Wind-Tunnel Investigation of the Low-Speed Aerodynamics of Slender Accelerator-Type Configurations

An investigation was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to determine the low-speed aerodynamic characteristics of a generic, hypersonic accelerator-type configuration. The model consisted of a delta wing configuration incorporating a conical forebody, a simulated wrap-around engine package, and a truncated conical aftbody. Six-component force and moment data were obtained over a range of angle of attack from -4° to 30° and for a sideslip range of ±20°. In addition to tests of the basic configuration, component build-up tests were conducted; and the effects of power, forebody nose geometry, a canard surface, fuselage strakes, and lower surface engines alone were also determined. Control power was investigated via the testing of wing flap deflections as well as the deflections of an aftbody flap in the exhaust flow. Surface pressure data were obtained at several longitudinal locations along the conical forebody. Surface oil flows and a smoke flow visualization technique using a laser light sheet were used for diagnostic analysis of the flow over the model and as an aid in the interpretation of the force and moment data.

The high fineness ratio conical forebody had a significant effect on the behavior of the configuration. Vortex flow from the conical forebody created large values of local inflow angles at the engine inlet locations on the lee side of the model at the moderate angles of attack associated with take-off and landing conditions. In addition, large asymmetric yawing moments resulted from asymmetric flow fields exhibited by the forebody. Increasing nose bluntness reduced the yawing-moment asymmetry, and the addition of a canard eliminated the yawing-moment asymmetry. The control power available from aftbody flap deflections was significantly increased during power-on conditions.