For large caliber spin stabilized projectiles (>50mm), in-bore clearance between the lands and the projectile bourrelet diameter are the primary source of in-bore axis tilt, followed by manufacturing defects. One potentially mitigating factor for large caliber artillery ammunition is the lack of a cartridge case for separately loaded ammunition (e.g. artillery systems with bagged or unitary propulsion charges). The reason for this is for these systems, there is no crimped cartridge case to control the initial position of the projectile with respect to the bore centerline. Gravity can and does influence the initial position of the projectile as its loaded into the barrel (assuming a barrel elevation angle not near 90 deg. during ramming), thus resulting in an initial position bias with respect to the bore centerline and a non-zero mean initial in-bore angle. However, using the Muzzle Exit dispersion module should provide a reasonable “worst case” dispersion estimate for this class of spin stabilized projectiles.
Previous
Top
Next