I am in the process of scratch building 2 x Tucano 86" span, 1/5 scale i have currently have a 1/5 PC9 84" span supertigre 3000 inverted fuel 12 % oil (50/50 cool power and castor ) the PC9 Fly scale speed. about inverted motors most of my planes have the motor inverted never any problems if set up right . Barry