guessing you got an ARTF bronco? no matter. you don't have to bother with mixes on the ZAP. there is a screen you can get up that allows you to assign any channel to any control stick/knob/switch. on my bronco i had 3 channels assigned to the appropriate joystick axis, 2 rudders and the nose wheel. use subtrim to match the centre positions and atv to match the rudders. by having a low atv on the nose wheel it made ground handling great. full rudder with minor nose wheel movement. i actually had it set in heli mode so i could use pitch and throttle curves to balance the engines. i'm not sure if the normal trim switch affects all the channels though. have a play
