RE: Cool
Hugh/Sport:
Your points are valid. I tried to stay as simple as I could. But I did address the radius/diameter in talking about the propellor's disc area.
And with sufficient airspeed even a 30 blade prop would have each blade entering undisturbed air. You will notice please, my counter example was a hovering helicopter with essentially zero airspeed. And when pitched for max air speed the inefficiency has a very bad effect on the airplane's accelleration, and running out of fuel before comong "On the pipe" isn't uncommon, all because the prop doesn't work very well at low speeds.
A good example is my old "Royal Rodent." On a paved or smooth clay circle it will take off, and run 140 mph in the air, using a 9x8 "Rev-Up" prop. On grass it wont take off with that prop. I have to switch to a 10x6 just to get off the ground.
Bill.