Hi David. I built the US+ per plans, with the engine inverted. It has a Magnum 52 XLS (2 stroke) and with all the power this engine puts out, the plane has trully unlimited vertical, it hovers easy with throttle at 2/3. As you can see, I like chinese engines, I have several and all of them work very well and last for a long time. My favourite is the Mag 52 XLS. Believe it or not, it is more powerful and reliable than my beloved Irvine .53 [X(]