I doubt you will find a fan that size with a 30-40mm hub, its just too small to be strong enough for a rotor 5 inches or more. My Extreme Alloy 127mm fan is a 5" fan, rotor hub is around 57mm and that's about as small as you can go, also your RPM goal is way too high, my fan runs at 27,000rpm on 14 cells at 7.7Kw and pushes over 22lb thrust at this power level. Motor is 50mm diameter inrunner and is very efficient in the combination.