Evaluation of a Conceptual High Altitude Valveless Internal Combustion Engine Fueled by Green Monopropellant

Busek Co. Inc. proposes to conduct critical studies and experiments to establish the feasibility of a novel High ALtitude Endurance aircraft (HALE) engine called MICE for Monopropellant Internal Combustion Engine. The reference fuel is the hydroxyammonium nitrate (HAN) based monopropellant AF-M315E developed by AFRL for small thrusters in space applications. The heat of combustion of AF-M315E is 4.52 megajoules/kg, or 2.76 times greater than the heat release of decomposed hydrazine used previously by NASA for the engine of its “Mini Sniffer” HALE. Thus, the MICE concept promises a reduction in specific fuel consumption from 4.7 lb/brake horsepower hour (bhph) to 1.7 lb/bhph, a decisive improvement. Unlike hydrazine, HAN is a green monopropellant thus simplifying handling. The basic MICE engine has no valves, no catalyst, no external combustion, and requires no air. Its performance improves with altitude. In Phase I, Busek will design and carry out critical Proof of Concept (POC) experiments to establish feasibility of the MICE concept, and, from the results, estimate performance and other critical factors for the MICE engine. Also, using Company resources, Busek will establish a team with an engine company to carry development of the MICE concept through and beyond Phase II.