Hi Nello73. The problem with your aileron movement is that you have got far too much movement, and if it is equal up and down, then you may well be getting drag from the down-going aileron. The accepted rule is that there should be more up aileron than down aileron. You can do this mechanically, by offsetting the control rods on the servo disc, ( I will have to refer to my bible in my shed for the full detail), or if you have a servo in each wing for the ailerons, then some transmitters allow you to adjust aileron differential electronically. It does make a difference, and I would certainly cut down the movement that you have now to half, test fly and increase the movements until you are happy with the flying!!!