Experimental and modeling capabilities will be developed to characterize the mixing and combustion of gelled propellants in a bipropulsion engine. The goal is to use experimentally determined propellant and engine characteristics to accurately predict engine combustion efficiency. The predictive capability will be based on establishment of a numerical model; which simulates propellant aerosol formation, mixing and combustion. Experimental tools will be designed to measure key characteristics of the aerosol formation and mixing processes so that detailed laboratory measurements can be used to calibrate the predictive model. The goal of the effort is to establish these capabilities from "First Principals" so that the modeling capabilities will not be empirically tied to one engine or propellant technology. The proposed program will provide significant improvements in the performance of bipropuslion engines. The modeling and experiemental studies planned for this effort will provide the framework for evaluation of future propulsion systems.