Reactivity and Hypergolicity of Solid Fuels with Mixed Oxides of Nitrogen

Abstract

This paper reports on the reactivity and hypergolicity of different solid fuels with both nitrogen tetroxide (NTO) and mixed oxides of nitrogen (MON) oxidizers using drop tests. The main objectives of the study were to identify hypergolic additives for use with a paraffin-based hybrid fuel, and to quantify the influence of pressure on the reactivity of these different potential additives. As expected, it was found that ignition delays decrease as pressure increases. With 75 wt.% NTO and 25 wt.% nitric oxide (MON-25) and borane-trimethylamine, a decrease in minimum ignition delays of 95% was observed when pressure was increased by 50 psi, whereas pararosaniline base went from nonhypergolic to hypergolic over the same pressure range. Also, all the compounds tested showed longer ignition delays with increasing concentration of nitric oxide. Finally, common features observed in silyl amides, amides, and organic compounds were investigated. Further work will be needed to verify whether these preliminary trends can be generally applied to the selection of additional solid hypergolic propellants.