Solid methane hybrid rocket engine. Regression speed increase by oxidizer doping and embedding wires. Vehicle optimization application through motor parameters.

Abstract

This paper presents a novel fuel to be considered for hybrid rocket motors: solid methane. We are showing the potential that this fuel has for hybrid rocket motors from technical perspective as well as from economical perspective. We present an internal ballistic model used to design a hybrid rocket motor with solid methane. We also present a comparison table for solid methane and various cryogenic and non-cryogenic oxidizers. The maximum specific impulse is obtained for the solid methane-LOX pair with a value of ~315 seconds under specific conditions. Although a solid methane-LOX motor shows higher than averages values for the regression speed, these values are still low by performance standards. We present two models that predict the regression speed increase for embedding wires and for oxidizer doping with a factor of ~2-3. An experimental setup that can be used to verify these models is further presented in the paper. Finally, we present a potential application for solid methane hybrid rocket motors in the form of an upper stage propulsion unit for orbital/suborbital vehicles. We find a practical interdependence relation between structural optimization (dry mass) of the launcher and the performance parameters of the motor. We present a study case of such a vehicle intended to place a 50 kg payload on low earth orbit (300 to 500 km altitude). Developing such a launcher is both environmentally safer than current approaches and economically more efficient because methane reserves are a rich resource worldwide.

Evaluation of Regression Rate Enhancing Concepts and Techniques for Hybrid Rocket Engines

“…A very effective heat transfer enhancing device for solid rocket motors are embedded wires in the fuel grain, with significant (around 400% increase) improvements to the regression rate [40,41]. It has, thus, been tested also in hybrid rocket engines [41,42]. For this, metallic wires are embedded into the fuel grain, perpendicular to the mass-flow.…”