An analysis of the spallation of carbon phenolic ablators

The phenomenon of spallation, a process by which pieces of char "pop off" a heat shield, has been investigated as it occurs in carbon-reinforced phenolic ablators. Spallation is shown to be the result of a pressure buildup within the char. This pressure increase results from occlusion of the char and the consequent blockage of now. By selective fiber orientation, the spallation process can be alleviated.