I recently tried a couple of airplanes with 3bladers. Both airplanes have been tested with a number of 2bladers and the best found for each. I went through different diameters and pitches. Didn't have to make a crusade out of it because I've got a fair amount of experience doing it PLUS there is a huge resource of flyers who've fun the same engines and the same models and the same engines on the same models. When I looked around for 3bladers to try, I found one each for the two airplanes to try first. They're expensive so I didn't buy up the other two 3bladers that might work.

With one airplane the 3blader I tried worked measurably better than all but one of the 2bladers I tried out on that airplane. I figured that was lucky to have hit so close to the bullseye with just one bullet. The airplane is overpowered with my choice of engine. I'm using a 90 on a 60 size/weight airplane. The flight envelope I'm applying to that airplane has no place in it for efficiency (whatever that'd be) because I chose not to include it. I'll fly that airplane until it's worn out with that 3blader, and it does more than I want from it.

The other 3blader on the other airplane didn't stack up as well against the list of 2bladers tested on that airplane. I'm not flying that 3blade on it now, but plan to buy another whenever I find one that looks like it'd apply. Did that prop "fail" because it wasn't efficient enough. lol..... who knows, but maybe the other 2bladers that didn't do as well as the chosen best 2blader were not chosen because they were less efficient than the winning 2blader.

"efficiency" is a great sound byte word.
Why? Because our props only come with diameter and pitch numbers printed on them, no efficiency ratings. So whatever we want to say about efficiency only has to sound "expert".