Performance of Dicyclopentadiene/-Based Hybrid Rocket Motors with Metal Hydride Additives

Abstract

An experimental performance evaluation of metal hydride fuel additives for hybrid rocket motor propulsion systems is examined in this paper. Some metal hydride additives offer improved performance, but a common issue is material aging. An accelerated aging study revealed that dicyclopentadiene can protect sodium borohydride () particles from exposure to air and water vapor much better than conventional hydroxyl-terminated polybutadiene. Static hybrid rocket motor experiments were conducted using dicyclopentadiene as the fuel. Sodium borohydride and aluminum hydride () were examined as fuel additives. Ninety percent rocket-grade hydrogen peroxide was used as the oxidizer. In this paper, the sensitivity of solid fuel regression rate and characteristic velocity efficiency to total fuel grain port mass flux and particle loading is examined. Chamber pressure histories revealed steady motor operation in most tests, with reduced ignition delays when using the fuel additive. The addition of and produces up to a 47 and 85% increase in regression rate over neat dicyclopentadiene, respectively. For all test conditions examined characteristic velocity efficiency ranges between 80 and 90%. The regression rate and characteristic velocity efficiency mass flux dependence indicate a shift toward a more diffusion controlled system with metal hydride particle addition.