Advanced Rotor Aerodynamics for Dynamic Stall Alleviation Using Robust Flow Control

Compliant structures technology, coupled with variable camber leading-edge dynamic stall control, has the potential to significantly improve the performance of modern rotorcraft. The objective of the Phase I effort and Phase II proposal is to use compliantstructures technology to design and test a hinge-less, variable camber, semi-span, leading-edge for rotor blade dynamic stall control utilizing monolithic structures. Significant aerodynamic and systems benefits are possible through the integration ofcompliant smart structures technology into modern rotorcraft. Phase I results have shown that a variable camber compliant structures rotor blade can be designed which will provide a significantly enhanced performance envelope for the rotorcraft in theform of increased speed, payload, maneuverability, and range as compared to traditional designs. The new compliant structures design will alleviate retreating blade stall with a robust and reliable variable camber leading-edge system. The new system willbe lightweight, rugged, maintainable, damage tolerant, and have a low radar cross-section, all while providing significantly enhanced performance. The commercialization potential for advanced, high performance helicopter blade airfoils, designed with areliable and robust variable camber leading-edge is excellent. It is recognized that future rotorcraft are expected to play an increasingly important role in military operations in the form of long range transport, low altitude deep penetration, andair-to-air/air-to-ground combat. The rotorcraft industry will be eager to exploit the advantages of the variable camber compliant structure based design. This new design approach will deliver the advantages sought by rotorcraft designers, but with muchlower weight and much lower cost of manufacture, while providing a robust and reliable system. Both commercial and military rotorcraft designers will find the technology extremely appealing, allowing significant commercialization potential.