Please don't misinterpret my earlier statement about the bushing 40,,, It did and still does fly the plane satisfactorily. I train at our club using the Eagle II's with a buddy box. I'll let students take the plane to the last second before a crash in order that they have every opportunity to recover on their own. However at that last possible opportunity I have found that the extra power of the 46 Ball Brg engines will snatch the plane from an untimely demise. As far as flying with the 46XLS you will never need more than 1/2 throttle and then you will be at a pretty peppy speed for the Eagle. Again, I recommend the 46 ball brg. due to shorter roll out on grass and recovery power for the instructor, but a I cannot say a 40 won't fly the plane,,, clearly it will and many including myself have had success with it.