The Soviet Kamov KA-56 folding helicopter. I don't believe it ever flew; these photos are of a full-scale mockup. Designed to be able to be launched out of a submarine's torpedo tube, and assembled in 15 minutes.
https://s3-us-west-1.amazonaws.com/hmt-forum/ka56_1.jpg
https://s3-us-west-1.amazonaws.com/hmt-forum/ka56_2.jpg
More: Kamov Ka-56 folding helicopter
Previously:
https://www.homemadetools.net/forum/...306#post135057
https://www.homemadetools.net/forum/...910#post133618
https://www.homemadetools.net/forum/...677#post132967