I was wondering if a rotorcraft, that descends very slowly compared to its nominal rotor rotation rate (for example an RC Helicopter vertically autorotating with 3m/s descent rate and 2200RPM on the rotor) can maintain the rotor rotation rate even though it is having a positive collective pitch.
Is this possible? If so can it be sustained or is it just for short time frames?
The following image might enhance the understanding (Source)
look at the speeds and look at the lift/drag curve, if the lift/drag ratio is big enough this should work, right?