1 X - 33 Hypersonic Aerodynamic Characteristics

Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604B0002G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate an aerodynamic flight database i n the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. At these Mach numbers, the vehicle also was shown to b e longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown t o be small relative to X-33 control authority. Nomenclature B ref lateral reference length C A axial-force coefficient C D drag-force coefficient C L lift-force coefficient C L0 lift-force coefficient at 0 deg angle of attack C l rolling-moment coefficient C lb rolling-moment derivative C m pitching-moment coefficient C n yawing-moment coefficient C nb yawing-moment derivative C N normal-force coefficient C Y side-force coefficient L ref longitudinal reference length p ¥ static pressure of free stream, psia p t tunnel stagnation pressure, psia q ¥ free stream dynamic pressure, psia Re/ft free stream unit Reynolds number S ref reference area T ¥ static temperature of free stream, ¡R T t tunnel stagnation temperature, ¡R a angle of attack, deg b angle of sideslip, deg d bf body flap deflection, deg d el elevon deflection, deg DC m increment in pitching-moment coefficient g ratio of specific heats r 2 /r ¥ shock density ratio Introduction As a first step towards development of an operational next-generation reusable launch system, Lockheed Martin Skunk Works (LMSW), under a cooperative agreement with NASA, will build and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). The objective of the X-33 program is to demonstrate key design and operational aspects of an SSTO vehicle in order to reduce the business and technical risks to the private sector in developing a commercially viable RLV …