Well EM drive is a cool idea but without super conductors its going exactly the same place as the 95% efficient electric motors, commercial mag lev trains and a boat engine that is just a tube wrapped in copper wire. (I will give you a clue, saline solution).
However, this does work.... https://www.youtube.com/watch?v=wg2T7MUULZQ
Ok the physics.. as many of you may already know, Mach 2.6 is about as fast as your going to go with a jet engine. Anything over that and friction heats the air to about 1000 degrees centigrade and you loose reaction. To get to escape velocity you need to be going pretty fast so you take the fuel and the oxygen needed to burn it, with you. Hence big Roman Candles at Cape Canaveral.
This thing simply super cools the air before it hits the reaction chamber. Mach 5+ and you can use the local O2 until you get high enough to kick in you on-board supply to finish the hop into space. It's also possible that this engine burns possibly hydozine or hydrogen, we Brits tended to avoid that horrible Kerosine RP1 stuff..