Development and Hover Testing of the Active Elevon Rotor

The Active Elevon Rotor (AER) is a 12.96 ft. diameter rotor with two on-blade elevons on each blade. Each elevon is a 15% chord, 8% span, plain, trailing-edge flap actuated by a piezoceramic-based conformal actuator. Development of the rotor and support systems has been completed and is documented, especially regarding the actuation system, blades, test stand, and controls. Development of two control algorithms - classical and Model Predictive Control (MPC) - is described for elevon position control. Two-bladed active rotor testing was conducted in hover, including elevon frequency dwells and logarithmic frequency sweeps, and initial test results are documented, especially from elevon and blade load measurements. Actuation system performance was good (±2° thru 1025 RPM), but actuator reliability at the design electric voltage limits was poor, and the actuation assembly flexure properties need improvement. The test stand was stiffened to ensure aeromechanical stability. The measured control bandwidth was 1.3/rev. The measured blade torsion frequency was found to be significantly lower than predicted.