Magnus effect over finned projectiles

Computations of steady flows over yawing and spinning axisymmetric projecti les are largely carried out by numerical algorithms using steady methods. O f particular interest is the prediction of the Magnus force and moment. How ever this axisymmetric characteristic is lost with fins addition, and the f low becomes unsteady whatever the framework is. ONERA and GIAT Industries h ave developed a new unsteady scheme, based on grid movement, that allows su ch a turbulent unsteady flow to be solved. This scheme has been used succes sfully 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 fo rce. 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.