Lift-to-drag ratio of an unmanned aerial vehicle

Abstract

Currently, the aerodynamics of unmanned aerial vehicles (UAVs) is not given due consideration, as it is generally believed that there is no need to improve something that already flies well. However, recent combat experience has demonstrated that UAV engagements will obviously raise questions about aerodynamic characteristics, particularly critical angles of attack. The goal of the study was to determine a drag polar for an abstract UAV that could provide information about critical angles of attack and the angle of maximum lift-to-drag ratio. Using the ANSYS CFX package, an aerodynamic simulation was performed for an UAV that was similar to UAVs typically used for monitoring main oil and gas pipelines. The simulation was performed at various angles of attack in the range of -30º to +30º at a cruising speed of 100 km/h. The calculation error was no more than 1 %. The simulation demonstrated a stable, continuous flow in this range. Previous studies have suggested that critical angles of attack for unmanned aerial vehicles are 15–17º; the calculations indicate that they can be increased to 30º if necessary. The point of maximum lift-to-drag ratio obtained at an angle of attack of approximately 25º may require further refinement.