Next generation active twist helicopter rotor blade - simulated results validated by experimental investigation

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 reduced significantly. An important issue during operation of these rotor blades is the centrifugal load which affects the actuators and can cause a failure [3]. 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. This paper builds on previous publications [1-5]. After a brief summary of the improved blade design and the manufacturing process, this publication mainly refers to the determination of the structural blade properties of the first manufactured rotor blades. Specifically, torsional stiffness, lead lag bending stiffness as well as chordwise elastic axis position and twist performance are determined. These results are compared to the simulation findings and especially analyzed with regard to blade-to-blade differences. The experimental setup and also the measuring method are explained in detail.