1. The concept of a condensed-phase exothermic reaction is much less plausible in an ammonium perchlorate, rubber composite propellant, and consequently attention was soon directed to models involving participation of gas-phase species in the exothermic reactions. A sequence of studies at Princeton University in the period 1956 to the present26'33included development of a "gas-phase" model in which a hot oxidizing environmental gas and fuel vapors from the propellant mixed