90% HYDROGEN PEROXIDE/POLYETHYLENE HYBRID ROCKET

The 90% rocket-grade hydrogen peroxide (R/G HP), concentrated by distillation from Japanese domestic production of 60% commercial grade HP, has been applied to single- and multi-perforation polyethylene (PE) experimental hybrid rocket solid fuel. HP decomposition had been performed with modified three-way catalyst, but auto ignition of solid fuel did not take place due to the accumulated stabilizer in the course of distillation that suppresses the decomposition. So, the solid fuel ignited with the assistance of igniter plug and JP-4-fueled liquid rocket torch. In order to find the oxidizer mass flux for sustaining hybrid rocket combustion, large fuel length/burning port diameter ratio (L/D=35) with transparent polymethylmetacrylate (PMMA) solid fuel small hybrid rocket studies have also been carried out. The oxidizer mass flux has to be over the flux that extends diffusion flame up to the aft end of the solid fuel. The required minimum oxidizer mass flux was confirmed for the multi-perforation solid fuel grain. Comparing with solid propellant rocket grain, multi-spoke wagon wheel and multi-hexagonal perforation solid fuel grain designs were discussed. Modified three-way catalysts utilized for decomposing the R/G HP were powerful even for the commercial grade (C/G); though, it was much too active for R/G HP and there were often steam blast explosions. In order to solve potential danger of a three-way catalyst, improved ignition devices have been developed without using a three-way catalyst.