Conventional and Unconventional Control Effectors for Load Alleviation in High-Aspect-Ratio-Wing Aircraft

Abstract

Civil transport aircraft typically use trailing-edge control surfaces for gust and maneuver load alleviation. However, wash-out effects due to wing flexibility reduce the effectiveness of these devices and may even result in control reversal. Future aircraft configurations with very flexible, high-aspect-ratio wings may use novel load alleviation solutions based on unconventional control effectors, such as leading-edge control surfaces and folding wingtips. This paper investigates the load alleviation performance of trailing-/leading-edge control surfaces and folding wingtips in a very flexible, high-aspect-ratio-wing aircraft representing a potential future civil transport configuration. The aircraft response is simulated in a coupled nonlinear aeroelastic-flight dynamics framework that can model different types of control effectors. The simulations show that inboard leading-edge control surfaces are ineffective compared with trailing-edge control surfaces at the same spanwise locations; however, outboard leading-edge control surfaces provide higher load alleviation capability than their trailing-edge counterparts while avoiding control reversal. Releasing folding wingtips while deploying control surfaces alleviates loads at flight conditions where aeroelastic effects are moderate, but causes higher loads in the presence of strong wash-out effects.