Continued Development of a Mach Scale Swashplateless Rotor with Integrated Trailing Edge Flaps

A Mach-scale swashplateless rotor is designed and fabricated. An integrated trailing edge flap controlled by a piezoelectric bender is designed and constructed. A soft pitch link replaces the rigid pitch link in the articulated hub in order to lower the blade torsional frequency. The rotor is designed to match the tip speed of the UH-60A rotor. This requires a high rotor rotational speed of 2400 RPM. This presents challenges (friction and propeller moment) to achieving the flap deflection goal of ±5.5°. Initial hover stand tests showed insignificant flap deflection (less than 2°) at 1500 RPM. At lower RPM, hover tests show that blade cyclic pitch control can be achieved through trailing-flap deflection. Using micro-washers at trailing-flap hinges, the friction was effectively reduced. Vacuum testing demonstrated extremely low friction. Propeller moment inertia of the trailing-flap was minimized, which in turn increased flap deflection amplitude. A new 10-layer bender actuator using a new piezoelectric material (M1876) has been designed and built. This new setup has been tested in the vacuum chamber demonstrating the ability to provide the needed flap deflection. Currently, the rotor model is undergoing hover testing.