>A properly-tuned quadcopter is more stable than a helicopter and performs better in most situations<p>This is not correct. All quadcopters are fiendishly unstable and require computer control. Helicopters can get away without computer control, but a computer-controlled helicopter is just as stable. The performance of a helicopter is vastly better in every way - more efficient due to increased swept area, and more maneuverable due to variable pitch. You won't see a quad fly like this: <a href="https://www.youtube.com/watch?v=AXSfFLGeVZA" rel="nofollow">https://www.youtube.com/watch?v=AXSfFLGeVZA</a><p>What quadcopters are is mechanically simpler, and therefore cheaper. This is why they are popular, and also why efforts to scale them up to human size are misguided.
The original video: <a href="https://www.youtube.com/watch?v=JoVmejDsMrM" rel="nofollow">https://www.youtube.com/watch?v=JoVmejDsMrM</a>
That concept as a wind energy system was called a Darrius Rotor. The same blade angle concept allows the blades to adjust to wind directions. Darrius Rotors have been built with fixed symmetrical blades; I built one with blades cambered according to the radius of the rotor arms. They all work pretty well. Darrius Rotors became famous with the "egg beater" design - <a href="https://en.wikipedia.org/wiki/Darrieus_wind_turbine" rel="nofollow">https://en.wikipedia.org/wiki/Darrieus_wind_turbine</a>
This is far from the wackiest (successful) flying machine.<p>There is one with just a half-wing, and a motor-and-prop mounted on one end, pointed crosswise. It flies by spinning the whole vehicle, sort of like a maple leaf. It is totally controllable, like any old quad, but is more efficient because it has just the one motor, and only half a wing. It is more nimble because it has no "front".<p>You could have video with a single vertical line of pixels, relying on rotation to scan the sensor across the scene, and "point" it just by choosing which part of the spin to sample, or have a real-time panorama all the time.
I'd be interested to see if wingtip devices might improve things. The foils seem rather low aspect ratio for the speed they are spinning at, and you wouldn't want to spin it much faster because of the massive parasitic drag you'd get from the linkages.
If you like that watch this: <a href="https://youtu.be/CiU71GFs4Fs?t=178" rel="nofollow">https://youtu.be/CiU71GFs4Fs?t=178</a><p>the weirdest (full sized) one I've ever seen