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. 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. 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 (see
next figure 
).
