Influence of ground effect on longitudinal aerodynamic damping of wing-in-ground effect vehicles

Accurate determination of longitudinal stability characteristics of wing-in-ground (WIG) effect vehicles is an essential step in their design. In order to estimate WIG vehicle's stability, one needs to determine aerodynamic derivatives, including unsteady ones. The latter are very hard to obtain via wind tunnel tests, so traditionally they are expressed via steady derivatives. The method presented in this paper allows calculating unsteady aerodynamic derivatives by means of Reynolds-averaged Navier-Stokes simulations. The effect of different aerodynamic derivatives on stability characteristics is investigated. It is demonstrated that the decrement is two times greater in case of taking into account the unsteady aerodynamic derivatives calculated according to the presented method.