vorticey,
Different thrust devices work better at different forward velocities. Under approximately 400 mph the propeller or ducted fan will be the most efficient. At higher velocities, your idea may well have merit.
Shawn,
I feel quite strongly that; lower rotor rpm, extremely rigid rotors, active blade twist, a separate horizontal thrust device, and the exclusion of the tail-rotor, are all mandatory features for the next (2nd) generation of
rotorcraft.
It will be interesting to see what, if any, horizontal thrust is provided by the main rotor(s) of these new rotorcraft. Perhaps there is consideration for giving the rotor-blades a slight positive twist in fast forward flight, but I suspect that total autorotation is not the optimal arraignment.
With the UniCopter, the intent is that the rotors will provide some of the forward thrust. One reason is because there is not enough room to swing a sufficiently large diameter propeller. The constant speed propeller will be linked to the forward cyclic, with consideration for linking it to the aft and lateral cyclics. The tail rotor is 'verboten'
.
donut king,
Yes, but I don't think that the S-72 was ever flown with its rigid rotor. Perhaps the reasons for this were; an insufficient number of blades for aerodynamic stability and/or the asymmetrical aerodynamics of a single rotor at high speeds.
Boeing's new Dragonfly is supposed to fly within the next few months.