High-Progressivity/Density (HPD) Propelling Charge Concepts; Progress of Programmed-Splitting Stick Propellant

摘要

This report summarizes progress to date on the manufacture and closed bomb evaluation of a new high-progressivity gun propellant configuration. The concept is known as programmed-splitting stick propellant and involves the use of embedded slits which are not initially exposed to hot ignition gases. Normal surface regression during burning, however, exposes the slits, typically after peak pressure has been reached in the gun, leading to a large increase in surface area and a corresponding increase in the mass generation rate. Accompanying increases in downbore pressures can lead to significant gains in muzzle velocity without any increase in maximum chamber pressure. At the time of this review, small lots of programmed-splitting stick propellant have been manufactured and subjected to closed bomb evaluation. The results of these tests indicate a high progressivity but not to the degree theoretically predicted. The disparity is postulated to be linked to a finite voidage associated with the slits in the actual grains and its possible influence on successful closure of the ends to ignition gases and mechanical behavior of the grains during the burning process.