Okay, the wise guys are through, I hope. When you mount an engine, depending on the plane you are putting it on, follow the instructions. Many airplanes, especially beginner planes need some down and right thrust. I bought a U-can-do ..60 recently, and whatever Tiwanese or Chinese assembled it, had the right and left sides of the fuselage reversed. yeah, you guessed it, the u-can-do, didn't. It flew horribly. It had right thrust, instead of left thrust and would not do a darned thing, I wanted, until I found and corrected the problem. so before you just stick it on there, like I did, look at the specs and QC setup, thrust line, wing straightness and so on, before you stick it together and go fly it. Oh, by the way, try taping your crystals in with some magic tape also. Mine vibrated loose after many flights and the airplane buried itself just off the run way. Control checked fine before takeoff, but the loose crystal secumbed to the 3D violence during the flight. Happy Landings.