slowrotor,
I agree with your comments regarding L/D.
You might find the patent 'Optimum speed rotor' US 6,007,298 very interesting.
US Patent Search It is directly related to this subject. It is very simply presented and it gives a good understanding about the attempt to take better advantage of the helicopter rotor, for your application.
Nick might not be too please with this suggestion 'cause the information in the patent was later massaged and a second patent 'Optimum speed tilt rotor' US 6,641,365 was obtained. I believe that Boeing acquired this company and it is now submitting one of two Boeing bids for a future heavy lift rotorcraft. These bids are in a competition with two Sikorsky coaxial X2 bids and a Bell quad tiltrotor bid.
Nick,
"Concentrating on the blade angle makes Dave's wonder-configuration seem better, but in truth, there are dozens more issues to be delt with...."
If my psychiatrist is able to give me a split personality, I work on two issues at the same time.
slowrotor, again,
It is a given that the fewer the blades ~ the more efficient the craft.
This suggests that the most efficient rotorcraft for your requirement might be a side-by-side configuration, with each rotor having only one blade.
Weird, but.....................
Nick, again,
Yes! There is a Santa Clause and a Magic Button.
