Editing General Dynamics F-111 Aardvark (section)

===Design phase===
General Dynamics' design team was led by [[Robert H. Widmer]].<ref>{{cite news |last= Martin |first= Douglas |url= https://www.nytimes.com/2011/07/03/business/03widmer.html?_r=1&ref=deathsobituaries |title= Obituary: Robert H. Widmer, Designer of Military Aircraft, Dies at 95 |newspaper= [[The New York Times]] |date= 2 July 2011}}</ref> Recognizing its lack of experience with carrier-based fighters, General Dynamics teamed with [[Grumman]] in November 1963 for the assembly and testing of the F-111B. In addition, Grumman would also build the aft fuselage and the landing gear of the F-111A.<ref name=Miller_p17_9/><ref name='knaack 236'>Knaack 1978, p. 236.</ref> The General Dynamics and Grumman team faced ambitious requirements for range, weapons load, and aircraft weight.<ref>Thomason 1998, pp. 9–10.</ref> Thus, the F-111 was designed to incorporate numerous features that were new to production military aircraft, such as variable-geometry wings and afterburning turbofan engines.<ref name=Miller_p17_9>Miller 1982, pp. 17, 19.</ref> This use of unfamiliar features has been attributed as a major cause of the aircraft's protracted development and weight increases.<ref name="Davies2013 p5">Davies 2013, p. 5.</ref>

The F-111A and F-111B shared the same airframe structural components and [[Pratt & Whitney TF30|Pratt & Whitney TF30-P-1]] turbofan engines. They featured side-by-side crew seating in an escape capsule as required by the Navy. The [[General Dynamics/Grumman F-111B|F-111B]]'s nose was {{convert|8.5|ft|m|sigfig=3|sp=us}} shorter as the aircraft could fit on existing carrier elevator decks, and had {{convert|3.5|ft|m|sigfig=3|adj=mid|-longer}} wingtips to improve on-station endurance time; it also carried an [[AN/AWG-9]] [[Pulse-Doppler radar]] to guide its [[AIM-54 Phoenix]] missiles. The USAF's F-111A would be equipped with the AN/APQ-113 attack radar and the [[AN/APQ-110]] [[terrain-following radar]] and air-to-ground armament.<ref name=Baug_F-111A>Baugher, Joe. [http://www.joebaugher.com/usaf_fighters/f111_1.html "General Dynamics F-111A."] ''USAAC/USAAF/USAF Fighters'', 23 December 1999. Retrieved: 5 October 2009.</ref>

During September 1963, the F-111A mockup was inspected.<ref name='knaack 226' /> On 15 October 1964, the first test F-111A was rolled out of [[Air Force Plant 4|Plant 4]] of General Dynamics' facility in Fort Worth, Texas; it was powered by YTF30-P-1 turbofans and used a set of ejector seats as the escape capsule was not yet available.<ref name=Baug_F-111A/><ref name='knaack 226' /> On 21 December 1964, the F-111A made its first flight from [[Carswell Air Force Base]], Texas.{{Sfn|Eden|2004|p=197}} Lasting for 22 minutes, less than planned due to a flap malfunction, this initial flight was considered to be satisfactory overall; category I testing commenced immediately thereafter.<ref name='knaack 226-227'>Knaack 1978, pp. 226-227.</ref><ref name=ctfiss>{{cite news |url= https://news.google.com/newspapers?id=qzhWAAAAIBAJ&sjid=wOgDAAAAIBAJ&pg=2676%2C1891540 |work= Spokesman-Review |location= Spokane, Washington, US |agency= Associated Press |title= Controversial TFX test flight is success |date= 22 December 1964 |page= 1}}</ref> Early flights of the F-111, which included supersonic flights, demonstrated favorably simplistic maintenance requirements, amongst other qualities.<ref name='knaack 227'>Knaack 1978, p. 227.</ref>

Various changes to the program were enacted throughout 1965; this was chiefly in response to a steep climb in unit costs from $4.5 million to $6 million.<ref name='knaack 227' /> The cause of the cost rises has been attributed, at least partially, to a directive issued to General Dynamics to incorporate improved avionics as well as to work on [[strategic bomber]] and aerial reconnaissance variants of the aircraft, the latter of which was eventually cancelled. During April 1965, General Dynamics was authorized to produce 431 F-111s, less than half the number of aircraft which had originally been forecast.<ref name='knaack 227, 233'>Knaack 1978, pp. 227, 233.</ref> On 10 May 1967, a new multi-year FPIP contract replaced the prior procurement process, increasing the total aircraft on order to 493 F-111s of multiple models, including 23 F-111Bs intended for the US Navy, 24 F-111Cs for the [[Royal Australian Air Force]], and 50 F-111Ks intended for the [[Royal Air Force]].<ref name='knaack 228'>Knaack 1978, p. 228.</ref>

Early flights of the F-111 were troubled by compressor surges and stalls across certain portions of the flight regime.<ref name='knaack 227-228'>Knaack 1978, pp. 227-228.</ref> General Dynamics had elected to use an uncommon spike-shaped variable intake for the engine for the performance.<ref name="Davies2013 p5"/> Studies performed by NASA, the USAF, and General Dynamics led to the engine inlet being redesigned; modifications were implemented between 1965 and 1966, culminating with the "Triple Plow I" and "Triple Plow II" designs.<ref name=Gunston_p25-7>Gunston 1978, pp. 25–27.</ref><ref name=FASweb>{{cite web |title= F-111 |url= https://fas.org/man/dod-101/sys/ac/f-111.htm |website= FAS.org |publisher= Federation of American Scientists |date= 24 December 1998 |access-date= 15 August 2014}}</ref><ref name='knaack 228-229'>Knaack 1978, pp. 228-229.</ref> During February 1965, the F-111A achieved a speed of Mach 1.3 while flying with an interim intake design.<ref name=Gunston_p25-7/> On 18 May 1965, the <!--first-->F-111B made its first flight; it was also equipped with ejector seats initially.<ref name=Baugher_F-111B>Baugher, Joe. [http://www.joebaugher.com/usaf_fighters/f111_4.html "General Dynamics/Grumman F-111B."] ''USAAC/USAAF/USAF Fighters'', 7 November 2004. Retrieved: 5 October 2009.</ref><ref>Thomason 1998, pp. 16, 20.</ref>

Separately, cracks in the F-111's [[wingbox|wing attach points]] were first discovered in 1968 during ground fatigue testing; during the following year, the crash of an F-111 was attributed to a cracked wingbox.<ref name='knaack 234'>Knaack 1978, p. 234.</ref><ref name=retplg/> On 22 December 1969, the USAF opted to ground the fleet due to this issue, save for those involved in flight testing.<ref name='knaack 230-231'>Knaack 1978, pp. 230-231.</ref> The resolution involved the redesigning of the attach structure and necessitated testing to ensure adequate design and workmanship.<ref name=Miller_p31_47>Miller 1982, pp. 31, 47.</ref> On 31 July 1970, the grounding was lifted.<ref name='knaack 231'>Knaack 1978, p. 231.</ref> Category I flight testing of the F-111A, which had started in 1964, continued through to 31 March 1972.<ref name=Logan_p32>Logan 1998, p. 32.</ref><ref name='knaack 227' /> Category II tests started in January 1966, while Category III testing was repeatedly postponed before being cancelled, having been deemed to be unnecessary.<ref name='knaack 227' />

During 1968, the F-111B was canceled by the Navy on account of weight and performance issues together with revised tactical requirements.{{Sfn|Boyne|2002|p=252}}<ref>Thomason 1998, pp. 52–53.</ref> Australia would procure its own model, the F-111C. Subsequently, the improved F-111E, F-111D, and F-111F models were developed for the USAF. The strategic bomber FB-111A and the EF-111 electronic warfare versions were later developed for the USAF.{{Sfn|Frawley|2002|p= 89}} Production of the F-111 ended in 1976,<ref name=Miller_p65>Miller 1982, p. 65.</ref> following the completion of 563 aircraft.<ref name=Logan_p9 />