Information supplied and copyrighted
by Joe Baugher
General Dynamics F-16
VISTA
Last revised March 30,
2000
The F-16 Multi-Axis Thrust-Vectoring
(MATV) program originally began as a joint General Electric/General Dynamics
privately-funded program for a thrust-vectored version of the Fighting Falcon. The USAF
initially declined to support the program, so the two companies agreed to collaborate with
the Israel Defense Force/Air Force, which was highly interested in the program for its own
F-16s. Under the terms of the agreement, the IDF/AF was to supply a F-16D for the tests,
with the two American companies doing the conversion. However, in 1991 the USAF's Wright
Laboratory became interested in the project, and the USAF now assumed an active role.
Israel withdrew from the program in 1992. The project was now known as the F-16 Multi-Axis
Thrust-Vectoring (MATV) program.
The USAF loaned the Lockheed Fort Worth
Company (LWFC) a F-16D Block 30 (serial number 86-0048) to be modified into a thrust
vectoring research aircraft. The aircraft is known as VISTA, which was an acronym which
stood for "Variable-stability In-flight Simulator Test Aircraft".
The heart of the VISTA is its
Axisymmetric Vectoring Exhaust Nozzle (AVEN), which is attached to the exhaust of the
aircraft's General Electric F110-GE-100 engine. The AVEN achieves the required thrust
vectoring within the divergent (supersonic flow) portion of the nozzle, which prevents
pressure fluctuations from being fed back into the engine where they could cause a
compressor stall. The divergent flaps are angled individually by means of a ring that is
positioned by three additional hydraulic actuators located at 120-degree intervals, with
power being supplied by an independent system. The exhaust nozzle can be deflected in any
direction through an angle of up to 17 degrees. Axial and side forces imposed by the jet
exhaust on the nozzle are transferred into the jetpipe and thus back into the engine. The
advantage of the AVEN is that it could be retrofitted to any F-16 that was powered by the
F110 engine and which had a digital flight control system.
The movement of the three actuators is
commanded by a Vector Electronic Control (VEC), which is a modified version of the
full-authority digital engine control used by the F110-GE-129 engine. In order to
counterbalance the additional weight of the AVEN, 700 pounds of ballast were added on the
inlet hardpoints to keep the center of gravity ahead of 38% chord in order to avoid the
danger of deep stalls should the thrust vectoring system fail. As an additional safety
measure, a spin-recovery parachute was installed high over the rear end of the aircraft to
assist in recovery from deep stalls should they occur.
The VISTA F-16D was redesignated NF-16D,
the N prefix meaning that the aircraft had a special test status and that the
modifications were sufficiently drastic that it would be impractical to restore the plane
to its original condition. The MATV aircraft first flew in this modified form on July 2,
1993. The aircraft was transferred to Edwards AFB on the 15th. Thrust vectoring in flight
was first used on July 30.
The program objectives included the
demonstration of the tactical utility of thrust vectoring in close-in air combat and in
the use of integrated control of thrust vectoring in flight. The aircraft has demonstrated
a steady angle of attack of as much as 86 degrees and a transient angle of attack of up to
180 degrees. In other words, the aircraft can fly BACKWARDS for a brief time. Thrust
vectoring provides a significant advantage in terms of bringing armament to bear on a
threat more quickly and in avoiding the risk of departure from controlled flight during
violent maneuvers. However, the use of really high AoA maneuvers should only be a
last-ditch operation in aerial combat in view of the increased vulnerability of the
aircraft when it is in a low-energy state.
Sources:
- Combat Aircraft F-16, Doug Richardson,
Crescent, 1992.
- General Dynamics Aircraft and their
Predecessors, John Wegg, Naval Institute Press, 1990.
- The American Fighter, Enzo Angelucci and
Peter Bowers, Orion, 1987.
- United States Military Aircraft Since
1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
- F-16 Fighting Falcon--A Major Review of
the West's Universal Warplane, Robert F. Dorr, World Airpower Journal, Spring 1991.
- The World's Great Interceptor Aircraft,
Gallery, 1989.
- Modern Military Aircraft--F-16 Viper, Lou
Drendel, Squadron/Signal Publications, 1992.
- Lockheed F-16 Variants, Part 1, World
Airpower Journal, Volume 21, Summer 1995.
- Thrust Vectoring Trio, Frank B. Mormillo,
Air International, July 1994, page 22.
- Vectored Viper, Roy Braybook, Air
International, March 1994, page 133.
Back to the main menu
[Advertisement]
|
|
