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Overturning moment coefficient derivative coefficient |
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Yaw of repose vector |
).
As soon as the transient yaw induced at the muzzle has been damped out
for a stable bullet, the yaw angle d
equals the yaw of repose.
The magnitude of the yaw of repose angle is typically only fractions of a degree close to the muzzle, but may take considerable values close to the summit especially for high-elevation angles.
The occurrence of the yaw of repose is responsible for the side drift of spin-stabilized projectiles even in the absence of wind. The spin-dependent side drift is also called derivation.
It can be shown that for right-hand twist, the yaw of repose lies to the right of the trajectory. Thus the bullet nose rosettes with an average off-set to the right, leading to a side drift to the right.
The above formula for the yaw of repose vector is an approximation for stable bullet flight.
