AN ELECTROMAGNETIC ACTUATOR FOR INDIVIDUAL BLADE CONTROL

The Heliflap™ is an electromagnetic actuator and trailing-edge control surface developed for helicopter rotor active control applications. It is a rugged, compact system with no external linkages and no moving parts except the flap itself, and has excellent force, deflection, frequency characteristics, and good power and thermal dissipation characteristics. The amplitude and frequency are controlled by modulation of the electrical current to the actuators. The net installed weight for the non-optimized prototype is 9.6 lb. The design and development of the Heliflap is described including bench testing as well as preliminary whirl testing on full-scale OH-58 helicopter rotor at up to 81% normal rotor speed at low rotor collective pitch. Test results are compared with design predictions from the Heliflap analytical model. Bench testing demonstrated 35.6 ft-lb static torque for 100 amps, ±8 degree deflections, and operation from 0-37 Hz. Whirl testing of the 6-by 24-inch prototype at 81% rotor speed, demonstrated ±6 degree deflections at 21 Hz (4.4/rev) requiring a total average electrical power of 220W. The actuator appears to be well suited for active control for rotor vibration reduction and may have significant potential for application to rotor primary flight control as well.