Testing of a Long-Burning-Time Paraffin-Based Hybrid Rocket Motor

Abstract

One of the main issues that prevents the widespread use of hybrid propulsion is the low regression rate of classical hybrid fuels. Recently, paraffin-based fuels have been proposed as a viable solution; however, concerns about paraffin thermomechanical properties have often been seen as a possible showstopper. A small-scale hybrid rocket, able to burn hydrogen peroxide and paraffin wax for an extended time, has been designed, built, and tested in order to investigate the suitability of paraffin wax as a hybrid fuel for actual missions. The motor has a nominal burning time of 80 s, which is compatible with the majority of the missions performed by rocket motors. The motor has been tested successfully, demonstrating that paraffin can be used on real missions. Two different types of paraffin were used: type A and type B, which have regression rates of 1.45 and , respectively, at a reference oxidizer mass flux of and at a reference pressure of 15 bar. Moreover, temperature measurements inside the fuel grain demonstrated the liquid layer theory to be valid. An instrumented nozzle has also been used to better investigate the thermal behavior of the nozzle assembly.