Experimental Investigation of Effect of Winglets on the Aerodynamic Performance of a Mini UAV

This experimental investigation focuses on the feasibility of attaching winglets to an indigenously developed fixed-wing mini unmanned aerial vehicle (UAV) to improve its aerodynamic efficiency. Winglets are well known for their application to reduce lift-induced drag and thereby saving fuel for manned aircraft. In this study, the effectiveness of winglets in the form of a simple end plate for a fixed-wing mini UAV, whose operating speed is low ($\mathrm{Re}<200\mathrm{k}$) is explored through wind tunnel tests and actual flight tests. To understand the flow field features, a flow diagnostics of wingtip flow with and without end plates was performed using a stereoscopic particle image velocimetry technique. Force measurements were also performed to quantify the improved aerodynamic efficiency of the mini UAV with the application of end plates. An approximately 10%–12% increase in the $L/D$ ratio is achieved by attaching the end plates to the wingtips of the fixed-wing mini UAV. An actual flight trial shows that flight endurance increased by 15% with the application of end plates compared to the baseline flight.