The YA-9 was a prototype ground support aircraft developed by Northrop for the United States Air Force A-X program . It lost to Fairchild Republic's YA-10 which entered into production as the A-10 Thunderbolt II.
McDonnell XF-88B Voodoo - photos
Douglas X-3 Stiletto test flight - video
Bell Boeing V-22 Osprey unfolding - GIF and photos
Kyushu J7W1 Shinden - photos