SMART Rotor Development and Wind Tunnel Test
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
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Boeing and a team from NASA, Army, DARPA, Air Force, MIT, UCLA, and U. of Maryland have successfully completed a wind tunnel test of the smart material actuated rotor technology SMART active flap rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. The Boeing SMART active flap rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing edge flap on each blade. The eleven-week test program evaluated the forward flight characteristics of the active-flap rotor at speeds up to 155 knots, gathered data to validate state-of-the-art codes for rotor aeroacoustic analysis, and quantified the effects of open and closed-loop active flap control on rotor loads noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness of the active flap control on noise and vibration was conclusively demonstrated. Results showed reductions up to 6dB in blade-vortex-interaction and in-plane noise, as well as reductions in vibratory hub loads of about 80. Trailing-edge flap deflections were controlled with less than 0.2 deg rms error for commanded harmonic profiles of up to 3 deg amplitude. The impact of the active flap on control power, rotor smoothing and performance was also demonstrated. Finally, the reliability of the flap actuation system was successfully proven in more than 60 hours of wind tunnel testing.