Large twist is good for hover, but bad for fast forward flight.
High rotor RPM is good for hover, but bad for fast forward flight.
Consider blades that are made of
Extension-Twist Coupled Laminates.
In addition, consider an intermeshing helicopter with a pusher prop. The pusher prop provides all the forward thrust. As the craft's horizontal velocity is increased, the rotational speed of the rotors will be decreased. This reduction of rotor RPM results in less centrifugal force and this, in turn, results in less blade twist, due to the Extension-Twist Coupled Laminates.
At the maximum forward speed, the rotor blades will have no twist. The rotors are only required to provide lift, so now these rotors will be operating with minimal engine driven torque, and the rotorcraft will be flying, at high speed
, in a semi-helicopter / semi-gyrocopter mode.
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