The forgoing discussion in this thread implies that widening the chord allows for a decrease in the speed of the rotors.
In addition, Wieslaw Z. Stepniewski was recommending twin single-speed slow turning rotors for faster, quieter rotorcraft.
Therefore,
these calculations were done to get a better understanding about the subject. They suggest that a single-speed slow turning rotor will be slightly more efficient in hover than it will in cruise.
The
original Coaxial ABC helicopter had a two-speed rotors. The tip speed was 650 fps for hover and 450 fps for cruise. The slower speed in cruise was necessary so that the advancing blade tip would not approach the speed of sound.
It will be very interesting to see if the
new X2 Coaxial ABC implements multi-speed rotors or single-speed rotors.
Dave
Opps!
This post (and most of the following posts) should have been placed on the [Why are Helicopters with the Flettner-System so slow?] thread.