The USAF Advanced Medium STOL Aircraft was an attempt to replace the venerable C-130 Hercules transport. Oddly this plane performed very well, but it was developed at a time when funding was unavailable, and so was canceled. It was remarkable in that the plane used upper surface blowing, where jet exhaust surrounded the wing surface and provided very good lift, as opposed to other jet planes that simply allow the forward motion to move air over wing surfaces. Circa 1976.
Source: Source: X-Planes And Prototypes. Jim Winchester; Barnes and Noble Books, 2000.