NACA twin spool compressor, c. 1956.
Fullsize image: https://diqn32j8nouaz.cloudfront.net...r_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...compressor.jpg
Previously:
https://www.homemadetools.net/forum/...837#post179141
https://www.homemadetools.net/forum/...114#post176359
https://www.homemadetools.net/forum/...281#post177015
https://www.homemadetools.net/forum/...740#post167337
https://www.homemadetools.net/forum/...767#post170965
