F-111
AARDVARK EF-111 RAVEN ECS USAF F-111B USN FB-111 SAC F-111C RAAF VIETNAM LIBYA
PANAMA IRAQ OP EL DORADO CANYON DESERT SHIELD / DESERT STORM
KEY PUBLICATIONS SOFTBOUND BOOK
in ENGLISH by BOB ARCHER
---------------------------------
Additional Information from
Internet Encyclopedia
The General Dynamics F-111
Aardvark is a retired supersonic, medium-range, multirole combat aircraft.
Production models of the F-111 had roles that included attack (e.g.
interdiction), strategic bombing (including nuclear weapons capabilities),
reconnaissance and electronic warfare. The name Aardvark was derived from
perceived similarities of the aircraft to the animal: a long nose and
low-level, terrain-following capabilities. Aardvark is literal translation from
Afrikaans, "earth-pig", and the source of the F-111's "Pig"
nickname during its Australian service.
Developed in the 1960s by
General Dynamics under Robert McNamara's TFX Program, the F-111 pioneered
variable-sweep wings, afterburning turbofan engines, and automated
terrain-following radar for low-level, high-speed flight. Its design influenced
later variable-sweep wing aircraft, and some of its advanced features have
become commonplace. The F-111 suffered problems during initial development,
largely related to the engines. A fighter variant intended for the United
States Navy, the F-111B, was canceled before production; it was intended for
aircraft carrier-based roles, including long-range interception. Several
specialized models, such as the FB-111A strategic bomber and the EF-111A
electronic warfare aircraft, were also developed.
The F-111 entered service in
1967 with the United States Air Force (USAF). The Royal Australian Air Force
(RAAF) also ordered the F-111 and began operating the F-111C in 1973. As early
as March 1968, the USAF were deploying F-111s into active combat situations;
the type saw heavy use during the latter half of the Vietnam War to conduct
low-level ground-attack missions, flying in excess of 4,000 combat missions
while incurring only six combat losses in the theatre. The F-111s also
participated in the Gulf War (Operation Desert Storm) in 1991; the F-111Fs
completed 3.2 successful strike missions for every unsuccessful one, better
than any other U.S. strike aircraft used in the operation. RAAF F-111s never
saw offensive action, but were deployed periodically as a deterrent, such as
for the Australian-led International Force for East Timor.
Being relatively expensive to
maintain amid post-Cold War budget cuts, the USAF elected to retire its F-111
fleet during the 1990s; the last F-111Fs were withdrawn in 1996 while the
remaining EF-111s also departed in 1998. The F-111 was replaced in USAF service
by the F-15E Strike Eagle for medium-range precision strike missions, while the
supersonic bomber role has been assumed by the B-1B Lancer. The RAAF continued
to operate the type up until December 2010, when the last F-111C was retired;
its role was transitioned to the Boeing F/A-18E/F Super Hornet as an interim
measure until the Lockheed Martin F-35 Lightning II became available.
Development
Early requirements
The May 1960 U-2 incident, in
which an American CIA U-2 reconnaissance plane was shot down over the USSR,
stunned the United States government. Besides greatly damaging USSoviet
relations, the incident showed that the Soviet Union had developed a surface-to-air
missile that could reach aircraft above 60,000 feet (18,000 meters).
Consequently, the United States Air Force Strategic Air Command (SAC) and the
RAF Bomber Command's plans to send subsonic, high-altitude Boeing B-47
Stratojet and V bomber formations into the USSR were realized to be much less
viable.
By 1960, SAC had begun moving to
low-level penetration, which greatly reduced radar detection distances. At the
time, SAMs were ineffective against low-flying aircraft while interceptor
aircraft had less of a speed advantage at low altitudes.[4] The USAF's Tactical
Air Command (TAC) was largely concerned with the fighter-bomber and deep
strike/interdiction roles. TAC was in the process of receiving its latest
design, the Republic F-105 Thunderchief, which was designed to deliver nuclear
weapons fast and far, but required long runways.[5] A simpler variable geometry
wing configuration with the pivot points farther out from the aircraft's
centerline was reported by NASA in 1958, which made swing-wings viable.[6][7]
This led USAF leaders to encourage its use.
In June 1960, the USAF issued
specification SOR 183 for a long-range interdiction/strike aircraft able to
penetrate Soviet air defenses at very low altitudes and high speeds.[9]
Specifically, it was to be capable of at least 800 miles of low-level flight,
400 of which was to be at a speed of no less than Mach 1.2.[10] Furthermore,
the specification also called for the aircraft to possess short takeoff and
landing (STOL) capabilities to permit operations from short, unprepared
airstrips that had a length of no more than 3,000 feet.[8] An internal payload
of 1,000lb was to be carried in the primary mission role. A variant suitable
for aerial reconnaissance flights was also included in the specification.
In the 1950s, the United States
Navy sought a long-range, high-endurance interceptor aircraft to protect its
carrier battle groups against long-range anti-ship missiles launched from
Soviet jet bombers and submarines. The Navy needed a fleet air defense (FAD)
fighter with a more powerful radar, and longer range missiles than the F-4
Phantom II to intercept both enemy bombers and missiles.[12][13] Seeking a FAD
fighter, the Navy started with the subsonic, straight-winged aircraft, the
Douglas F6D Missileer in the late 1950s. The Missileer was designed to carry
six long-range missiles and loiter for five hours, but would be defenseless
after firing its missiles.[12][14] The program was formally canceled in
1961.[12] The Navy had tried variable geometry wings with the XF10F Jaguar, but
abandoned it in the early 1950s.[15] It was NASA's simplification which made
the variable geometry wings practical.[6][10] By 1960, increases in aircraft
weights required improved high-lift devices, such as variable geometry wings.[16][17]
Variable geometry offered high speeds, and maneuverability with heavier
payloads, long range, and the ability to take off and land in shorter
distances.
Tactical Fighter Experimental
(TFX)
The USAF and Navy were both
seeking new aircraft when Robert McNamara was appointed secretary of defense in
January 1961.[18] The aircraft sought by the two armed services shared the need
to carry heavy armament and fuel loads, feature high supersonic speed, twin
engines and two seats, and probably use variable geometry wings.[19][20] On 14
February 1961, McNamara formally directed the services to study the development
of a single aircraft that would satisfy both requirements. Early studies
indicated that the best option was to base the design on the USAF requirement,
and use a modified version for the Navy.[21] In June 1961, Secretary McNamara
ordered the go ahead of Tactical Fighter Experimental (TFX), despite USAF and
Navy efforts to keep their programs separate.[22][23] According to aviation
author Peter E. Davis, military officials were disconcerted by McNamara's focus
on compromised requirements for financial reasons.
The two services could agree
only on swing-wing, two-seat, twin-engine design features. The USAF wanted a
tandem-seat aircraft for low-level penetration ground-attack, while the Navy
wanted a shorter, high altitude interceptor with side-by-side seating to allow
the pilot and radar operator to share the radar display.[21][25] Also, the USAF
wanted the aircraft designed for 7.33 g with Mach 2.5 speed at altitude and
Mach 1.2 speed at low level with an approximate length of 70 ft (21.3 m). The
Navy had less strenuous requirements of 6 g with Mach 2 speed at altitude and
high subsonic speed (approx. Mach 0.9) at low level with a length of 56 ft
(17.1 m). The Navy also wanted the aircraft with a nose large enough for a 48
in (1.2 m) diameter radar dish.
McNamara developed a basic set
of requirements for TFX based largely on the USAF's requirements and, on 1
September 1961, ordered the USAF to develop it.[21][26] Nevertheless, a request
for proposals (RFP) for the TFX was provided to industry in October 1961.[27]
In December, proposals were received from Boeing, General Dynamics, Lockheed,
McDonnell, North American and Republic. The evaluation group found all the
proposals lacking, but Boeing and General Dynamics were selected to submit
enhanced designs.[28] Boeing's proposal was recommended by the selection board
in January 1962, with the exception of the engine, which was not considered
acceptable. Switching to a crew escape capsule, instead of ejection seats and
alterations to radar and missile storage were also needed. Both companies
provided updated proposals in April 1962. USAF reviewers favored Boeing's
offering, while the Navy found both submissions unacceptable for its
operations.[28] Two more rounds of updates to the proposals were conducted, with
Boeing being picked by the selection board.
In November 1962, McNamara
selected General Dynamics' proposal due to its greater commonality between USAF
and Navy versions.[28] The Boeing aircraft shared less than half of the major
structural components. On 21 December 1962, General Dynamics signed the TFX
contract.[30] A congressional investigation into the procurement processed was
conducted, but did not change the selection.[23][29][31] On 1 May 1964, the
definitized contract was issued for the program, including flight testing,
spares, ground equipment, training devices, static and fatigue test data, and
the production of an initial 23 F-111 aircraft; it was structured as a fixed
price incentive fee (FPIF) contract with a ceiling price of $529 million along
with provisions for deficiency correction amongst other operational clauses and
performance criteria.
Design phase
General Dynamics' design team
was led by Robert H. Widmer.[33] 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.[34][35] The General
Dynamics and Grumman team faced ambitious requirements for range, weapons load,
and aircraft weight.[36] 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.[34] This use of
unfamiliar features has been attributed as a major cause of the aircraft's
protracted development and weight increases.
The F-111A and F-111B shared the
same airframe structural components and Pratt & Whitney TF30-P-1 turbofan
engines. They featured side-by-side crew seating in an escape capsule as
required by the Navy. The F-111B's nose was 8.5 feet (2.59 m) shorter as the
aircraft could fit on existing carrier elevator decks, and had 3.5-foot-longer
(1.07 m) 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.
During September 1963, the
F-111A mockup was inspected.[32] On 15 October 1964, the first test F-111A was
rolled out of 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.[38][32] On 21 December 1964, the F-111A
made its first flight from Carswell Air Force Base, Texas.[39] 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.[40][41] Early flights of the F-111, which included supersonic
flights, demonstrated favorably simplistic maintenance requirements, amongst
other qualities.
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.[42] 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.[43] 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.
Early flights of the F-111 were
troubled by compressor surges and stalls across certain portions of the flight
regime.[45] General Dynamics had elected to use an uncommon spike-shaped
variable intake for the engine for the performance.[37] 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.[46][47][48]
During February 1965, the F-111A achieved a speed of Mach 1.3 while flying with
an interim intake design.[46] On 18 May 1965, the F-111B made its first flight;
it was also equipped with ejector seats initially.
Separately, cracks in the
F-111's 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.[51][31] On 22 December 1969, the USAF opted to ground the
fleet due to this issue, save for those involved in flight testing.[52] The
resolution involved the redesigning of the attach structure and necessitated
testing to ensure adequate design and workmanship.[53] On 31 July 1970, the
grounding was lifted.[54] Category I flight testing of the F-111A, which had
started in 1964, continued through to 31 March 1972.[55][42] Category II tests
started in January 1966, while Category III testing was repeatedly postponed
before being cancelled, having been deemed to be unnecessary.
During 1968, the F-111B was
canceled by the Navy on account of weight and performance issues together with
revised tactical requirements.[56][57] 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.[58] Production of the F-111
ended in 1976,[59] following the completion of 563 aircraft.
Design
The F-111 was an all-weather
attack aircraft, capable of low-level penetration of enemy defenses to deliver
ordnance on the target.[60] The F-111 featured variable-geometry wings, an
internal weapons bay and a cockpit with side-by-side seating. The cockpit was
part of an escape crew capsule.[61] The wing sweep varied between 16 degrees
and 72.5 degrees (full forward to full sweep). The wing included leading edge
slats and double slotted flaps over its full length.[62] The airframe was made
up mostly of aluminum alloys with steel, titanium and other materials used in
places.[63][64] The fuselage was made of a semi-monocoque structure with
stiffened panels and honeycomb structure panels for skin.[62][63] The
horizontal stabilizer was an all-moving stabilator.
The F-111 used a three-point
landing gear arrangement, with a two-wheel nose gear and two single-wheel main
landing gear units. The landing gear door for the main gear, which was
positioned in the center of the fuselage, also served as a speed brake in flight.[62][67]
Most F-111 variants included a terrain-following radar system connected to the
autopilot. The aircraft was powered by two Pratt & Whitney TF30
afterburning turbofan engines. The F-111's variable-geometry wings, escape
capsule, terrain following radar and afterburning turbofans were new
technologies for production aircraft.
Armament
Weapons bay
The F-111 featured an internal
weapons bay that could carry bombs, a removable 20 mm M61 cannon or auxiliary
fuel tanks.[69][70] For bombs, the bay could hold two 750 lb (340 kg) M117
conventional bombs, one nuclear bomb or practice bombs. The F-111B for the US
Navy was to carry two AIM-54 Phoenix long-range air-to-air missiles in the bay.
The cannon had a large 2,084-round ammunition tank, and its muzzle was covered
by a fairing; however, it was rarely fitted on F-111s.
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 featured a forward looking infrared (FLIR) sensor, optical camera and
laser rangefinder/designator. The Pave Tack pod allowed the F-111 to designate
targets and drop laser-guided bombs on them.[72] Australian RF-111Cs carried a
pallet of sensors and cameras for aerial reconnaissance use.
The FB-111 could carry two
AGM-69 SRAM air-to-surface nuclear missiles in its weapons bay.[74] General
Dynamics trialed an arrangement with two AIM-9 Sidewinder air-to-air missiles
carried on rails in a trapeze arrangement from the bay, but this was not adopted.[71]
Early F-111 models had radars equipped to guide the AIM-7 Sparrow medium-range
air-to-air missile, but it was never fitted.
External ordnance
Each wing was equipped with four
underwing pylons. The inner two pylons on each wing rotated to align with the
fuselage, while the outer two were fixed. Each pylon had a capacity of 5,000
pounds (2,300 kilograms). Various bombs and missiles could be carried on the
pylons. Auxiliary fuel drop tanks with 600 US gallons (2,300 litres) capacity
each could be fitted.
The design of the F-111's
fuselage prevented the carriage of external weapons under the fuselage, but two
stations were available on the underside for electronic countermeasures (ECM)
pods and/or datalink pods; one station was on the weapons bay, and the other on
the rear fuselage between the engines.[75] The F-111's maximum practical
weapons load was limited, since the fixed pylons could not be used with the
wings fully swept.
Tactical F-111s were fitted with
shoulder rails on the four inner swiveling pylons to mount AIM-9 Sidewinder
air-to-air missiles for self-defense.[71] Australian F-111Cs were equipped to
launch the Harpoon anti-ship missile, and the Popeye stand-off missile.[77]
FB-111As could carry the same conventional ordnance as the tactical variants,
but their wing pylons were more commonly used for either fuel tanks or
strategic nuclear gravity bombs. They could carry up to four AGM-69 SRAM
nuclear missiles on the pylons.
Historical significance
The F-111 was the first
production variable-geometry wing aircraft.[68] Several other types have
followed with similar swing-wing configuration,[68] including the Soviet Sukhoi
Su-17 "Fitter" (1965), Mikoyan-Gurevich MiG-23 "Flogger" (1967),
Tupolev Tu-22M "Backfire" (1969), Sukhoi Su-24 "Fencer"
(1970) and Tupolev Tu-160 "Blackjack" (1981); the U.S. Rockwell B-1
Lancer bomber (1974); and the European Panavia Tornado (1974). The Sukhoi Su-24
was very similar to the F-111.[79] The U.S. Navy's role intended for the F-111B
was instead filled by another variable-geometry design, the Grumman F-14
Tomcat.
Operational history
U.S. Air Force
The first of six initial
production F-111s was delivered on 17 July 1967 to fighter squadrons at Nellis
Air Force Base.[80][81] These aircraft were used for crew training. 428th
Tactical Fighter Squadron achieved initial operational capability on 28 April
1968.
After early testing, a
detachment of six aircraft from the 474th Tactical Fighter Wing (474th TFW
Roadrunners) were sent in March 1968 to Southeast Asia for Combat Lancer
testing in real combat conditions in the Vietnam War.[83] During the
deployment, 55 night missions were flown against targets in North Vietnam, but
two aircraft had been lost. 660022 was lost on 28 March, and 66-0017 on 30
March. Replacement aircraft left Nellis, but the loss of a third F-111A
(66-0024) on 22 April halted F-111A combat operations. The squadron returned to
the United States in November. The cause of the first two losses is unknown as
the wreckages were never recovered. It turned out that the third loss was
traced to a failure of a hydraulic control-valve rod for the horizontal
stabilizer which caused the aircraft to pitch up uncontrollably. Further
inspection of the remaining fleet of F-111As revealed 42 aircraft with the same
potential failures.[84] It is speculated that this failure could also have
contributed to the two earlier losses had the failure caused a pitch down while
at low altitude. It was not until 1971 that 474 TFW was fully operational.
The word "aardvark" is
Afrikaans for "earthpig" and reflects the look of the long nose of
the aircraft that might remind one of the nose of the aardvark. The origin of
the name has been attributed to F-111A Instructor Pilot Al Mateczun in 1969, as
the aircraft had not received an official USAF name.
During September 1972, the F-111
returned to Southeast Asia, stationed at Takhli Air Base, Thailand.[87] F-111As
from Nellis AFB participated in the final month of Operation Linebacker and
later flew 154 low-level missions in the Operation Linebacker II aerial
offensive against the North Vietnamese,[88] who called the aircraft
"Whispering Death".[89] They also supported regional aerial
operations against other communist forces such as Operation Phou Phiang III
during the Laotian Civil War in Laos.[90] Crews described their flying in
Vietnam as "speed is life", "one pass, haul ass", and
"you do more than one pass in a target area you die". The F-111's
ability with terrain-following radar ("the best in the fighter world",
according to F-111 pilot Richard Crandall) to fly as low as 200 feet (61 m)
above ground level at 480 knots (890 km/h) or faster in most weather conditions
made it very effective;[89] missions did not require tankers or ECM support,
and they could operate in weather that grounded most other aircraft. One F-111
could carry the bomb load of four McDonnell Douglas F-4 Phantom IIs. The worth
of the new aircraft was beginning to show; F-111s flew more than 4,000 combat
missions in Vietnam with only six combat losses.
One of the most unusual missions
occurred on 14 February 1986, when two FB-111s of the 509th Bombardment Wing
were dispatched from then Pease Air Force Base, New Hampshire to Tinker Air
Force Base, Oklahoma to pick up a heart for transplant. The aircraft landed at
Bradley International Airport to deliver the organ to a waiting ambulance.
On 14 April 1986, 18 F-111s and
approximately 25 Navy aircraft conducted air strikes against Libya under
Operation El Dorado Canyon. The 18 F-111s of the 48th Tactical Fighter Wing and
4 EF-111As from the 20th Tactical Fighter Wing flew what turned out to be the
longest fighter combat mission in history.[97] The round-trip flight between
RAF Lakenheath/RAF Upper Heyford, United Kingdom and Libya of 6,400 miles
(10,300 km) spanned 13 hours. One F-111 was lost over Libya and crashed into
the Mediterranean Sea, probably shot down.
F-111s participated in the Gulf
War (Operation Desert Storm) in 1991. During Desert Storm, F-111Fs completed
3.2 successful strike missions for every unsuccessful one, better than any
other U.S. strike aircraft used in the operation.[98] The group of 66 F-111Fs
dropped almost 80% of the war's laser-guided bombs, including the penetrating
bunker-buster GBU-28.[99] Eighteen F-111Es were also deployed during the
operation.[98][100] The US Air Force credited F-111s with destroying more than
1,500 Iraqi tanks and armored vehicles.[100] Their use in the anti-armor role
was dubbed "tank plinking".
Expensive to operateCrandall
said that the aircraft "was nine percent of Tactical Air Command's fleet
but ate up a whopping 25 percent of the maintenance budget"[89]the
F-111[N 1] was in service with the USAF from 1967 through 1998. The FB-111s
were operated by Strategic Air Command from 1969 before conversion to F-111G
and transferred to Air Combat Command (ACC) until their retirement in
1993.[104] At a ceremony marking the F-111's USAF retirement, on 27 July 1996,
it was officially named Aardvark, its long-standing unofficial name.[103] The
USAF retired the EF-111 electronic warfare variant in 1998.
Royal Australian Air Force
The Australian government
ordered 24 F-111C aircraft to replace the RAAF's English Electric Canberras in
the bombing and tactical strike role.[106] While the first aircraft was
officially handed over in September 1968, structural issues delayed the entry
into service.[107] The first F-111C was accepted at Nellis Air Force Base on 15
March 1973.[108] The RAAF's first six F-111Cs arrived at RAAF Base Amberley on
1 July 1973, and three subsequent flights of six F-111s arrived on 27 July, 28
September and 4 December.[108] F-111Cs were allocated to No. 1 Squadron and No.
6 Squadron, under the control of No. 82 Wing. In Australia, the F-111 was
affectionately known as the "Pig".
The purchase proved to be highly
successful for the RAAF. Although it never saw combat, the F-111C was the
fastest, longest range combat aircraft in Southeast Asia,[111] providing
Australia with independent strike capability.[112] Benny Murdani told Kim Beazley
that when others became upset with Australia during Indonesian cabinet
meetings, Murdani told them "Do you realise the Australians have a bomber
that can put a bomb through that window on to the table here in front of
us?"
Australian F-111s were ready to
attack Indonesian forces during the establishment of East Timor's independence
and the deployment of the Australian-led International Force for East
Timor.[114] In 2006, an RAAF F-111 scuttled the North Korean ship Pong Su on 23
March 2006.
Because of the high maintenance
time required for every flight hour,[116] the F-111's retirement began with the
F-111G models operated by No. 6 Squadron in late 2007. Twenty-four Boeing
F/A-18E/F Super Hornets were procured as an interim replacement as the Lockheed
Martin F-35 Lightning II program was delayed.[117][118] The last F-111s were
retired on 3 December 2010.
Variants
F-111A
The F-111A was the initial
production version of the F-111. Early A-models used the TF30-P-1 engine. Most
A-models used the TF30-P-3 engine with 12,000 lbf (53 kN) dry and 18,500 lbf
(82 kN) afterburning thrust[38] and "Triple Plow I" variable intakes,
providing a maximum speed of Mach 2.3 (1,450 mph, 2,300 km/h) at altitude.[120]
The variant had a maximum takeoff weight of 92,500 lb (42,000 kg) and an empty
weight of 45,200 lb (20,500 kg).
The F-111A'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 lower in the nose and a
Litton AJQ-20 inertial navigation and nav/attack system. The terrain-following
radar (TFR) was integrated into the automatic flight control system, allowing
for "hands-off" flight at high speeds and low levels (down to 200 ft
or 61 m).
A total of 159 F-111As were
produced, including 30 pre-production aircraft that were rebuilt to production
standards.[123][124] 42 F-111As were converted to EF-111A Ravens for an
electronic warfare tactical electronic jamming role.[125] In 1982, four surviving
F-111As were provided to Australia as attrition replacements and modified to
F-111C standard, including its longer-span wings and reinforced landing
gear.[126] Three pre-production F-111A were used by NASA for various tests. The
13th F-111A received new wing designs for the Transonic Aircraft Technology and
Advanced Fighter Technology Integration programs in the 1970s and 1980s.[127]
It retired to the United States Air Force Museum at Wright-Patterson Air Force
Base in 1989. Unconverted F-111As were mothballed at Aerospace Maintenance and
Regeneration Center at Davis-Monthan Air Force Base in June 1991.
F-111B
A US Navy F-111B approaching the
aircraft carrier USS Coral Sea during trials in 1968
The F-111B was to be a fleet air
defense (FAD) fighter for the U.S. Navy, fulfilling a requirement for a
carrier-based fighter aircraft armed with heavy, long-range missiles to defend
aircraft carriers and their battle groups from Soviet bombers and fighter-bombers
equipped with anti-ship missiles. General Dynamics, lacking experience with
carrier-based aircraft, partnered with Grumman for this version. Seven F-111Bs
were completed for testing but it never entered fleet service.[129] It had a
troubled development and Navy requirements changed to a maneuverable aircraft
for dogfighting. The swing-wing configuration, TF-30 engines, AIM-54 Phoenix
air-to-air missiles and AWG-9 radar developed for the F-111B were used on its
replacement, the Grumman F-14 Tomcat. The Tomcat was large enough to carry the
AWG-9 and Phoenix missiles while exceeding both the F-111's and the F-4's
maneuverability.
F-111C
A Royal Australian Air Force
F-111C performing a dump-and-burn, a procedure where fuel is intentionally
ignited using the aircraft's afterburner
Main articles: General Dynamics
F-111C and List of General Dynamics F-111 aircraft operated by the Royal
Australian Air Force
The F-111C is the export version
for Australia, combining the F-111A with longer F-111B wings and strengthened
FB-111A landing gear.[131] Australia ordered 24 F-111s and, following delays,
the Royal Australian Air Force accepted the aircraft in 1973.[132] Four were
converted to the RF-111C reconnaissance variant in 197980. Australia also
purchased four ex-USAF F-111As and converted them into F-111Cs.
In the 1990s, the F-111C
underwent a comprehensive digital avionics upgrade program (AUP) which
introduced new nav/attack systems (PAVE TACK Laser/infrared targeting system)
and digital flight control computers.[133][134] Later, the C model was upgraded
with a unique version of the TF-30 engine known as the P-108. This local
version mated the P-109 engine to a P-107 afterburner, delivering 20,840 lb of
thrust and significantly increased reliability.[135] The RAAF retired its last
F-111Cs in December 2010 after 37 years of service.
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.[137][138] It was first ordered in
1967 and delivered from 197073 after delays due to avionics issues.[139] The
F-111D reached initial operational capability in 1972; the sole operator was
the 27th TFW stationed at Cannon AFB, New Mexico. 96 were built.
The F-111D used the new Triple
Plow II intakes, which were located four inches (100 mm) 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-9
engines with 12,000 lbf (53 kN) dry and 18,500 lbf (82 kN) afterburning thrust.
The Mark II avionics used
digitally integrated microprocessors, some of the first used by the USAF,
offering new capability but substantial problems.[142] The Rockwell Autonetics
digital bombing-navigation system included an inertial navigation system, AN/APQ-130
attack radar system, Doppler radar, digital computer set, and multi-function
displays (MFDs). The terrain-following radar was the Sperry AN/APQ-128.[143]
The attack radar featured a Doppler beam-sharpening, moving target indication
(MTI), and Continuous-wave radar for guiding semi-active radar homing
missiles.[73][144] Avionics reliability improved but some issues were never
fully resolved;[73][140] according to Crandall, "The truth is that the D
model didn't work. They parked every single one of them in Fort Worth for
several years as they worked to fix the bugs".[89] The F-111D was
withdrawn from service in 1991 and 1992.
F-111E
A simplified, interim variant
ordered after the F-111D was delayed, the F-111E used the Triple Plow II
intakes, but retained the F-111A's TF30-P-3 engines and Mark I
avionics.[146][147] The weapon stores management system was improved and other
small changes made.[148] Crandall described the F-111E as "all analog,
just like the A model, but It worked".
The F-111E was first ordered in
1968. Its first flight occurred on 20 August 1969 and achieved initial
operational capability late that year.[149][150] 94 F-111Es were delivered
between 1969 and 1971.[148] Many F-111Es were assigned to the 20th TFW at Upper
Heyford, UK until 1991.[151] It saw action during the Gulf War. Some F-111Es
received an Avionics Modernization Program and improved TF30-P-109 engines in
the early 1990s. All were retired to AMARC by 1995.
F-111F
The F-111F was the final variant
produced for Tactical Air Command, with a modern, but less expensive, Mark IIB
avionics system, more powerful TF30-P-100 engine, and strengthened wing
carry-through box.[153][154] Crandall described it as "the Cadillac of the
F-111 force".[89] The USAF approved its development in 1969. 106 F-111Fs
were produced between 1970 and 1976.
The F-111F could reach Mach 1.2
at sea level on full afterburner.[157] It had the Triple Plow II intakes along
with the substantially more powerful TF30-P-100 turbofan with 25,100 lbf (112
kN) afterburning thrust, 35% more thrust than the F-111A and E.[47] An
adjustable engine nozzle was added to decrease drag.[155] The P-100 engine
greatly improved performance.The engines were upgraded to the TF30-P-109
version between 1985 and 1986.
The F-111F's Mark IIB avionics
suite used a simplified version of the FB-111A's AN/APQ-144 radar, it lack some
operating modes but added a new 2.5 mi (4.0 km) display ring. Although tested
with digital moving-target indicator (MTI) capacity, it was not used in
production sets.[153] The Mark IIB avionics combined some Mark II components
with FB-111A components, such as the AN/APQ-146 terrain-following radar. The
F-111E's weapon management system was also included.[161] In the early 1980s,
the F-111F began to be equipped with the AVQ-26 Pave Tack forward looking
infrared (FLIR) and laser designator system, which enabled the use of precision
laser-guided munitions and was mounted in the internal weapons bay.[162][89]
The Pacer Strike avionics update program replaced analog equipment with new
digital equipment and multi-function displays.[163] The last USAF F-111s were
withdrawn from service in 1996, replaced by the McDonnell Douglas F-15E Strike
Eagle.
F-111K
The British government canceled
the BAC TSR-2 strike aircraft in 1965, citing the lower costs for the TFX and
ordered 50 F-111K aircraft in February 1967 for the Royal Air Force.[165] The
F-111K was to be supplemented later by the Anglo-French Variable Geometry
Aircraft then under development. The F-111K was based on the F-111A with longer
F-111B wings,[165] FB-111 landing gear, Mark II navigation/fire control system,
and British supplied mission systems. Other changes included weapons bay
modifications, addition of a centerline pylon, a retractable refueling probe,
provisions for a reconnaissance pallet, and a higher gross weight with the use
of FB-111A landing gear.
In January 1968, the United
Kingdom terminated its F-111K order,[166] citing higher cost; increased costs
along with devaluation of the pound had raised the cost to around £3 million
each.[168] The first two F-111Ks (one strike/recon F-111K and one trainer/strike
TF-111K) were in the final stages of assembly when the order was canceled.[166]
All of the components that had been assembled for the production of the main
F-111K fleet that shared commonality were diverted to the FB-111A program,
while the two aircraft under construction were re-designated as YF-111As with
the intention that they be used as test aircraft in the F-111A program.
Ultimately however, the two F-111Ks were never operated as test aircraft in
July 1968, almost exactly a year after the first airframe began construction,
the USAF decided not to take them over, and General Dynamics were ordered to
use them for component recovery.
FB-111A / F-111G
The FB-111A was a strategic
bomber version of the F-111. The USAF's Strategic Air Command needed an interim
bomber due to the Advanced Manned Strategic Aircraft program proceeding slowly
and the B-52 fleet's fatigue. The FB-111A was selected in 1965 and ordered in
1966 to replace the supersonic Convair B-58 Hustler and early B-52s.[169][170]
In 1968, plans called for 263 FB-111s, but the total was reduced to 76 aircraft
in 1969. The first production aircraft flew in 1968.[171] After the UK canceled
its order for the F-111K in 1968, components for the 48 F-111Ks in production
were reused on the FB-111A.[172][173] Deliveries began in 1969 and ended in
1971.
The FB-111A had a redesigned aft
fuselage, longer F-111B wings for greater range and load-carrying ability, and
a maximum speed of Mach 2.[175][174] Fuel capacity was increased by 585 gallons
(2,214 L) and strengthened landing gear permitted a higher maximum takeoff
weight of 119,250 lb (54,105 kg). All but the first FB-111A had the Triple Plow
II intakes and the TF30-P-7 with 12,500 lbf (56 kN) dry and 20,350 lbf (90 kN)
afterburning thrust.
The FB-111A was fitted with the
SAC Mark IIB avionics suite.[178] It had an attack radar improved from the
F-111A's radar, along with kit later used on the F-111D, such as the inertial
navigation system, digital computers, and multi-function displays.[179] The
suite also had custom items to support the strategic mission, such as a star
tracker navigation system mounted forward of the cockpit, a satellite
communications receiver, and an automatic stores release system that replaced
the manual arrangement on other F-111 models.[65] Armament for the strategic
bombing role was the Boeing AGM-69 SRAM (short-range attack missile); two could
be carried in the internal weapons bay and four more on the inner underwing
pylons; nuclear gravity bombs were also usable. Fuel tanks were often carried
on the third non-swivelling pylon of each wing. The FB-111A had a total weapon
load of 35,500 lb (16,100 kg).
Multiple advanced FB-111
strategic bomber proposals were made in the 1970s. The first, referred to as
"FB-111G" by General Dynamics,[180] was a larger aircraft with more
powerful engines, greater payload and range. The next was a lengthened "FB-111H"
fitted with more powerful General Electric F101 turbofan engines, a 12 ft 8.5
in longer fuselage and redesigned fixed intakes. The rear landing gear were
moved outward so armament could be carried on the fuselage there. The FB-111H
was offered as an alternative to the B-1A in 1975.[180][181] The similar
FB-111B/C was offered in 1979 without success.
The FB-111A became surplus to
SAC's needs after the B-1B Lancer entered service; they were subsequently
reconfigured for tactical use and redesignated F-111G.[183] The conversions
began in 1989 and ended after 34 F-111Gs were produced. After SAC's disestablishment,
the FB-111As and F-111Gs were transferred to the newly established Air Combat
Command (ACC) and used primarily for training.[184] The remaining FB-111As were
retired in 1991 and the F-111Gs were retired in 1993.[104] Australia bought 15
F-111Gs in 1993 to supplement its F-111Cs.[104] They were retired in 2007.
EF-111A Raven
Main article: General
DynamicsGrumman EF-111A Raven
To replace the aging Douglas
EB-66, the USAF contracted Grumman in 1972 to convert 42 existing F-111As into
electronic warfare aircraft. The EF-111A can be distinguished from the F-111A
by the equipment bulge atop their tails. In May 1998, the USAF withdrew the
final EF-111As from service, placing them in storage at Aerospace Maintenance
and Regeneration Center (AMARC) at DavisMonthan Air Force Base.
Operators
For other operators of other
variants, see General DynamicsGrumman F-111B, General Dynamics F-111C, and
General DynamicsGrumman EF-111A Raven.
An F-111 operated by NASA
Australia
Royal Australian Air Force
No. 82 Wing RAAF Base Amberley
No. 1 Squadron F-111C
(19732009)[citation needed]
No. 6 Squadron F-111C
(19732010), F-111G (19932007)[citation needed]
United States
United States Air Force operated
F-111A/D/E/F/G, FB-111A and EF-111A.[186] Officially retired its F-111s in 1996
and the EF-111A in 1998.
Tactical Air Command 19681992
Air Combat Command 19921998
27th Tactical Fighter Wing
Cannon AFB
428th Tactical Fighter Training
Squadron F-111G (19901993), F-111E (19931995)
481st Tactical Fighter Squadron
F-111A/E (19691973), F-111D (19731980)
522d Tactical Fighter Squadron
F-111A/E (19711972), F-111D (19731992), F-111F (19921995)
523d Tactical Fighter Squadron
F-111A/E (19711972), F-111D (19731992), F-111F (19921995)
524th Tactical Fighter Squadron
F-111A/E (19711972), F-111D (19731992), F-111F (19921995)
366th Tactical Fighter Wing
Mountain Home AFB
389th Tactical Fighter Squadron
F-111F (19711977), F-111A (19771991)
390th Tactical Fighter Squadron
F-111F (19711977), F-111A (19771982)
391st Tactical Fighter Squadron
F-111F (19711977), F-111A (19771990)
474th Tactical Fighter Wing
Nellis AFB
428th Tactical Fighter Squadron
F-111A (19681977)
429th Tactical Fighter Squadron
F-111A (19691977)
430th Tactical Fighter Squadron
F-111A (19691977)
442nd Tactical Fighter Training
Squadron F-111A (19691977)
United States Air Forces in
Europe
20th Tactical Fighter Wing RAF
Upper Heyford
55th Tactical Fighter Squadron
F-111E (19711993)
77th Tactical Fighter Squadron
F-111E (19711993)
79th Tactical Fighter Squadron
F-111E (19711993)
48th Tactical Fighter Wing RAF
Lakenheath
492d Tactical Fighter Squadron
F-111F (19771992)
493d Tactical Fighter Squadron
F-111F (19771992)
494th Tactical Fighter Squadron
F-111F (19771992)
495th Tactical Fighter Squadron
F-111F (19771991)
Strategic Air Command
340th Bombardment Group (Medium)
Carswell AFB
4007th Combat Crew Training
Squadron FB-111 (19681971)
380th Bombardment Wing (Medium)
Plattsburgh AFB
528th Bombardment Squadron
(Medium) FB-111 (19711991)
529th Bombardment Squadron
(Medium) FB-111 (19711991)
530th Combat Crew Training
Squadron FB-111 (19861991)
4007th Combat Crew Training
Squadron FB-111 (19711986)
509th Bombardment Wing (Medium)
Pease AFB
393d Bombardment Squadron
(Medium) FB-111 (19701990)