Effects of Projectile and Gun Parameters on the Dispersion

Abstract

Main battle tanks constitute one of the most powerful fire powers for the armoured land forces. To use this very high fire power efficiently, the dispersion of shot impacts becomes crucial. Dispersion is affected by the aerodynamic factors, gun-projectile interactions, projectile and gun dependent factors, manufacturing tolerances and environmental factors. The change in aerodynamic factors and environmental conditions varies the aerodynamic forces applied on the projectile and this affects the dispersion characteristics of the projectile. In this study, the effects of the changes in recoil stiffness, gun support stiffness, projectile muzzle velocity and manufacturing tolerances of projectile forward/rear bourrelet diameters on the dispersion for 120 mm L44 and L55 calibre guns are investigated. Armour piercing fin stabilised discarding sabot type projectile is used in the analysis. Statistical dispersion analyses including interior ballistic, in-bore balloting and exterior ballistic analyses are conducted using PRODAS ballistic software. According to the results, it is determined that the decrease in projectile/bore clearance (forward/rear bourrelet diameter) results in improved dispersion of ammunition. The 10% changes from the nominal recoil stiffness and the vertical support stiffness values have negligible effects on the dispersion. In addition, the results show that muzzle velocity variations influence the dispersion in vertical direction substantially. Using the procedure applied in this study, it is shown that different clearance conditions can be analysed and most suitable tolerances may be determined taking into consideration of both the gun system performance and manufacturability.