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.

Minimising induced drag with weight distribution, lift distribution, wingspan, and wing-structure weight

“…A beam cross-sectional area b wingspan b δ characteristic length associated with the deflection-limited design, Equation (55) b σ characteristic length associated with the stress-limited design, Equation (38)…”

Analytic and computational analysis of wing twist to minimize induced drag during roll

“…Feifel's results were obtained numerically using a potential flow threedimensional vortex lattice method. 80 To understand how the induced drag changes during this pure rolling motion, it is insightful to consider the ratio of the increase in induced drag due to the rolling moment and rolling rate given in equation (53) to that of the increase in induced drag at roll initiation given in equation (34). This can be found by using equations (58), (60), and (19)…”

“…31,32 For unswept wings of aspect ratio greater than about 4, lifting-line theory agrees well with experimental data and computational fluid dynamics solutions, and lifting-line solutions are widely accepted. 33–76 Nickel 75,76 found a solution for the optimum lift distribution to create a rolling moment while minimizing induced drag using lifting-line theory. However, his work neglected the influence of rolling rate.…”

Combined droop nose and trailing-edges morphing effects on airfoils aerodynamics

“…Kamliya et al [2] have showed that morphing with higher camber flap increase the lift coefficient while a little decrease the lift to drag ratio is observed. Gamble et al [3] have used morphing hinge at airfoil trailing edge which was capable of delay the inception of stall to higher angle of attack but with slight reduction in lift coefficient. Kimaru and Bouferrouk [4] have showed experimentally the wing with morphing camber which has a better aerodynamic performance for different angles of attack than traditional wings.…”