Props in the OS manual are props that can fly various airplanes and not destroy the engine. I have a friend who has done the same thing for electric saying "the book said." I have had three planes that I stuck old OS 40 FPs on. My son's trainer, a WW1 parasol, and a 3D profile. All different props. Trainer 10x6 wood, WW1 11x4 wood, 3D 12x4 APC. The simple answer is the biggest diameter with the most pitch you can put on and not lug the engine. Your AX probably needs 1 13x6. I doubt it can spin more. The type of plane you have needs some pitch for speed as the plane will want to fly fast to not stall. A plane like yours may need 100 feet to take off and the initial climb might be 20 ft of altitude for a 100 yards of flight until it gets leveled off and speed built up. Back through the early 80s airplanes at contests could not use an engine bigger than a .61. Plenty of 60 size planes, back then, at 12 pounds were flying then wishing for a 90. What you really need is someone at your club to give the plane a look over for CG and other stuff. It can save it the next time and hopefully get some hands on explanations. What type of planes were you flying before you started the Corsair?