If you set Controls>Aim up/down/left/right to mouse movement, you can control the quadcopter turret using the mouse, but you can't fly it using the mouse.
If you delete these key bindings, you can fly the quadcopter using the mouse, but you can no longer aim the turret using the mouse.
I can't find a way around this.
Under controls>aim up/down/left/right set these to mouse up/down/left/right.
(Have helicopter controls also assigned to the mouse)
Fly a quadcopter - you can't use the mouse to control it. Take over the turret - you can use the mouse to move the turret.
Go to controls>aim up/down/left/right and delete the mouse bindings.
Now you can control the quadcopter with the mouse, but no longer move the turret using it (since you deleted the bindings).
This hasn't always been the case - I used to be able to both fly and control the turret of the UAV with the mouse.
I've found the solution!
Turn 'Vehicle Freelook' off.
I still believe there's a bug:
IF 'Vehicle Freelook' is on, you can control the UAV if 'look' keybindings are not assigned. You can't if they are.
ALSO Occasionally it will all work fine. One game every so often(with the 'look' keybindings assigned), the UAV controls will work as normal. The next game they won't.
Also toggling freelook (with alt) has no effect.