Yeah, actually the efficiency trade off on number of blades really doesn't have any real value with most fullscales.

Those 2,000 hp fighter engines basically required pretty much a set load bearing capability from the prop, no matter how many blades on the sucker. And their clearance decided how that blade area was divided up.

In fact, if they had put all the blade area that could be swung into just two blades, the aspect ratio of those fat suckers would have hurt the efficiency of each blade measurably. So they played with airfoil a bit and went with more blades. When the power improved even more, they went with even more. And actually got better efficiency out of each blade but lost efficiency with the increased number of blade tips and airflow disruption.

With our model props, the 2blades we compare to the 3blades that are available differ so greatly in blade area and aspect ratio and a few others, that we actually aren't comparing apples to apples. Differences in efficiency that exist in theory are lost in the major practical differences in the props themselves with our models.

But why a prop that says it's an 8" pitch flies like a flatter one going slow and a variable one when going vertical is a different thing all together.