Originally Posted by
DroneDog
But also in auto rotations, again my understanding of helicopters if the engine quits you quickly drop the pitch to maintain rotor rpm relying on the inertia of the rotor system to provide the flare as you land, if you could introduce a degree of negative pitch you could build rotor rpm as you descended.
Helicopters autorotate with positive pitch. Normally if you lower the collective fully the rotor rpm will exceed the limit (blades fly off etc!). A stabilised autorotation will be with the collective low but probably not fully down. Therefore there is no need for negative pitch in this context.