Paraffin-Based Fuel for Hybrid Rocket Engines Application Feasibility Studies

Abstract

This paper describes combined analysis performed in pure waxes and paraffin based mixtures that can be used as fuels in hybrid engines. The feasibility of the use of such materials as fuels in hybrid rockets is under study at SPLab in Politecnico di Milano and at the DLR Institute of Space Propulsion in Germany. Density measurements of pure waxes were performed using a dilatometer. An experimental facility was set up and, after preliminary measurements and calibration, a repeatable procedure was implemented. The implemented instrumentation set up allowed the measure of density in softening and melting intervals. Mechanical uniaxial tensile tests were performed according to Standard ISO 527-1, on pure macro paraffin and microcrystalline wax and on these waxes doped with stearic acid and graphite; elastic modulus, elongation and maximum stress were calculated. Data indicates that ductile rupture is achievable even on pure tested macro paraffin. Moreover micro-crystalline wax was mixed with a synthetic wax characterized by higher nominal melting temperature in order to improve the softening point up to higher temperatures without compromising regression rate values. Thermal, rheological, viscosimetric and ballistic experiments were performed on this new formulation, promising for applications characterized by wide temperature ranges.