3D Warping Actuation Driven Dynamic Camber Control Concept for Helicopter Rotor Blades

In a rotorcraft, optimized camber change not only reduces vibratory hub loads and noise but also increases available thrust and improved flight control augmentation. Therefore, the ability to dynamically change airfoil camber is a significant technology advancement leading to improved overall rotorcraft performance. Research efforts in recent years have led to the application of active material actuation for rotorcraft blades in order to dynamically change blade camber. Small-scale bench top system validations have been successful. However, when scaled-up to full-scale aircraft, the performance of current actuation systems in a demanding rotor blade environment gets significantly degraded by operational factors including friction, free play, and, aerodynamic and inertial loads.

We propose a unique three dimensional concept wherein the typically closed section blade is cut open to create a torsionally compliant mechanism that acts as its own amplification device; the deformation of the blade is dynamically controlled by out-of-plane warping. Our innovative approach for camber control is a radical departure from the current techniques. The proposed development and engineering effort will lead to a new camber control technology suitable for full-scale aircraft that would result in improved operational efficiencies at lower costs. Concept feasibility will be demonstrated both analytically and through experiments on blade sections of a Sikorsky Blackhawk. A Phase II program will follow for technology scale-up and optimized full blade testing.