Propfan Boeing 727. 2:31 video:
https://www.youtube.com/watch?v=APzO7OVGakw
More: https://en.wikipedia.org/wiki/Propfan
Previously:
https://www.homemadetools.net/forum/...621#post147510
https://www.homemadetools.net/forum/...168#post145644
https://www.homemadetools.net/forum/...136#post145451
https://www.homemadetools.net/forum/...079#post141127
https://www.homemadetools.net/forum/...612#post139601
https://www.homemadetools.net/forum/...111#post134347
https://www.homemadetools.net/forum/...2518#post96512
https://www.homemadetools.net/forum/...790#post133254
