There was a Channel 4 documentary a few years ago where they made and tested one of these. I didn't see it, but there are clips online: https://www.youtube.com

There was a Channel 4 documentary a few years ago where they made and tested one of these. I didn't see it, but there are clips online: https://www.youtube.com/watch?v=8IeGYkwVIWw https://www.youtube.com/watch?v=8IeGYkwVIWw