As I commented in another thread tonight, it depends upon the airframe you are flying, its OAW and your expectations.

When flying in the dead of Summer when the density altitude was at its worst, we used to drop back to a 10x5 with excellent results. An 11x5 or 6 would not have provided us with enough ground clearance for the trainers of the day. Some of the larger trainers, such as the Kadet Senior, etc., would have had plenty of ground clearance with even a 12" prop, so they might have done just fine with the 11" props. I am all for anything that works satisfactorily.

What did surprise me with the OS.40FP and its clones was how well they responded to the 10x5 props when used for competition fun flying. Again, we are talking about an unusual airframe when compared to just about anything else flying in R/C, so it goes back to the application. Obviously, the OS .40FP will handle 11" props, but it really comes alive and on the ports on something smaller than a 10x6. That is all I was trying to point out - not that the 10x5 was THE prop to use. Only that it was a surprisingly good alternative for lightly loaded airframes where instant throttle response is at a premium.


Ed Cregger