Originally Posted by Nerobro

I believe it would be legal. I've seen no rules about fans beyond like... 30 and 40mm... so.. this is 30mm.

Honestly, unless you have a proper exhaust duct, you're not gonna get much from it.

That fan won't take more than a couple amps to run, and if you "poorly calibrated" the ESC endpoints, you could use the same signal as from your main ESC. alternativlely, hook it up to your third channel, and do some mixing. Idle at 20%, crank it to 100% anytime the throttle is something other than idle....