The C-142 tiltrotor failed to make it into service but 'United States of America' titles were worn as on VIP aircraft, probably because it was originally a joint USAF, Army and Navy project. Note the little horizontal tail rotor for pitch control. 62-5924 to NASA in 1968, to USAF Museum in 1970. Photo by: John Dominis / Life

This was a Tri-Service Tilt wing V/STOL experimental transport, which first flew in Dec.1964. Problems with its cross linked drive shaft, instability and a fatal crash were amongst reasons why the programme ceased after 420 flight hours in 1967. Now preserved at Wright Patterson AFB.