Performance of Swashplateless Ultralight Helicopter Rotor with Trailing-Edge Flaps for Primary Flight Control

This study evaluates the rotor performance, trailing-edge deflections and actuation requirement of a helicopter rotor with trailing-edge flap for primary flight control. The swashplateless design is implemented by modifying a two-bladed teetering rotor of an ultralight helicopter through the use of plain flaps on the blades, and by replacing the pitch link. A comprehensive rotorcraft analysis based on UMARC is carried out to obtain the results for both the swashplateless and a conventional baseline rotor configuration. The predictions show the swashplateless configuration achieves better performance than the conventional rotor, because of the reduction of parasite drag resulting from eliminating the swashplate mechanical system. The optimal selection of blade pitch index angle, flap location, length, and chord ratio reduces flap deflections and actuation requirements, with virtually no effect on rotor performance.