The Mustang needed aileron trim for for long distance cruising. It's a long range escort fighter. The spit is a short range interceptor. Not so important to cruise for hours comfortably.
I always assumed it was prop torque I was ruddering against to fly straight. Now I'm reading about a whole range of factors that influence the plane.
Experimenting I've found the spit mkII rolls left at low power and right a full power. With 2lbs of boost at 200mph it doesn't roll either way.
It would be great if the game allowed us to tinker with the fixed aileron tabs in the load out section. The tail tabs are animated now
