The General Dynamics F-111C (nicknamed the "Pig") is a variant of the F-111 Aardvark medium-range interdictor and tactical strike aircraft, developed by General Dynamics to meet Australian requirements. The design was based on the F-111A model but included longer wings and strengthened undercarriage. The Australian government ordered 24 F-111Cs to equip the Royal Australian Air Force (RAAF) in 1963, but the aircraft were not delivered until 1973 because of long-running technical problems. During 1979 and 1980 four of these aircraft were converted to the RF-111C reconnaissance variant. Four ex–United States Air Force (USAF) F-111As were purchased by Australia and converted to F-111C standard in 1982 to replace F-111Cs destroyed during accidents. Australia also operated 15 F-111Gs between 1993 and 2007, mainly for conversion training. In Australian military and aviation circles, the F-111 Aardvark was affectionately known as the "Pig", due to its long snout and terrain-following ability."When pigs fly!" USAF Air Combat Command, 12 March 2009. Retrieved: 30 December 2010.Klesius, Michael. "When Pigs Could Fly" . airspacemag.com, 31 January 2011. Retrieved: 3 February 2011.

The F-111Cs gave the RAAF a powerful strike capability but were never used in combat. The aircraft went through modernization programs in the 1980s and 1990s, and the RAAF acquired improved weapons to maintain their ability to penetrate hostile airspace. Despite this, by the 2000s the F-111Cs were becoming outdated and expensive to maintain, leading to a decision to retire them in 2010 rather than 2020 as originally planned. The F-111s were replaced by 24 Boeing F/A-18F Super Hornets, who were later supplemented with F-35 Lightning IIs in the early 2020s.

Development Background

In June 1960, the United States Air Force (USAF) issued a requirement for an F-105 Thunderchief replacement.Wilson 1989, p. 129. The U.S. Navy began a program to develop a new air defense fighter for use on its large aircraft carriers. On 14 February 1961, newly appointed United States Secretary of Defense Robert McNamara formally directed that the services study the development of a single aircraft that would satisfy both requirements.Gunston 1978, pp. 8–17. The Tactical Fighter Experimental (TFX) requirements were based largely on the Air Force's needs.Miller 1982, pp. 11–15. A request for proposals (RFP) for the TFX was provided to industry in October 1961. After four rounds of proposals, General Dynamics (GD) was selected over Boeing; GD signed the TFX contract in December 1962.Gunston 1978, pp. 18–20.

The USAF F-111A and Navy F-111B variants used the same airframe structural components and TF30-P-1 turbofan engines. They featured side-by-side crew seating in an escape capsule, as required by the Navy. Because of conflict between the Air Force and Navy over whose requirements had precedence, McNamara intervened in 1961, declaring that the Air Force desires would override suggestions by the Navy. The F-111A variant first flew on 21 December 1964 from Carswell AFB, Texas.Eden 2004, p. 197. It was followed by the F-111B, which first flew on 18 May 1965.Thomason 1998, pp. 16, 20.

As F-111 development continued, stall issues arose in certain parts of the flight regime; these were addressed by modifying the engine inlet in 1965–66, ending with the "Triple Plow I" and "Triple Plow II" designs.Gunston 1978, pp. 25–27. The F-111B was cancelled by the Navy in 1968 due to weight and performance deficiencies.Donald, David, ed. "General Dynamics F-111". The Complete Encyclopedia of World Aircraft. New York: Barnes & Noble Books, 1997. . The improved F-111E, F-111D, F-111F models were subsequently developed for the USAF. The FB-111A strategic bomber and the EF-111 electronic warfare versions were also later developed for the USAF.Frawley, Gerald. "General Dynamics F-111 Aardvark". The International Directory of Military Aircraft, 2002/2003. London: Aerospace Publications, 2002. . Production ended in 1976,Miller 1982, p. 65. with a total of 563 F-111s of all variants built,Logan 1998, p. 9. well below the prediction of 1,500.

Replacing the Canberra

The Menzies government first publicly discussed the need for replacing the English Electric Canberra in 1954, only a year after the RAAF began receiving the bomber.Weisbrod 1969, p. 7. The non-supersonic Canberra lacked radar and electronic countermeasures, all disadvantages based on Korean War experience. The RAAF believed that it needed a new strategic bomber to fulfill the nation's obligations to the Commonwealth Strategic Reserve in Malaysia, ANZUS, and SEATO. Air Staff Requirement 36 that year mandated an all-weather attack aircraft by 1959 capable of delivering a variety of bombs and missiles. A study recommended one of the British V bombers, but Minister of Defence Frederick Shedden decided in 1956 that at £1 million each they were too expensive.Lax 2010, pp. 9–10, 13–14.

Air Marshal Valston Hancock, Chief of the Air Staff, stated in April 1960 that Australia needed a replacement for the Canberra.Weisbrod 1969, pp. 7–27. Although in mid-1962 the Menzies government again decided to not replace the Canberra, Indonesia's increasingly aggressive statements regarding Malaysia soon caused Australia to reevaluate the decision.Lax 2010, p. 14. The Sydney Morning Herald reported in October 1962 that the Indonesian Air Force's Soviet Tupolev Tu-16 bombers could reach Sydney or any other Australian city with a light bomb load, while the Canberras could not fly in all weather and had a range of , insufficient to reach Jakarta. The opposition Labor Party, led by Arthur Calwell, used the report to criticize Menzies. The government denied that the Tu-16 could reach Sydney,Lax 2010, p. 15. but Minister for Air Frederick Osborne acknowledged that the Canberras were "the weakest link in our armory at the present moment". He stated, however, that the available foreign bombers were unsuitable for the RAAF. The American Boeing B-52 Stratofortress and Convair B-58 Hustler, for example, were too large for existing Australian runways. More suitable aircraft such as the British BAC TSR-2 and the American TFX (later the F-111) would soon be available, Osborne said.

Hancock study In May 1963 Menzies announced an A£200 million increase in defense spending over the next five years, and proposed to send a team led by Hancock overseas to evaluate Canberra replacements. Early candidates were the French Dassault Mirage IV, the TSR-2, and the U.S. North American A-5 Vigilante, McDonnell Douglas F-4 Phantom II and the TFX.Wilson 1989, p. 146.Eden 2004, p. 200. From June to August, Hancock's team visited France, Britain and the United States to evaluate the competitors, and determined that the TFX would be the aircraft best suited for the role.Lax 2010, p. 25. The Mirage IV had insufficient range and the A£108 million price was too expensive. The F-4 and the A-5 were immediately available, but the less expensive F-4 would need air-to-air refueling to reach Indonesia from Australia. The TSR-2 was behind schedule and over budget, was the most expensive at A£122 million for 24 aircraft, and British government support for the program was uncertain. While the TFX was also controversial in the United States, its promised performance specifications and per-aircraft cost were superior to that of the TSR-2. As he did not expect TFX to be available before 1970, however, Hancock recommended buying 36 A-5 aircraft for A£88 million to counteract the perceived imminent threat from Indonesia.Lax 2010, pp. 26–27.

The Menzies government was reluctant to choose as interim replacement the A-5 or the F-4, which could not be deployed until 1966 and would cost A$120–180 million. Waiting for the TSR-2 or TFX in 1969 or 1970 seemed to pose great risk, but when considering Hancock's findings in September 1963 it wanted to be able to offer a substantial response to the Labor party's criticism of its defense strategy.Lax 2010, p. 28. The British and American governments competed on behalf of their nations' unbuilt bombers, as both believed that export sales would increase domestic support for the aircraft. The Menzies government viewed the British promise to deploy a squadron of V bombers in Australia for interim defense until the TSR-2 was ready as unacceptable for both technical and political reasons. Beyond its cost, the Royal Air Force had not ordered the TSR-2; the Chief of the Defence Staff Lord Louis Mountbatten, who opposed it, advised the Australians against buying the aircraft and the RAAF feared being the only customer.Lax 2010, pp. 17–18.

Decision The government determined that it did not need to go ahead with an immediate replacement for the Canberra and preferred Hancock's original choice of the TFX as a long-term solution, leading to the Menzies government's announcement on 24 October that it was ordering 24 F-111sStephens, The Royal Australian Air Force, pp. 283–286. for US$125 million, enough for two squadrons.Lax 2010, p. 30. The announcement came during the campaigning for the 1963 general election. Calwell's Labor party had on 22 October reiterated its pre-campaign promise that it would replace the Canberras as soon as it formed a government. The government's announcement, and the consequent improvement of its chances against Labor, likely also benefited the United States; the purchase helped rebut American critics of the TFX, and the Kennedy administration preferred Menzies' defense policies to the opposition's.Lax 2010, pp. 30–31. The contract was signed the following year through the U.S. Department of Defense.Miller 1982, p. 30. The British government's cancellation of the TSR-2 in April 1965 showed that Australia's decision to not order it was correct.Lax 2010, pp. 18–19.

Procurement, delays, and renaming The U.S. offered two squadrons of Boeing B-47 Stratojets for free lease pending the delivery of the F-111; Australia declined the offer in June 1964Wilson 1989, pp. 146, 150.—despite the aircraft having been demonstrated around the country just before the 1963 election as an interim Canberra replacement, likely another sign of the American preference for Menzies—Lax 2010, p. 38. because the B-47 did not offer significant improvements over the Canberra and, like the V bombers, would require longer runways.

The immensely complex and ambitious F-111 design and construction process forced the Australian government to quickly adopt sophisticated American procurement and project management methods. Although Australia originally planned to buy the American F-111A design, RAAF liaison officers requested country-specific changes such as a long-distance radio, Aeronautical Research Laboratories in Melbourne participated in an intake redesign and provided metal fatigue expertise, and an Australian test pilot evaluated the Australian version's longer wings and performance in tropical conditions. The differences from the F-111A caused it to be designated the F-111C in 1966.Lax 2010, pp. 43–45, 48–50, 82.

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