Being fixed-pitch isn't the only thing that makes autorotation on these impossible. Rotor system inertia is incredibly important in autorotation, and this fact

Being fixed-pitch isn't the only thing that makes autorotation on these impossible. Rotor system inertia is incredibly important in autorotation, and this fact will pretty much make autorotation in quad+-rotor aircraft a no-go. The only option here is a ballistic parachute / BRS, and personally that's not a system I'd stake my life on.