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NASA Dryden Past Projects: CV-990 Landing System Research Aircraft
August 13, 2009

CV-990 on rampConvair 990 was used as Landing Systems Research Aircraft

A Convair 990 (CV-990) aircraft was used as Landing Systems Research Aircraft (LSRA) to test space shuttle landing gear and braking systems. These tests were part of NASA's continuing effort to upgrade and improve space shuttle capabilities. The aircraft is operated by the NASA Dryden Flight Research Center, Edwards, CA, where it was modified into a Landing Systems Research Aircraft.

First check flights of the CV-990 with the shuttle test components at Dryden were in April 1993. A series of tests with the CV-990 were then conducted at Edwards and at the Kennedy Space Center, FL, in 1993 and 1994 to study shuttle tire wear. The tests were very significant to the Space Shuttle Program by allowing the Return to Landing Site (RTLS) crosswind limits of the orbiters to be increased from 15 to 20 knots. The tests at Kennedy were carried out on several sample runway surfaces that were evaluated for smoothness and tire wear. Tests results aided in the selection of a runway surface that allowed the landings at higher crosswind limits. Additional flights by the CV-990 then made at Edwards to test shuttle tires on the main runway at low air pressures, on the natural lakebed surface.

A landing gear retraction system was installed in the lower fuselage area of the CV-990, between the aircraft's main landing gear. The landing capability of the CV-990 was unaffected by the test components which represent a space shuttle landing gear unit.

During tests, the landing gear unit was lowered by a high-pressure hydraulic system once the CV-990 main landing gear had contacted the runway. The tests allowed engineers to assess and document the performance of the space shuttle's main and nose landing gear systems, tires and wheel assemblies, plus braking and nose wheel steering performance. As soon as an individual landing test is completed, the loads on the shuttle gear, up to 150,000 lb, were reduced and the landing roll is completed on the CV-990's landing gear. The landing gear of the CV-990 was always fully extended and served as a backup for normal landing if a component of the shuttle gear system failed during the tests.

The CV-990 was built by the Convair Division of General Dynamics Corp., Ft. Worth, TX, in 1962. The aircraft was used for commercial passenger service by American Airlines and Modern Air Transport until acquired by NASA in 1975 for use as a research aircraft at the Ames Research Center, Moffett Field, CA. The aircraft, which had a cruise speed of 432 kph (496 mph), was 139 feet long and had a wing span of 120 feet. Landing speeds of the CV-990 duplicated those of the space shuttle orbiters - about 230 kph (256 mph).It was powered by four General Electric CJ805-23 engines, each producing 16,000 pounds of thrust.

The Space Shuttle landing gear test project was managed by the Johnson Space Center, Houston, TX. Other agencies and organizations involved were: Shuttle Landing Facility, Kennedy Space Center, FL; Landing Impact Dynamics Facility, NASA Langley Research Center, Hampton, VA; Landing Gear Development Facility, Wright-Patterson AFB, Dayton, OH; B.F. Goodrich Facility, Troy, OH; and Rockwell International's Space Transportation Systems Division, Downey, CA; and a special LSRA panel formed by SAE's Aerospace Landing Gear Systems Committee.

The Dryden project pilot was C. Gordon Fullerton, a veteran of two space shuttle missions. Fullerton was also a member of the NASA flight crews that carried out the space shuttle approach and landing tests at Dryden in 1977 with the prototype orbiter Enterprise.

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