Hmmmm... for a .40-.46-size plane, like the Kaos 40-size, we'd run an APC 10 x 7 or 8 prop. We'd expect to see the engine turn in the mid- to high-12,000's when leaned to just rich of peak RPM on the ground.

Actually, though, if your O.S. Max .46 AX engine is turning 12,000+ RPM on the ground, and your plane flies just how you like it, then the propeller you're using is the "correct" one. The only way to be sure if you're using the "right" propeller is if the engine is turning where it should and the model flies the way you want.

For hovering and vertical climbout, you'll need lots of RPM and a flatter-pitch prop. You'll likely want the engine turning close to 13,000 RPM or slightlly higher, which means a low-pitched prop. Ed's suggestions above are good ones for 3D.

The props we tend to use suit the old-style Pattern-type flying, where you go for large smooth maneuvers, one per pass down the flight line. You'll get higher airspeeds, but don't try that with your 3D machine...it will likely get flutter and blow apart!