Exploratory investigations on metal-based fuels for air-breathing propulsion

Air-breathing solid fueled propulsion devices represent rugged, cheap, and rather simple options, out of the ramjet (RJ) category, which can contribute to volume containment and structural weight reduction. In the case of a ducted rocket, a fuel-rich propellant is burned in a primary combustion chamber and part of the oxidizer is taken from the atmosphere to complete the combustion inside a ram burner before exhaust. The use of metal additives contributes to the development of high-energy density materials, featuring better volumetric specific impulse. Metal powders are characterized by high energetic content per unit volume but can feature issues of difficult ignition, generation of condensed combustion products (CCPs), and incomplete combustion. The present work discusses a series of exploratory investigations on aluminum-based pyrolants. Thermochemical analyses, calorimetric investigations, and combustion tests will be considered, looking at improvements introduced by metal addition.