[marvin]

Things get a lot better when you do a ducted fan approach, preferably with variable geometry and/or counter-rotating rotors. Electrical engines also have the advantage of being more maneuverable, which means that creating an Osprey-like design with both VTOL and flight with wings will be mechanically much simpler. You need wings to have efficient forward flight, and I think a design like this will not be practical until we use a purely electrical design.