Magnus characteristics of finned and nonfinned projectiles

This is a summary of the Magnus force and moment measurements obtained on finned and nonfinned projectiles during the past several years. Most of the measurements have been obtained in the Ballistic Research Laboratories' (BRL) supersonic wind tunnels, with a few measurements taken in the BRL transonic range and the Naval Ordnance Laboratory's wind tunnels. The results have provided considerable insight into the generation of the Magnus force and moments on both finned and nonfinned projectiles. For nonfinned bodies at small angles of attack, having a laminar boundary layer, the Magnus force, at least on short bodies, obeys Martin's theory. At high angles of attack the Magnus force can be estimated from the lift force on a spinning cylinder flying perpendicular to the flow. The Magnus force on a spinning finned projectile is composed of two forces: a body force and a fin force. The forces normally act in opposite directions, thereby tending to cancel one another. However, the forces do not act at the same location; therefore a Magnus moment is created which is nearly independent of the center of gravity position. There are also two other known sources of Magnus moments on finned bodies which are created under certain conditions. These conditions are defined in this paper and the magnitude of the moments are estimated.