The History of the Helicopter, an old film from 1952. 17:43 video.
https://www.youtube.com/watch?v=6_hScNDX53Y
Previously:
https://www.homemadetools.net/forum/...285#post134952
https://www.homemadetools.net/forum/...910#post133618
https://www.homemadetools.net/forum/...690#post159457
https://www.homemadetools.net/forum/...617#post159170
https://www.homemadetools.net/forum/...219#post149989
