Failure or success? It depends how you look at it.
The holy grail of fighter aircraft is one aircraft that meets the operational requirements of both the Air Force and the Navy. The most current attempt at a multi-service design is the Lockheed Martin F-35 “Lighting II.” Historically, the result of such ambitious efforts is an aircraft that does nothing really well, or worked well for one service or had limited combat capabilities.
The F-111 was an earlier attempt at a supersonic multi-role, multi-service all-weather fighter-bomber. The F-111 was handicapped from the beginning, based on a rather poorly conceived operational specification, with both the Air Force and the Navy pressured to commit to a civilian concept of the “Tactical Fighter Experimental” (TFX) program.
The concept called for a single aircraft that was both a nimble, carrier-based Navy fleet-defense interceptor and a more beefy land-based Air Force supersonic strike aircraft. Development focused on the Air Force role, and the F-111B—the naval variant—never made into production.
The F-111 Arrdvark was produced in a variety of models, including the F-111A, F-111D, F-111E, and F-111F, as well as an FB-111A strategic bomber. What the Pentagon had touted as a “cost effective” solution, ironically would be labeled a major aeronautical and financial fiasco in the 1960s. Other designations were assigned to aircraft sold to other nations.
Initially, F-111As had major engine problems. Intense testing by NASA pilots and engineers it was determined that engine inlet dynamics created pressure fluctuations that led to compressor surges and stalls. The engine problems were solved by a major inlet redesign.
The F-111 could operate from tree-top level to altitudes above 60,000 feet (18,200 meters). The major design feature were the variable sweep wings that would allow the pilot to fly from slow approach speeds to supersonic velocity at sea level and more than twice the speed of sound at higher altitudes. The wing angle could be swept to any angle from 16 degrees (full forward for takeoff, landing, and slow flight) to 72.5 degrees (full aft for maximum speeds).
In terms of fighter design, the F-111 was unusual in that the two crew members—a pilot and a weapons system/radar operator sat side-by-side in an air-conditioned, pressurized cockpit module that served as an emergency escape vehicle and as a survival shelter on land or water.
In an emergency, both crew members remained in the cockpit and an explosive charge separated the cockpit module from the aircraft. The module descended by parachute. The ejected module included a small portion of the wing fairing to stabilize it during aircraft separation. Airbags cushioned impact and helped keep the module afloat in water. The module could be released at any speed or altitude, even under water. For underwater escape, the airbags raised the module to the surface after it has been separated from the plane.
Using internal fuel only—tanks in the fuselage and the wings–the plane had a range of more than 2,500 nautical miles. External fuel tanks could be carried on the pylons under the wings and jettisoned if necessary. It also could be refueled in flight via a refueling boom receptacle on top of the aircraft aft of the cockpit.
The F-111 carried conventional or nuclear weapons. It could carry up to nuclear bombs or additional fuel in the internal weapons bay. External ordnance included combinations of bombs, missiles and fuel tanks. The loads nearest the fuselage on each side pivoted as the wings swept back, keeping ordnance parallel to the fuselage.
The avionics systems included communications, navigation, and electronic counter measure self-defense systems. A radar bombing system was used for precise delivery of weapons on targets during night or bad weather.
The FB-111 also had an automatic terrain-following radar (TFR) system that flew the craft at a constant altitude following the Earth’s contours. It allowed the aircraft to fly in valleys and over mountains, day or night, regardless of weather conditions. The pilot could adjust the ride of the TFR from a “soft” ride to a “hard” ride. In the “soft” mode, the aircraft would anticipate requirements to climb or descent and begin climbs and descents to “smooth” the flight. In the “hard” setting, the aircraft followed the shape of the terrain, making climbs and descents roughly match the rise and fall of the terrain.
F-111A, D, E, and F: The A model first flew in December 1964. The first operational aircraft was delivered in October 1967 to Nellis Air Force Base, Nevada. F-111A models were used for tactical bombing in Southeast Asia. The D. E, and F models incorporated incremental improvements in avionics and weapons systems, aerodynamics and engine performance. These aircraft remained operational through 1995, when they were replaced by the F-16 C/D aircraft.
EF-111A Raven: F-111As were converted to serve as electronic warfare platforms. The primary modifications were the ALQ-99 jamming system, N/ALQ-137 self-protection system, and an AN/ALR-62 terminal threat warning system. A total of 42 aircraft were converted to the EF-111A.
FB-111: The FB-111 was assigned to the Strategic Air Command (SAC) as a strategic nuclear-capable attack aircraft. With refueling, the aircraft could reach any target on the globe, and return. In 1990, FB-111s were retired from the SAC role, and converted to the F-111G transferred to the Tactical Air Command as high-performance fighter aircraft.