Dispersion of an Artillery Projectile Due to Unbalance

The ballistic dispersion of conventional artillery shells is due mainly to the dispersion of the initial velocity, the quadrant elevation, the angle of bearing, the projectile mass and the initial transversal angular velocity. This paper presents a method to calculate the contribution to ballistic dispersion of the initial transversal angular velocity. The latter is assumed to be the consequence of the gap between the tube and the projectile and to be due to the static and dynamic unbalance of the projectile. This method also permits to determine a maximum allowed unbalance level during fabrication of the projectile, to determine the tolerances between the tube and the projectile, and so to contribute to the prediction of the ballistic life of the tube.