<p>Colloquially known as the 'Aardvark', the General Dynamics F-111 is assured of a place in aviation history by virtue of the fact that it was the first variable-geometry, or 'swing-wing', aircraft to attain quantity production for any air arm in the world. Today, of course, VG is a commonplace feature of modern combat aircraft, types such as the Panavia Tornado, Grumman F-14 Tomcat and Mikoyan-Gurevich MiG-23/27 'Flogger' all using such wings to achieve satisfactory low-speed handling qualities, good range/payload characteristics and superior field performance without compromising capability at the other end of the speed scale.
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<p>The design and manufacturing teams for these later aircraft seem to have encountered few serious development problems. But the same was most certainly not true of the F-111, General Dynamics running into great difficulty during the course of development. Even after the type attained operational service it continued to fall victim to a succession of problems, being grounded on several occasions as a result of accidents, while the fact that it was something of a political 'hot potato' added fuel to the fires of controversy which raged around the F-111 for several years. Like most innovative types, it took time to develop fixes, but once these had been incorporated the F-111 began to show definite signs of living up to its early promise.
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<hi style=hdr1>Fighter Requirement</hi>
<p>Development of what eventually evolved into the F-111 can be traced back to July 1960, when Specific Operational Requirement No. 183 was issued by the USAF. In essence this called for a new fighter capable of fulfilling such disparate missions as air superiority, conventional and nuclear strike, and reconnaissance.
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<p>One of the key aspects of SOR183 concerned the VG wing, the USAF being of the opinion that this represented the most suitable line of approach while also expressing the view that a turbofan engine would be worthy of consideration. Had the Air Force been allowed to proceed independently the F-111's subsequent history might have been less checkered, but the fact that the US Navy was also engaged in the preliminary stages of the search for a new fighter to replace the McDonnell Douglas F-4 Phantom prompted Secretary of Defense Robert McNamara to recommend that the two requirements be combined into a single program known by the acronym TFX. Not surprisingly, this recommendation met considerable opposition within the two armed forces, but McNamara stuck to his guns, a new request for proposals being issued at the end of September 1961. In the event, nine responses were received during December of that year, the same month in which the designation F-111 was allocated to the new fighter.
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<hi style=hdr1>Competition Victory</hi>
<p>Study of these submissions revealed that none was acceptable in its original form, but Boeing and General Dynamics were invited to refine their concepts further and the next few months witnessed considerable in-fighting as the services sought to reconcile their requirements in the face of McNamara's continuing intransigence. Eventually, after extensive redesign and despite Air Force recommendation of the Boeing contender, the General Dynamics submission emerged victorious, initial procurement of 23 development aircraft (18 USAF F-111As and five USN F-111Bs) being authorized. Manufacture of the USAF examples was entrusted to General Dynamics' Fort Worth factory, while the Navy aircraft was the responsibility primarily of Grumman at Bethpage. The two variants made their first flights on 21 December 1964 and 18 May 1965 from Carswell AFB and Calverton, respectively.
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<p>Flight testing soon began to reveal problems, but the F-111A model did eventually attain operational status almost three years later when the first production examples began to join the 474th Tactical Fighter Wing at Cannon AFB, New Mexico, in mid-October 1967, this unit moving to Nellis AFB, Nevada, early in 1968.
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<p>Like most types then in, or about to enter, USAF service, the F-111 was introduced to combat at the earliest possible date, 'Combat Lancer' being the codename assigned to the deployment of six F-111As from Nellis to Takhli, Thailand, in March 1968. This initial exposure to the hazards of combat proved to be inauspicious, two F-111As being lost during the course of the first 55 missions against targets in North Vietnam. Replacements were dispatched from Nellis, but before they arrived another F-111A was reported missing on 22 April, this effectively marking the end of the combat debut of the 'Aardvark', although it was not until November that the surviving aircraft returned to the USA.
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<p>Several years elapsed before the F-111 returned to the rigors of war during the final stages of the Vietnam conflict. This time, two entire squadrons with a combined strength of about 50 aircraft were committed to action at the end of September 1972, and despite several losses the aircraft performed well, logging more than 3,000 missions before Linebacker II prompted the North Vietnamese to return to the negotiating table in earnest.
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<p>Often operating alone or in small 'packages', the 'Aardvark' repeatedly flew when other types were grounded by poor weather, this period effectively signalling that the F-111 was at last maturing into an effective warplane. Nevertheless, there were still many problems to be overcome.
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<p>Although the Air Force eventually succeeded in getting the aircraft it had originally wanted, the same claim could not be made for the Navy which had never been particularly enthusiastic about the F-111B. Eventually, unacceptable weight growth coupled with a serious performance shortfall resulted in a production hold order being placed on the type during July 1968. By that time, the five development F-111Bs had been joined in the flight test program by the first two production examples, which eventually proved to be the last F-111Bs completed, funding for 30 more of the latter being blocked by the Senate and the House Armed Services Committee. This effectively killed the F-111B, but it was not until August 1968 that the F-111B program was officially cancelled, a further blow to General Dynamics which was still recovering from the British decision to abandon plans to acquire 50 examples of a variant designated F-111K.
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<hi style=hdr1>Further Models</hi>
<p>As far as the initial model was concerned, only 17 RDT&E F-111As were completed, the 18th and last example being employed as the FB-111A prototype. These initial aircraft were followed by 141 production machines, the last of which was delivered to the USAF at the end of August 1969. By then, the first example of the second production version (rather confusingly designated F-111E) had flown, this being the forerunner of 94 aircraft, and it initially entered service with the 27th TFW at Cannon AFB, New Mexico, in the autumn of the same year, although most of these aircraft were subsequently deployed overseas with the 20th TFW at RAF Upper Heyford, England. There followed some 96 examples of the considerably more capable F-111D, which featured much revised avionics, this variant also making its debut with the 27th TFW. Production of tactical fighter models for the USAF terminated with 106 copies of the F-111F. Introducing a considerably more-powerful version of the TF30 turbofan engine, the F-111F was first assigned to the 347th TFW at Mountain Home AFB, Idaho, but, following a complex realignment exercise involving the F-111A, F111D and F-111F versions, this too went to Europe, equipping four squadrons of the 48th TFW at RAF Lakenheath.
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<p>The remaining major version developed for service with the USAF was the FB-111A, which equipped two Strategic Air Command bomb wings in the northeastern corner of the USA. Optimized for strategic rather than tactical missions, the FB-111A prototype (originally laid down as the 18th RDT&E F-111A) flew for the first time at the end of July 1967 and was followed into the air by the first production example just under a year later. Even then, it was not until mid-October 1969 that deliveries to SAC began, this command eventually receiving 75 of the 76 production specimens built, one being written off in a pre-delivery accident. Very much a hybrid, the FB-111A was essentially a marriage of the F-111D fuselage and inlets to the larger wing of the F-111B/C. It also features stronger landing gear and has a different variant of the TF30 engine. FB-111As were stripped of their strategic role and transferred to the 27th TFW, receiving the designation F-111G.
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<p>Several years after it last saw action in Southeast Asia, the F-111 was called upon for one of the more daring raids of recent years; F-111Fs of the 48th TFW spearheaded the US attack on Libya in April 1986, striking several targets in and around Tripoli with laser-guided and retarded bombs. The aircraft is still in service, and is described in detail in the Modern Aircraft section.
<item><hi format=bold>Powerplant:</hi> two Pratt & Whitney TF30-P-3 turbofans, rated at 18,500 lb thrust with afterburner
<item><hi format=bold>Performance:</hi> maximum speed 1,650 mph at 40,000 ft; service ceiling 60,000 ft; range 3,800 miles
<item><hi format=bold>Weights:</hi> empty 45,200 lb; maximum take-off 92,500 lb
<item><hi format=bold>Dimensions:</hi> wing span 63 ft 0 in (minimum sweep), 31 ft 11 in (full sweep); length 73 ft 6 in; height 17 ft 01/2 in; wing area 525 sq ft
<item><hi format=bold>Armament:</hi> internal weapons bay for two 2,000-lb bombs or one M61A1 20-mm cannon; maximum ordnance load 30,000 lb
