General Dynamics F-111

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The General Dynamics F-111 is a medium-range strategic bomber, reconnaissance, and tactical strike aircraft. The United States Air Force (USAF) variants were officially named Aardvark, their longtime nickname, at their ceremony of retirement from service in 1996. In Australian service the F-111 is known as the Pig.

The F-111 was initially promoted as a triumph of versatility as a replacement for the F-4 Phantom II in service with both the Air Force and US Navy. With its swing wings, it could take off slowly and fly fast from aircraft carriers and unprepared airfields with a big payload over long ranges and shoot down aircraft with long range missiles. But it would be the Phantom which would demonstrate just how versatile a multi-role fighter can be as bomber, dogfighter and reconnaissance platform in 3 services and many nations. The F-111 would demonstrate the inflexibility of a heavy fighter designed around a single point. It pioneered many new technologies, such as the crew escape capsule, swing wings with consequent moving weapon pylons, supersonic turbofan engines, terrain following radar, and digital electronics. The F-111 was, however, successful in the role of deep interdiction/strike aircraft.

In capabilities and role, it can be compared to the B-58 Hustler medium bomber, the A-6 Intruder all-weather attack bomber, A-5 Vigilante strike bomber and F-105 Thunderchief. It has been effectively replaced in United States Service by the F-15E Strike Eagle for medium range precision strike missions, while most fighter missions have been taken over by the F-15 and F-16. The supersonic bomber role has been replaced by the B-1 Lancer. The Royal Australian Air Force is currently intending to replace its F-111 aircraft with the F-35 Joint Strike Fighter.

Contents

Development

The beginnings of the F-111 were in the TFX, an ambitious early 1960s project to combine the U.S. Air Force requirement for a fighter-bomber with the U.S. Navy's need for a long-range carrier defense fighter to replace the F-4 Phantom II and the F-8 Crusader. The fighter design philosophy of the day concentrated on very high speed, raw power, and air-to-air missiles.

The USAF's Tactical Air Command (TAC) was largely concerned with the fighter-bomber and deep strike/interdiction role, which in the early 1960s still focused on the use of nuclear weapons. The aircraft would be a follow-on to the F-105 Thunderchief, which was designed to deliver nuclear weapons low, fast and far. Air combat would be an afterthought until encountering MIG Migs over Vietnam in the mid 1960s. In June 1960 the USAF issued a specification for a long-range interdiction/strike aircraft able to penetrate Soviet air defenses at very low altitudes and very high speeds to deliver tactical nuclear weapons against crucial Soviet targets like airfields and supply depots. Included in the specification were a low-level speed of Mach 1.2, a high-altitude speed of Mach 2.5, a combat radius of 890 mi (1,430 km), good short-field performance, and a ferry range long enough to reach Europe without refuelling.

Meanwhile the U.S. Navy had, since 1957, been searching for a long-range, high-endurance interceptor to defend its carrier groups against the new generation of Soviet jet bombers, which by then were being armed with huge anti-ship missiles with nuclear warheads. The Navy needed a Fleet Air Defense (FAD) aircraft with better loitering performance and load-carrying ability than the F-4 Phantom II, equipped with a powerful radar and a battery of long-range missiles to intercept both bombers and their missiles.

The Navy had studied, but rejected a slow straight-winged missile carrier, the F6D Missileer. In December 1960 the Navy had been reconsidering variable geometry for the FAD requirement. The trend toward ever bigger, more powerful fighters posed a problem for the Navy: the current generation of naval fighters were already barely capable of landing on an aircraft carrier deck, and a still larger and faster fighter would pose even greater problems. An airframe optimised for high speed — most obviously with a high-angle swept wing — is inefficient at cruising speeds, which reduces range, payload, and endurance, and leads to very high landing speeds. On the other hand, an airframe with a straight or modestly swept wing, while easier to handle and able to carry heavy loads over longer distances on a minimum of fuel, has lower ultimate performance. Variable geometry, which the Navy had tried and abandoned for the XF10F Jaguar in 1953, offered the possibility of combining both in a single airframe.

Robert McNamara, CEO and fighter designer

Both of these requirements were about to be marred by politics, and then checkered by considerable controversy.^{[[Citing sources citation needed]]} The newly appointed Secretary of Defense Robert McNamara, who had just come from a successful stint as president of the Ford Motor Company, was a great believer in "commonality" — using a single versatile platform instead of several fighters specialized for each service would lead to substantial cost savings. He had already directed the Air Force to adopt the highly successful F-4 Phantom and A-7 fighters. On 16 February 1961, less than a month after taking office, McNamara ordered the services to combine the Air Force requirement for a strike bomber with the Navy's requirements for a long range missile interceptor. At one stage, it was even planned to use it for the U.S. Army and Marine Corps as a close air support platform. Although the services insisted that a single aircraft was not technically feasible, McNamara ordered the development of a common aircraft to proceed anyway.

The program was dubbed Tactical Fighter Experimental (TFX). Requests for proposals were issued to Boeing, General Dynamics, Lockheed, Northrop, Grumman, McDonnell, Douglas Aircraft, North American Aviation, and Republic Aviation. Nine proposals were received in December 1961, and while the USAF and Navy felt that none were entirely suitable, on 19 January 1962 they indicated that the Boeing and General Dynamics proposals looked most promising.

After a series of subsequent proposals, in September 1962 the USAF and Navy indicated they preferred the Boeing design, but McNamara again overrode their decision, and the Department of Defense awarded the contract to General Dynamics on 24 November 1962, in part because the General Dynamics design promised to be more affordable and allow greater commonality. This decision was to seem particularly ironic considering what followed. Grumman, which had greater experience with carrier aircraft, was engaged as the primary subcontractor. The Boeing design featured an intake above the cockpit, which would have been free of ground debris, and air disturbed by the wing, which would later plague the F-111 inlet design. Boeing would later redesign their Boeing SST wing design to incorporate a wing that would sweep into a delta configuration like the GD F-111.

The TFX design eventually emerged as an aircraft in the 20-ton (empty) class with a maximum take-off weight of almost 50 tons. It had been intended to use titanium for large portions of the airframe to save weight, but this proved prohibitively expensive. Grumman would later make extensive use of titanium in the F-14. The TFX was powered by two afterburning Pratt & Whitney TF30-P-100 turbofans in the 80 kN class. Previous supersonic aircraft had used afterburning turbojets which do not have the cruise efficiency of turbofans which also move unburned air for thrust.

The shoulder-mounted wings were attached to a pair of giant pivots, allowing it to take off, land, and loiter with a modest 16° sweep (for maximum lift and minimum landing speed), cruise at high subsonic speeds with a 35° sweep, or sweep back to a 72.5° maximum for fast supersonic dashes at more than Mach 2. Despite its high maximum speed, its modest thrust-to-weight ratio made it underpowered for a fighter, though less so than the J79 engined 80,000 lb A-5 Vigilante. This situation was exacerbated by compressor stalls and other engine problems that forced a hasty redesign of the engine inlets.

Largely at Navy insistence, the F-111 seated the crew of two side-by-side as it helped create a shorter aircraft which would be easier to store and move on carrier decks, along with the shorter nose fitted to the Navy B version. However this would have an impact on aircraft agility because of increased drag and weight. Production versions did not have ejection seats, instead using what would be the only operational crew escape capsule. A 27,000 lb thrust rocket would blow the entire crew compartment and the root of the wing aft of the cabin off the nose of aircraft. It would descend below a 70 ft (21 m) parachute, landing on an airbag to cushion the impact. The escape module meant that two crew could work in a "shirt sleeves" environment without pressure suits or oxygen masks. The B-58 Hustler and XB-70 had employed single seat capsules, while the only the first prototype B-1A were built with an escape capsule. Initial crews objected to the "matiness" of the tight side-by-side seating, since the aircraft was originally intended to be a fighter, not attack aircraft.

First flight of the F-111A, as the USAF version was designated, was 21 December 1964, and entry into service with the USAF began 18 July 1967.

Lessons of the F-111B cancellation

The winning contractor General Dynamics chose Grumman to apply their carrier aircraft expertise to the F-111B. However adapting a low-level bomber meant compromises such as a smaller radar than the Navy required, and it was drastically overweight at nearly 80,000 lb at takeoff. It was judged underpowered, as agile as a Greyhound bus, and its visibility was judged ill-suited to carrier operations, even though the successfully deployed RA-5C Vigilante also had a gross weight of 80,000 lb with less powerful J79 engines.

The final undoing of McNamara's vision of commonality would be the one factor overlooked by both the Navy and Air Force from the lengthy TFX specification. Maneuverability was thought to be obsolete by the missile age, yet it had been one of the most decisive factors in every previous air conflict. In 1965, the fighter community was shocked when the F-111's forerunner, the supersonic F-105 was shot down by post-Korean war vintage Mig-17s which were slow but nimble, and Navy F-4 pilots were scoring their first kills.Rand report: Return of the Air Superiority Fighters The Sparrow medium range missile was unreliable and ineffective at close range. Guns, which were deleted as excess weight from the F-4, often were effective. When the Navy ordered Grumman to study the effectiveness of the F-111B in such a scenario, they concluded it "could not cope" in a dogfight. In 1967, Vice Adm Tom Connolly, call sign "Tomcat" testified before Congress that "Gentlemen, there isn't enough thrust in Christendom to make that airplane into a fighter". Combined with issues of weight and carrier suitability, that testimony effectively killed the F-111B.[link] Flight Journal June 2006 Tomcat: hail & farewell, by Barrett Tillman.

The Senate Armed Services Committee cancelled the F-111B on March 28, 1968.General Dynamics F-111 "Aardvark" by Jay Miller Aero Series 29 1982 p. 54 Seven planes had been completed. The Navy would conduct sea trials after the cancellation in late 1968, and pilots reported that it flew quite well, with no problems with takeoffs, arrests, or onboard storage. The ironic positive legacy was that the F-111's dogfight performance was so abysmal, and the accountant's approach to fighter design was so discredited that in effect, the program would serve as expensive lesson in how not to build a fighter.Modern Marvels F-14 "Grumman: we had a pretty good idea what not to do" The TFX incident would be a major blemish on the record of Robert McNamara, along with his micromanaging of the air war over Vietnam. Both the Navy and USAF embarked on the FX and VFAX studies on what would become a generation of 4 new air superiority fighters. The first of these would be the F-14 Tomcat. Grumman had already produced an internal study, the Grumman 303, which essentially transplanted the long range Phoenix missiles, AWG-9 radar and TF30 engines of the F-111B into their VFAX agile fighter design. The VFAX was originally intended to supplement the F-111B which could not tangle with MiGs, once Grumman showed that one airframe could do both, there was no need for the F-111B at all. The Air Force would in parallel, formulate an entirely new F-15 Eagle which put agility as its first design priority. Contrary to McNamara's vision, the DOD would successfully field 4 new specialized fighters for both services, all built around the F-4 as a benchmark for payload and speed.

F-111s and F-14s are created equal at the scrapyard.

Versatility, versatility, versatility

For all of the talk about "versatility", this did not exist in any one airframe. The navalized F-111B had a single mission of fleet air defense (FADF). Its outstretched wings would allow a long time on station, then swept back, it would dash to meet oncoming targets and clear the sky with its 6 heavy AIM-54 Phoenix missiles. It was never meant for combat air patrol or escort. Whoever had written up the requirements never fitted it with armanent as basic as a gun or even the simple Sidewinder fielded by the elegant F-8 Crusader. Neither would it be equipped to deliver bombs, even though the nearly identical F-111A had a prodigious range, payload and low level navigation capabilities far exeeding either the A-6 Intruder or A-5 Vigilante. Similarly, the F-111A was not even equipped to fire missiles as simple as the Phantom's AIM-7 Sparrow.

All of these new fighters were planned to have both air superiority and basic ground attack capabilities. The shadow of commonality was so deep that planners would limit both the F-14 Tomcat and F-15 to the dedicated air superiority or fleet defence role until the 1990s. The F-15E growth variant would eventually replace the F-111 as well, and adapted as the "Bombcat", the F-14 would also be adapted to a precision long range strike role.

The F-111B would prove to be an utter failure. But when the F-111A finally reached combat service in Vietnam, new tactics would prove to be able to evade fighters like the Mig-17 and the series went on to serve with the USAF through the mid-1990s, performing with distinction in the 1991 Gulf War as bombers and jammers. Although the United Kingdom had expressed interest in the program in 1965 in preference to the home grown BAC TSR-2, the British order for the F-111 was cancelled. Somewhat ironically for a plane widely considered to be a failure,^{[[Citing sources citation needed]]} the F-111s only export customer, the Royal Australian Air Force, will be flying their "Pigs" well after the USN has retired the F-14 in 2006. After a protracted delay for deliveries using loaned F-4E Phantoms in the 1970s, they have been quite pleased, and they continue to upgrade the aircraft with modern avionics and updated weapon systems.

Similar swing wing aircraft

The F-111 was the first production variable-geometry aircraft. The earlier subsonic Navy XF10F Jaguar had been cancelled in 1953. It inspired a number of aircraft throughout the 1980s, and even fictional aircraft on the Thunderbirds (TV series), but swing wings are extinct in newer designs due to higher cost, and the extra weight imposed by the swing wing mechanism. Nevertheless, several other types have followed, including the Soviet Sukhoi Su-17 (1966), Mikoyan-Gurevich MiG-23 (1967), Tupolev Tu-22M (1969) and Tupolev Tu-160 (1981), the U.S. F-14 Tomcat naval fighter (1970) and B-1B Lancer bomber (1974), and the European Panavia Tornado (1974). The Sukhoi Su-24 (1970), which resembles the F-111, also has side-by-side seating.

Armament

F-111 cockpit prior to a night flight.

Although conceived as a multi-role fighter, the F-111 became a long-range attack aircraft primarily armed with air-to-surface ordnance.

Weapons bay

The F-111 has a small internal weapons bay under the fuselage for various weapons.

Cannon: All tactical combat versions (that is, not the EF-111A or FB-111A/F-111G) could carry a single M61 Vulcan 20 mm cannon with a very large (2,084 round) ammunition tank, covered by an eyelid shutter when not in use. Although carried by some USAF aircraft, the cannon was never actually used in combat, and was removed by the early 1980s; provision for the cannon has also been deleted from Australian F-111Cs.
Bombs: The bay can alternately hold two conventional bombs, usually the Mk 117 type of nominal 750 lb/340 kg weight, although weapons up to the Mk 118 (3,000 lb/1,362 kg) were cleared.
Nuclear weapons: All F-111 models except the EF-111A and the Australian F-111C were equipped to carry various free-fall nuclear weapons: tactical models generally carried the B43, B57, or B61, the FB-111A those weapons or the B83. The FB-111A could also carry one or two AGM-69 SRAM nuclear missiles in its weapons bay.
Sensor pod: The F-111C and F-111F were equipped to carry the AN/AVQ-26 Pave Tack targeting system on a rotating carriage that kept the pod protected within the weapons bay when not in use. Pave Tack is a FLIR and laser rangefinder/designator that allows the F-111 to designate and drop laser-guided bombs.
Reconnaissance pallet: Australian RF-111Cs carry a package of reconnaissance sensors and cameras for tactical recce missions. It contains two video cameras, a Honeywell AN/AAD-5 infrared linescan (recorded on video or film), a Fairchild KA-56E low-altitude and KA-93A4 high-altitude panoramic cameras, and a pair of CAI KS-87C split vertical cameras. It can also record photographs of the attack radar's display.
Missiles: The F-111B was intended to be capable of carrying two AIM-54 Phoenix air-to-air missiles in the bay. General Dynamics proposed an arrangement that would allow two AIM-9 Sidewinders to be carried on a trapeze mounting in the bay (at the expense of the M61 cannon), along with a single (usually nuclear) bomb. This was not adopted, with the USAF and RAAF opting for the cannon instead. The AIM-7 Sparrow or Falcon, standard on the F-4, was never fitted, though later F-111 models had radars equipped to guide the Sparrow.
Other equipment: Auxiliary fuel tanks and baggage pods were sometimes carried.

External ordnance

F-111F aircraft releasing its load of Mark 82 high-drag bombs over the Bardenas Reales range.

The potential supersonic speed with swept wings compared with subsonic types such as the A-6 is offset by the inability to carry any more external stores than can be carried internally or on 2 pylons. Most missions are subsonic with weapons carried on two inner pylons on each wing. By contrast, the F-14 and Tornado can carry full bomb loads with fully swept wings. The design of the F-111's fuselage prevents the carriage of external weapons under the fuselage (although there are two small stations, one on the weapon bay, the other on the rear fuselage between the engines, for ECM pods). All aircraft have provision for eight underwing pylons, four under each wing, with a capacity of 6,000 lb (2,722 kg) each. The inner pylons (3, 4, 5, and 6) pivot with the wing, but only one on each side can be loaded at maximum sweep. The outer pylons (1, 2, 7, and 8) are fixed, and can be loaded only if the wings are spread at less than 26°, causing drag at takeoff angle. The outermost pylons (1 and 8) have never been used operationally, and the second pair of fixed pylons (2 and 7) are fitted only rarely for the carriage of fuel tanks. FB-111/F-111G models have provision to jettison their empty pylons in flight, reducing drag.

An F-111 carrying BLU-107 Durandals.

The primary external armament of USAF tactical F-111s included:

Free-fall GP bombs:
* Mk 82 (500 lb/227 kg)
* Mk 83 (1,000 lb/454 kg)
* Mk 84 (2,000 lb/907 kg)
* Mk 117 (750 lb/340 kg)
Cluster bombs
BLU-109 (2,000 lb/907 kg) hardened penetration bomb
Paveway laser-guided bombs, including:
* GBU-10 (2,000 lb/907 kg)
* GBU-12 (500 lb/227 kg)
* GBU-28, a very specialized 4,800 lb (2,177 kg) penetration bomb using spare naval gun barrels as casings, hastily developed for the Gulf War
BLU-107 Durandal runway-cratering bomb
GBU-15 electro-optical bomb (using a Mk 84 or BLU-109 penetration weapon with a TV or infrared TV seeker from an AGM-65 Maverick, with guidance via an AXQ14 or ZWS-1 datalink pod
AGM-130 stand-off bomb (essentially a Mk 84 or BLU-109 with GBU-15 guidance and a rocket booster, making it a powered missile with a range of 40 miles (64 km)).

Although all F-111s can carry laser-guided munitions, only those with Pave Tack (that is, F-111F and Australian F-111C) are capable of designating targets. Others can drop laser-guided weapons only with the aid of another ground or air designator.

From the early 1980s onward, tactical F-111s were fitted with shoulder rails on the sides of the outboard swiveling pylon (designated stations 3A and 6A) for two AIM-9 Sidewinder air-to-air missiles for self-defense. The standard Sidewinder fit was the AIM-9P, rather than the more modern AIM-9L or AIM-9M, whose larger fins were not compatible with the shoulder rail. The RAAF has considered replacing the Sidewinder with ASRAAM.

FB-111As could carry the same conventional ordnance as their tactical brothers, but their wing pylons were more commonly used for either fuel tanks or strategic nuclear gravity bombs. Until the weapon was withdrawn in 1990, they could carry up to four AGM-69 SRAM nuclear missiles on the wing pylons, although two was the more normal fit.

Australian F-111Cs are not nuclear-capable, but have been equipped to launch the AGM-84 Harpoon anti-ship missile, AGM-88 HARM anti-radiation missile, and the AGM-142 Popeye stand-off missile.

Service life

The F-111 was in service with the USAF from 1967 through 1998. It entered active service with the Royal Australian Air Force in 1973 and is currently scheduled to remain with the RAAF until 2010. There are concerns by some that this will leave a capability gap in the event of a delay in F-35 Lightning II deliveries.

Variants

F-111A

An F-111A dropping 24 Mark 82 low-drag bombs in-flight over a bombing range.

The F-111A was the initial production version of the F-111. It had TF30-P-3 engines with 12,000 lbf (53.38 kN) dry and 18,500 lbf (82.29 kN) afterburning thrust and "Triple Plow I" variable intakes, providing a maximum speed of Mach 2.2 (1,453 mph / 2,325 km/h) at altitude.

The -A's Mark I avionics suite included the General Electric AN/APQ-113 attack radar mated to a separate Texas Instruments AN/APQ-110 terrain-following radar under the nose and a Litton AJQ-20 inertial navigation and nav/attack system.

Total production of the F-111A was 158, including 17 preproduction aircraft that were later brought up to production standards.

The first production F-111s were delivered on 18 July, 1967 to the 428th, 429th and 430th Tactical Fighter Squadrons of the 474th Tactical Fighter Wing based at first out of Cannon AFB, New Mexico, which relocated in 1968 to Nellis AFB.

After early testing a detachment of six aircraft were sent in March 1968 to Southeast Asia for Combat Lancer testing in real combat conditions in Vietnam. In little over a month, three aircraft were lost and the combat tests were halted. It turned out that all three had been lost through malfunction (primarily with the terrain-following radar), not by enemy action. This caused a storm of political recrimination, with U.S. Senators denouncing Secretary of Defense McNamara's judgment in procuring the aircraft.

Behind the scenes, lessons were being learned and fixes being applied, but it was not until July of 1971 that the 474 TFW was fully operational. Testing in 1969 had revealed that a contractor had been paying off inspectors to approve sub-standard work on structural wing components, and all aircraft had to have the component replaced at significant cost (since most F-111As had been already completed). More failures were found and corrected in the wing pivot forgings.

1972 saw the F-111 back in Vietnam, participating in the Operation Linebacker II aerial offensive against the North. F-111 missions did not require tankers nor ECM support, and they could operate in weather that grounded most other aircraft. One F-111 could carry the bomb load of four F-4 Phantom IIs. The worth of the new planes was beginning to show, and over 4,000 combat F-111A missions were flown over Vietnam with only six combat losses.

In 1977 the remaining F-111As were transferred to the 366 TFW based at Mountain Home AFB, equipping the 389th and 391st TFS.

In 1982 four surviving F-111As were converted to F-111C standard and provided to Australia as attrition replacements. They were fitted with the longer-span wings and reinforced landing gear of the -C, and subsequently were almost indistinguishable from new-build F-111Cs. Some of the -As delivered to the RAAF were Vietnam veterans, purportedly still bearing the scars of anti-aircraft fire.

42 F-111As were converted as the EF-111A Raven for an electronic warfare tactical electronic jamming role. They can be distinguished from other -As by the equipment bulge atop their tails, a featuring leading to the nickname "Fat Tail." The fin-tip pod held the receiving antennae, while the emitters were in a narrow 16 ft (4.88 metre) radome along the underside of the fuselage. The major component was the ALQ-99 tactical jamming system. The total EW package weighed 6,000 to 8,000 pounds (2,700 to 3,600 kg) and replaced all weapons systems, with the second crew-member becoming solely concerned with the EW systems. The final twelve Ravens were retired in 1998 when the increased complement of EA-6Bs and the addition of the new Prowler made them finally surplus.

Three pre-production—s were provided to NASA for various testing duties. One was fitted with a variable-camber wing as part of the Advanced Fighter Technology Integration program in the 1980s; it was retired to the United States Air Force Museum at Wright Patterson AFB in 1989.

Most of the unconverted surviving F-111As were retired in 1992 and mothballed at AMARC, Davis Monthan AFB.

F-111B

The F-111B was to be a fleet-defense fighter for the U.S. Navy, fulfilling a long-standing naval requirement for a fighter capable of carrying heavy, long-range missiles to defend carriers from Soviet anti-ship missiles. The F-111B was equipped with the Hughes AN/AWG-9 pulse-Doppler radar and up to six of the new AIM-54 Phoenix long-range air-to-air missiles. General Dynamics, having no experience with carrier-based aviation, partnered with Grumman for this version.

The F-111B was a compromise that attempted to reconcile the Navy's very different needs with an aircraft whose basic configuration was largely set by the USAF need for a supersonic strike aircraft, and those compromises were to prove its undoing. The B was shorter than the F-111A, to enable it to fit on carrier lifts, but had a longer wingspan (70 ft/21.3 m compared to 63 ft/19.2 m) for increased range and cruising endurance. Although the Navy had wanted a 48-inch (122 cm) radar dish for long range, they were forced to accept a 36-inch (91.4 cm) dish for compatibility. The Navy had requested a maximum take-off weight of 50,000 lb (22,686 kg), but Secretary of Defense McNamara forced them to compromise at 55,000 lb (24,955 kg). This weight goal proved to be overly optimistic.

Excessive weight plagued the B throughout its development. Not only were prototypes far over the 55,000 lb limit, efforts to redesign the airframe only made matters worse. The excessive weight made the aircraft seriously underpowered. Worse, its visibility for carrier approach and landing were abysmal, and its maneuverability, especially in the crucial medium-altitude regimen, was decidedly inferior to the F-4 Phantom II. During the congressional hearings for the aircraft, Vice Admiral Thomas "Tom Cat" Connolly, then CNO (Air), famously responded to a Senator's question as to whether a more powerful engine would cure the aircraft's woes, "Senator, all the thrust in Christendom will not make a [carrier] fighter out of this aircraft."

By October 1967, the Navy was finally convinced that the F-111B program was a lost cause and recommended its cancellation, which occurred in 1968 after seven had been delivered[link], two of which had crashed. The Phoenix missiles and radar developed for this plane (and the earlier, cancelled F6D Missileer) were eventually used on its replacement, the F-14 Tomcat.

F-111C

The F-111C was an export version for Australia, combining F-111A/E avionics with the long-span wings and heavier landing gear of the F-111B. Twenty-four were originally ordered in 1963, although development delays and structural problems kept them from entering service until 1973.

Four aircraft were modified to RF-111C reconnaissance configuration, retaining their strike capability.

F-111C aircraft have been equipped to carry Pave Tack FLIR/laser pods, and later underwent an extensive Avionics Upgrade Program, with AN/APQ-169 attack radar replacing the elderly AN/APQ-113, Texas Instruments AN/APQ-171 terrain-following radar, twin Honeywell H423 ring-laser gyro INS, GPS receiver, modern digital databus, mission computer, and stores-management system, and cockpit multi-function displays (MFDs). Their engines were updated to TF30-P-108/109RA standard, with 21,000 lbf (93.4 kN) thrust. Four ex-USAF F-111As were refitted to F-111C standard and delivered to Australia as attrition replacements.

A series of upgrades has kept the Australian F-111 fleet up to date, and it is planned to keep them in service until about 2010.

F-111D

The F-111D was an upgraded F-111A equipped with newer Mark II avionics, more powerful engines, improved intake geometry, and an early "glass cockpit." First ordered in 1967, extensive development problems delayed service entry until 1974, and only 96 were built.

The F-111D used the new Triple Plow 2 intakes, which were located four inches (about 10 cm) further away from the airframe to prevent engine ingestion of the sluggish boundary layer air that was known to cause stalls in the TF30 turbofans. It had more powerful TF30-P-3 engines with 12,000 lbf (53.4 kN) dry and 18,500 lbf (82.3 kN) afterburning thrust.

More significant--and problematic--were the Mark II avionics. These were digitally integrated microprocessor systems, some of the first used by the USAF, offering tremendous capability, but substantial teething trouble. The main radar was the General Electric AN/APQ-114, with Doppler beam-sharpening, moving-target indicator (MTI), and continuous-wave mode for guiding semi-active radar homing missiles (which the standard AN/APQ-113 set could not). This was matched with an Autonetics inertial navigation/attack radar system, Marconi Doppler radar for navigation, a horizontal situation display, an IBM processor, and a Norden integrated systems display, with modern multi-function displays (MFDs). These last proved to be a major source of trouble, serving to multiply the development problems experienced with the individual systems. Considerable acrimony between the contractors resulted, and it took years before the bugs were worked out. F-111 crews considered the -D the most capable (and user-friendly) version of the aircraft when everything worked, but that was all too rare before the 1980s.

Incidentally, the F-111D was never equipped to carry what proved to be the 'Aardvark's' most useful sensor system, the AN/AVQ-26 Pave Tack pod.

The F-111D was withdrawn from service in 1992 for mothballing at AMARC.

F-111E

The F-111E was a simplified, interim model ordered after the prolonged teething troubles of the F-111D. It used the -D's Triple Plow 2 intakes and more powerful TF30-P-3 engines, but retained the -A's Mark I avionics.

Although conceived after the -D, the F-111E was actually delivered before it. The first flight of an -E was 20 August 1969. A total of 94 were built.

Some F-111Es were based at RAF Upper Heyford in Oxfordshire (United Kingdom) until 1993, and the type saw service in Operation Desert Storm. All F-111Es were withdrawn to storage in 1993 and 1994.

F-111F

Ground crew prepares a 48th Tactical Fighter Wing F-111F aircraft for a retaliatory air strike on Libya.

The F-111F was the final F-111 variant produced for Tactical Air Command, with more modern and advanced Mark IIB avionics that were more capable than the F-111E and much more reliable than the F-111D. A total of 106 were produced between 1971 and 1976. The aircraft were mostly assigned to the 48 TFW based at RAF Lakenheath in the United Kingdom, with some assigned to the 57th Fighter Weapons Wing at Nellis AFB.

The F-111F's Mark IIB avionics suite used a simplified version of the FB-111A's radar, the AN/APQ-144, lacking some of the strategic bomber's operating modes but adding a new 2.5 mi (4.0 km) display ring. Although it was tested with digital moving-target indicator (MTI) capacity, it was not used in production sets. It used Texas Instruments AN/APQ-146 terrain-following radar, Litton inertial navigation, and the F-111E's Weapon Control Panel. The internal weapons bay was normally occupied by a AVQ-26 Pave Tack FLIR and laser designator system for the delivery of precision laser-guided munitions. The radar was subsequently upgraded to AN/APQ-161, with the AN/APQ-171 terrain-following set. The later Pacer Strike avionics update program added new digital electronics and databus.

The -F also used the Triple Plow 2 intakes, along with the substantially more powerful TF30-100 turbofan with 25,100 lbf (111.6 kN) afterburning thrust. This substantially improves the -F's performance, allowing a top speed of Mach 2.5 at altitude and enabling an unloaded F-111F to supercruise (fly at supersonic speeds without afterburner). In 1985-86, engines were upgraded to the TF30-P-111 turbofan.

The F-111F made its combat debut in Operation El Dorado Canyon against Libya in 1986, and performed superbly in Operation Desert Storm against Iraq, where it unexpectedly added the anti-armor ("tank-plinking") role to its resume.

Various plans to upgrade the F-111F, including the adoption of the General Electric F110 engine (used in the F-14D Tomcat), were proposed, but not implemented because they might have interfered with the USAF's political efforts to build the F-22 Raptor. As a result, the last USAF F-111s were withdrawn from service on 27 July 1996, replaced by the F-15E Strike Eagle.

FB-111A strategic bomber

An air-to-air front overhead view of two FB-111 aircraft in formation.

The FB-111A was a strategic bomber version of the F-111 developed as an interim aircraft for the Strategic Air Command to replace the elegant but troublesome supersonic B-58 Hustler and early models of the B-52 Stratofortress. The planned replacement program, the Advanced Manned Strategic Aircraft, was proceeding slowly, and the Air Force was concerned that fatigue failures in the B-52 fleet would leave the strategic bomber fleet dangerously under strength. Although 263 planes were planned originally, the total was finally cut to just 76. The first production aircraft was delivered in 1968. The FB-111A never had an official popular name, but it was commonly called the "Switchblade."

The FB-111A was 2 ft 1.5 in (650 mm) longer than the F-111A, allowing carriage of about 585 gallons (2,214 L) extra fuel, and was fitted with the longer wings of the abortive F-111B and F-111K for greater range and load-carrying ability. A stronger undercarriage and landing gear compensated for the higher take-off weights (gross weight rose to 119,250 lb/54,105 kg). All but the first aircraft had the Triple Plow 2 intakes and the TF30-P-7 with 12,500 lbf (55.58 kN) dry and 20,350 lbf (90.49 kN) afterburning thrust.

The FB-111A had new electronics, known as the SAC Mk IIB suite. The Mk IIB retained the F-111A's Texas Instruments AN/ANPQ-134 terrain-following radar and Honeywell AN/APN-167 radar altimeter. Radar was the General Electric AN/APQ-114, with a new north-oriented display, a beacon tracking mode, and a photo recording mode. To those components, the FB-111A added a Rockwell AN/AJN-16 inertial navigation system, Singer-Kearfott AN/APN-185 Doppler radar, and the Litton AN/ASQ-119 Astrotracker astrocompass, which allowed navigation by stellar positioning (a similar system had been used on the SR-71 Blackbird). A Horizontal Situation Display was added along with the AN/AYK-6 cockpit display. A unique feature of the FB-111A was that the TFR was integrated into the automatic flight control system, allowing "hands-off" flight at high speeds and low levels (down to 200 feet), even in adverse weather.

Armament for the strategic bombing role was the Boeing AGM-69 SRAM (short-range attack missile) with had Mach 3 speed and 110 mile range. Two could be carried in the internal weapons bay and four more on the inner underwing pylons. Nuclear gravity bombs were also typical FB armament.Fuel tanks were often carried on the 3rd non-swivelling pylon of each wing. Promotional photos showed a conventional bombload to a theoretical total of fifty 750 lb (340 kg) M117 weapons on 8 pylons and bomb bay, but it was never used in a conventional role. In 1990, the SRAM was withdrawn from service amid concerns about the integrity of its nuclear warhead in the case of fire, and subsequently only unpowered bombs were available.

The FB-111 became surplus to SAC's needs after the introduction of the Rockwell B-1B Lancer, and the remaining FB-111s were converted to a tactical configuration and renamed the F-111G. They were used primarily for training.

The F-111G did undergo an avionics upgrade program that added a digital computer, dual AN/ASN-41 ring-laser gyro INS, AN/APN-218 Doppler navigation, and an updated terrain-following radar. The astrocompass system was deleted.

The G model did not remain in USAF service for long, being mothballed in 1993, but 15 were bought by Australia to supplement its F-111Cs.

Several "stretched" FB-111 variants (the FB-111B, with F101 engines and a longer fuselage, and the greatly enlarged FB-111H, intended as a possible replacement for the B-1A after that project's cancellation) were proposed in the late 1970s, but none were ever built.

EF-111A Raven electronic warfare aircraft

The EF-111 Raven electronic warfare variant.

To replace the elderly and obsolescent Douglas EB-66, in 1972 the USAF contracted Grumman to convert some existing F-111As into electronic warfare/ECM aircraft. The Air Force had considered the Navy Grumman EA-6B Prowler, but was reluctant to adopt a Navy aircraft.

A contract to develop the EF-111A was awarded to Grumman in 1974, modifying existing -A airframes. The first fully equipped model flew on 10 March 1977,known then as the "Electric Fox", and deliveries to combat units began in 1981. A total of 42 conversions were completed, the last delivered by the end of 1985. The EF-111A received the official popular name Raven, although in service it acquired the nickname "Spark 'Vark".

The Raven retained the F-111A's navigation systems, with a revised AN/APQ-160 radar primarily for ground mapping. The primary feature of the Raven, however, was the AN/ALQ-99E jamming system, developed from the Navy's ALQ-99 on the Prowler. Its primary electronics were installed in the weapons bay, with transmitters fitted in a 16 ft (5 m) long ventral "canoe" radome; the complete installation weighed some 6,000 lb (2,723 kg). Receivers were installed in a fin-tip pod,or "football," similar to that of the EA-6B. The aircraft's electrical and cooling systems had to be extensively upgraded to support this equipment. The cockpit was also rearranged, with all flight and navigation displays relocated to the pilot's side, and flight controls except throttles being removed from the other seat, where the electronic warfare officer's instrumentation and controls were installed.

EF-111s were unarmed, although a few sources indicated that the inner wing pylons could be fitted to allow carriage of AIM-9 Sidewinders for self-defense. The aircraft's considerable speed and acceleration were its main means of self-defense. The EF-111 was not capable of firing AGM-45 Shrike, AGM-78 Standard, or AGM-88 HARM missiles in the lethal SEAD role, which was a tactical limitation.

In 1986 the EF-111A's engines were upgraded to the more powerful TF30-P-9 of the -D model, with 12,000 lbf (53.4 kN) dry and 18,500 lbf (82.3 kN) afterburning thrust.

From 1987 to 1994 the Spark 'Vark underwent an Avionics Modernization Program (AMP), similar to the Pacer Strike program for the F model. This added a dual AN/ASN-41 ring-laser gyro INS, AN/APN-218 Doppler radar, and an updated AN/APQ-146 terrain-following radar. Cockpit displays were upgraded with multi-function displays borrowed from the F-16 Fighting Falcon.

EF-111s saw combat use during Operation Eldorado Canyon (the 1986 retaliatory attack on Libya) and Operation Desert Storm in 1991. On 17 January 1991, a USAF EF-111 was credited with a kill against an Iraqi Dassault Mirage F1, which it managed to maneuver into the ground, making it the first and only F-111 to achieve an aerial victory over another aircraft.

The last deployment of the Raven was a detachment of EF-111s stationed at Al Kharj Air Base in Saudi Arabia until April 1998.

Shortly afterward, in May 1998, the USAF withdrew the final EF-111As from service, placing them in storage at AMARC. These were the final F-111s in service with the USAF. In the short term, EA-6B Prowlers are fulfilling this function for both the Navy and Air Force, but the EA-18G Growler, which is now in production, is expected to perform this role in the long term.

Foreign sales

Australia

An Australian F-111 in 2006.

The Australian government ordered 24 F-111 aircraft in 1963 to replace the RAAF's English Electric Canberra in the bombing and tactical strike role. While the first aircraft was officially handed over in 1968, structural integrity problems found in the USAF fleet delayed the service entry of the F-111C until 1973, USAF F-4 Phantom IIs being leased as an interim measure. Four aircraft were modified to RF-111C reconnaissance configuration, retaining their strike capability.

A number of ex-USAF aircraft have been delivered to Australia, as attrition replacements and to enlarge the fleet. Four aircraft modified to F-111C status were delivered in 1982, while eighteen F-111G aircraft were purchased in 1992 and delivered in 1994. Additional stored USAF airframes are reserved as a spares source.

Australian F-111s equip No. 1 Squadron and No. 6 Squadron of the RAAF, and are likely to remain in service through 2010 when it will probably be replaced by the F-35 Lightning II (the Australian Government is, however, yet to formally commit to purchasing F-35 aircraft).

While the F-111 has not seen combat in Australian service, it is known that F-111 aircraft were placed on high alert during the initial phase of the Australian-lead intervention (INTERFET) into East Timor in 1999. During the first Gulf War in 1991 the United States Government asked Australia to deploy RF-111 aircraft to the Persian Gulf. This request was denied as the Australian government judged that these aircraft were too important to Australia's security to risk in a distant war.

The Royal Australian Air Force's F-111 fleet has at times been controversial. Controversies surrounding the F-111 include:

the long delay to the delivery of the aircraft was a significant political issue in the late 1960s and early 1970s.
their use by the Hawke federal government to take surveillance photos of the Franklin Dam project in Tasmania.
poor work conditions for F-111 groundcrew involved in sealing/de-sealing F-111 fuel tanks resulted in permanent brain damage to a number of groundcrew before conditions were improved.
an emergency landing of an RAAF F-111 at the Brisbane International Airport on October 8 2005 which caused several delays.
in 2004 an RAAF F-111C in a training operation off the eastern coast of Queensland hit supersonic speeds whilst it was too close to the coastline, causing windows to shatter and large amounts of other damage.
on 18 July 2006, an F-111 with faulty landing gear performed an emergency landing at RAAF Base Amberley. This resulted in the closure of the Cunningham Highway through Ipswich, and closure of the western leg of Toongarra Road, as a precaution against airborne particles should the aircraft explode. Immediately after landing the undercarriage was doused with foam by on-scene fire-fighters.

In Australian military and aviation circles the F-111 Aardvark is affectionately known as the 'Pig,' because of its ability to hunt amongst the weeds like its namesake, referring to the F-111's unique Terrain Following ability. Another, less generous explanation of the source of the nickname refers to the colloquialism "Pigs Might Fly". A third origin can be posited from the word Aardvark, which translates into English as "Earth Pig"

An RAAF F-111C with wings swept fully back doing a "torching" (dump and burn) routine.

United Kingdom

The British government cancelled the BAC TSR-2 in 1965, citing the lower costs of the TFX and ordered 50 F-111K aircraft in 1967. However, the order was cancelled just over a year later; the reason given was the escalating F-111 price, and Buccaneers and F-4 Phantoms were purchased instead.

Specifications (F-111)

References

External links

[Aerospaceweb.org profile of the F-111]
[F-111.net]
[Combataircraft.com F-111 page]
[32°9′28.2″N, 110°50′6.8″W] - F-111s scrapped next to F-14s at the Aerospace Maintenance and Regeneration Center

Cultural reference

American artist James Rosenquist immortalised the aircraft in his acclaimed 1965 room-sized pop art painting entitled F-111 that features an early natural-finish example of the plane in USAF markings. The painting hangs in the Museum of Modern Art in New York City.

The Australian band Cold Chisel has a song F-111. [The lyrics] appear on the band's website. The English band Sigue Sigue Sputnik had a minor hit in 1986 with its song "Love Missile F-111," whose popularity was fuelled in part by its inclusion in the American film Ferris Bueller's Day Off.

The small die-cast F-111s commonly available in US toy stores is actually the EF-111 as identified by the large tail fairing and underbody fairing.