Stall Recovery of a Morphing Wing via Extended Nonlinear Lifting-Line Theory

Abstract

Aircraft morphing provides advantages to traditional flight including drag reduction and maneuverability. Previous research indicates that smooth spanwise transitions in trailing-edge camber, representative of a biological analog, provide aerodynamic benefits at small angles of attack by eliminating vortices at geometric discontinuities but lack nonlinear aerodynamic investigations. This work aims to analyze the adaptability of a spanwise morphing wing concept with respect to nonlinear aerodynamics using an optimized nonlinear extended lifting-line model. In this novel approach, it is shown that adaptation, including stall recovery, can be achieved solely through geometric tailoring as opposed to attitude correction for a range of flight conditions while reducing the drag penalty associated with operating at the unadapted condition. The range of conditions for which the wing can recover are restricted by the limited trailing-edge deflections and the inability of the actuators to substantially shift the stall angle of the section lift curve. These results provide insight into improving morphing wing designs, indicating that, by adding another degree of freedom to the chordwise deformation such as a morphing hinge capable of larger actuation and reflex camber, stall recovery via geometric tailoring may be feasible for an even larger range of conditions.