In the figure above, a bullet is viewed from behind and is assumed to have right-handed twist. Additionally, the bullet should have an angle of yaw d, its longitudinal axis should be inclined to the left. Then there is a component of the flowfield velocity vn, perpendicular to the bulletīs axis of symmetry.
Due to bullet spin and air molecules adhering to the bulletīs surface, the flowfield in the vicinity of the bullet becomes asymmetric. Air stream velocity and the rotational velocity of the body subtract at point A and add at point B (see above figure). However, according to Bernoulliīs rule (see any elementary physics book), this coincides with a pressure difference. A higher pressure at A and a lower pressure at B give rise to a downward directed force, which is called the Magnus force FM .