Solid Rocket Augmentation for Ram Accelerator Initial Launch

Abstract

The ram accelerator is a hypervelocity launcher capable of speeds over 2 km/s and theoretically much higher. It operates by launching a projectile into a tube pre-filled with gaseous propellant, which combusts and generates thrust. The ram accelerator requires a minimum initial velocity which must be attained with a supplementary initial launcher. Single-stage light gas and conventional powder guns have traditionally been used for the initial launch. This study details the modeling and testing of an onboard solid rocket as an initial launcher for the ram accelerator. A quasi-one-dimensional model was developed and executed with a second-order MacCormack scheme with second- and fourth-order artificial diffusion terms. Atmospheric static fire and in-tube projectile cases were both considered theoretically and experimentally to evaluate the quasi-one-dimensional model. The accuracy of the model’s inert gasdynamics were supported by experiment, but the combustion dynamics of the pro- pellant were inaccurate. The rocket augmented projectile did not provide the velocity gains predicted by the quasi-one-dimensional model.