Preliminary piloted simulation studies of the HL-20 lifting body

Abstract

NASA Langley Research Center is developing a lifting body vehicle, designated the HL-20, as one option of the proposed Personnel Launch System for NASA's future manned access to space requirements. Data derived from wind-tunnel and computational fluid dynamics analyses of the conceptual design led to the derivation of a flight simulator model to investigate the potential flight characteristics of the HL-20. A simulation investigation was initiated to determine if satisfactory unpowered horizontal landings could be accomplished. Control law design and trajectory development were directed toward this end. The study uncovered several deficiencies subsequently corrected through design changes, and it validated the predicted subsonic aerodynamic properties. Expanding the investigation to the Mach 4 to Mach 1 regime revealed flight characteristics necessitating the development of innovative control techniques. This article will present the significant results uncovered to date by flight simulator evaluations of a lifting body class of vehicle, and will demonstrate the effectiveness of flight simulation as an integrated part of the conceptual design phase.