Feasibility study and demonstration of an aluminum and ice solid propellant

Aluminum-water reactions have been proposed and studied for several decades for underwater propulsion systems, and other applications such as hydrogen generation. Aluminum and water has also been proposed as a propellant and there have been proposals for other refrigerated propellants that could be mixed, frozen in place and used as solid propellants. However, little work has been done to determine the feasibility of these concepts. With the recent availability of nano-scale aluminum (nAl), a simple binary formulation of nAl and water is now plausible. Nano-sized aluminum has a lower ignition temperature than micron-sized aluminum particles, partly due to its high surface area, and burning times are much faster than micron Al. We have previously reported that frozen nAl and ice mixtures considered are stable, as well as insensitive to electrostatic discharge, impact and shock. Here we report a study of the feasibility of a nAl-ice propellant in small-scale rocket experiments. The focus here is not to develop an optimized propellant, however improved formulations are possible and could be explored in future work. Several static motor experiments have been conducted, including using a flight-weight casing. In this flight-weight test the grain configuration was 6.75" long, 3" outside diameter, with a 1" center perforation. It produced a peak 500lb _f of thrust at 1650 psi. The flight weight casing will be used in the first sounding rocket test of an aluminum-ice propellant soon.