Recent Development on Piezoelectric Actuation Systems for Rotor Active Control

A piezo flap system for rotor active control has been proofed to be successful in an ongoing test flight campaign since September 2005. An experimental BK117 was the first worldwide flying helicopter with an active rotor system based on piezoelectric driven trailing-edge flaps [3]. The subsequent intensive flight-test campaign revealed superior results regarding system performance as well as endurance. After having taken this first important step further research is oriented on optimization of the technical performance as well as reducing system effort. This includes to optimize actuator-flap modules, power and signal electronics, and monitoring algorithm. These activities are backed by investigating the alternative technical concept of morphing rotor blade structures. Integrated piezoelectric actuators are used to deform the blade structure for aerodynamic control. This technology allows very simple and elegant mechanical design avoiding any parasitic gaps and complicated mechanism.