Do not limit fuel at all. Both percentage and absolute amounts make very little sense with respect to real life. In R/L it is either you get the fuel you need or you do not fly. With respect to the game, each method affect different kind of planes differently - neither is fair.
Limiting fuel does not accomplish anything gamewise. Just forget about it. If you want to disable planes - kill the hangars.
I agree with this methods. I was gonna say the same thing Bozon.....
