The drag force
The drag force FD is the component of the force FW
in the direction opposite to that of the motion of the centre of gravity
(see figure ).
The force FW results from pressure differences at the
bullet's surface, caused by the air, streaming against the moving body.
In the case of the absence of yaw, the drag FD is the
only component of the force FW .
The drag force is the most important aerodynamic force. Given the atmosphere
conditions p,T,h, the reference area A and the momentary
velocity vw, the drag force is completely determined
by the the drag coefficient cD