Experimental investigation of a variable-span morphing wing model for an unmanned aerial vehicle

Abstract This paper concerns design, development, and testing of a morphing wing for an unmanned aerial vehicle with the aim of improving the vehicle’s performance over its flight envelope. For this purpose, a variable-span morphing wing (VSMW) model that allows changes in wing span, was developed and exposed to wind tunnel testing. The morphing wing model was tested in a low-speed wind tunnel facility at a variety of Reynolds numbers from 250 × 103 to 620 × 103 under steady wind speeds (i.e., 35, 60, and 80 m/s). Experimental wind tunnel results were then compared against base wing test specimen to evaluate the performance of the morphing wing. The experiment demonstrated an improvement in the aerodynamic efficiency of the VSMW in the form of a reduction in the drag and a subsequent increase of 5 and 17 percent in flight range and endurance, respectively. It was also found that the maximum aerodynamic efficiency of the wing model occurs at 4 degree angle of attack, which was 17.4 for the morphing wing with 100 percent increase in the wing span. This research also shows how the VSMW can be used as an alternative and effective method of roll control instead of the conventional method using aileron control surfaces.