 Apparently, use of the "117" radio call became commonplace and when Lockheed released its first flight manual (i.e., the Air Force "dash one" manual for the aircraft), F-117A was the designation printed on the cover.When the Air Force first approached Lockheed with the stealth concept, Skunk Works Director Kelly Johnson proposed a rounded design.He believed smoothly blended shapes offered the best combination of speed and stealth.