [[swept wing]] [[Sukhoi Su-7]]). The limitation of the wide spacing, however, was that it reduced the benefits of variable geometry as much as it reduced their technical difficulties.{{Citation needed|date=November 2020}}

As such, producing new, "clean-sheet" Soviet designs remained desirable. For this, TsAGI devised a more narrowly-spaced arrangement somewhat similar to that of the F-111. This design was used, albeit at different scales, for the [[Mikoyan-Gurevich MiG-23]] fighter and the Sukhoi Su-24 tactical bomber, both of which flew in prototype forms around the end of the 1960s and entering service during the early 1970s. During 1962, Tupolev's design team, recognising room for improvement on the recently introduced [[Tupolev Tu-22]] bomber, begun work on an extensively redesigned derivative that incorporated a variable geometry wing, intended to address the Tu-22's poor handling characteristics more so than bolstering its efficiency at high speeds.<ref name=KD_124>Kandalov & Duffy 1996, p. 124.</ref><ref name=Eden>Eden, Paul, ed. "Tupolev Tu-22/22M". ''Encyclopedia of Modern Military Aircraft''. London: Amber Books, 2004. {{ISBN|1-904687-84-9}}.</ref> {{asof|2014}} more than 100 [[Tupolev Tu-22M]] strategic bombers are in use.<ref>{{citation |last=Hoyle |first=Craig |url=http://www.flightglobal.com/news/articles/kings-of-the-swingers-top-13-swing-wing-aircraft-404176/ |title=Kings of the swingers: Top 13 swing-wing aircraft |work=[[Flightglobal]] |publisher=Reed Business Information |date=26 September 2014 |access-date=27 September 2014 |archive-url=https://web.archive.org/web/20140927223525/http://www.flightglobal.com/news/articles/kings-of-the-swingers-top-13-swing-wing-aircraft-404176/ |archive-date=27 September 2014 |url-status=live}}</ref>

During the late 1950s and early 1960s, Britain was developing the [[BAC TSR-2]], a supersonic low-level strategic bomber. Later variants of the type would have been fitted with variable-geometry wings.<ref>Murray, Iain. "Bouncing-Bomb Man: the Science of Sir Barnes Wallis." Haynes, 2009. p. 191.</ref> However, on 1 April 1965, development of the TSR-2 was terminated during the flight testing phase primarily due to the programme's spiralling costs.<ref name="cc(65)20">''Conclusions of a Meeting of the Cabinet held at 10 am. 10 Downing Street, S.W.1, on Thursday, 1st April, 1965'',  CC(65)20, CAB/128/39. London: Public Record Office, 2010.</ref><ref name="cc(65)21">''Conclusions of a Meeting of the Cabinet held at 10 Downing Street, S.W.1, on Thursday, 1st April, 1965, at 10 p.m.'',  CC(65)21, CAB/128/39. London: Public Record Office, 2010.</ref> To replace the TSR-2, the Air Ministry initially placed an option for the American [[General Dynamics F-111K]];<ref name="c(65)58">Healey, D. W. ''The Need for an Option on the F-111A'', C(65)58, CAB/129/121. London: Public Record Office, 2010.</ref><ref>DeWeerd, H.A. [http://www.rand.org/pubs/papers/2008/P3347.pdf "P-3347: The 1966 Defense Review."] ''The Rand Corporation'', April 1966. Retrieved: 13 December 2010.</ref> while the F-111K was promoted as being cheaper,<ref name="Wood p. 181">Wood 1986, p. 181.</ref> this too was terminated during January 1968 on grounds of cost.<ref name=Logan_p278-80>Logan 1998, pp. 278–80.</ref>

Following the TSR-2's cancellation, BAC moved their variable-geometry work to Warton, there submitting the P.45 light attack/trainer to AST 362. This work fed into a joint Anglo-French programme to develop a [[variable-geometry wing|variable geometry]] strike aircraft – the [[AFVG|Anglo French Variable Geometry Aircraft]] (AFVG). This multirole aircraft was to be equipped with a variable geometry wing and was intended to perform the [[strike aircraft|strike]], reconnaissance, and [[interceptor aircraft|interceptor]] roles.<ref name="dual Role.">[http://www.flightglobal.com/pdfarchive/view/1967/1967%20-%200114.html "Anglo-French projects go ahead... The AFVG and its dual role."] ''Flight'' via ''flightglobal.com,'' 26 January 1967.</ref><ref name = "wood 202">Wood 1975, p. 202.</ref> However, as early as 1966, the French aircraft manufacturer [[Dassault]] began to actively undermine the AFVG, as it was working on two competing in-house projects: the variable geometry [[Dassault Mirage G|Mirage G]] and the [[Dassault Mirage F1|Mirage F1]].<ref>DeVore, Marc. [http://www.allacademic.com//meta/p_mla_apa_research_citation/3/1/1/3/1/pages311317/p311317-1.php "Making Collaboration Work: Examining Sub-Optimal Performance and Collaborative Combat Aircraft."] ''allacademic.com.'' Retrieved: 2 February 2011.</ref> According to aviation author Derek Wood, both Dassault and the [[French Air Force]] were unenthusiastic participants in the AFVG, the former wanting to pursue its own indigenous variable geometry aircraft, while the latter had determined that the type did not align with its future equipment plans.<ref name = "wood 202"/> In June 1967, the French government announced their withdrawal from the AFVG project ostensibly on the grounds of cost.{{#tag:ref|According to aviation publication [[Flight International]], Dassault had gained valuable data on variable-geometry configurations from the AFVG programme and may have used the excuse of cost issues in order to divert funds and data to their own VG projects.<ref>[http://www.flightglobal.com/pdfarchive/view/1967/1967%20-%200917.html "Military and Research."] ''Flight'' via ''flightglobal.com,'' 1 June 1967. Retrieved: 29 January 2011.</ref>|group=N}}<ref name = "wood 203 204">Wood 1975, pp. 203–204.</ref>

[[File:Royal Air Force (RAF) Panavia Tornado F3 (ZE764) at Kemble Air Day 2008, in Gloucestershire, England, UK - arp.jpg|thumb|A [[Panavia Tornado ADV|Tornado F3]] with wings swept]]
Despite the AFVG programme's collapse, the design was revamped by BAC into a larger strike-oriented variable geometry aircraft. Holding contracts were issued to BAC to support the project, which had been re-designated as the United Kingdom Variable Geometry (UKVG) aircraft.<ref name="torn birt 11">Heron 2002, p. 11.</ref><ref name = "wood 204">Wood 1975, p. 204.</ref> In November 1967, BAC issued a brochure on the UKVG proposal; various proposals would be issued to cover the use of multiple different engines. The quick production of a demonstrator aircraft, powered by a pair of [[Rolls-Royce/MAN Turbo RB153]] turbofan engines, was also mooted.<ref name = "wood 204"/> As solely funding for the UKVG was unrealistic, the British government pursued partners within its fellow NATO members,{{#tag:ref| Belgium, Canada, Italy, the Netherlands and West Germany were approached.<ref name="guardian obit">[https://www.theguardian.com/news/2003/may/24/guardianobituaries.obituaries "Obituary: Handel Davies."] ''The Guardian,'' 24 May 2003. Retrieved: 29 January 2011.</ref>|group=N}} promoting the concept of developing and procuring a common NATO strike aircraft. In July 1968, a [[memorandum of understanding]] was signed between Britain, [[West Germany]], [[Italy]], the [[Netherlands]], [[Belgium]], and [[Canada]].<ref name = "wood 204 206">Wood 1975, pp. 204, 206.</ref> This memorandum eventually led to the launch of the multinational Multi-Role Combat Aircraft (MRCA) project, which successfully produced a variable geometry aircraft for the strike, reconnaissance, and interception missions in the form of the Panavia Tornado.<ref name="guardian obit"/><ref name = "wood 206">Wood 1975, p. 206.</ref><ref>Buttler, Tony. ''British Secret Projects: Jet Bombers Since 1949''.{{page needed|date=May 2013}}</ref>

Following the AFVG effort, Dassault Aviation constructed a prototype fighter, the Mirage G, completing two aircraft, the Mirage G4 and G8, in 1968.<ref>Green 1972, p. 84.</ref> Furthermore, Dassault also worked in cooperation with the American manufacturing interest [[Ling-Temco-Vought]] to develop the ''LTV V-507'', which was submitted for US Navy's [[Grumman F-14 Tomcat|VFX project]].<ref>[[Claude Carlier (historian)|Claude Carlier]], Une formule aérodynamique gagnante. La grande aventure des «Mirage» à géométrie variable, 2, Le Fana de l’aviation, 537, août 2014.</ref> From the VFX submissions, the US Navy procured the Grumman F-14 Tomcat to replace the canceled F-111B fleet interceptor during the 1970s. The F-14 was a more nimble fighter than the F-4 Phantom II and, unlike the F-111, its variable-sweep wings automatically adjusted over its speed range, and could be moved even during turns. Furthermore, the wings could be swept forward for tight "bat" turns in close quarters aerial combat, as well as rearwards for dash speeds.<ref name="TomVS">Kress, Bob and RADM Gilchrist USNRet. [http://209.196.57.95/Me2/dirmod.asp?sid=&nm=The+Magazine&type=PubPagi&mod=Publications%3A%3AArticle+Title&mid=13B2F0D0AFA04476A2ACC02ED28A405F&tier=4&id=660129034AD142DEB047684EBF25581F "F-14D Tomcat vs. F/18 E/F Super Hornet."] {{webarchive|url=https://web.archive.org/web/20090404105502/http://209.196.57.95/Me2/dirmod.asp?sid=&nm=The+Magazine&type=PubPagi&mod=Publications%3A%3AArticle+Title&mid=13B2F0D0AFA04476A2ACC02ED28A405F&tier=4&id=660129034AD142DEB047684EBF25581F |date=4 April 2009}} ''Flight Journal Magazine'', February 2002 Issue. Quote: "dedicated air combat occurs at below about 0.8 because of high turning drag – an arena in which the F-14's 20-degree sweep is optimal ... it has only 36 percent of the F-14's payload/range capability."</ref><ref>{{Cite news |url=http://news.bbc.co.uk/1/hi/world/americas/2551409.stm |title=Fact file: F-14 Tomcat |date=11 December 2002 |access-date=22 January 2009 |archive-url=https://web.archive.org/web/20090330100613/http://news.bbc.co.uk/1/hi/world/americas/2551409.stm |archive-date=30 March 2009 |url-status=live }}</ref>

[[File:B1s.jpg|thumb|left|A B-1B Lancer with wings swept full forward |alt=Top forward view of gray aircraft with wings swept forward banking right. Underneath are strips of white clouds and uninhabited terrain.]]
[[Rockwell International|Rockwell]] adopted variable geometry for the much larger Advanced Manned Strategic Bomber (AMSA) program that produced the [[B-1 Lancer]] bomber, intended to provide an optimum combination of high-speed cruising efficiency and fast, [[supersonic]] penetration speeds at extremely low level. The B-1's variable-sweep wings provide a relatively high level of [[lift (force)|lift]] during takeoff and landing, while also generating little drag during a high-speed dash.<ref name="lee p.13"/> When the wings were set to their widest position the aircraft had considerably better lift and power than the B-52, allowing the B-1 to operate from a much wider variety of bases.<ref name="lee p.13">Lee 2008, p. 13.</ref> Rockwell submitted its proposal in January 1970, competing against bids by Boeing and General Dynamics.<ref name=Pace_p22-3>Pace 1998, pp. 22-23.</ref><ref>Kocivar, Ben. [https://books.google.com/books?id=9AAAAAAAMBAJ&pg=PA86 "Our New B-1 Bomber&nbsp;– High, Low, Fast, and Slow."] ''Popular Science'', Volume 197, Issue 5, November 1970, p. 86.</ref> The B-1's development was authorised in October 1981 as a stopgap between the increasingly vulnerable B-52 and the more capable [[Advanced Technology Bomber]] (ATB).<ref name="lee p.13"/><ref name="Reagan approves">Coates, James. [https://web.archive.org/web/20120417123825/http://pqasb.pqarchiver.com/chicagotribune/access/635722892.html?dids=635722892:635722892&FMT=ABS&FMTS=ABS:AI&type=historic&date=Oct+03%2C+1981&author=&pub=Chicago+Tribune&desc=Reagan+approves+B-1%2C+alters+basing+for+MX&pqatl=google "Reagan approves B-1, alters basing for MX."] ''Chicago Tribune'', 3 October 1981. Retrieved: 28 July 2010.</ref> Initial operational capability was reached on 1 October 1986 and the B-1B was placed on nuclear alert status.<ref>Pace 1998, pp. 62, 69.</ref><ref name=Jenkins_p83>Jenkins 1999, p. 83.</ref>

The Soviet Union also opted to develop a large strategic bomber equipped with variable geometry wings. During the early 1970s, Tupolev's design, which was initially designated ''Aircraft 160M'', featured a lengthened [[blended wing]] layout and incorporated some elements of the [[Tupolev Tu-144|Tu-144]], competed against the [[Myasishchev M-18]] and the [[Sukhoi T-4]] designs.<ref>{{cite web|last=Sergeyev|first=Pavel|url=http://pda.lenta.ru/articles/2008/04/30/tu/|script-title=ru:Белый лебедь|language=ru|trans-title=White Swan|work=[[Lenta.ru]]|date=30 April 2008|access-date=5 August 2009 |url-status=live |archive-url=https://web.archive.org/web/20110717041514/http://pda.lenta.ru/articles/2008/04/30/tu/|archive-date=17 July 2011}}</ref> Designated as the [[Tupolev Tu-160]], it entered operational service with the 184th Guards Heavy Bomber Regiment located at [[Pryluky Air Base]], [[Ukrainian SSR]], during April 1987.<ref>{{cite book |last1=Miller |first1=David |title= The Cold War: A Military History |date= 1998 |publisher=John Murray, Random House |location=London |isbn=1-44813793-4 |page=162 |edition=Pimlico 2001 |url= https://books.google.com/books?id=6L_moj5Fo74C&pg=PT162}}</ref> The aircraft is the largest and heaviest combat aircraft, the fastest bomber in use and the largest and heaviest variable-sweep wing airplane to have ever flown as of 2020.<ref>{{cite web |url=http://www.guinnessworldrecords.com/world-records/largest-military-aircraft-by-weight-operational-bomber |title=Largest military aircraft by weight, operational bomber |publisher=Guinness World Records |access-date=2018-12-29 |archive-url=https://web.archive.org/web/20181006225602/http://www.guinnessworldrecords.com/world-records/largest-military-aircraft-by-weight-operational-bomber |archive-date=6 October 2018 |url-status=live |df=dmy-all}}</ref>