Experimental Hypervelocity Firings Using Stick and Granular Propellant Configurations

The suitability of lumped-parameter interior ballistic models for prediction of the interior ballistic performance of very high velocity guns is limited by use of a predetermined pressure gradient which is superimposed on the solution to approximate the relationship between space-mean, breech and projectile base pressures. Even modern two-phase flow interior ballistic models, specifically formulated to address the hydrodynamics of the problem, have not been extensively exercised in this regime. Only recently have limited, large- caliber gun firings with realistic projectile masses been conducted to provide required data in this velocity regime. In this study, firings were conducted in a long 120-mm gun at propellant charge to projectile mass ratios (C/M) of about 3 to 6, yielding muzzle velocities in the 2 - 2.7 km/s range. The tube was instrumented with pressure gages at various locations along its length to provide data for comparison to predictions of various interior ballistic codes.