Whirl Testing of a Pneumatic Artificial Muscle Actuation System for a Full-Scale Active Rotor

A novel active trailing edge flap system sized for the Bell 407 rotor system is under development. This system differs significantly from previous active rotor concepts in that it is driven by a pneumatic actuator technology. Pneumatic Artificial Muscles were chosen because of several attractive properties, including high specific work and power output, an expendable operating fluid, and robustness. The actuation system is sized with the goal of producing flap deflections appropriate for vibration reduction at frequencies up to 5/rev (N+1/rev), as well as larger deflections at 1/rev to open up the possibility of primary control of the rotor. The actuation system consists of a pair of Pneumatic Artificial Muscles mounted antagonistically in the root of the blade. A linkage system transfers the force and motion of these actuators to the flap. In order to validate the performance of certain key technologies of this system, a whirl test on a sub-span actuation system prototype has been performed in the vacuum whirl chamber at the University of Maryland. This whirl rig was designed to expose the components of the actuation system to full-scale inertial, centrifugal, and simulated aerodynamic load levels prior to integration with a rotor blade. The performance of the system under a range of operating conditions was evaluated. The results of this experiment show the promise of this novel actuation system.