Originally Posted by puntosaurus
Propellers autorotate; ever tried restarting an engine in a twin engined aeroplane ?
Of course they do. (No, I haven't. Only windmilled/zero-thrusted/feathered.)
But whether they'd store enough energy while autorotating to allow the helicopter fitted with such a lift source to successfully flare and land at a reasonably survivable speed might be another story.