This is a rehost of his Joe Baugher's
original article.
Joe Baugher has written
and published an enormous amount of aircraft articles.
The General Dynamics F-111 is one of the most controversial
aircraft that ever flew. Perhaps no other aircraft before or since has been so bitterly
criticized in the media. It suffered a protracted development cycle in which numerous
serious problems had to be identified and repaired, and cost overruns came to be a serious
concern. Of the several thousand that had originally been planned, only 562 flightworthy
examples of seven different variants were completed. The F-111 was the subject of
protracted and bitter debates within the Congress, with opponents denouncing the aircraft
as a "flying Edsel" that was more dangerous to the US than it was to any
potential enemy.
However, after a prolonged gestation period in which many,
many problems had to be identified and fixed, the F-111 turned out to be one of the most
effective all-weather interdiction aircraft in the world. Although vilified by some as
being an unsafe and dangerous plane, the F-111 series of combat aircraft established the
best safety record of any of the aircraft in the Century Series of fighters --- only 77
aircraft being lost in a million flying hours. There is no other aircraft in service with
the USAF which can carry out the F-111's mission of precise air strikes over such long
ranges in all-weather conditions. It is still in service with the USAF today, and should
remain in service at least until the year 2010.
The history of the F-111 begins back in the late 1950s. At
that time, the Tactical Air Command (TAC) of the USAF expressed a future need for a
replacement for the F-100, F-101, and F-105 fighter-bombers which were currently in
service. With this goal in mind, on March 27, 1958, the Air Force issued General
Operational Requirement (GOR) Number 169, calling for Weapon System 649C, which was a Mach
2+, 60,000 foot altitude, all-weather fighter capable of vertical and short takeoff and
landing. The Air Force wanted this aircraft to be ready for operational deployment by
1964.
This GOR lasted only a year. GOR 169 was cancelled on March
29, 1959, the Air Force recognizing that a V/STOL fighter capable of such performance was
simply not feasible with the current technology. On February 5, 1960, the Air Force
rewrote its requirements and issued System Development Requirement (SDR) No. 17,
incorporating most of the provisions of GOR-169 but eliminating the VTOL requirement. It
allowed the subsequent development of specific requirements for a new weapon
system--WS-324A.
The general requirements of SDR-17 were brought together into
Specific Operational Requirement number 183 (SOR-183), issued on June 14, 1960. It called
for an attack aircraft capable of achieving a Mach 2.5 performance at high altitude and a
low-level dash capability of Mach 1.2. It was to have a short and rough airfield
performance, and was to be capable of operating out of airfields as short as 3000 feet in
length. The low-level radius was to be 800 miles, including 400 miles right down on the
deck at Mach 1.2 speeds. In addition, it was to have an unrefuelled ferry range capable of
crossing the Atlantic Ocean. It was to have a 1000-pound internal payload plus a lifting
payload between 15,000 and 30,000 pounds. The Air Force considered that a variable sweep
wing and a turbofan engine would be needed to satisfy these requirements.
At the same time, the Navy had a requirement for a two-seat
carrier-based fleet air defense (FAD) fighter that would replace the McDonnell F-4 Phantom
and the Vought F-8 Crusader. This aircraft was to have the ability to loiter on patrol for
much longer times with substantially larger and more capable air-to-air missiles, and was
to be able to meet and counter threats to the carrier group at much larger ranges.
Originally, the Navy had planned to meet this FAD requirement
with the Douglas F6D-1 Missileer. The F6D-1 was a subsonic aircraft that looked a lot like
a scaled-up F3D Skyknight. It was to be powered by two 10,000 lb.s.t. Pratt & Whitney
TF30-P-2 turbofans, and was to carry a three-man crew (pilot, co-pilot, and weapons system
operator). The Missileer was to be capable of remaining on patrol for up to six hours,
tracking targets at long range using its powerful Hughes pulsed-Doppler track-while-scan
radar and attacking threats with its six long-range Bendix XAAM-10 Eagle air-to-air
missiles. The Eagle was a massive long-range air-to-air missile with a maximum speed of
Mach 4. It was equipped with an advanced pulse-Doppler active radar homer. The warhead of
the Eagle could be either conventional or nuclear.
The F6D aircraft was considered by the Navy to be too costly
and too specialized, and was thought to be too slow to be capable of defending itself once
its missiles had been launched. Consequently, the F6D and its Eagle missiles were both
cancelled in December of 1960 in the last waning days of the Eisenhower administration.
This still left the FAD requirement unfulfilled.
The Air Force and Navy requirements were at first sight
completely different. However, on February 16, 1961 the new Secretary of Defense, Robert
McNamara, directed that the Services study the development of a single aircraft that would
satisfy both the requirements of the Air Force's SOR 183 mission and the requirements of
the Navy's FAD mission. In addition, McNamara wanted the aircraft to be capable of being
used by the Army and the Marine Corps as a close-support aircraft. It was hoped that this
strategy would reduce procurement costs substantially. The project came to be known as the
Tactical Fighter Experimental, or TFX for short.
It did not take long for the services to convince Secretary
McNamara that the close air support mission requirement could not be satisfied by the TFX,
and the Marine Corps and the Army were dropped from the program at an early stage.
However, Secretary McNamara stuck doggedly to his idea of maximum commonality between USAF
and Navy versions of the TFX, and in June 1961, he instructed the Air Force and the Navy
to work closely together to combine their requirements before issuing a joint RFP.
Although both the USAF and the Navy thought that this idea was completely unrealistic,
Secretary McNamara was the boss and they reluctantly followed orders.
Both the USAF and the Navy agreed that the use of
variable-geometry wings would be a good idea. However, on just almost everything else,
they differed substantially. The Navy favored side-by-side seating for its FAD fighter,
whereas the Air Force preferred tandem seating. The Navy wanted an aircraft equipped with
a long-range search and intercept radar having a dish 48 inches in diameter, whereas the
Air Force needed an aircraft equipped with a terrain-following radar optimized for
low-altitude operations. The Navy wanted an aircraft that was optimized for long loiter
times at medium to high altitudes at subsonic speeds, whereas the Air Force insisted on an
aircraft capable of low-altitude operations and supersonic dash performance. Undaunted,
Secretary McNamara pressed forward with the project and directed that the Air Force would
be the lead service for the development of a common TFX aircraft.
By August of 1961, the Secretary of the Navy reported to
Secretary McNamara that the compromise TFX design could not meet the Navy requirements.
The Air Force wanted an aircraft weighing 75,000 pounds gross, while the Navy wanted the
gross weight to be kept below 50,000 pounds. In addition, carrier operational requirements
necessitated that the overall length be kept below 56 feet so that it could fit aboard
existing carrier elevators. McNamara ordered the Navy to accept a design sized to
accommodate a 36 inch radar rather than the 48 inch radar it really wanted and to accept a
gross takeoff weight of 55,000 pounds.
On September 29, 1961, a new Request For Proposals was issued
to Boeing, General Dynamics, Lockheed, Northrop, Grumman, McDonnell, Douglas, North
American, and Republic. The Air Force's version of the TFX was to be designated F-111A,
with the Navy's version being designated F-111B. In the spirit of commonality, the Air
Force and Navy versions did not carry separate designation schemes.
Nine responses were received in early December of 1961. Only
Northrop turned down the invitation to submit. In their first evaluation of the proposals
on January 19, 1962, the Air Force Selection Board and a Navy representative endorsed the
Boeing proposal, but the Air Force Council rejected the Boeing bid as requiring much more
work. In late January of 1962, both the Air Force and Navy agreed that none of the
proposals were really acceptable, but that two of them --- the Boeing and General Dynamics
proposals --- warranted further study. A letter contract was issued to each company
requesting more design data.
In the spring of 1962, Boeing and General Dynamics submitted
second proposals. In May of 1962, both the Air Force and Navy Secretaries rejected the two
contractor's second proposals for lack of sufficient data. A third submission took place
in late June. At this time, the Air Force endorsed the Boeing proposal, but the Navy was
unhappy with their version and refused to commit themselves. A frustrated Secretary
McNamara ordered a final competition for later that year on the basis of a point system
for categories based on performance, cost, and commonality.
Boeing and General Dynamics resubmitted their final proposals
in September of 1962. The Air Force Council, the Air Force Logistics Command, and the
Bureau of Naval Weapons (the Navy organization which had replaced the Bureau of
Aeronautics in 1959) all indicated that they preferred the Boeing design, but on November
24, 1962 the Defense Department announced that the General Dynamics design had been
selected. The reason given for the selection of the General Dynamics proposal was its
promised greater degree of commonality and its more realistic approach to the cost
problem.
A political storm broke out, with Senator Henry Jackson
leading the fray in Congress in loudly denouncing the choice in no uncertain terms. The
Boeing company was located in Jackson's home state of Washington and would lose a lot of
business if the decision were allowed to stand. A series of congressional investigations
was initiated, and the TFX stayed in the headlines for many months. Nevertheless, the
decision of the Secretary stood, and the contract remained with General Dynamics.
The F-111A and B aircraft shared the same primary structure,
the same fuel system, the same pair of Pratt & Whitney TF30-P-1 turbofans, and the
same two-seat cockpit in which the two crew members sat side-by-side. The side-by-side
seating was a concession to Navy demands. The Navy also insisted that the cockpit be
capable of doubling as an escape capsule for the crew which could blown free from the
aircraft in the case of an emergency to parachute to the ground. The F-111B's nose was 8
feet 6 inches shorter than the F-111A's because of the need of the aircraft to fit on
existing carrier elevator decks, and had 3 feet 6 inch extended wingtips in order to
increase the wing area so that the on-station endurance time would be improved. The Navy
version would carry a Hughes AN/AWG-9 pulse-Doppler radar and an armament of six Hughes
Phoenix missiles, which had both evolved from the F6D program. The Air Force version would
carry the General Electric AN/APQ-113 attack radar and the Texas Instruments AN/APQ-110
terrain- following radar and an armament of air-to-ground stores.
On December 21, 1962, the Air Force amended the Letter
Contract that had initially covered General Dynamics' second competitive proposal and
initiated procurement of 18 F-111As (serial numbers 63-9766/9782) and 5 F-111Bs (BuNos
151970/151924). These were to be exclusively research, development, test, and evaluation
(RDT&A) aircraft.
Plans originally envisaged using titanium for almost all the
airframe in order to save weight, but this proved to be too costly and more conventional
materials had to be used.
Since General Dynamics lacked any experience with
carrier-based fighters, it teamed with Grumman for the integration of the naval
electronics package and Grumman was to assemble and test the entire F-111B aircraft. In
addition, Grumman would build the aft fuselage and the landing gear of the F-111A
aircraft.
The F-111A mockup was inspected in September of 1963.
By the spring of 1964, AiResearch, AVCO, Bendix, Collins
Radio, Dalmo Victor, General Electric, Hamilton Standard, Litton Systems, McDonnell, Texas
Instruments and seven other major subcontractors had become involved with the F-111
project. An associate prime contract for the F-111B's Phoenix missiles had been awarded to
Hughes. These major subcontractors were doing business with no less than 6703 suppliers
located in 44 states. The TFX project became a close approximation to the ideal weapons
project --- one with at least one contractor located in each Congressional district. :-)
The first test F-111A (serial number 63-9766) rolled out of
the General Dynamics Fort Worth, Texas plant on October 15, 1964, 37 months after the OSD
go-ahead decision, 22 months after the program's actual beginning, and two weeks ahead of
schedule. It was powered by YTF30-P-1 turbofans. Pending the availability of the escape
capsule, it was fitted with a pair of conventional ejector seats.
63-9766 took off on its maiden flight from Carswell AFB,
Texas on December 21, 1964. Dick Johnson and Val Prahl were at the controls. Although the
flight was shortened to 22 minutes because of a flap malfunction, the results were
generally satisfactory. On its second flight, on January 6, 1965, the wings were swept
form the minimum 16 degrees to the full aft 72.5-degree position. During early flight
testing, the F-111A achieved Mach 1.3. A second F-111A took off on its maiden flight on
February 25, 1965.
In 1965, a cost rise from an estimated 4.5 to 6.3 million
dollars per aircraft caused the Defense Department to cut the F-111 program sharply. A
contract for 431 production aircraft was placed on April 12, 1965. This was more than 50
percent less than than the amount originally planned. Eleven production F-111As were added
to the extensive test and engineering program.
The ninth aircraft (63-9775) crashed on approach to Edwards
AFB on January 19, 1967 because of an incorrect wing setting.
The escape capsule was first fitted to F-111A number 11
(63-9777).
The Pratt & Whitney TF30-P-1 turbofan was first flown on
an F-111A on July 20, 1965. The first 30 F-111As were equipped with this engine, but they
experienced numerous engine compressor stalls, particularly at high speeds and at high
angles of attack. These necessitated a change to the 18,500 lb.s.t. TF30-P-3 and to new
"Triple Plow I" variable-geometry inlet ducts with larger areas. This engine was
later retrofitted in several of the first 30 F-111As. These changes did not entirely cure
the stall problems, but the did help somewhat. Many fixes and many years of hard work were
necessary before the appropriate air intake geometry was finally found.
Movable underwing pylons were introduced from the fourth
production aircraft onward, and from the eleventh production aircraft onward a 20mm M61A1
Vulcan cannon was installed in the internal weapons bay in place of two 750 lb. bombs.
However, this cannon was rarely carried by actual operational aircraft, the space in the
weapons bay being used for bombs, fuel, or electronics.
In the spring of 1967, a series of tests known as Combat
Bullseye I were carried out with test F-111As. They confirmed the superior bombing
accuracy of the aircraft's radar.
A total of 141 production F-111As were delivered from July
17, 1967. The electronics package was known as the Mk I avionics system. It included a
Litton AJQ-20 inertial navigation and attack system, a General Electric AN/APQ-112 attack
radar, a Honeywell APN-167 pulsed-type radar, a Texas Instruments AN/APQ-110
terrain-following radar, and Collins ARC-109 UHF and ARC-112 HF radio transceivers.
The underside of the central fuselage of the F-111A is
occupied by a giant airbrake which is forced open by a large hydraulic jack. Together with
the main landing gear, the presence of this airbrake precludes carrying any bombs or fuel
tanks underneath the fuselage. The massive main landing gear has two huge low-pressure
tires which, together with the long-stroke legs that are pivoted near the aircraft
centerline, enable no-flare landings to be made at high weights. The large airbrake helps
cover the retraction bay, and is partially extended when the main gear is down. The nose
landing gear has twin wheels and is hydraulically steerable.
The Triple Plow I air intakes for the TF30 turbofans are
mounted underneath the leading edge of the fixed wing glove. A triangular-shaped wedge is
fitted to the upper, inner corner of each intake, and a large planar wedge is mounted
ahead of each intake parallel to the sides of the fuselage . The entire intake cowls could
be moved forwards or backwards as needed to optimize the air flow into the engines for the
given speed or angle of attack. A set of vortex generators is fitted inside the intake
ducts to provide a homogeneous flow of air to the engine. The low-mounted air intakes have
a disadvantage in that they tend to suck up a lot of runway debris, dictating that the
F-111A use only prepared runway surfaces that are kept thoroughly swept at all times.
The fixed inner wing has a set of pivoted surfaces that
normally lie flush to the surface but at high angles of attack or in high-lift situations
they can be extended to improve air flow over the glove-wing junction.
The variable-geometry wing outer panels are pivoted to the
fixed inner wing gloves and can be driven symmetrically to any sweep angle from 16 degrees
to 72.5 degrees. The upper surface of the wing has a set of spoilers which are used for
roll control, no ailerons being provided. The main wing has a set of double-slotted flaps
which occupy the entire trailing edge of the wing. The flaps are disconnected when the
wing is at maximum sweep so that they cannot be operated in such a configuration. A set of
slats occupy the entire width of the wing leading edge. These slats can be extended by a
rack and pinion system when the aircraft is flying at low speeds or at high angles of
attack to increase lift and to prevent the aircraft from stalling.
In an emergency, the cockpit can be used as an escape capsule
which separates completely from the aircraft and is blown free from the aircraft by a
rocket motor. The pilot and systems officer sit side-by side in a shirt-sleeve
environment, eg, wearing no pressure suits or oxygen masks. If they decide to eject, first
a bunch of explosive guillotines sever all the hydraulic lines and cables. Then, a quite
hefty rocket charge separates the entire cockpit from the plane. The ejection capsule
takes with it a small portion of the fuselage above and to the rear of the cockpit which
acts as a stabilizing airfoil. After the chutes are opened, anti-radar chaff is dispersed,
and a cushion/flotation bag is inflated. All of this can be accomplished from zero/zero
airspeed/altitude (eg. from an F-111A parked at rest on a runway). In the case of an
over-water ejection, the capsule is supposed to be completely submersible and is capable
of floating for a considerable amount of time. While the capsule is floating in the water,
the joy stick can double as a bilge pump by moving a pin in its base.
The escape capsule was used with success on several
occasions. However, there was a problem with excessively hard landings which were so
jolting that they injured the crew members. However, I suppose it's better to be injured
than to end up as a smoking hole in the ground :-).
The horizontal tailplane is of the all-flying variety with no
separate elevator.
At the rear of the tailcone, between the two engine exhausts,
is a fuel vent for the dumping of fuel. This device is sometimes used for a rather
spectacular airshow demonstration, in which the pilot vents fuel while in afterburner,
producing a spectacular torch behind the aircraft.
There are six underwing pylons for carrying bombs, rockets,
or fuel tanks. The two outboard underwing pylons on each wing are fixed and do not pivot.
Consequently, they can only be used between 16 and 26 degrees of wing sweep. However the
four inboard pylons do pivot and remain parallel to the aircraft centerline throughout the
entire sweep range. There is a small internal weapons bay which can accommodate a pair of
750-pound bombs. Alternatively, the bombs in the internal weapons bay can be replaced by a
20-mm M61A1 rotary cannon with 2000 rounds of ammunition.
In an extreme situation, the F-111A could carry as many as 50
750-pound conventional bombs (two of them being carried internally, the rest on the six
underwing hardpoints), or 26 1000-pound bombs. However, such loads could only be carried
if the wing is swept no more than 26 degrees and would therefore be unlikely to be carried
in actual combat. If the wing needs to be swept back at an angle of 54 degrees, the bomb
load is limited to 26 750-pound bombs. In standard USAF form, the F-111A's useful payload
varies from 8000 pounds to 20,000 pounds, according to range. For example, for a mission
range of 1725 miles, the payload is of the order of 16,000 pounds.
The APQ-113 forward-looking attack radar is a large
liquid-cooled set that operates in the J-band (16-16.4 GHz). It is used by the navigator
sitting in the right hand seat for navigation, air/ground ranging and weapons delivery. It
can also be used in the air-to-air mode in conjunction with the 20-mm M61A1 cannon or
Sidewinder missiles, although the air-to-air role is not the primary mission of the
F-111A.
The F-111A is equipped for midair refueling. A receptacle for
a refuelling boom is fitted on the top of the fuselage behind the cockpit. The F-111A has
no provision for refuelling by the probe/drogue method.
The first F-111A deliveries took place on July 18, 1967 to
the 428th, 492th and 430th Tactical Fighter Squadrons of the 474th Tactical Fighter Wing
based at Cannon AFB in New Mexico. In early 1968, this outfit moved to Nellis AFB.
Based on the results of the Combat Bullseye I tests of
the spring of 1967, the Air Force decided to rush a small detachment of F-111As to
Southeast Asia under a program known as Combat Lancer. This program was preceded by
the Harvest Reaper program of June 1967 which was intended to identify known F-111A
shortcomings and to prepare the aircraft for combat. It was anticipated that the Harvest
Reaper modifications would enter the F-111A production lines if they were successfully
proven in combat.
Six 428th TFS F-111As were allocated to the Combat Lancer
program, and departed Nellis AFB for Thailand on March 15, 1968. By the end of that month,
55 night missions had been flown against targets in North Vietnam, but two aircraft had
been lost. Replacement aircraft had left Nellis, but the loss of a third F-111A on April
22 halted F-111A combat operations. However, the aircraft remained poised for combat, but
they saw little action before their return to the USA in November. It turned out that the
three F-111A losses were not due to enemy action but were caused by wing and tail
structural defects. One of the Combat Lancer crashes had been traced to a
malfunction of the aircraft's tail servo actuator. The USAF later discovered (as a later
returning prisoner of war would confirm) that a tailplane problem could cause a sudden and
uncontrollable pitch-up and roll. This failure in the flying controls system caused the
aircraft to break up in flight. The other two crashes in Vietnam were traced to poor
mounting of the M61A1 cannon and to pilot error.
These losses caused a storm of controversy in the USA ---
Senator William Proxmire denouncing the F-111A as an unsafe and defective plane. The
aircraft became known as "McNamara's Flying Edsel", and was accused of being a
potential "technological gold mine for the Reds".
However, the Air Force and General Dynamics remained hard at
work trying to fix the problems with the F-111A. The 428th TFS of the 474th TFW reached an
initial operational capability in the spring of 1968. Harvest Reaper modifications
validated by the Combat Lancer operations followed shortly thereafter. The Harvest
Reaper modification took a lot longer than expected, and the Wing was not fully
operational until July of 1971.
F-111 testing and training incidents (including two crashes
in early 1968) had dictated a detailed and involved investigation. On August 27, 1969, a
wing-carry-through-box failed during a ground fatigue test. This failure was traced to the
manufacturers of the box, the Selb Manufacturing Corp, which had been paying off
inspectors for approving unauthorized weldings. Extensive retrofits were required because
most F-111As had already cleared the production lines.
The last of 158 F-111As was delivered on August 39, 1969.
This total included 17 of the 18 RDT&E F-111As initially ordered in December 1962. The
18th test F-111A was used as a test prototype for the FB-111A bomber program.
The Air Force lost its 15th F-111A on December 22, 1969, due
to failure of the forged wing pivot fitting. All F-111As were grounded the next day. The
grounding was lifted on July 31, 1970. This accident cast doubt on the structural
integrity of the aircraft and compounded the aircraft's modernization. Each F-111A had to
be carefully checked and fixed as necessary.
The F-111A returned to Southeast Asia in September of 1972.
They entered combat not long after yet another crash and yet another grounding. Two F-111A
squadrons (the 429th and 430th) left Nellis AFB for Thailand. They participated in the Linebacker
II aerial offensive against North Vietnam. They flew bombing missions against targets
in North Vietnam and Laos in the midst of the monsoon season. They flew without electronic
countermeasures escort aircraft or KC-135 tankers. On November 8, 1972, they flew 20
strikes over North Vietnam in weather that grounded other aircraft.
Four F-111As could deliver the bomb loads of 20 F-4s. Shortly
after returning to SEA, an F-111A experienced double engine rollback after encountering
heavy rain. There were continual problems with the terrain-following radar and the attack
radar. Malfunctions of the internal navigation and weapons release system also cropped up
on a regular basis. Nevertheless, the 429th and 430th TFS flew some 4000 combat missions
with excellent success rates in hitting targets even when visibility was near zero. Only
six aircraft were lost in action.
In 1977, surviving F-111As were transferred to the 366th TFW
based at Mountain Home, Idaho, where they equipped the 389th and 391st Squadrons.
42 F-111As were converted into EF-111A Raven electronic
warfare aircraft.
In 1982, four F-111As were transferred to the Royal
Australian Air Force to cover attrition in their F-111C fleet.
Two of the pre-production F-111As (serial numbers 63-9771 and
63-9777) were used for tests by NASA at the Dryden Flight Research Facility between the
years 1967 and 1971. Another pre-production F-111A (63-9778) became the Transonic Aircraft
Technology demonstrator for NASA. It was fitted with a supercritical wing with a shorter
span and blunt wingtips and reduced aspect ratio. It flew for the first time at Edwards
AFB on November 1, 1974. During mid-1980, it was flown with laminar flow glove-sections on
the wing then rebuilt with a Boeing variable-camber "mission adaptive" wing for
Advanced Fighter Technology Integration tests. The F-111/AFTI continued further flight
testing until early 1989 when it was retired to the USAF Museum at Wright Patterson AFB in
Ohio. However, I don't remember seeing it there when I visited the museum in 1992
The F-111A never had an official Air Force popular name.
However, because of its long, pointed nose, the F-111A came to be known unofficially as
the "Aardvark", or just 'Vark for short.
F-111A serial number 67-0067 is currently on display at the
USAF Museum at Wright Patterson AFB in Ohio. An escape pod that was successfully used to
eject from F-111A 63-9780 is also on display.
Serials of F-111A:
63-9766/9782 General Dynamics F-111A
9776 converted to RF-111A recon aircraft
65-5701/5710 General Dynamics F-111A
66-0011/0058 General Dynamics F-111A
66-9277 General Dynamics F-111A
67-0032/0114 General Dynamics F-111A
Specifications of the F-111A:
Two Pratt & Whitney TF30-P-3 turbofans, 12,000 lb.s.t.
dry and 18,500 lb.s.t. with afterburning. Weights: 46,172 pounds empty, 63,051 pounds
combat, 82,819 pounds gross, 98,850 pounds maximum takeoff. Maximum speed 1453 mph at
53,450 feet, 914 mph at sea level. Initial climb rate 25,550 feet per minute (clean).
Service ceiling 58,000 feet, combat ceiling 56,650 feet, absolute ceiling 66,000 feet.
Combat radius was 1330 miles, with ferry range being 3165 miles with maximum external fuel
being carried. Internal fuel capacity was 5043 US gallons. With underwing fuel tanks, a
maximum of 7443 US gallons of fuel could be carried. Dimensions: wingspan 63 feet 0 inches
(maximum) and 31 feet 11 1/2 inches (minimum), length 73 feet 5 1/2 inches, height 17 feet
6 inches, wing area 525 square feet. Armed with one 20-mm M61A1 rotary cannon with 2000
rounds, which was only rarely actually fitted. Up to 30,000 pounds of bombs, missiles, or
fuel tanks could be carried on six underwing hardpoints and in the internal weapons bay.
The RF-111A was to have been a tactical reconnaissance
version of the F-111A with additional avionics and camera installations in the weapons
bay. It was authorized on December 3, 1965.
One pre-production F-111A (63-9776) was converted as a
prototype for the RF-111A and first flew on December 17, 1967. Imagery testing of the
converted F-111A took place between December 1967 and October 1968 achieved fairly good
results, indicating that the RF-111A might make a good reconnaissance aircraft. The
Defense Department had hoped that the conversion from F-111A to RF-111A configuration
could be done in the field in only a few hours, with the reverse conversion being just as
simple and straightforward. However, the conversion turned out to be much more cumbersome
than expected, taking several days to complete rather than just a few hours. These
difficulties caused the Air Force to cancel the whole RF-111A program. The sole prototype
is now on display at Mountain Home AFB in Idaho.
In the late 1960s and early 1970s, the Air Force was shopping
around for possible replacements for its Douglas EB-66 electronic warfare aircraft.
Although the EB-66 still continued to fly combat missions over North Vietnam, it was
rapidly beginning to show signs of age.
The Air Force rejected the development of a completely new
type of aircraft for this role as being economically impractical because of the small
number of aircraft required. At one time, some thought had been given to acquiring the
Grumman EA-6B Prowler carrier-based electronic warfare aircraft, but the Air Force was
reluctant to acquire yet another aircraft originally developed for the Navy. After some
thought, the Air Force concluded in 1972 that the modification of some existing F-111A
strike fighters would be the most cost-effective solution.
However, the EA-6B was a four-seat aircraft, and it was
concluded that it was impractical to adapt the F-111A to a four-seat configuration because
it would reduce internal capacity too much. The only alternative was to develop equipment
similar to the Tactical Jamming System of the EA-6B, but capable of being operated by a
single electronics warfare officer.
In December 1974, the Grumman Aircraft Corporation of
Calverton, Long Island was selected as the prime contractor for this conversion. On
January 30, 1975, Grummann was awarded a contract for the modification of two F-111As
(serials 66-0041 and 66-0049) as EF-111A prototypes, the E prefix standing for
"Electronic".
The modifications included the installation of an AN/ALQ-99E
jamming subsystem. Exciters, antennae, and other items were mounted on a pallet inside the
internal weapons bay. Other components were mounted inside a 16-foot ventral
"canoe"-shaped radome. A fin-tip pod accommodated the electronic countermeasures
receivers. The self-protection subsystem consisted of a jamming system and a
countermeasures dispensing set. A terminal threat warning subsystem was installed which
consisted of infrared and electronic countermeasures receiver sets. The vertical fin had
to be reinforced in order to support the fin-tip pod, new electrical wiring had to be
installed, 60 kVA generators were replaced by 90 kVA units, and an improved environmental
system for electronic equipment cooling was fitted. The cockpit had to be rearranged to
accommodate the new electronic warfare officer position, with the flight controls being
removed from the right-hand cockpit, the navigation equipment being relocated so that
could be used by the pilot in the left-hand seat, and the controls and displays for the
electronics warfare officer being installed in the right-hand cockpit.
These modifications resulted in an increase of empty weight
from 46,172 pounds for the F-111A to 55,275 pounds for the EF-111A. However, since the
EF-111A carried no weapons, its maximum takeoff weight was only 88,848 pounds as compared
with 98,850 pounds for the F-111A. The Pratt & Whitney TF30-P-3 turbofans of the
F-111A were retained.
Grumman first flew a partially-modified F-111A fitted with a
mockup of the ventral canoe in December of 1975. The first EF-111A prototype (serial
number 66-0049) flew at Calverton on March 10, 1977. It was complete with fin-tip pod and
ventral fairing, but still lacked most of its electronic equipment.
The first flight of a fully-equipped EF-111A (serial number
66-0041) was made on May 17, 1977. This aircraft was delivered to the Air Force to be used
by Detachment 3 of the Tactial Air Warfare Center at Mountain Home AFB in Idaho for
operational test and evaluation.
Satisfactory results from these tests led to the issuance of
a contract for the modification of six more aircraft. Later, 34 more conversions were
ordered.
The name Raven was officially adopted for the EF-111A.
First deliveries of EF-111A Ravens were made to the 390th
Electronic Combat Squadron of the 366th Tactical Fighter Wing at Mountain Home AFB in
Idaho in November 1981 and to the 42nd ECS of the 20th TFW at RAF Upper Heyford in
February 1984. 42 Ravens had been delivered to the 366th TFW and the 20th TFW by December
of 1985. Mountain Home AFB received most of them.
The first operational mission for the Raven took place during
Operation Eldorado Canyon, the retaliatory attack on Libya on the night of April
14-15, 1986. During that mission, the 42nd ECS provided three EF-111As plus two spare
aircraft to jam the Libyan radar network.
In 1986, General Dynamics was given a contract to install
more powerful TF30-P-9 turbofans in the EF-111A.
In May of 1988, a contract for the update of the AN/ALQ-99E
by the AIL Division of the Eaton Corporation was cancelled due to cost overruns.
Under an Air Force contract awarded in January 1987, Grumman
and TRW Inc. developed the Avionics Modernization Program (AMP) kit for the EF-111A. These
kits provided the EF-111A with improved terrain following and navigational radars, a ring
laser gyro inertial navigation system, the capability for using the global positioning
system, two digital computers, improved cockpit displays, and upgraded communication
systems. The first AMP kit was installed in EF-111A 66-0018 in January of 1989. Most
existing EF-111As were later to receive this upgrade.
Eighteen EF-111A Ravens were deployed in support of Operation
Desert Storm in 1991. They flew over 900 sorties. None were lost in combat, but one
was lost in a non-combat related accident and both crew members were killed.
The EF-111A Raven was even credited with a "kill"
during Desert Storm. On the night of January 17, 1991, an Iraqi Mirage F.1 flew
into the ground while chasing EF-111A serial number 66-0016. Even though the Raven is
unarmed and has no air-to-air capability, the Raven crew was given credit for the kill.
Serials of the EF-111A Raven (all conversions from
F-111A blocks):
66-0013/66-0016, 66-0018/66-0021, 66-0023, 66-0027, 66-0028,
66-0030, 66-0031, 66-0033, 66-0035/66-0039, 66-0041, 66-0044, 66-0046/66-0051,
66-0055/66-0057, 67-0032/67-0035, 67-0037/67-0039, 67-0041, 67-0042, 67-0044, 67-0048,
67-0052.
Specifications of the EF-111A Raven:
Two Pratt & Whitney TF30-P-3 turbofans, 10,750 lb.s.t.
dry, 18,500 lb.s.t. with afterburning. Maximum speed: 1377 mph at 40,000 feet. Initial
climb rate 11,000 feet per minute. Service ceiling 45,000 feet. Normal range 929 miles.
Dimensions: wingspan 63 feet 0 inches (maximum), 31 feet 11 1/2 inches (minimum), length
76 feet 0 inches, height 20 feet 0 inches, wing area 525 square feet. Weights: 55,275
pounds empty, 70,000 pounds loaded, 88,948 pounds maximum takeoff.
The F-111B was the naval version of the TFX fighter project,
which had been decreed by Secretary of Defense McNamara to be designed in common with the
Air Force version, even though the requirements were completely different. In retrospect,
this turned out to be a serious mistake.
The F-111A and B aircraft shared the same primary structure,
the same fuel system, the same pair of Pratt & Whitney TF30-P-1 turbofans, and the
same two-seat cockpit in which the two crew members sat side-by-side. In an emergency, the
cockpit doubled as an escape capsule which was blown free from the aircraft to parachute
to the ground. However, the F-111B's nose was 8 feet 6 inches shorter than the F-111A's
because of the need of the aircraft to fit on existing carrier elevator decks, and had 3
feet 6 inch extended wingtips in order to increase the wing area so that the on-station
endurance time would be improved. The Navy F-111B version would carry a Hughes AN/AWG-9
pulse-Doppler radar and an armament of six Hughes Phoenix missiles. The Air Force F-111A
version would be provided with the General Electric AN/APQ-113 attack radar and the Texas
Instruments AN/APQ-110 terrain- following radar and would carry an armament of
air-to-ground stores.
Both the Phoenix missiles and the AN/AWG-9 radar had evolved
from the earlier Douglas F6D Missileer program. The Phoenix missile fire-control system
owed much to the USAF's ASG-18 system which had originally been developed for the abortive
F-108 Rapier project.
Since General Dynamics lacked any experience with
carrier-based fighters, it teamed with Grumman (an experienced builder of naval fighters)
for the development and subsequent manufacture of the F-111B. It was decided that Grumman
would do the integration of the naval electronics package and would assemble and test the
entire F-111B aircraft. In addition, Grumman was selected as a subcontractor to build the
aft fuselage and landing gear of both Navy and Air Force F-111 aircraft.
The first F-111B (Bu No 151970) was assembled at Bethpage
from components produced by both General Dynamics and Grumman. It was powered by the same
pair of Pratt & Whitney TF30-P-1 turbofans that powered the F-111A. Pending the
availability of the escape capsule, the first F-111B was equipped with a pair of
conventional ejector seats. It was rolled out at Bethpage on May 11, 1965 and transported
to Calverton. It made its first flight at Calverton on May 18, flown by Ralph
"Dixie" Donnell and Ernie von der Heyden. Aside from a problem with compressor
stall (as already experienced by the F-111A), the first flight was trouble-free.
The first Naval Preliminary Evaluation was held at NATC
Patuxent River in October of 1965. The F-111B was already in trouble since it was
seriously overweight. Takeoff weight for a fully-equipped aircraft was estimated at nearly
78,000 pounds, well over the upper limit of 55,000 pounds as required by the Navy.
The problems with the overweight F-111B were so severe that
General Dynamics and Grumman were forced into a Super Weight Improvement Program (SWIP),
most of the changes being incorporated into the fourth and subsequent F-111Bs. The fourth
F-111B (BuNo 151973) was fitted with an escape capsule in place of the individual ejector
seats that were fitted to the first three F-111Bs. However, the fitting of this capsule
more than offset the weight reductions achieved by the SWIP, and the F-111B remained
grossly underpowered. Range was also below specifications and could only be increased by
adding more fuel, making the aircraft even heavier.
In order to correct the underpower problem and to eliminate
compressor stalls (which were also problems for the land-based F-111As), the first of 32
production F-111Bs (BuNos. 152714/152717, 153623/153642, and 156971/156978) which had been
ordered was powered by a pair of TF30-P-12 turbofans, each rated at 12,290 lb.s.t. dry and
20,250 lb.s.t. with afterburning.
The third F-111B (BuNo 151972) was allocated to trials with
the Phoenix missile system. Four Phoenix missiles were to be carried on swiveling pylons
underneath the wings, with two Phoenix missiles being housed inside the fuselage weapons
bay. The first successful firing of a Phoenix missile took place in July of 1967.
By October 1967, the Navy was finally convinced that the
F-111B was a lost cause and would never be developed into a useful carrier aircraft and
recommended that the project be terminated. The axe finally fell in May of 1968 when both
houses of Congress refused to fund F-111B production. On July 19, 1968, a stop-work order
was issued and the terms of formal contract termination were agreed upon in December of
that year. This included the cancellation of 28 production F-111Bs (BuNos 153623/153642
and 156971/156978). The seventh and last F-111B (152715) was delivered on February 28,
1969, after $377 million had spent on the program.
Tests continued at Point Mugu and China Lake even after the
F-111B program had been terminated. BuNo 151974 was used for carrier trials aboard the USS
Coral Sea (CVA-43) in July of 1968. The Hughes Aircraft Corporation flew BuNo
1542715 (the last F-111B completed before project termination) until the spring of 1971.
By that time, a total of 1748 hours had been flown and two F-111Bs had been lost in
crashes. 151973 went down off the coast of Long Island on April 21, 1967, and 151971 was
lost off the coast of California on September 11, 1968. The surviving five aircraft were
permanently grounded in 1971. I am uncertain if any F-111Bs still survive today.
Serials of the F-111B:
151970/151974 Grumman/General Dynamics F-111B
152714/152717 Grumman/General Dynamics F-111B
152716 and 152717 were not completed.
153623/153642 Grumman/General Dynamics F-111B
- contract cancelled
156971/156978 Grumman/General Dynamics F-111B
- contract cancelled
Specifications of the F-111B:
Two Pratt & Whitney TF30-P-1 turbofans, 12,000 lb.s.t.
dry and 18,500 lb.s.t. with afterburning. Later, two TF30-P-12 turbofans, rated at 12,290
lb.s.t. dry and 20,250 lb.s.t. with afterburning were fitted. Maximum speed 1450 mph at
40,000 feet, 780 mph at sea level. Initial climb rate: 21,300 feet per minute. Service
ceiling 44,900 feet. Normal range 1092 miles. Maximum range 3178 miles. Weights: 46,500
pounds empty, 72,421 pounds loaded, 86,563 pounds maximum takeoff. Dimensions: wingspan 70
feet 0 inches (maximum) and 33 feet 11 inches (minimum), length 68 feet 10 inches, height
16 feet 8 inches, wing area 550 square feet. Armed with six Hughes AIM-54A Phoenix
air-to-air missiles, four underneath the wings and two inside the fuselage weapons bay. In
addition, a 20-mm M61A1 cannon could be fitted.
On October 24, 1963, the government of Australia agreed to
purchase 24 F-111As. The Australian version was to be designated F-111C.
The F-111C was sort of a hybrid between the F-111A, the
F-111B, and the FB-111A (to be described later). The F-111C was equipped with eight
underwing pylons mounted on an F-111B-type larger span wing (span of 70 feet when fully
extended). It was equipped with with an FB-111 type of reinforced undercarriage. The
twenty-four F-111Cs were given the USAF serial numbers 67-0125/0148. Their RAAF serials
were A8-125/148.
The first F-111C was delivered on September 6, 1968. However,
the problems with the F-111A's wing carry-through box slipped delivery of the remaining 23
F-111Cs to late 1969. To make matters worse, the whole F-111 fleet had to be grounded
pending verification of their overall structural integrity. The remaining F-111Cs awaiting
delivery to Australia were stored at Fort Worth until the structural integrity of the
F-111 could be confirmed. In April of 1970, a joint agreement between General Dynamics and
Australia deferred the RAAF's acceptance of the F-111C pending the verification of their
structural integrity. The RAAF was to lease F-4E Phantoms as an interim aircraft while new
wing carry-through boxes were installed on all F-111Cs before being delivered to the RAAF.
This refurbishment program began on April 1, 1972.
In 1973 the F-111C was finally ready for delivery to the
RAAF. Australian crews came to the USA, and, one-by-one, these crews flew their new mounts
from Fort Worth to McClellan AFB. Once at McClellan, the Australian crews flew several
training missions before leaving for Australia. The first F-111Cs reached Australia on
June 1, 1973, replacing the RAAF's fleet of English Electric Canberra bombers that has
been in use since the 1950s. They were operated by Nos. 1 and 6 Squadrons based at
Amberley, Queensland.
The F-111C carries the APQ-113 forward-looking attack radar,
which is used for navigation, for air-to-ground ranging and for weapons delivery. In
theory, this radar can also be used in the air-to-air mode in conjunction with the
internal 20-mm cannon or Sidewinder missiles carried underwing, although this is not the
primary mission of the F-111C.
Four F-111As were converted for the RF-111C reconnaissance
role by General Dynamics and delivered to Australia. The first of these
(A8-126) was flown on April 17, 1979. The reconnaissance
"kit" comprises two KS-87C framing cameras, a KA-56E low-altitude and KA-93A4
high altitude panoramic camera, and an AN/AAD-5 Infrared Linescanner. There is a TV
viewfinder which assists with line up for the photo run. The RF-111C retains full
conventional attack capability. The four RF-111Cs bear the serials A8-126, -134, -143, and
-146.
The F/RF-111C fleet is currently undergoing an upgrade by
Rockwell at its Palmdale plant. Fully 90 percent of the electronics in the F-111C are
being replaced by more capable units. The first upgraded F-111C is to be A8-132. This
should keep the RAAF F-111Cs flying until the year 2020.
In October 1992 it was announced that Australia planned to
buy 18 surplus F-111s from the USAF to augment the 22 surviving F-111Cs in the RAAF fleet.
The price was described as "bargain basement", about $AUD60-80M; plus $AUD10-15M
per plane for upgrades. ($AUD 1 =~ $USD 0.72). Delivery is expected to begin sometime in
1994. These planes are (will be?) in mothballs in the US, but delivery is not expected to
begin until sometime in 1994.
F-111D was the designation given to a more advanced version
of the F-111. It was powered by a pair of Pratt & Whitney TF30-P-9 engines, each rated
at 12,000 lb.s.t. dry and 18,500 lb.s.t. with afterburner. The aircraft were equipped with
Mark II microprocessor avionics with improved air-to-air capability. This system was a
first generation version of what later came to be known as a "glass" cockpit.
In addition, the F-111D was provided with Triple Plow 2 air
intakes, which were intended to correct the F-111's seemingly chronic problems with
compressor stall. The Triple Plow 2 intakes were mounted four inches farther from the
airframe in order to improve the boundary layer "plow", and the translating cowl
was replaced by a series of blow-in doors. These blow-in doors were a set of auxiliary
inlets which enabled extra airflow to reach the inlet duct during takeoff or when the
engine is at full power but the aircraft is moving slowly. They are normally sealed closed
by spring-loaded doors which are pushed open by air pressure when additional air flow is
needed.
The Mark II system included 7 major components--an inertial
navigation set and attack radar built by the Autonetics Division of North American
Rockwell, an IBM computer system, converter and panels by the Kearfott Division of
Singer-General Precision, Inc., an AN/AVA-9 integrated display set by the Norden Division
of United Aircraft Corporation, a Doppler radar by the Canadian Marconi Company, a
horizontal situation display by the Astronautics Corporation of America, and a stores
management set by the Fairchild Hiller Corporation. The main forward-looking attack radar
of the F-111D was the APQ-130, with MTI, Doppler beam sharpening, and illumination for
radar-guided AAMs.
The F-111D was ordered on May 10, 1967. The first F-111D
(68-0085) flew on May 15, 1970. It was equipped with the new P-9 engines but did not have
a complete Mark II system. It was delivered to the Air Force on June 30, 1970, only one
day after the lifting of the F-111 delivery hold order imposed after the F-111A crash of
December 11, 1969.
The F-111D went through a rather protracted development cycle
before it was deemed fit for service. There were difficulties in integrating the various
complex electronic components with each other. The Autonetics attack radar needed several
improvements in its initial design, and the Norden integrated display set required
extensive changes. The radar problems required that the radar doppler unit be redesigned,
which in turn caused interface problems with the Norden integrated display set. By late
1969, the Mark II system was still not ready. By mid-1970, the problems with the Norden
integrated display set were still not resolved. Several months of acrimonious arguments
between Autonetics and Norden followed, Norden claiming that the IDS's original
specification was beyond the state of the art.
Development problems with the F-111D's advanced avionics
caused so many delays that the Air Force decided to acquire the simpler F-111E as an
interim version.
It was not until November 1, 1971 that the first F-111D was
delivered to the 27th TFW at Cannon AFB in New Mexico, the third TAC Wing to receive the
F-111. This aircraft was the sixth F-111D produced (68-0090). It was equipped with a full
Mark II avionics system, featuring one of Norden's early IDS productions. The initial
operational capability with the 27th TFW was in September 1972. Eventually, the F-111D
equipped the 522nd, 523rd, and 524th Squadrons of the 27th TFW.
Throughout the rest of 1972, TAC's few F-111Ds continued to
be crippled by avionics problems. The horizontal situation display was prone to frequent
failures, delivery of field ground equipment was late, and depot support was poor.
Operational readiness remained low all throughout 1973, and the abort rate of the F-111D
was higher than that of other F-111s. It was not until January of 1974 that the F-111D was
finally declared operationally ready.
96 F-111Ds were delivered between June 30, 1970 and February
20, 1973. The serials were 68-0085/0180. In 1993, the F-111D remains with the 27th TFW at
Cannon AFB.
The RF-111D was a proposed but unbuilt reconnaissance version
of the F-111D with very sophisticated avionics. The program was abandoned in September of
1969 because of lack of funds. Cheaper RF-111As were to be acquired, which were in turn
cancelled as well.
Because of late delivery and protracted development of the
F-111D, 94 F-111Es were ordered with simplified avionics and the TF30-P-3 turbofan engine,
but with the Triple Plow 2 air intakes of the F-111D. They were ordered in 1968. Even
though the F-111E had a later series letter than the F-111D, the E preceded the D into
service.
As compared to earlier F-111 variable-geometry air intake
configurations, the Triple Plow 2 air intakes were four inches farther from the airframe
in order to improve boundary layer "plow", and the translating cowl was replaced
by a series of three blow-in doors. These blow-in doors are a set of auxiliary inlets
placed on the sides of the main intakes which enable extra airflow to reach the engine
inlet ducts during takeoff or when the engines are at full power but the aircraft is
moving slowly. They are normally sealed closed by spring-loaded doors which are pushed
open by air pressure when additional airflow to the engines is needed.
The F-111E carries the APQ-113 forward-looking attack radar
which is used by the navigator for navigation, air-to-ground ranging and weapons delivery.
It can also be used in the air-to-air mode, although this is not the primary mission of
the F-111E.
The first flight of an F-111E took place on August 20, 1969,
and deliveries to the Air Force took place from 1969 to May 28, 1971. A total of 94 were
built, and serials were 67-0115/0124 and 68-0001/0084.
TAC's 27th Tactical Fighter Wing at Cannon AFB reached
initial operational capability with the F-111E in the fall of 1969. The wing had 29
F-111Es by December, but these flew under restrictions until the Air Force was convinced
that the wing longerons were safe.
The F-111E program slipped another six months following the
December 1969 loss of the 15th F-111A. The Air Force grounded the entire fleet and refused
to accept the delivery of any more F-111s until the problems were fixed. All F-111Es went
through the Recovery Program and other structural inspections that stemmed from the
December 1969 accident. The order that grounded the fleet was finally lifted in July of
1970.
The F-111E had integral radar homing and warning equipment
and possessed electronic countermeasures capability. This made the aircraft needed in
Europe right away. Despite the program's slippage, the first two of the 70 F-111Es slated
for the 20th Tactical Fighter Wing in Europe were sent to the RAF Upper Heyford base in
Oxfordshire, England on September 11, 1970. The wing became fully operational with the
type in November of 1971. These F-111Es remained based at Upper Heyford up to 1993, when
defense cutbacks and the overall decline in the threat from the East resulted in their
withdrawal to stateside bases.
F-111Es of the 20th TFW were used in Operation Desert
Storm in early 1991, flying out of bases at Incirlik, Turkey. They lacked the
precision guided munitions capability of the later F-111F, and so they carried mainly Mk
82 or Mk 84 standard conventional bombs and other conventional ordnance against targets in
the northern part of Iraq. None were lost in combat, which is a remarkable testament to
the efficacy of the F-111E in combat.
The first prototype of the F-111E series (67-0115) was loaned
to NASA for tests in support of the Integrated Propulsion Control System. This was a
"fly-by-wire" system installed in the weapons bay which automatically controlled
the variable-geometry inlet and the turbofans. The first IPCS flight was carried out on
September 4, 1975. The last flight was on February 27, 1976. After the tests were
completed, the F-111E was returned to the Air Force and restored to its original
configuration. It later served as a chase plane for the Rockwell B-1 strategic bomber.
The F-111F was the final F-111 version produced for the
Tactical Air Command (TAC). It was ordered on July 1, 1970. It differed from the F-111D in
having more advanced electronics which were nevertheless simplified and more reliable. It
carried the Mark IIB avionics suite which combined F-111D and FB-111A navigational and
digital computer systems (but excluding the F-111D's AN/APN-189 Doppler radar navigation
set) plus numerous other FB-111A components such as the AN/APQ-144 attack radar and some
simpler, less costly avionics systems used by earlier F-111s. The APQ-144 attack radar of
the F-111F has a new 2.5-mile display ring made possible by a 0.2 s pulse-width
capability. The F-111F also featured an improved landing gear. It was powered by a pair of
25,100 lb.s.t. TF30-P-100 turbofans (although the first 30 had TF30-P-9s and were
subsequently re-engined).
On October 13, 1971, a modified F-111A started the F-111F
Category I flight test program. A problem with overheating of the aft centerbody fuselage
was corrected by an engineering change. The first F-111F entered service with the 374th
TFW based at Mountain Home AFB in Idaho in January 1972. The entire wing became
operationally ready in October of 1972. There were some initial problems with the
TF30-P-100 engine --- difficulties were encountered with afterburner stalls in cold
weather, with tail-feather seal leakage, and with inlet guide vane cracking
The last F-111F was delivered to the USAF in September of
1976. 106 F-111Fs were built. Their serials were 70-2362/2419, 71-0883/0894, 72-1441/1452,
73-0707/0718, and 74-0177/0188. Another twenty-four were cancelled (serials were
71-0895/0906 and 75-0210/0221).
After serving with the 366th TFW, the F-111Fs were reassigned
to the 48th TFW based at RAF Lakenheath in the United Kingdom. F-111Fs also serve with the
57th Fighter Weapons Wing based at McClellan AFB in California.
The F-111F has an internal weapons bay, but in most aircraft
this bay is normally occupied by extra fuel or by other equipment. Many F-111Fs carry the
Ford AVQ-26 Pave Tack pod semi-recessed in the weapons bay. The Pave Tack is
equipped with a laser designator and forward-looking infrared (FLIR) which are used for
the delivery of laser-guided bombs with pinpoint accuracy. The laser and FLIR are
boresighted in a powered turret giving magnified clear pictures of targets integrated with
the cockpit avionics displays and weapons-aiming systems. Although all of the F-111 marks
can drop laser-guided bombs, only the F version has the laser suite to designate targets.
24 F-111Fs from the 48th TFW based at Lakenheath spearheaded
the US attack on Libya on the night of April 14, 1986, striking targets in Tripoli with
laser-guided and retarded bombs. The lead ship during the Libya strike was 70-2390. One
F-111F (serial number 70-2389) was lost to ground fire during the attack.
During Desert Storm, the 67 F-111Fs of the 48th TFW
operated from air bases in Saudi Arabia. Because of their ability to deliver
precision-guided ordinance in all-weather conditions, they played a key role in the
destruction of the Iraqi command and control structure and in the elimination of key
targets in the Kuwait theatre of operations. These aircraft flew 2500 sorties, destroyed
2203 targets, including direct hits on 920 tanks, 252 artillery pieces, 245 hardened
aircraft shelters, 13 runways, 113 bunkers, and 12 bridges. A total of 5500 bombs were
dropped. Almost 85 percent of these bombs were precision guided munitions. When Iraqi
forces deliberately opened a oil pumping station manifold to allow oil to leak into the
Persian Gulf, an F-111F was selected to deliver the GBU-15 electro-optically guided bomb
against the manifolds to stop the flow.
On the last night of the war, two F-111Fs delivered the
hastily-devised GBU-28 deep-penetrator bombs against Iraqi command and control bunkers.
These bombs could penetrate over 100 feet of earth or 22 feet of concrete.
No F-111Fs were lost in combat during the Persian Gulf War,
which is a remarkable testament to its combat effectiveness.
Specification of F-111F:
Two Pratt & Whitney TF30-P-100 turbofans, 25,100 lb.s.t.
with afterburning. Maximum speed: 1453 mph at 53,450 feet, 914 mph as sea level. Initial
climb rate 25,550 feet per minute (clean). Service ceiling 56,650 feet. Combat radius 1330
miles. Maximum ferry range 3634 miles with external fuel. Dimensions: wingspan 63 feet 0
inches (maximum), 32 feet 0 inches (minimum), length 73 feet 6 inches, height 17 feet 0
inches, wing area 525 square feet. Weights: 46,172 pounds empty, 82,819 pounds gross,
98,950 pounds maximum takeoff. Internal fuel capacity was 5043 US gallons, with a total
capacity of 7443 US gallons when maximum external fuel is carried.
The FB-111A was the all-weather strategic bombing version of
the F-111, intended as an interim successor to the B-52 and B-58 of the Strategic Air
Command. It was initially developed as Weapon System 129A.
The FB-111A differed from the F-111A primarily in having a
longer fuselage (75 feet 7 inches as compared to 73 feet 5 1/2 inches) to accommodate the
additional fuel required for its strategic mission. In order to provide a longer range and
greater load-lifting capability, the FB-111A had the extended wing of the F-111B (unfolded
span of 70 feet as compared to 63 feet). It also had a stronger undercarriage and landing
gear, and was powered by TF30-P-7 turbofan engines. It featured the Mark IIB avionic
subsystem planned for the F-111E, which comprised an improved F-111A attack radar, an
inertial navigation system, digital computers, plus some advanced displays of the later
Mark II that equipped the delayed F-111D
The FB-111A was actually the first F-111 version to fly with
the new Triple Plow II air intakes, beginning with the third example (67-0161). The Triple
Plow II intakes were mounted four inches farther from the airframe in order to improve the
boundary layer "plow", and the translating cowl was replaced by a series of
blow-in doors which fed additional air to the engines during takeoff or when the aircraft
was moving slowly.
The development of the FB-111A was prompted by the slow
progress of the Advanced Manned Strategic Aircraft (AMSA) program and by fears that
fatigue failures in the B-52 fleet might come earlier than expected. A proposal to resume
production of the Convair B-58 Hustler was rejected as being too costly. In the spring of
1963, the Air Force turned to General Dynamics for a solution to its problem. In November
of 1963, General Dynamics responded with a suggestion for two strategic versions of the
F-111A. In order to hasten availability, the Air Force decided on June 2, 1965 that the
least modified version was the one that they would go with. The designation FB-111A was
applied, which is sort of curious since the design was basically a modified F-111A, which
would have suggested that the designation should have been BF-111A.
The Air Force initially planned to order 263 FB-111As (210 to
equip 14 squadrons, plus 20 for combat crew training and the remaining 33 for support and
testing). It wanted them in service quickly, the first FB-111As being expected to be
operational as early as fiscal year 1969.
Secretary of Defense Robert McNamara publically announced
plans to develop the FB-111A on December 10, 1965. However, the implementation of the
program was postponed until February 1966, when the FB-111A had been added to the basic
F-111A RDT&E contract and Congress had approved the funds. In January of 1966,
Secretary McNamara asked the Air Force to begin contract definition on Mark II avionics
systems for both the FB-111A and the delayed F-111D, with maximum commonality being a key
requirement. The primary weapon of the FB-111A was to be the Boeing-designed AGM-69A
Short-Range Attack Missile (SRAM).
A modified RDT&E F-111A (serial number 63-9783) was
converted as the prototype of the FB-111A and flew for the first time on July 30, 1967. It
achieved Mach 2 on its first test flight.
Pending the availability of the P-7 engine, it was decided
that the first few FB-111As would receive P-12A engines (the USAF version of the Navy P-12
engine that was used in the F-111B) and these engines would subsequently be brought up to
the P-7 configuration once the aircraft was in service.
The first production FB-111A aircraft flew on July 13, 1968.
It was accepted by the Air Force on August 30, 1968. A second FB-111A was delivered on
October 25. These two planes were powered by TF30-P-12A engines. Problems with the Mark
IIB avionics slowed further deliveries, with the Air Force not accepting its next FB-111A
until June 23, 1969. This aircraft featured a fully-developed Triple Plow II air diverter,
a complete Mark IIB avionics system, and the new P-7 engines.
The first 6 FB-111A production aircraft were used for
testing. Category III tests did not finish until July 31, 1972.
A total of 263 planes was projected when the FB-111A program
began. This was reduced to 126 on November 28, 1968 because of rising costs and production
delays with the basic F-111 program. The final cut took place on March 16, 1969, with the
total FB-111A order being reduced to 76.
On October 8, 1969, the 7th FB-111A entered service with the
4007th Combat Crew Training Squadron of the 340th Bomb Group at Carswell AFB. Even though
the FB-111A was officially declared operational, it had yet to reach the combat forces.
After reaching operational capability, the 4007th CCTS relocated to Plattsburg and became
part of the 380th Strategic Aerospace Wing.
The primary offensive armament of the FB-111A was the
Boeing-designed AGM-69A SRAM, a missile designed primarily to neutralize enemy defense
systems such as radars, SAMs, and other anti-aircraft systems. The launch weight of the
SRAM was 2230 pounds, and it was powered by a two-pulse solid-fuel rocket motor. Maximum
speed was Mach 2.8-3.2, and the range varied from 35 to 105 miles, depending on the
mission. The guidance system consists of a Singer Kearfott inertial guidance operating in
conjunction with a Delco on-board computer. Various attack trajectories could be chosen,
ranging from semi-ballistic to terrain-following. During an actual operational mission,
the bombardier would selects each missile in turn, update the inertial guidance system,
then would let the missile drop. The rocket motor would then fire and accelerate the
missile to Mach 3. fast enough to fly and steer with body lift and three tail fins. When
the missile neared the target, the second propulsion stage would then ignite for the final
run in to the target. The SRAM carried a W6 nuclear warhead with an explosive yield of 200
kilotons.
FB-111A testing of the SRAM began on March 27, 1970. Initial
test started poorly --- in almost a year, there were only seven successes out of 11
launches. However, by early 1961, the results began to get better, with the final score
being 15 successes out 19 launches during the entire test series.
In January 1971, the FB-111A achieved initial operational
capability with the 509th Bomb Wing (393 and 715 Squadrons) based at Pease AFB in New
Hampshire. After many difficulties, the 509th was finally declared fully combat-ready in
October of 1971. The 380th Strategic Aerospace Wing (528 and 529 Squadrons, plus the
4007th Combat Crew Training Squadron) at Plattsburg AFB in New York became combat ready in
1972. These were the only two SAC wings to receive the FB-111A.
The last production FB-111A (68-0291) was delivered to SAC on
June 30, 1971.
The FB-111A could carry two AGM-69A SRAMs in the internal
weapons bay along with two more on the inner underwing pylons. Typically, four 600-US
gallon drop tanks were carried on the outermost underwing pylons, although the SRAMS
carried underneath the innermost underwing pylons could be replaced by another pair of
600-gallon drop tanks, bringing the total number of drop tanks to six. The non-swiveling
outer pylons are intended for subsonic flight only and are jettisoned when wing sweep
exceeds 26 degrees. Alternatively, up to 24 750-pound conventional bombs could be carried
externally. The FB-111A could also carry six gravity nuclear weapons or a B77 nuclear
bomb. A total offensive load of 35,500 pounds could be carried.
The FB-111A carries the APQ-144 forward-looking attack radar,
which was derived from the APQ-113 of the F-111A. It adds a beacon mode, a photo recording
capability, and a north-oriented display.
Landing gear malfunctions persisted throughout mid-1971 and
were finally solved by a simple field modification. In late 1971, weapons delivery was
still marginal, reflecting failures in the inertial navigation system. There were some
problems with engine flameouts following use of the afterburner, these being probably
caused by moisture in the engine sensing line.
In April 1972, new SRAM-carrying equipment was installed on
the FB-111A.
In November 1970, the FB-111A took top honors in bombing and
navigation during SAC's competition at McCoy AFB in Florida. The first overseas deployment
of the FB-111A was the entrance of two Pease FB-111As in a Royal Air Force bombing and
navigation meet at RAF Marham.
As the Rockwell B-1B Lancer came into service, the FB-111A
became redundant to SAC needs, and most surviving FB-111As were converted into ground
attack configuration and assigned to training units operating out of Cannon AFB in
California. During 1988, the designation F-111G was adopted for the FB-111As that were to
be converted eventually to serve in the tactical role when displaced from SAC.
In June of 1990, the SRAM missiles were removed from the
inventory because of safety concerns regarding the integrity of their W69 nuclear warheads
in the event of a fire. After that, the FB-111As stood alert with only gravity bombs.
Serials of the FB-111A:
67-0159/0163
67-7192/7196
68-0239/0202
69-6503/6514
Specification of the FB-111A:
Two Pratt & Whitney TF30-P-7 turbofans, 12,500 lb.s.t.
dry and 20,350 lb.s.t. with afterburner. Maximum speed (clean): 1453 mph at 50,000 feet,
1320 mph at 36,000 feet, 838 mph at sea level. Initial climb rate (clean) 23,418 feet per
minute. Service ceiling: 50,263 feet. Range: 2500 miles with four SRAMs and internal fuel
only. Maximum ferry range: 4786 miles with six 600-US gall. auxiliary fuel tanks mounted
on underwing pylons. Weights: 47,980 pounds empty, 119,250 pounds gross. Dimensions:
Wingspan 70 feet 0 inches (minimum sweep), 33 feet 11 inches (maximum sweep), length 73
feet 6 inches, height 17 feet 0 inches. Internal fuel capacity of 5010 US gallons. With
six 600 US gallon underwing drop tanks, a total of 9223 US gallons of fuel can be carried.
Armed with up to six Boeing AGM-69A SRAMs on external pylons or in internal weapons bay,
or a conventional ordnance load of up to 37,500 pounds of bombs, rockets, or fuel tanks.
The FB-111B was proposed in 1979 as an improved version of
the FB-111A powered by General Electric F101 turbofan engines in place of the Pratt &
Whitney TF30s. The fuselage was to be lengthened to 88 feet 2 1/2 inches, and additional
SRAMs were to be carried on underwing pylons. According to the proposal, 155 FB-111Bs were
to have been converted from existing F-111Ds and FB-111As. However, the project was
abandoned as being too costly and nothing was every produced.
As the Rockwell B-1B long-range strategic bomber entered
service, the FB-111As still remaining with SAC were converted into tactical configuration
under the designation F-111G. Under this program, the FB-111A's short range attack missile
(SRAM) system for stand-off nuclear delivery was retained, and a conventional weapons
release system was installed to provide for dual-role capability. Other improvements
included the installation of a Have Quick UHF radio and a new ECM system.
The first two F-111G conversions were completed in early
1989. The program was originally scheduled to continue at a rate of approximately twelve
conversions per year. The first F-111Gs and FB-111As were transferred from SAC to TAC
between June and December 1990. Deployment in Europe was considered for a brief time, but
the F-111G aircraft were added instead to the 27th TFW stationed at Cannon AFB, NM,
(augmenting the wing's F-111Ds) following the 1990-91 disbandment of SAC's 509th BW at
Pease AFB, NH, and the 380th BW at Plattsburgh AFB, NY.
The USAF currently has 62 FB-111s/F-111Gs on strength. The
F-111G has been used primarily for training, but is scheduled to be supplanted in the
training role by the F-111E. This makes the F-111G now surplus to USAF requirements. On
June 29, 1993, Australia announced that it was going to purchase 15 of these surplus
F-111G aircraft. They will enter service at RAAF Amberley in late 1994, joining 18 F-111Cs
and four RF-111Cs already in RAAF service.
In 1977, General Dynamics proposed an advanced version of the
FB-111A, the FB-111H, to compete with the Rockwell B-1 bomber. The FB-111H was quite
similar to the proposed FB-111B, with advanced avionics, General Electric F101 turbofans,
and six underwing stores pylons. However, it had an enlarged internal weapons bay capable
of carrying up to 12 SRAMs.
A modified version would have had a ten-foot longer fuselage
and would have carried twelve cruise missiles on underwing pylons plus four SRAMs carried
internally.
Since the Rockwell design was the winner of the contest, the
FB-111H never progressed beyond the study phase.
On February 1, 1967, the Royal Air Force ordered 46 F-111K
strike fighters and four TF-111K proficiency trainers. These were intended to fill the gap
left by the cancellation of the BAC TSR-2. The F-111Ks were assigned RAF serials
XV902/947, but they were also assigned the USAF serial numbers 68-0152/0158, 68-0181/0210,
and 68-0229/0238. The TF-111Ks were assigned RAF serials XV884/887, with equivalent USAF
serials being 67-0149/0152.
However, the Royal Air Force order was cancelled at the
beginning of 1968, the reason being given that they were much too expensive.
When the RAF order was cancelled, two TF-111Ks were almost
ready. They were taken over by the USAF, which designated them YF-111A and intended to use
them for tests. Their serial numbers were 67-0149/0150. However, these planes were never
actually completed.
United States Military Aircraft Since 1909, Gordon
Swanborough and Peter M. Bowers, Smithsonian, 1989.
General Dynamics Aircraft and their Predecessors, John Wegg,
Naval Institute Press, 1990.
Post-World War II Fighters: 1945-1973, Marcelle Size Knaac,
Office of Air Force History, 1986.
The American Fighter, Enzo Angelucci and Peter Bowers, Orion,
1987.
Modern Air Combat, Bill Gunston and Mike Spick, Crescent
Books, 1983.
Grumman Aircraft Since 1929, Rene J. Francillon, Naval
Institute Press, 1989.
The Fury of Desert Storm--The Air Campaign, Bret Kinzey,
McGraw-Hill, 1991.
The Illustrated Encyclopedia of Aircraft Armament, Bill
Gunston, Orion, 1988.
F-111 Aardvark --- USAF's Ultimate Strike Aircraft, Tony
Thornborough, Osprey Aerospace, 1993.
F-111 Aardvark, Hans Halberstadt, Specialty Press, 1992.
The World Guide to Combat Planes, William Green, Macdonald,
1966.
Flying the Frontiers --- NACA and NASA Experimental Aircraft,
Arthur Pearcy, Naval Institute Press, 1993.
Joe Baugher
