Beating Gravity - Bell Model 68 / X-14

The X-14 marked a more subtle approach by the US to vertical takeoff experimentation, in which thrust deflection was evaluated, in contrast to the straightforward prop-hanging designs such as the Convair XFY-1 or the Lockheed XVF-1.

The Model 68 was ordered by the USAF and intended only as a low-speed trials aircraft, and was therefore designed with an open cockpit and fixed tricycle landing gear. Like other Bell VTOL designs of the 1950s it used components of existing aircraft; the wing, ailerons and tricycle landing gear were from a Beech Model 33 Bonanza, and the tail came from a Beech Model 45 Mentor.

The two Viper turbojets were mounted well forward in the very nose, and simple thrust deflectors at the centre of gravity were used to divert the exhaust downwards at ninety degrees for vertical take-off. The deflection was then progressively reduced until thrust to rearwards enabled wing-borne flight.

Compressed air nozzles in the wingtips and tail were used for control at low speeds or whilst hovering, a development of a concept tested by Bell in their earlier ATV.

The Type 68, or X-14, first flew on 17 February 1957 in the hover, and achieved a full transition to wing-borne flight on 24 May 1958.
Soon after this, the USAF accepted the X-14, and allocated it to NASA, who decided it was underpowered.

The Viper engines were replaced by 2,680 lb thrust General Electric J85-GE-5s in 1961. In 1971, as the X-14B, it was again fitted with new engines, J85-GE-19s. It was also fitted with a computer to enable duplication of landing characteristics of other VTOL aircraft then available.

The X-14B continued its test role until badly damaged in a landing accident on 29 May, 1981, and deemed unworthy of repair. Development of an X-14C with an enclosed cockpit, and an X-14 T trainer, got no further than the project stages.