The Magnus force
force coefficient; cMag(B,Ma,Re,w,d)
The Magnus force FM arises from an asymmetry in the flow
field, while the air stream against a rotating and yawing body interacts
with its boundary layer and applies at the CPM (see figure ).
Depending on the flow field, the CPM may be located ahead or behind the
CG. The Magnus force vanishes in the absence of rotation and in the absence
of a yaw angle.
The Magnus force is usually very small and mainly depends on bullet
geometry, spin rate, velocity and the angle of yaw. In exterior ballistics,
the above expression is used for the Magnus force.