I'd be real interested to know of the .91 out there that can spin a 12x12 at 20,000rpm. I've never heard of such a thing. From my calcs the power to spin a 12x12 prop at 20,000rpm is somewhere around 10-12hp which is more than double of any of those engines on their best day.
ORIGINAL: dhal22
the real fast engines, ops, os .91 vr-df engines, rossi .91 df's need continuous strand carbon fiber props as i understand. 20,000+ rpm's is what i thought you were talking about.
david