|Primary user||United States Navy|
The Rockwell XFV-12 was a prototype supersonic United States Navy fighter which combined the Mach 2 speed and AIM-7 Sparrow armament of the F-4 Phantom II in a VTOL (vertical takeoff and landing) fighter for the small Sea Control Ship which was under study at the time. On paper, it looked superior to the subsonic Hawker Siddeley Harrier attack fighter. It used a thrust augmented wing concept in which exhaust would be directed through spaces in a wing opened up like venetian blinds to increase available lift, somewhat like Lockheed's unsuccessful XV-4 Hummingbird. Such arrangement restricted weapons carriage to under the narrow fuselage and 2 conformal missile mounts. Its canards were extremely large, with almost 50% of the area of the wings, making it effectively a tandem biplane.
The 30,000 lbf (130 kN)-class afterburning turbofan engine had enough thrust to lift the weight of the 20,000 lb (9070 kg) aircraft. It was modified to further increase thrust for vertical lift. The rear engine exhaust was closed and the gases redirected through ducts to ejector nozzles in the wings and canards for vertical lift.
In 1972, the United States Navy in issued a request for proposals for a next generation V/STOL fighter/attack aircraft. The XFV-12A, despite its concept being considered risky compared to that of the Harrier, was selected for development.
To reduce costs, the nose from an A-4 Skyhawk and intakes from the F-4 Phantom II were used. Engine rig testing began in 1974. Free-flight model tests conducted at the NASA Langley full-scale wind tunnel showed that the projected thrust augmentation levels were highly optimistic, and that the aircraft would most likely be incapable of vertical flight on the thrust available. However, the model's configuration did prove suited for conventional flight.
Ground testing of the XFV-12A began in July 1977, and the aircraft was officially rolled out at the Rockwell International facility in Columbus, Ohio on 26 August. Due to increasing costs, construction of the second prototype was abandoned.
Tethered hover tests of the XFV-12A were conducted in 1978. Over the course of six months, it was determined that the XFV-12A design suffered from major deficiencies with regard to vertical flight, especially a lack of sufficient vertical thrust. Lab tests showed that 55% thrust augmentation should be expected, however differences in the scaled-up system dropped augmentation levels to 19% for the wing and a mere 6% in the canard. While the augmenters did work as expected, the extensive ducting of the propulsion system degraded thrust, and in the end the power-to-weight ratio was such that the engine was capable of vertically lifting only 75% of the weight of the aircraft it was mounted in.
Following the tests, and with the program suffering from cost overruns, the Navy decided that the XFV-12A was not worth further development, and cancelled the aircraft in 1981. Aviation Week would later publish an article with drawings of an even more ambitious proposal to fit a similar wing to the huge C-130 Hercules, but the plan never made it off the drawing board.
- Crew: 1
- Length: 43 ft 11 in (13.4 m)
- Wingspan: 28 ft 6 in (8.69 m)
- Height: ft in (m)
- Wing area: ft² (m²)
- Empty weight: 3,890 lb ()
- Loaded weight: 19,500 lb (8,850 kg)
- Powerplant: 1× Pratt & Whitney F401-PW-400 afterburning turbofan
- Dry thrust: lbf (kW)
- Thrust with afterburner: 30,000 lbf (kW)
- Missiles: 2× AIM-7 Sparrow carried under fuselage
- Winchester, Jim. X-Planes and Prototypes. Barnes and Noble Books.
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