Ferndales got a point but your problem seems a bit strange in that it flys streight with no turn input but turns sharp one way while barely turns the other. If the trim were off it whould be turning on no-turn stick input. I have one that does the same. It just flops over and crashes to the left if I give it much left turn while barely turns to the right I just had to learn how to make it turn both ways the way it wanted. These things have strange and independent personalities - that's the nature of cheap planes (even my Firebird and Aerobird seem to have really off days that make them are vertually uncontrolable - only my Preditor always does what I "ask" it to do). I just have learned to play it their way and not try so hard to make them behave the way I think they should. Hope some one else has a better solution (I could use it to).