Hi VX Kat! I think it has something to do with damping the fan/propeller noise. Albeit, not that well

The new fan you put in looks very similar to the vertical stabilizer fan on the super, not so secret, Stealth Copter that crashed on the Bin Laden raid. Their fan blades were designed around super quiet operation.

Every VX owner seems to notice the fan noise, guess I got used to it. Now because of this thread I'm noticing it again

Good luck John,

BTW still holding off on that Davis Radiator... Im gonna do it but my Chinese cheapo seems to be better than the old cheapo I took off. Anyway bought a Samarai last week and thats using up a litttle of my time and money. Keep us posted and let us know if that new fan works!!