The flowfield on a body of revolution operating at high angles of attack is characterised by the formation of steady asymmetric vortices. Steady asymmetric vortices form because it is not possible for two strong counter-rotating vortices to co-exist symmetrically on the body. 1 Any small perturbation, generally resulting from manufacturing imperfections on or near the nose, is responsible for changing the flowfield from an unstable symmetric state to a stable, steady asymmetric state. 1 The formation of steady asymmetric vortices on the body results in the development of side forces, the magnitude of which can sometimes exceed the magnitude of the normal force. 1

Two different types of vortex asymmetry exist. For pointed slender bodies, vortex asymmetry usually begins at the nose of the body with the angle of attack at which vortex asymmetry occurs dependent on the cone half-angle. 2 For blunt-ogive bodies, vortex asymmetry begins at the rear of the body and moves closer to the nose as angle of attack of the body is increased. The angle of attack at which asymmetric vortices develop is determined by 4. 2D/l. 2