Development of an Active Trim Tab System for Onboard Rotor Tracking

The design, fabrication, and spin-testing of an active trim tab system for onboard rotor tracking are presented. Aerodynamic and aeroelastic analyses were conducted to determine the optimal size for the trim tab and to examine the effect of the added weight of the trim tab actuator and mechanism. A novel crank-arm/slider mechanism was designed for transferring motion from an electromechanical actuator to the trim tab while remaining fully-contained within the blade envelope. Kinematic analysis of this mechanism is presented. A prototype of the active trim tab mechanism and actuator were fabricated, and performance under high G-load was examined in the UTRC spin-test facility. Spin-test results indicated that the actuator and mechanism were fully capable of smoothly moving and accurately positioning the trim tab at high-G conditions. The design is non-back-drivable under simulated aerodynamic load, which greatly reduces power requirements. Overall, the prototype discussed in this work shows great promise for onboard rotor tracking. The remaining critical risks for this technology are also discussed.