[upofadown]

I think the big issue with this sort of scheme would be noise. Small, heavily loaded props will be super loud. There are a lot of them in this case. The noise wouldn't linearly increase with the number of propellers but it would increase with the addition of each one.

[FabHK]

From the Volocopter FAQ [1] (in somewhat charming Denglish):

> DOES A VOLOCOPTER MAKE LESS NOISE THAN A HELICOPTER?

> Yes, the Volocopter is much more pleasant in terms of its acoustics due to its design and above all much quieter than conventional helicopters.

Listening to the video [2], this doesn't seem altogether implausible - the sound seems ok, like a fan more than a chopper.

[1] http://www.volocopter.com/index.php/en/kontakt-en/faq-en

[2] https://www.youtube.com/watch?v=OazFiIhwAEs

[upofadown]

In comparing the Volocopter noise to helicopters it would be something with no main rotor noise and 18 heavily loaded open tail rotors:

* https://en.wikipedia.org/wiki/Helicopter_noise_reduction#Tai...

My guess would be that the noise wouldn't carry as far due to the higher frequency but would be very loud closer in, again due to the higher frequency.

[FabHK]

Interesting, could well be. So not a problem for people on the ground, but you'd want to have a good noise-cancelling headset while on board.