For a bullet, moving at velocity v, having a yaw angle, the flowfield pressure differences result in a net force which is called the wind force F1 (see figure). This force seems to apply at the centre of pressure CPW of the wind force, which, for spin-stabilized bullets, is located in front of the centre of gravity CG. For fin-stabilized bullets the CPW is located behind the CG. The location of the CPW depends on the flowfield conditions and varies as the velocity decreases. Two forces FW and F2, applying at the CG, which mutually neutralize, can be added to the wind force. The forces F1 and F2 form the overturning moment MW (see next figure).
