ORIGINAL: dithersail
So we decided to put on a 9x8 APC just to see what we would get, speed dropped into the 115 range.
So my question is for all you speed guys, I think the 9x9 is about right (?). But should I get a APC racing prop or other brand to play with. And with a "better" prop how much more speed could I squeeze out of the setup?
Some will take you to task for running Cool Power aka Cruel Power in your nice Jett. (Ah, DaveN already did while I was slowly typing I see..)
APC sport props are actually very efficient. One issue you may run into is that the US40 has more frontal area than most or all racers. In order to make use of the thinner pylon props you need low frontal area. Otherwise, it is quite common that the sport props can perform better on many aircraft die to greater blade area. Unless someone chimes in and says "I did this to my US40 and it works" my suggestion would be to try one, simple as that - 8.8" x 8.5/8.75/9.0" I'd say would be the starting range. Just keep those ground rpm up where Jett says to and don't bake it lean. What was static rpm on those two props you tried?
MJD