The Active Materials and Structures Lab at MIT is working in conjunction with Boeing Helicopters on reducing rotor vibrations and noise. Normal operation of helicopter rotor blades involves high vibration levels resulting from aerodynamic disturbances. Active rotor blades are being designed with high bandwidth active twisting capabilities. Higher harmonic control of the individual blade twist can be used to reject disturbances. As a result, the performance of the rotor blades can be significantly improved.
Two strategies for twisting the blades are being pursued. The first is the integral twist design in which the main spar of the blade is twisted along the span, directly changing the section angle of attack. In the second, a discrete trailing edge flap actuator is the control input for the blade twist. Both concepts will be evaluated experimentally in the MIT Hover Test Stand, which is currently being designed for 1/6th Mach-scale Chinook 47D model blades.