The small demonstration that made it click for me is from that video: https://www.youtube.com/watch?v=yCsgoLc_fzI&t=812s https://www.youtube.com/watch?v=yCsgoL

The small demonstration that made it click for me is from that video: https://www.youtube.com/watch?v=yCsgoLc_fzI&t=812s https://www.youtube.com/watch?v=yCsgoLc_fzI&t=812s This is exactly what the blackbird does, only with a propeller pushing air in place of the big wheel, and it's a much clearer and simpler demonstration of the same idea, which you can trivially verify.