Coaxial-Compound Helicopter Flight Control Design and High-Speed Handling Qualities Assessment

To provide the government with independent control-system design, handling qualities analysis, and simulation research capabilities in support of Future Vertical Lift, the U. S. Army Combat Capabilities Development Command Aviation & Missile Center has developed generic high-fidelity flight-dynamics models of several advanced high-speed rotorcraft configurations. One of the configurations modeled is a lift offset coaxial-compound helicopter with a pusher propeller. Full flight envelope explicit model following control laws were designed for the generic coaxial-compound helicopter using a multiobjective optimization approach to meet a comprehensive set of stability, handling qualities, and performance specifications. Helicopter response types were used for hover/low-speed, while typical fixed-wing response types (normal acceleration and sideslip command) were used at high speed. The control laws were evaluated in a piloted simulation experiment at the NASA Ames Vertical Motion Simulator using a series of previously developed high-speed handling qualities demonstration maneuvers. This paper discusses the control laws and the results of the piloted handling qualities assessment, which showed assigned Level 1 handling qualities for six of the seven maneuvers evaluated.