A subsonic lifting surface theory for wing-in-ground effect

Lifting surface theory is generalized to the case of wing-in-ground effect in subsonic flow. Solid ground and free surface are taken into account for a three-dimensional wing solved by lifting surface theory from an inviscid point of view. The wing can be divided into a finite number of panels, and each of them is placed by horseshoe vortices. The aerodynamic behavior of a wing-in-ground effect in subsonic flow is investigated. Numerical examples and experimental results are given for comparison. Finally, numerical examples are given to study the influence of clearance and Mach number on the lift for wing-in-ground effect.