The Roton features a unique propulsion concept for its Earth-to-orbit phase.  It has 72 small combustion chambers arranged in a circle around the perimeter of the heat shield at its base.  These engines are mounted to a rotating disk assembly with the heat shield attached to the bottom and when spun up to 750 rpm, the centrifical force thus generated is used to force the fuel into the combustion chambers, eliminating the complex and heavy fuel pumps used on other boosters.  The disk is rotated to speed by the combination launch platform / ground power pedestal the vehicle rests on before launch.  This system is not designed to be restarted in orbit, the de-orbit burn maneuver will be accomplished with the RCS (Reaction Control System) quads mounted to the sides of the Roton.