X-33 Hypersonic Aerodynamic Characteristics Instrumentation and Data Reduction

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 (S S T O) , 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 l e s s than half of the total body flap deflection capability across the angle of attack range at b o t h 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 f l i g h t attitudes. This configuration was directionally unstable and the use of reaction control j e t s (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 …