First of all this is not a perpetual motion machine. This type of transit drive works in theory by having two combustion chambers positioned parallel to the spacecraft's width and perpendicular to its length. Each of the two exhaust nozzles are also positioned parallel to the spacecraft's width and perpendicular to its length. Fuel is pumped into the combustion chambers and goes out the two exhaust nozzles at high velocity, and each fuel exhuast half next travels through a half of the U shaped tunnel until they both collide against the ship's midship bulkhead pushing the spacecraft forwards. The fuel is made up of multitudes of theorized systematic new elements in which each element provides an incremental acceleration when it combusts (each latter fuel element is more combustible than the former fuel element). The fuel exhausts don't exit the spacecraft. The structure of the U tunnel, combustion chambers, exhaust nozzles, etc. are made up of a theorized new super element I call superglass (the superglass structure negates the necessity of magnetic fields to contain the exhaust particles to keep them from melting spacecraft structure).