The X-14 in its early form, with British Viper engines. Photo presumably taken during early hovering tests, in front of a building at KIAG that was torn down recently at time of upload. Later got J85 engines as the X-14A. Became NASA 234, later NASA 704. Photo from: Wright State University

The Bell X-14A in a wind tunnel at NASA Ames. It is said to have become NASA 704 with its upgrade to X-14B in 1971 but that date is apparently wrong. Matching civil identity N704NA was registered in 1969. More Beech than Bell, the aircraft had a Bonanza wing and a Mentor tail. Two smal turbojet engines with thrust deflectors for VTOL, plus compressed-air nozzles at wingtips and tail. Photo by: Art Melliar / NASA

Built as X-14 USAF s/n 56-4022. Converted to X-14A (GE J-85 engines) in 1962, and to NASA as N234NA. Converted to X-14B in 1971 and reregistered N704NA by NASA. Retired in 1981.

VTOL development aircraft, built as Bell X-14 for the USAF as 56-4022. Converted to X-14A and became NASA 234.