Adding two forces to the wind force

For a bullet, moving at velocity v, having a yaw angle d, the flowfield pressure differences result in a net force which is called the wind force F₁ (see also previous 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 F_W 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 M_W (see next figure ).