Do not try to use smaller diameter prop, no advantages for your draggy plane. I think your optimal prop is 68" 3-blade. Scimitar blade will provide more thrust and higher efficiency for 150 HP at 2700 RPM max engine. I can supply you an optimal prop.I'm rebuilding a Woody's Pusher and need a prop for it. I have space for a maximum prop diameter of 68 inches to clear the fuselage. I'd like to lower the engine to keep the CG lower and the engine mount shorter is possible without sacrificing too much thrust. I'm looking for take-off/climb performance, not speed (too much drag - open cockpit etc.).
Would a 3 bladed 68" prop give more thrust than a 3 bladed 68" prop?
Would a 4 bladed 60" prop give the same thrust as a 3 bladed 68" prop?
Engine is an O-320-E2D - stock, 150 HP.