- Jun 23, 2007
- Reaction score
The Rockwell International XFV-12A, a thrust-augmented wing prototype supersonic fighter/attack aircraft, was designed to operate from small ships. The single engine, single seat prototype aircraft used parts from the A-4 and F-4; the fuselage was 44 ft long with a 28.5 ft wingspan and a 12 ft canard span. Operational vertical take-off weight was expected to be 19,500 lb, with a maximum speed of over Mach 2 anticipated by Rockwell.
In the fall of 1972, the US Navy issued a request for proposals of the next generation V/STOL aircraft. Unfortunately, the list of candidates did not include any further development of the Harrier. Instead, the Navy favored the North American Rockwell XFV-12A supersonic fighter design. The XFV-12A used a thrust augmentation scheme that diverted the total exhaust flow of the main engine and ejected it through a venetian blind arrangement in the wings to give vertical-lift capability. The concept was considered by many to be very risky when compared with the proven Harrier approach, but the Navy was prepared to fully fund the development of the aircraft and close out further development of the Harrier.
The results of the tests at Langley influenced the Navy’s decision to cancel the XFV-12A Program. Lift improvement testing and plans to modify the ejector/augmentor system were discontinued in 1981 due to cost overruns and waning Navy V/STOL interest.
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 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's augmented wing concept was 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.
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. 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.
After it's cancellation Aviation Week published an article with drawings of an even more ambitious proposal to fit a similar wing to the huge C-130 Hercules, but that plan never made it off the drawing board.
Do you think they should have stuck with it or do you think they did the right thing by abandoning the project? Does anyone think that the thrust-augmented wing concept can, will, or should be used on future combat aircraft?