Deviation of Projectiles

With smooth bore guns, the departure of the projectile from the plane of fire is the result of many causes, principally the balloting of the projectile on leaving the muzzle, the excentric position of the center of gravity, the unequal air resistance due to rotation, etc. With elongated projectiles the deviation is much le than with spherical balls. In the former the rotation cannot exactly coincide with the axis of figure figure in any case. The relatively small angular velocity arising from the moment of air resistance with respect to the center of gravity, combined with the great angular velocity due to the rifled motion, produces a resultant angular motion about an instantaneous axis, which is continually shifting and thus changing the direction of the axis of figure of the projectile. The deviation will change with the initial velocity, IMG:content-1138.jpg:[graphic] the character of the rifling, the range, and atmospheric conditions, and therefore the exact solution is a problem of extreme intricacy. comers.