SHOCK LOCATION SENSOR FLIGHT TESTED AT NASA DRYDEN January 7, 1997 Release: 97-02 Printer Friendly Version
Flight tests of a newly-developed aerodynamic shock-wave location sensor which could improve the efficiency and performance of future high-speed aircraft have concluded at NASA's Dryden Flight Research Center, Edwards, Calif.
According to Dryden researcher Tim Moes, principal investigator for the Shock Location Sensor Development (SLSD) tests, the device was developed by Tao Systems of Hampton, Va. The sensor utilizes a multi-element hot-film sensor array, a multi-channel constant voltage anemometer system and specially-designed flow diagnostics software to capture the exact location of the shock wave and its dynamic characteristics as it passes over an aircraft surface.
The shock location sensor experiment was the focus of seven test flights by Dryden's F-15B testbed aircraft last fall, with the final flight on Dec. 12, 1996.
For the flight experiments aboard the F-15B, Moes designed a small 21 percent thick airfoil upon which the sensor arrays were mounted. The airfoil was attached to the left side of the Flight Test Fixture which is carried in place of the centerline external fuel tank on the F-15B. Tests were conducted while the aircraft was flying at transonic speeds of about Mach 0.7 to Mach 0.9, adequate to produce a shock wave on the low aspect ratio airfoil.
"The sensor picked up shock phenomena via the mean output voltage and phase reversal," Moes said. "It picked up the shock location within a half inch. That may be good enough for many potential applications."
The major future applications of the technology would be impingement of the shock wave inside the engine inlets of the proposed High-Speed Civil Transport or other supersonic aircraft.
Moes noted that spacing of the sensors on the test airfoil was dictated by the underlying pressure orifices, which were a quarter inch apart. Closer spacing of the sensors would allow even more precise determination of the shock wave location.
"If you know where the shock wave is, you can control it," Moes added. "If you can control the shock, you can improve the efficiency."
Moes said the experiment was a significant step toward development of a sensor system which could provide a pilot with shock location information in real time. He indicated such a system could be the focus of a future flight test program once appropriate software and hardware is developed.
Dryden's Roy Bryant, project manager for the F-15B testbed, said the next flight tests on the aircraft will involve the Boundary Layer Heat Experiment developed by Eidetics Corp. under a NASA Small Business Innovative Research project.
Bryant estimated about five flights will be flown in Phase II of this experiment, beginning in mid-February and extending through at least April.
The experiment is designed to explore the potential reduction of aerodynamic drag by heating the turbulent portion of the air flow over the fuselage of a large transport aircraft. Bryant said wind tunnel tests during Phase I of the project demonstrated significant boundary-layer drag reductions at low speeds. The Phase II flight tests are intended to determine if such reductions can be achieved at transonic flight speeds, as well as determine the amount of electrical power that would be required to achieve them.
--nasa-- Note to Editors: The following photos are available from NASA Dryden External Affairs Office to support this release: EC96-43815-2 NASA F-15B testbed aircraft with SLSD experiment mounted on flight test fixture. EC96-43669-4 Closeup of SLSD test airfoil showing sensor array, mounted on flight test fixture.
Photos are also available on the Internet under NASA Dryden Research Aircraft Photo Archive, Dryden News and Feature Photos, URL: /centers/dfrc/Gallery/Photo/index.html | |
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