Hello again, been to bed and then work since I last looked on here;
the first picture is the Sikorsky S-67 Blackhawk, as opposed to the completely different S-70 Black Hawk of 'Black Hawk Down' fame. This aircraft
met a tragic end by running out of sky at the 1974 Farnborough air show.
Pic 2 shows the Sikorsky S-69 Advancing Blade RSRA demonstrator after conversion to the X-wing demonstrator.
You are right with pic three, it shows the Kawasaki EC-1 surveillance version.
Pic 4 shows the rather crude basic demonstrator/test rig for the Dornier Do 31 which later became the only true VTOL Jet transport ever to fly.











