HOVER TESTING OF A SMALL-SCALE ROTOR WITH ON-BLADE ELEVONS

A two-blade, 7.5-ft dia 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 300 ft/sec. The model was designed to maximize elevon actuator performance and succeeded in achieving deflections of +/-5 deg at the nominal rotor speed of 760 RPM. Nonlinear actuator response characteristics were evaluated. Aeroelastic and structural dynamic response characteristics were evaluated over a wide rotor speed range using sine sweep excitation of the elevon up to 100 Hz. The CIFER® post processing method was very useful for determining frequency response magnitude and phase of measured blade root flap bending and torsion moments to elevon input and elevon response to actuator input voltage. Preliminary experimental results include actuator effectiveness, effects of low Reynolds number on elevon pitch moments, elevon control reversal, and variation of flap bending mode responses with rotor speed and elevon excitation. The model 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.