Magnus effect over finned projectiles

Computations of steady flows over yawing and spinning axisymmetric projectiles are largely carried out by numerical algorithms using steady methods. Of particular interest is the prediction of the Magnus force and moment. However this axisymmetric characteristic is lost with fins addition, and the flow becomes unsteady whatever the framework is. ONERA and GIAT Industries have developed a new unsteady scheme, based on grid movement, that allows such a turbulent unsteady flow to be solved. This scheme has been used successfully over a spinning and yawed body-tail configuration. The Magnus effect is generated on the body by the spin-induced boundary-layer distortion at moderate incidences, whereas asymmetric vortices tend to invert this effect at upper incidences. Fins contribute to an opposite and greater lateral force. The total Magnus force appeared to be linear with respect to angle of attack and spin rate, but the range of linearity of angle of attack is much smaller than for a nonfinned body.