Flight Dynamics Model of a Rotorcraft with Trailing Edge Flap Controlled Rotor

Abstract

*† In the study, an unconventional rotorcraft concept is considered. This concept differs from the conventional helicopters in that its main rotor control is maintained by trailing edge flaps located on the blades instead of blade pitch control by swash plate, which is the means of rotor control utilized in almost all helicopters flying. The concept with trailing edge flaps is compared with conventional pitch control concept in terms of flight and control behavior. The rotor equations to find rotor forces and moments, and in conjunction with them, to relate blade flapping with control angles for the rotor with trailing edge flap controls as well as the conventional rotor. Then, simplified trim equations for steady straight symmetrical flight conditions are derived for both concepts. To compare the behavior of the vehicle with trailing edge flap controls with the conventional one, the same configuration, AH-1S Cobra helicopter, is assumed. The performance of both concepts is examined for hover and steady symmetrical forward flight. Thereby, trailing edge flap control, which can be very beneficial for active IBC (Individual Blade Control) to improve flying qualities, is examined to see whether it alone can be considered as a significant alternative to pitch control by swash plate.