Steady-State and Pulsed Performance Results of a Tripropellant Autophage Engine Architecture

This paper discusses the design, development, and testing of a novel tripropellant autophage-hybrid rocket propulsion system. An autophage, or self-consuming, rocket uses its own fuselage mass as fuel. This concept operates by continuously melting the polymer fuselage at the engine interface, consuming it as soon as it is no longer needed to house the other propellants, and injecting it into the engine itself. The vehicle gets shorter during the ascent. The architecture reduces structural mass fraction, approaches infinite staging, and provides a route toward the miniaturization of launch vehicles for small satellites seeking rapid low-Earth-orbit access. The reduction in rocket length throughout the flight may also increase maneuverability, with applications in defense systems. This report presents the performance of a 100 N autophage engine in hot-fire test campaigns. The tests were performed in a laboratory environment and showed an autophage contribution (i.e., the fraction of fuselage being consumed as additional fuel) of between 5.1 and 15.7% of the total propellant mass during steady-state operation. A total of five tests operated the engine across a range of inlet conditions as well as in pulsed mode. The performance results of these tests form an operational baseline for future work on scaling the autophage architecture to a higher thrust class.