BTW, some people call the angle on a prop the Angle of Incidence. It sort of suggests the true value/purpose of the twist you see change along the blade.

Some mfg's also offer combined pitch props. I think they actually call them "two pitch" or something like that, but truth is, any short name would be scientifically wrong. But the idea they're trying to convey, and to sell, is that there is more or less pitch to those props toward the tips. Truth is, there always is.

But the existence of those props with the funny names illustrates just how different design can produce better performance in specific performance envelopes. Those 12x6-8 sticks are supposed to do special in certain ways, aren't they. Do we see them landing at the speed we've come to expect from a 7" pitch (average of the example 6-8) or not. Heck, who has thought to look. (ok, I have for one)....... Nonetheless, they are gentle reminders that the pitch written on our props is pretty much just advertising and the mfg's guess.