[treetoppin]

Your comment about automating autorotations got me interested, and it appears that one UAV company has done a tech demo for it, at least from my cursory search. From what I can tell though the design space would be extraordinarily difficult to fully automate. Management of rotor RPM requires finesse, functioning flight controls and also quick decision making about where and how you are going to land. Usually the automatic flight control system would require either enough battery power to power your servo actuators after an engine failure or a system designed to run in AC power which is generated by your rotor system (which of course means it’s depleting rotor RPM at a time when rotor RPM is what is most important to manage). I think you’d have to design a lot of the aircraft systems with automation in mind, so it really would have to be a new aircraft in many regards, and you’d be unlikely to be able to retrofit an older airframe to do it. I think there’s just too many trade offs to make the system worthwhile in the low margin business of crop spraying, tour rides, or electronic news gathering. Medevac, oil rig transportation or military applications could make use of an automatic autorotation system, but those aircraft also tend to be medium to heavy twin engine aircraft which negates a lot of the need to focus as much on autos when you are designing the overall system.