Aerodynamic performance investigation on a morphing unmanned aerial vehicle with bio-inspired discrete wing structures

The excellent flight ability of birds is closely related not only to the morphing skeleton structure that can cause large-scale geometrical changes of their wings but also to the discrete or discontinuous wing structure composed of many feathers. In this study, a bio-inspired morphing discrete wing inspired from a pigeon's wing structure was designed with bionic feathers, with the explicit aim of improving the aerodynamic performance of an unmanned aerial vehicle. The bio-inspired discrete wing structure, controlled by a morphing skeleton structure, can actively morph into different swept-wing configurations similar to the wing postures of the pigeon and maintain a discrete wing surface similar to the pigeon wing surface at the same time. The results reveal that the bio-inspired morphing UAV can always maintain an optimal lift-to-drag ratio at three different Reynolds numbers utilizing the symmetrical wing morphing. The asymmetrical wing morphing can well achieve rolling control of the UAV. Furthermore, compared with a continuous wing surface structure, the bio-inspired discrete wing surface structure not only can achieve the induced drag reduction of the UAV through effectively decreasing the wing-tip vortex strength but also improve the lateral stability of the UAV.