> A traditional rotary-wing helicopter with collective pitch can autorotate safely in to a controlled landing in the event of an engine failure. But not in the

> A traditional rotary-wing helicopter with collective pitch can autorotate safely in to a controlled landing in the event of an engine failure. But not in the event of a propeller or pitch-control failure. Also probably single propeller failure in this quad will mean "we lost 1/8 of power, we must land". Also if you lose gasoline engine, you have battery backup for 5min.