Now that's interesting. Another thread on Rossis led me to their web page (thanks for the link Chuck ) where they claim the R40 Aero puts out 1.9HP at 17K revs. I happen to have a chart for various props and it shows that the APC 10x6 needs 1.88HP to drive it at 17K revs, virtually exactly the same as apapa is getting. A manufacturer that's honest with their HP ratings?? Just for interest's sake, that prop needs just over 6.3HP for 25,500rpm.

The MDS40 is developing .66HP and the LA .75HP