General Dynamics FB-111A (S/N 67-163, the 5th production FB-111A), taken Aug. 31, 1971, at Edwards Air Force Base, Calif. Note the two rows of white dots painted on the sides of the fuselage for precise tracking from ground stations during test flights. (U.S. Air Force photo)
The USAF bought 76 production FB-111As to fill a gap in the strategic bomber force between the time when the Boeing B-52C and F models and the Convair B-58As were being phased out in the late 1960s into the early 1970s.
The Advanced Supersonic Manned Aircraft project, which eventually resulted in the Rockwell International B-1A, was still in its early phases in the mid-1960s, and production of a new bomber was more than a decade off (the prototype B-1A's first flight was in November 1974). The proposal to modify the F-111A to a strategic bomber was seen as a relatively quick and inexpensive way to give the United States supersonic bomber capability.
The prototype FB-111A was converted on the assembly line from the last F-111A (S/N 63-9783). The aircraft featured a larger wing, stronger landing gear and the capability to carry up to six AGM-69A Short Range Attack Missiles -- two in the enlarged internal bomb bay and four mounted on wing pylons.
General Dynamics proposed an enlarged version of the FB-111A, designated FB-111H, which would have included a 15-foot fuselage extension, new and more powerful engines and increased weapons capability. The FB-111H never progressed past the design stage, however.
Converted from F-111A
TECHNICAL NOTES: Armament: Six AGM-69A SRAMs or up to 37,500 lbs. of conventional or nuclear weapons (B43, B61 or B77) Engines: Two Pratt & Whitney TF30-P-7 turbofans of 20,350 lbs. thrust each with afterburner Maximum speed: 1450 mph at 50,000 ft (Mach 2.2) Cruising speed: 565 mph Range: Approx. 4,500 miles without refueling Service ceiling: Approx. 50,000 ft. Span: 70 ft. (16-degree sweep) and 33 ft. 11 in. (72.5-degree sweep) Length: 73 ft. 6 in. Height: 17 ft. 1.4 in. Weight: 119,243 lbs. maximum takeoff weight (overload); 114,300 lbs. normal maximum takeoff weight Crew: Two (pilot and weapon systems officer) Serial numbers: FB-111A (prototype) 63-9783 (originally F-111A); FB-111A (production) 67-159 to 67-163; 67-7192 to 67-7196; 68-239 to 68-292; 69-6503 to 69-6514