RE: OS 46AX Prop Size
My personal favorite prop for that engine is the APC 11X5 for trainers, and APC 12X4 for aerobatics. That hits the top end (on the ground) around 13,000, which provides excellent thrust for take off, and gives a nice slow speed at low throttle for landings. Many trainers with an 11x7 are hard to slow down enough to give a good sink rate for landing.
Brad