Analysis and testing of Mach-scaled rotor with trailing-edge flaps

Ongoing research is presented directed toward the development of a Mach-sca led rotor model with piezoelectric bender-actuated trailing-edge Raps for i ndividual blade control of helicopter vibration. First, an analytical model is developed for the coupled actuator-flap-rotor dynamic response in hover , Then, the analysis is validated by using test data obtained by hover test ing a 6-ft (1.82-m)-diam, Froude-scaled rotor with piezo-bender-actuated tr ailing-edge Raps. The analytic model shows good correlation with experiment al Rap deflections and oscillatory hub loads. For the Froude-scaled model f lap deflections of +/-4 to +/-8 deg, for 1 to 5 /rev flap excitation, were achieved at 900 rpm. This flap activation resulted in a 10% variation in th e steady rotor thrust level at 6 deg collective. Next, two Mach-scaled roto r blades with piezo-bender actuation were designed and fabricated. The roto r was tested in the vacuum chamber, and flap deflections of is deg were ach ieved in vacuum at the Mach-scaled operating speed of 2000 rpm. The analysi s predicts that in hover flap deflections of +/-5 deg can be achieved at 20 00 rpm. Future work will involve hover tests followed by forward Right test s in the wind tunnel to confirm these predictions and demonstrate concept f easibility.