Aerodynamics effect of holes in UAV wings modified for VTOL capability

Abstract

This research investigates the possibility of modifying the X8 Skywalker from a fixed-wing unoccupied aerial vehicle into a convertiplane to utilize the advantages of vertical take-off and landing and maintain the benefits of fixed-wing design. In this study two configurations were tested; the first one includes sharp holes embedded in the wings for the propellers and the second one has filleted holes. The purpose of the study is to analyze the new configurations’ ability to generate enough lift after reducing the wings area. The aerodynamic coefficients are calculated through computational fluid dynamics. Simulation results were validated experimentally by using the wind tunnel. Even though the holes reduced the wing area by about 20%, the proposed modifications could lead to a lift to drag ratio around 7. The results showed that the new configurations can generate five times the lift compared to the drag, while the maximum lift to drag ratio dropped by 50% compared to the original design. At the same time, the filleted hole configuration showed less drag and turbulence effects, especially at a low angle of attack, compared to the sharp hole configuration.