good question Mark. This is one of those "try and see" projects with information coming from a temp probe stuffed down in the windings. I plan to run it with the fan, without the fan, just having a big hole and with a stock spinner. there are a lot of variables and I'll post the results.  Hopefully it just works and doesnt turn into another one of "those" projects. FYI the blades are angled at 35deg has a 7/8" dia hub and is 1 7/8 on the outside. Probabley just sealing everything up (there is seperate cooling blowing on the outside of the motor) leaving the air no where to go but through the motor will be the biggest gain.  I am changing alot of things on the plane so I'm still a few weeks out from its maiden voyage.