I was wondering what that sound was. every time I was pulling up and adding throttle, I could hear that sound! Thanks for the info. I was wonding about some thing. Is every one putting the bigger engines on the plane for better hovering? Or for more speed? I know that I am still a long way from hovering, but I can take the plane down the runway at a brisk walk and still have control over the air plane(most of the time) Isn't there more to flying than just hovering? What about the blenders, spins, water falls and other maneuvers? How dose the u-can-do handle them? I am not trying to start any thing ( I have a hard enough time starting my engine)