General Dynamics/Grumman F-111B

Last revised November 7, 2004

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 Navy F-111B was intended as a fleet defense fighter, whereas the F-111A was intended as a long-range air-to-ground strike aircraft. 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 abortive 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 by land 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 crashed during takeoff at Grumman's Calverton, Long Island facility 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:

Engines: 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. Performance: 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. Armament: 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.


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  2. United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.

  3. General Dynamics Aircraft and their Predecessors, John Wegg, Naval Institute Press, 1990.

  4. Post-World War II Fighters: 1945-1973, Marcelle Size Knaac, Office of Air Force History, 1986.

  5. The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.

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  7. Modern Air Combat, Bill Gunston and Mike Spick, Crescent Books, 1983.

  8. The Illustrated Encyclopedia of Aircraft Armament, Bill Gunston, Orion, 1988.

  9. F-111 Aardvark--USAF's Ultimate Strike Aircraft, Tony Thornborough, Osprey Aerospace, 1993.

  10. F-111 Aardvark, Hans Halberstadt, Specialty Press, 1992.

  11. E-mail from Douglas Reynolds on crash of 151973.