Active Controller For Comanche Air Resonance Stability Augmentation

A description is presented of an active controller designed to augment the air resonance stability of the Boeing-Sikorsky RAH-66 Comanche. The controller was successfully flight-tested on the RAH-66 demonstrator aircraft. An active feedback scheme was simple and cost effective to implement as flight control software using existing flight control hardware: Body pitch and roll rate signals were used to calculate swashplate control inputs that enhance rotor damping. The RCAS computer program (Rotorcraft Comprehensive Analysis System) was used to perform the detailed design of the active feedback. Extensive correlation was first performed between RCAS and the baseline aircraft for key flight conditions. Several feedback designs were developed and the best were selected for flight-testing. The flight test approach is described and RCAS predictions are compared with flight test results with and without active control.