Investigation on the unsteady aerodynamic characteristics of sliding-skin variable-sweep morphing unmanned aerial vehicle

Abstract In order to explore the unsteady aerodynamic characteristics and its mechanism of aircraft during shape morphing, wind tunnel experiments of a slidingskin variablesweep morphing unmanned aerial vehicle(UAV) were conducted, and unsteady aerodynamic characteristics were studied. The results demonstrate that: the unsteady aerodynamic characteristics curves of the UAV during shape morphing generate hysteresis loops around corresponding quasisteady curves; the faster the UAV morphs, the greater the hysteresis effect is; when the UAV varies sweep with a speed of 7.5°/s, the value of the unsteady aerodynamic characteristics will deviate corresponding quasisteady value by exceeding 5%; the main reasons of the formation of the above unsteady aerodynamic characteristics may be flowfield structure hysteresis and wing additionalvelocity.