Studies on coning in end-burning rocket motors

Coning of the burning propellant surface in end-burning rocket motors arises from an increased burn rate at the side walls of the propellant grain. Causes of this increased burn rate have been investigated, mainly through the use of small scale motor firings. The nature of the propellant inhibitor material is shown to be important, and various possible mechanisms are examined. Mechanisms identified by other workers in previous studies were found to be not involved. Strain in the propellant has been shown to produce coning. Considerable evidence was found that coning also results from migration of curing agent while the propellant is curing during manufacture although the precise mechanism involved has not been established.