The overturning moment

The forces F₁ and F₂ (see previous figure ) form a free couple, which is said to be the aerodynamic moment of the wind force or simply overturning moment M_w (see  ). This moment tries to rotate the bullet about an axis through the CG, perpendicular to the axis of symmetry of the bullet. The overturning moment tends to increase the angle of yaw d.

The force F_W, which applies at the CG can be split into a force, opposite to the direction of the movement of the CG (the direction of the velocity vector v), which is called the drag force F_D  or simply drag and a force, perpendicular to this direction, which is called the lift force F_L  or simply lift.