Aerodynamic characteristics and optimization techniques of a variable camber compliant wing

Abstract

This paper describes the initial steps of second phase aerodynamic testing of the Variable Camber Compliant Wing at the Vertical Wind Tunnel Facility in US Air Force Research laboratory. A novel single linear actuation of the compliant rib is used to control both leading and trailing edge deflection. Individual control of each rib’s deformation allows the wing to achieve a variety of aerodynamically useful camber distributions along the span, such as: uniform, linear, and non-symmetric shapes. The entire skin is seamless and continuous, constructed from a single piece of non-stretchable composite skin. In order to investigate potential aerodynamic capability of the Variable Camber Compliant Wing, a two-dimensional cambered airfoil was compared with an airfoil with flap deflection to explore aerodynamic performance. Three-dimensional wing shape was measured prior to wind tunnel entry enabling development of a relationship between actuator position and maximum section camber. A 3D optical scanner was used to digitize the entire wing surface, and examples of the scanning results and their performance corresponding to the wing camber variations were demonstrated. In addition, sectional shape optimization of the Variable Camber Compliant Wing were considered to investigate its capability for the greatest aerodynamic performance at various flight conditions. Shape optimization routines were performed for a take-off condition to increase lift, and a cruise condition to reduce induced drag, respectively. The optimization results were successful, causing about a 4% lift improvement for the take-off condition, and about 15% reduction of induced drag for the cruise condition.