Rationale for choosing the airfoil of a UAV wing using a dynamic ground effect principle

Vehicles that use the principle of dynamic ground effect principle are innovative vehicles that have prospects for use as high-speed unmanned vehicles. It is known that when an aircraft moves near the ground, the phenomenon of increasing lift occurs, which allows for contactless movement at high speeds. However, the effectiveness of this ground effect depends on the airfoil shape. The object of this study is the aerodynamic processes that occur during the movement of an unmanned aerial vehicle near the ground. The influence of the effect of approaching the ground on the aerodynamic characteristics of four airfoil of different shapes has been considered: Clark YH-12, NACA-M6, USA-35B, TsAGI-721, which are used in subsonic high-speed aircraft, including unmanned aerial vehicles. The aim of the work is to evaluate the performance of these aerodynamic airfoils in near-surface operation and to determine the most promising shape for use in small unmanned WIGs. CFD modeling methods were used as a research tool. The pressure and velocity fields around the wing airfoils were determined and the influence of the distance to the ground and the angle of attack on the aerodynamic characteristics was established. It was found that the best aerodynamic quality for all airfoils is achieved at angles of attack of 4–6°. It is not recommended to use airfoils with angles of attack close to 0° as the ground may have a negative effect on lift. The USA-35B airfoil demonstrated the greatest increase in aerodynamic quality when approaching the surface, with a maximum increase of 67 %. This makes it possible to recommend USA-35B as small unmanned aerial vehicles with a dynamic ground effect principle