Vertical Take-Off and Landing (VTOL) with transitioning to conventional forward flying had filled the minds of aviation engineers for decades before the jet engine made such though possible. Bell Aircraft developed its Type 68 along these lines for testing by the United States Air Force (USAF) and NASA during the 1950s with the goal of utilizing a vectored thrust arrangement to provide the lift needed in taking off, landing, and hovering while also adapting the aircraft to conventional horizontal flight. While only one Type 68 was built for the program the vehicle generally flew trouble-free and was not retired until a crash in May of 1981. It was given the formal x-plane designation of "X-14".
To expedite construction and development of the vehicle, the Bell team delivered a rather gangly-looking aircraft that featured an open-air cockpit, long landing gear legs, low-mounted wing mainplanes, and dual engine layout consisting of a pair of British Armstrong Siddeley "Viper 8" turbojets rated at 1,750 lb thrust (each). The basic shape was formed from the body sections of a Beechcraft Bonanza civilian aircraft and a T-34 Mentor military trainer - both originally prop-powered airframes. Thrust deflectors were added to serve in guiding the resultant engine thrust forces in the required directions depending on the flight action at hand. A pair of circular intake openings dominated the nose section of the fuselage. Fuel tanks were fitted externally under each wing. Unfortunately for the pilot, no ejection seat was fitted as a weight-saving measure.
First flight of the X-14 was recorded on February 19th, 1957 and this accomplished the required vertical takeoff and landing action with a hovering effect managed in-between. The transition to forward flying was added in a test flight recorded on May 24th, 1958. In 1959, the aircraft was delivered to NASA for further testing and had its British engines replaced with General Electric J85 models producing the revised "X-14A" designation. Despite its appearance, the X-14 actually proved a valuable platform for VTOL research considering the Cold War was rife with VTOL projects in both the United States and Europe. NASA astronauts also trained some on the X-14 when personnel were expected to land the Lunar Lander on the surface of the moon during the Apollo rocket age.
Another engine change - this to the J85-GE-19 series - begat the revised designation of "X-14B" during 1971 which also saw an upgraded avionics suite added with fly-by-wire function. X-14B was a NASA test regular until it crashed on landing in a May 29th, 1981 accident - however, the crash yielded no injuries but did mark the X-14 as irreparable and the product's test life formally ended.
Only the three aforementioned designations were ever realized. A dedicated trainer was entertained under the "X-14T" designation but never furthered. Likewise, the "X-14C" was to include a more conventional enclosed cockpit but never evolved beyond the early design stage. The sole X-14 (X-14B) example was reclaimed from a scrapyard during 1999 by a private collector with the intent of bringing the aircraft back to showpiece condition.
Performance specifications for the X-14A (with British Viper engines installed) included a maximum speed of 172 miles per hour, a range out to 300 miles, and a service ceiling of 20,000 feet. Dimensions included a length of 7.6 meters, a wingspan of 10.4 meters, and a height of 2.4 meters.