Hover testing of a small-scale rotor with on-blade elevons

A two-bladed, 7.5-ft diameter dynamic rotor model with 10% chord on-blade elevons driven by piezoceramic bimorph actuators was designed and tested in hover at tip speeds up to 298 ft/s. The elevon actuator succeeded in achieving deflections of +/-5 deg at the nominal rotor speed of 760 RPM. Aeroelastic and structural dynamic response characteristics were evaluated over a wide rotor speed range using frequency sweep excitation of the elevon up to 100 Hz. The CIFER (R) post processing method was very useful for determining frequency response magnitude, phase, and coherence of measured blade root flap bending and torsion moments to elevon input, as well as elevon response to actuator input voltage. Experimental results include actuator effectiveness, effects of low Reynolds number on elevon pitching moments, elevon reversal, and variation of flap bending mode responses with rotor speed and elevon excitation. The active rotor performed satisfactorily and the results provide an encouraging basis for future wind tunnel testing that will evaluate on-blade elevon effectiveness for reducing rotor blade vibratory loads.