BTW, I've been asked many, many times how I get "the wrong prop" to work as good as I do all the time.

First answer is that a lot of mfg's numbers are just their best guess. Second answer is that most of the rest are bad guesses. Third answer (and probably a the closest to the truth) is that mfg's numbering haven't been updated since day one. And chances are good that none of the mfg's have recently tested on the real models that're being flown today.... and they don't need to.

Every time any modeler has actually realised that I just said the prop on my Tiger60 has an 8" pitch, they've asked how the devil I get the airplane to land so slowly. I usually start the answer with the sentences in the above paragraph. And if they're still around when I get to it, I try and explain about blade area.

Lot's of things about props are really fun to talk about. And about as applicable as the one, "a 3 bladed prop isn't as efficient.... etc etc"