Development and test of magnesium-based additive for hybrid rockets fuels

Hybrid rockets have been suggested as an alternative to the solid and liquid propulsion systems since the middle of the 2000s due safety concerns and high specific impulse. In general, the classical hybrid fuels are HTPB, HDPE and Polymethylmethacrylate that experience low regression rate of the solid fuel and this characteristic can limit its application. In 2003 Stanford University had tested paraffin wax as hybrid fuel and it showed regression rate from 3 to 4 times higher than the classical fuels and this new class of fuel has the potential to make the hybrid propulsion system more interesting in the commercial point of view. However, paraffin suffers of very poor structural characteristics. A well know way to improve mechanical properties and the burning rate in solid propellants is by the mixing of metal powders into the fuel grain. Thus, in this research we doped paraffin with Magnesium Diboride in order to study the mechanical property of this fuel and its combustion characteristics. The tests were running with pure paraffin (control sample) and paraffin with different percentages of MgB₂ and the results observed during burning tests with nitrous oxidizer demonstrate that this new fuel matrix is fully able to increase the overall performances of hybrid motors.