Yeah, they really do spin up near that. I haven't kept up with F5D setups for a long time, but back when my friends were doing it the De Riguer setup in 2000 was an APC 4.7-4.7 spinning at 32-34krpm static, closer to 40k unloaded. The trend since has been smaller props and higher voltage from what little I've heard, I do know that some guys were flying 4.1-4.1's with really hot winds/cell counts back in 2004 or so.

A Cyclon will turn a 4.7-4.7 at 27.5krpm. It's a little unhappy with it, but it's close. I didn't have time to play with compression, but I think a larger prop at a little slower RPM might be the ticket. I know that when Matchless and I talked about his new Caliente I told him to try the "E" props and rotate the motor to the wing/fuse junction. Don't remember exactly how much faster it was than before, but 14mph sticks in my head. At any rate, an APC 4.7-4.7 at 27.5k is about what an F5D motor used to turn that prop in the late 90's and those were 150mph planes that weighed 32oz. and had minimum wing areas that had to be met. I think 165-170 is possible out of a 1/2A with the right airframe, prop and motor setup. If the CL guys can hit 150 while dragging a set of lines, we can definitely go faster.

This video claims 42k, don't know if that's loaded or not. Sounds like loaded. http://www.youtube.com/watch?v=0U9N0...eature=related

This is a single blade prop from SuperCool on an Avionik. Bigger to take advantage of efficiency at better Reynold's numbers and to put enough load on the motor. Obnoxious-loud, perfect for doing a doppler reading! http://www.youtube.com/watch?v=Y3Z0p...eature=related

ETA: Here's another super high rpm setup in a Speed400 racer that's got an insane brusless setup: http://www.youtube.com/watch?v=68_75...layer_embedded