Aeroelastic Applications of a Variable-Geometry Raked Wingtip

Abstract

This study investigates the effects of a variable-geometry raked wingtip on the aeroelastic behavior and the maneuverability of transport aircraft with very large aspect-ratio truss-braced wings. These truss-braced wing designs are obtained from the multidisciplinary design optimization environment presented here while minimizing the fuel burn of a double-aisle aircraft having a flight mission similar to that of a Boeing 777-200 long-range aircraft. The wingtip can be swept forward and aft relative to the wing by a novel control effector mechanism. Results show that a variable-geometry raked wingtip can be used to achieve required roll control by judiciously sweeping it relative to the wing at various flight conditions. It has an added benefit that it can also be used for flutter avoidance. Such benefits of the variable-geometry raked wingtip allow the operation of truss-braced wing configurations, which have up to 10% lower fuel burn than comparable optimized conventional cantilever wing designs. Without the variable-geometry raked wingtip, such configurations fail to meet the required flutter speed and roll control capability. The variable-geometry raked wingtip is thus an enabling technology for truss-braced wing aircraft and other large aspect-ratio configurations.