AOH :: FA-18.TXT|
NASA FA-18 THRUST VECTORING FLIGHT
NASA F/A-18 FLIES FIRST THRUST VECTORING FLIGHT
NASA's F/A-18 High-Alpha Research Vehicle (HARV) has maneuvered in flight
for the first time using a specially- designed thrust vectoring system. The
successful test sets the stage for research flights over the next 2 years that
could make future jet fighters safer and easier to fly at very high angles-of-
Angle-of-attack or "alpha" is the term for the angle of an aircraft's
body and wings relative to its actual flight path. When "alpha" increases
during tight turns and maneuvers, control surfaces may not generate enough
force for the pilot to maintain stability and control.
The F/A-18 HARV has three spoon-shaped paddles around the exhaust nozzle
of each of its two engines. The nozzles deflect ("vector") engine thrust in
different directions to maneuver and stabilize the aircraft. Thrust vectoring
should give the plane better controllability at alphas up to 70 degrees.
The July 15 flight at NASA's Ames-Dryden Flight Research Facility,
Edwards, Calif., is part of a continuing NASA program aimed at developing
better methods to predict and control air flow over aircraft designs. The goal
is to enhance aircraft controllability at high angles-of-attack.
NASA officials believe the flight was also the first time a three-axis
vectoring system was controlled entirely by pilot input to a computerized
flight control system during flight. NASA research pilot Edward R. Schneider
called the flight "very smooth." He said the thrust vectoring control system
was "more responsive" to commands than expected and control of the aircraft
felt "very crisp."
During the system's first aerial test, the paddles -- made of Inconel
steel and able to withstand exhaust temperatures of nearly 2000 degrees F. --
were moved by the aircraft's modified flight control system into the exhaust
plume up to a maximum of 10 degrees. This amount of movement by the paddles
raised the nose of the aircraft to 20 degrees angle-of-attack.
Over the next 6 months, the F/A-18 HARV is expected to fly research
missions at up to 70 degrees angle-of-attack with the thrust vectoring system.
During previous flights in the program, the aircraft was limited to 55 degrees
The first thrust vectoring flight test took place at 32,500 feet and 250
mph (223 knots). Schneider pitched the aircraft up and down, yawed it right
and left and did several mild roll maneuvers during the test period. Aircraft
speed, angle-of-attack and maneuvering will expand in each subsequent research
The thrust vectoring system has been installed on the NASA aircraft to
expand high-alpha maneuvering capability. It is not a prototype or production
model for use on any other aircraft.
The F/A-18 flight program at Ames-Dryden is part of an integrated high
angle-of-attack research and technology program conducted jointly by Langley
Research Center, Hampton, Va.; Ames Research Center, Mountain View, Calif.; and
Lewis Research Center, Cleveland.
The thrust vectoring system and control laws that operate it through the
computerized flight control system were designed and built by McDonnell
Aircraft Co., St. Louis. The software and hardware for the aircraft's
computerized flight control system was developed by General Electric
Corporation's Aircraft Control System Division, Binghamton, N.Y.
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