OVERRAMMING 16-INCH GUN PROPELLANT CHARGES

Abstract

There was an explosion in the center gun of a 16-inch gun turret. The paper describes an investigation to see if the explosion could have been caused by over ramming the propellant charge. A sprocket driven chain pushes the projectile, then the charge, into the gun. A computer model was developed to calculate the response of a 16–inch charge assembly to overramming. The calculations with without explosions were studied to explain the physical process that results when an overram occurs: A strong stress wave starts at the contact point between the charge and projectile and propagates rearward through the charge assembly. Fracture of propellant grains can cause a spark that can ignite the 660 pound charge. When this occurs, the rammer and chain are driven violently backward by an explosion. The serpentine shape of the chain and its deep impression in the loading tray were accurately calculated.