We have to operate our engines in their power band for them to produce their best horsepower.

The number and length and width and airfoil and tip shape and progression of pitch all effect the props ability to move our airplanes. And diameter is the simplest for us to see and understand when trying to keep an engine turning to a chosen rpm. So the sound byte wisdom says we should reduce the diameter to bring up rpm. And when we throw extra blades at an engine, it slows and we then figure we need less diameter on that new, slower prop.

Higher aspect wings and higher aspect prop blades are aerodynamically more efficent all else being equal. In our situation, all else won't be, but what the heck. We only need to sound like an expert, not actually prove it.

And longer blades are almost always higher aspect ratio blades. So there is one probably true part to the efficiency buzz phrase. And it's actually based in fact. So how "much" efficiency are we talking about? Darned if anyone has any numbers I've ever seen.

One problem we have is that we also don't have any really proven and tested way to get the numbers. So it's cool to live with our sound byte wisdom.