Swashplateless Helicopter Rotor System with Active Trailing-Edge Flaps for Primary and Vibration Controls

Abstract

The objective of this study is to demonstrate the concept of active trailing-edge flaps as primary rotor control and vibration reduction devices for a typical full-scale helicopter. A comprehensive rotorcraft analysis based on UMARC is developed to obtain the results for the swashplateless rotor. A parametric study of various key design variables involved in the trailing-edge flap design was carried out. An optimal design of trailing-edge flap system that provides effective control authority within the complete flight envelope as well as minimum actuation requirements was achieved. Trailing-edge flaps demonstrated the capability of performing both primary control and active vibration control functions. At a high forward speed (advance ratio of 0.32), the 4/rev vertical force, and roll and pitch moments at hub are successfully eliminated (by about 90%), and the 4/rev in-plane hub forces are reduced by more than 40%. The half peak-to-peak value of the trailing-edge flap deflection for primary control is about 7.1 ‐ and additional 4.7 ‐ is required for active vibration control.