Manufacturing of a next generation active twist helicopter rotor blade and experimental results of functionality test

Abstract

Vibration and noise are omnipresent in a helicopter environment and therefore their reduction is an important goal in helicopter research. Actuators embedded into the skin of a helicopter rotor blade can produce a twist, which influences the propagation of the air turbulence. Hence, vibration and noise levels can be significantly reduced. An important issue during operation of a rotor blade are the centrifugal loads which affect the actuators and can cause a failure. Based on the German Aerospace Center (DLR) project STAR(Smart Twisting Active Rotor), the design of an active Twist rotor blade has been adapted, such that the loads in the actuator system can be significantly reduced and furthermore distributed evenly. Besides a new actuator design, described in an earlier study of the authors, this paper focus on the use of carbon fiber composite for the spar and additional straps near to the trailing edge. This increases the durability of a new generation of active twist rotor blades, which is the basis for a specific and efficient use of the active Twist technology. A first prototype of the new designed rotor blade has already been built. The design changes are addressed in this paper as well as the manufacturing process. Finally results of the numerical model are validated experimentally in the whirl tower and blade properties of the prototype blade are presented.