PRELIMINARY PILOTED SIMULATION STUDIES OF THE HL-20 LIFTING BODY

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