Dual-Oxidizer Metallized Solid Propellants for Low-Cost Space Access

Owing to technology maturity, simplicity, and reliability, in the near future (2010-2020) solid rocket propulsion will continue to play a main role in the development of Expendable Launch Vehicles (ELVs), both as first stages of heavy launchers and main stages of small/medium launchers. In this context, a co-operation was started between Avio and Politecnico di Milano addressed to the study of Ammonium Nitrate - based composite solid rocket propellant combustion. Ammonium Nitrate is a very cheap oxidizer, producing environmentally friendly combustion products but with a low specific impulse compared to Ammonium Perchlorate. To improve the thermal response of raw AN, different types of Phase Stabilized Ammonium Nitrate were investigated. For a better ballistic behavior of AN-based propellants, compositions including ballistic modifiers and metallic additions were tested. To extend the low pressure burning of AN-based propellants, possible use of AN and AP co-crystals was also checked The objective is to identify an optimum AN+AP dual oxidizer system and understand its basic combustion properties in view of possible space propulsion applications.