An interesting aspect of the HiMAT program was the flight test maneuver autopilot, which was based on a design developed by Teledyne Ryan Aeronautical. Teledyne also developed the backup flight control system for the aircraft (with modifications done by Dryden engineers). The autopilot system provided precise, repeatable control of the vehicle during prescribed maneuvers so that large quantities of reliable test data could be recorded in a comparatively short period of flight time. Dryden engineers and pilots tested the control laws for the system, developed by the contractor, in a simulation facility and then in flight, adjusting them to make the system work as intended.
Once adjusted, the autopilot was a valuable tool for obtaining high-quality, precise data that would not have been obtainable employing standard piloting methods; the autopilot enabled the pilot to control multiple parameters simultaneously and to do so within demanding, repeatable tolerances. As such, the flight test maneuver autopilot showed itself to be a broadly applicable technique for flight research with potential benefit to any flight program.Program Development
The three-phase HiMAT project began in 1973. In August 1975 Rockwell International was awarded a contract to construct two HiMAT aircraft. The aircraft allowed researchers to test advanced technologies at a reduced cost. The goals of HiMAT included a 100 percent increase in aerodynamic efficiency over 1973 technology and maneuverability that would allow a sustained 8-G turn at 0.9 Mach and an altitude of 25,000 feet. The program achieved both goals.
The HiMAT project represented a shift in focus by researchers at Dryden. Through the Vietnam era, the crux of fighter research had been speed. In the 1970s, driven by a national energy crisis, new digital technology, and a changing combat environment, researchers sought to develop efficient research models for experiments into the extremes of fighter maneuverability. As a result, the quest for speed, long considered the key component of successful air combat, became secondary.
Dryden researchers were developing ground-based, digital fly-by-wire control systems; they made experiments into new, highly maneuverable aircraft designs possible. The HiMAT project's maiden flight occurred on July 27, 1979, and used the newly developed remote-piloting technologies for supersonic aircraft. Flight research continued through January 1983.
One of the HiMAT project's important contributions to flight technology was the use of new composite materials in structural design. HiMAT engineers used materials such as fiberglass and graphite to strengthen the plane and allow it to stand up to the high G-force conditions it encountered during maneuverability tests. Knowledge gained in composite construction from HiMAT strongly influenced other advanced research and the materials are now used extensively on commercial and military aircraft.
The X-29 employed much of the technology developed from HiMAT research, including the successful use of the forward canard and the rear-mounted swept-wing constructed from light-weight composite materials. The wing allowed for vast increases in maneuverability.
HiMAT research brought about far-reaching advances in digital flight control systems, which can monitor and automatically correct potential flight hazards.
Experiments with small wingtip fins known as winglets were also conducted on HiMAT planes. Winglets, which reduce drag and can dramatically increase airplane fuel efficiency, are used extensively on private and commercial aircraft.
The two research planes are now on exhibit, one at the NASA Dryden Flight Research Center and the other at the Smithsonian Institution's National Air and Space Museum.
Robert W. Kempel and Michael R. Earls, "Flight Control Systems Development and Flight Test Experience with the HiMAT Research Vehicles" (NASA TP-2822, 1988).
Dwain A. Deets, V. Michael DeAngelis, and David P. Lux; "HiMAT Flight Program: Test Results and Program Assessment Overview", NASA TM 86725, June 1986
Dwain A. Deets, NASA Ames Research Center, Dryden Flight Research Facility, Edwards, CA; and Lewis E. Brown, Rockwell International Corp., North American Aircraft Operations Division, El Segundo, CA; "Wright Brothers Lectureship in Aeronautics: Experience with HiMAT Remotely Piloted Research Vehicle - An Alternate Flight Test Approach", AIAA Aircraft Systems, Design & Technology Meeting October 20-22, 1986/Dayton, Ohio
E. L. Duke, F. P. Jones, and R. B Roncoli, "Development of a Flight Test Maneuver Autopilot for a Highly Maneuverable Aircraft" (NASA TP-2218, 1986).
Robert W. Kempel, "Flight Experience with a Backup Flight Control System for the HiMAT Research Vehicle," AIAA-82-1541 Aug. 1982.
HiMAT AV-1 Fact Sheet (OFS 870-81-1, May 5, 1981, Dryden Historical Reference Collection).
Henry H. Arnaiz and Paul C. Loschke, "Current Overview of the Joint NASA/USAF HiMAT Program" (NASA CP-2162, 1980), pp. 91-121.
Kevin L. Petersen, "Flight Control Systems Development of Highly Maneuverable Aircraft Technology Vehicle," AIAA-79-1789, Aug. 1979.