[msandford]

Low power only works with incredibly large wings/blades. So large as to be highly impractical. The smaller your blades get the worse your efficiency. That means you need more batteries. But that adds more weight and means you need a bigger motor, which requires bigger batteries and so on.

I don't think we'll be seeing electric helicopters with any practicality until battery tech gets much, much better. I can't really even think about possibilities unless it gets at least 5x better with 10x being more interesting.

[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.

[markvdb]

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