Science and Technology of Energetic Materials

Vol.78, No.5 (2017)

Research paper

Improvement in the manufacture of wax-based fuel for hybrid rockets
Ichiro Nakagawa and Yutaro Usui


Although wax-based fuels for use in hybrid rockets have the desirable property of high regression rate, they are composed of brittle thermoplastic materials that can crack easily in the molding process. Correspondingly, improved manufacturing methods are necessary. In this study, we conducted non-steady thermal conductivity cooling calculations to model the molding process and calculate the maximum thermal stress of such fuels. Our results show that maintaining a higher ambient temperature during the molding process can be effective in reducing cracking. We then conducted tensile testing of microcrystalline wax-based fuel, which has a higher tensile strength than that of normal alkane wax. By adding ethylene vinyl acetate copolymer (EVA) to microcrystalline wax based fuel, we could effectively improve its physical properties. The results of thermal stress analysis using tensile test data showed that it is possible to manufacture a 20% EVA content microcrystalline wax-based fuel with a radius of over 250 mm.

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molding, microcrystalline wax, hybrid rocket

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