<title>Testing and validation of a Froude-scaled helicopter rotor model with piezo-bimorph-actuated trailing edge flaps</title>

Abstract

This paper presents the testing of a Froude scaled rotor featuring piezoceramic bimorph actuated trailing-edge flaps for active vibration suppression. An analytical model for the coupled bimorph actuator trailing-edge flap dynamic response in the rotating environment was developed. The analysis takes into account the aerodynamic, centrifugal, inertial and frictional loads acting on the actuator-flap system. The linkage arm length associated with the mechanical amplification mechanism was selected in order to maximize flap performance in the rotating environment. The bimorph clamping was improved to prevent actuator slippage under high centrifugal loads. The analytical model was validated by carrying out a series of bench tests, vacuum chamber tests and hover tests. In hover, flap deflections of plus or minus 6 degrees at 4/rev flap excitation were achieved at 900 rpm, thus demonstrating the potential of the piezoceramic bender as a lightweight and compact actuation system for individual blade control purposes. This paper also includes a feasibility study for piezo-bimorph actuation of a trailing-edge flap for a Mach scaled rotor model.