The Bell X -14 was an experimental aircraft for Research on VTOL capabilities by deflection of the push beam and at the same time the first of its construction. Since essentially only vertical take-offs and landings and transitions ( transition from hover to level flight and vice versa) should be carried out, the X -14 was not designed for high speeds: the cockpit was open and the tricycle landing gear rigidly, so do not retractable. The wings were not cambered, the leading edge was approximately at right angles to the aircraft fuselage. Deflecting the thrust jet was not due to variable engine nozzle, such as in Hawker Siddeley Harrier, but by simple Deflektorbleche. These called the jet for takeoff and landing by 90 ° downwards, to hold level flight the angle was gradually reduced until the speed was sufficient to generate the required lift on the wings. To control the hover the X -14 had additional nozzles at the rear and at the wing tips, which enabled the required pitch and tilt movements by means of compressed air.
After the mid-1950s a variety of VTOL and V / STOL concepts had been tested already or were in the testing, now the practical use of a jet plane with variable thrust jet should be tested. Bell then constructed a simple pattern that the term " X -14 " was given by the USAF. Technical innovations were found in the X -14 barely, only the stability system was something entirely new and should still find years later, with only slight changes in similar types of aircraft use. The first flight took place on February 17, 1957, a pure hover without transition. The first vertical take-off with transition to horizontal flight took place only in 1958. Numerous test flights led to a better understanding of the drive concept and the VTOL concept in general. Flight data from the X -14 program served even later the design of the Hawker P.1127, Hawker Siddeley Harrier of a prototype. 1969, leaving the USAF, the single copy of the X -14 NASA, which replaced the Viper engines through stronger. This led to the renaming in the X -14A, which often mistakenly lead to believe it would be more than one instance been built. Later there was a further name change to X -14B. After further tests by NASA's X -14B was used as a VTOL training aircraft before it was handed over to the Army Aviation Museum at Fort Rucker, Alabama. Later she went to a private collection in Indiana. The last flight took place on 29 May 1981.