Makes sense. Thanks.If you limit the throttle, you limit the horsepower. Full horsepower is when you get maximum manifold pressure at maximum rpm. With too small a prop, if you limit the rpm because it’s easy to spin the prop, it might only take 40 hp to spin it. You might have a 65 hp engine, but you can’t use it. Same with too much prop. If it’s so big, the engine struggles to only 40 hp, you are still at a loss of performance.
All fixed pitch combinations play with this. A climb prop is easy to spin but overspeeds when trying to fly fast. A cruise prop is just slightly too much for max rpm so it’s always trying to get the plane a little faster until it can’t. You pitch a prop to the flavor you want the most and put up with the rest.