Your gearbox is not suitable at all. First, for a RC helicopter model you want precision. Your gear is rather excentric, will cause vibrations. Then, the Motor`s weight should be mounted in front of the main rotor`s shaft to maintain the center of gravity. And you don`t need an centrifugal clutch on a brushless motor. An helicopter`s ESC should provide governor and active freewheeling. You are showing, how to not build an RC helicopter`s gearbox, my friend.
