General Dynamics F-
The General Dynamics F-111 Aardvark (the nickname was unofficial for most of its lifespan, but it was officially named "Aardvark" at its retirement ceremony for the United States Air Force) is a long-range strategic bomber, reconnaissance, and tactical strike aircraft. The F-111 project was long considered an expensive failure, but the end result was a capable, albeit costly, aircraft.
The F-111's beginnings were in the TFX, an ambitious early 1960s project to combine the USAF requirement for a fighter-bomber with the U.S. Navy's need for a long-range air defence 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 guided missiles. (This would change within a few years as experience showed that close-in dogfighting remained important in air combat — guns and an emphasis on agility were reintroduced to fighter design, but only after the F-111 was developed.)
For the U.S. Navy, the trend to ever bigger, more powerful fighters posed a problem: 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 be more difficult again. An airframe optimised for high speed (most obviously with a high angle wing sweep) 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 a long way on a minimum of fuel, has lower ultimate performance for combat. It was these considerations that led to the famous F-111 variable geometry, the "swing-wing."
The birth of the TFX was marked by controversy, with the Air Force, the Navy and the U.S. Government all pulling the project in different directions. At one stage, it was even planned to use it for the United States Army and the United States Marine Corps as a close support aircraft! Several manufacturers submitted bids; the final two shortlisted were General Dynamics and Boeing. The USAF and the USN, in one of the few matters they were able to agree on, both wanted the Boeing design, but United States Secretary of Defense Robert McNamara overruled them and chose the General Dynamics aircraft instead, citing cost issues—an extraordinary irony considering the eventual price of F-111s!
The design eventually emerged as a 20 tonne aircraft (empty) with a maximum takeoff weight of almost 50 tonnes, powered by two afterburning Pratt & Whitney TF30 turbofans in the 80 kN class, with side-by-side accommodation for a crew of two. The high mounted wings were attached to a pair of giant swivels, allowing it to take off, land, and loiter with a modest 16° sweep (for maximum lift and minimum landing speed), cruise at high sub-sonic speeds with a 35° sweep, or sweep back to a 72.5° maximum for a very fast maximum speed of Mach 2.5—particularly so for a bomber, which the F-111 had become by this time, its "F" (for "fighter") designation notwithstanding.
Production versions of the F-111 did not have ejection seats. The pressurized crew compartment ejected as a self contained survival module and descended under a 70 ft (21 m) parachute. The two crew could work in "shirt sleeves" without pressure suits or oxygen masks.
First flight was in December 1964 and entry into service with the USAF began in 1967. It was the first variable geometry aircraft. Despite its clear advantages, variable geometry remains a relatively unusual feature in military aircraft, 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), MiG-23 (1967) and Tupolev Tu-160 bomber (1981), the U.S. F-14 Tomcat naval fighter (1970) and B-1 bomber (1974), the European Panavia Tornado (1974). Of notable interest is the Sukhoi Su-24 Fencer (1983), which bears a more than superficial resemblance to the F-111.
Although conceived as a multi-role fighter, the F-111 became a long-range attack aircraft primarily armed with air-to-ground ordnance.
The F-111 has a small internal weapons bay under the fuselage for various weapons.
All tactical combat versions (i.e., not the EF-111A or FB-111A/F-111G) could carry a single M61 Vulcan 20mm 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.
The bay can alternately hold two conventional bombs (usually the Mk 117 750-lb/340-kg type, but weapons up to the Mk 118 (3,000 lb/1,362 kg) were cleared), two nuclear gravity bombs (B43, B57, or B61), fuel tanks, baggage pods, or a package of reconnaissance sensors.
The F-111F primarily used the bay to carry the AN/AVQ-26 Pave Tack targeting system, mounted on a rotating carriage that kept the pod protected within the bay when not in use.
The FB-111A could also carry one or two nuclear gravity bombs or one or two AGM-69 SRAM nuclear missiles in its weapons 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 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. The outer pylons (1, 2, 7, and 8) are fixed, and can be loaded only if the wings are spread at less than 26°. The outermost pylons (1 and 8) have never been used operationally, and the second pair of fixed pylons (2 and 7) are only rarely fitted for the carriage of fuel tanks. FB-111/F-111G models have provision to jettison their empty pylons in flight, reducing drag.
The primary external armament of USAF tactical F-111s included:
Although all F-111s can carry laser-guided munitions, only the 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. 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.
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 Joint Strike Fighter deliveries.
The first production F-111s were delivered on July 18, 1967 to the 428th, 492nd 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, 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 474th 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 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 Phantoms. 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 366th TFW based at Mountain Home AFB, equipping the 389th and 391st TFS. Numbers dwindled from that point; 42 aircraft were converted into EF-111A Raven electronic warfare aircraft, and a number were sent to Australia. From the early 1990s planes began to be mothballed at AMARC, Davis Monthan AFB.
The F-111B was to be the Navy fighter version of the F-111. Intended for the fleet air defense role, it was to be equipped with a very powerful radar and up to six of the new AIM-54 Phoenix long-range air-to-air missiles. 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. General Dynamics, having no experience with carrier-based aviation, partnered with Grumman for this version. The F-111B was severely overweight for carrier use, underpowered, and lacked the range the Navy required. Its visibility in carrier approach and landing was abysmal, and its maneuverability was decidedly inferior to the existing F-4 Phantom. 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. The Phoenix missiles and AN/AWG-8 radar developed for this plane (and the earlier, cancelled F6D Missileer) were eventually used on its replacement, the F-14 Tomcat.
So fundamental were the aircraft's flaws that it led Navy Vice Admiral Thomas Connolly to remark that "There isn't enough thrust in Christendom to fix this plane" in reply to a question by a Senator on whether improved engines would correct the airplane's inadequacies. His frank comment lost him a chance at a fourth star, but won him a namesake (the F-14).
Export version for Australia (see below), combining F-111A/E avionics with the long-span wings and heavier landing gear of the F-111B. The only F-111 model still in service, F-111C aircraft have been equipped to carry Pave Tack FLIR/laser pods, and later underwent an extensive Avionics Upgrade Program. Four ex-USAF F-111As were refitted to F-111C standard and delivered to Australia as attrition replacements.
The F-111D was an upgraded F-111 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 TF30-3 engines with 12,000 lb (53.4 kN) dry and 18,500 lb (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.
Ironically, 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 the very early 1990s to AMARC for mothballing.
The F-111E was a simpler F-111 ordered after the prolonged teething troubles of the F-111D, with the F-111D's greater power and improved intakes but without the troublesome electronics. The F-111E was actually delivered before the D model. 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.
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 48th TFW based at RAF Lakenheath in the United Kingdom, with some assigned to the 57th Fighter Weapons Wing at McClellan 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 lb (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).
The F-111F made its combat debut in Operation Eldorado 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), were proposed, but not implemented because they might have interfered with the USAF's political efforts to build the F/A-22 Raptor. As a result, the last USAF F-111s were withdrawn from service in 1995/1996, replaced by the F-15E.
FB-111A strategic bomber
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 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 lb (55.58 kN) dry and 20,350 lb (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). 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), two of which could be carried in the internal weapons bay and two more on the inner underwing pylons. Nuclear gravity bombs were also typical FB armament, although it could also carry a substantial conventional bombload to a theoretical total of 50 750 lb (340 kg) M117 weapons. 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-1 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 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 competitor for the B-1) were proposed in the late 1970s, but none were ever built.
EF-111A Raven electronic warfare aircraft
An electronic warfare variant of the F-111, the EF-111A Raven (pilots nicknamed the aircraft the "Spark 'Vark"), was developed to replace the outdated Douglas EB-66 in USAF service. The U.S. Navy's Grumman EA-6B Prowler was considered, but the USAF did not want a Navy design. A contract to develop the EF-111A was awarded to Grumman in 1974 to modify F-111 airframes for the new role. The first fully equipped model flew in 1977 and deliveries to combat units began in 1981, all 42 conversions being delivered by the end of 1985.
The AN/ALQ-99E jamming subsystem's electronics were installed in the weapons bay, while transmitters were fitted in a 16 ft (5 m) long ventral "canoe" radome. Receivers were installed in a fin-tip pod 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 extensively rearranged, with all flight and navigation displays relocated to the pilot's side, controls 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 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.
EF-111s saw combat use during Operation Eldorado Canyon (the 1986 retaliatory attack on Libya) and Operation Desert Storm in 1991, after which a detachment of EF-111s was 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 U.S. Navy and Air Force, but the EA-18G Growler, which is now in production, will perform this role over the long term.
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. Originally intended to be identical to USAF F-111As, the F-111C aircraft eventually delivered were a combination of F-111A and FB-111A features — the latter including the eight underwing pylons, longer wings and reinforced undercarriage.
While the first aircraft was officially handed over in 1968, structural integrity problems found in the USAF fleet delayed their entry into service until 1973. Four aircraft were modified to RF-111C reconnaissance models, 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.
A series of upgrades has kept the Australian F-111 fleet up to date, and it is planned to keep them in service until at least 2020.
In Australian military and aviation circles, the F-111 Aardvark is affectionately known as the 'pig', so named because the name 'aardvark' is originally derived from the Dutch for 'earth pig'.
Upon cancellation of the BAC TSR-2, the British government 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.