| X-22 | |
|---|---|
 Bell X-22 in flight | |
| General information | |
| Type | V/STOLprototype |
| Manufacturer | Bell Helicopters |
| Status | 1 stored, 1 destroyed |
| Primary user | United States |
| Number built | 2 |
| History | |
| First flight | 17 March 1966 |
| Retired | October 1984 |
TheBell X-22 is an AmericanV/STOLX-plane with four tiltingducted fans. Takeoff was to selectively occur either with thepropellers tilted vertically upwards, or on a short runway with thenacelles tilted forward at approximately 45°. Additionally, the X-22 was to provide more insight into the tactical application of vertical takeoff troop transporters such as the precedingHiller X-18 and the X-22's successor, theBell XV-15. Another program requirement was a true airspeed in level flight of at least 525 km/h (326 mph; 283 knots).
The X-22 was not a prototype of theV-22 Osprey, although it was a part of the development of tilt-rotor aircraft and Bell's work in this field of study.
In 1962, theUnited States Navy announced their request for twoprototype aircraft with V/STOL capability, powered by four ducted fan nacelles. Bell Helicopters already had extensive experience withVTOL aircraft and was able to utilize an already developed test mockup. In 1964 the prototype, internally referred to by Bell as Model D2127, was ordered by the Navy and received the X-22 designation. It was unveiled at an event in Niagara Falls in May 1965.[1][2]
Three-bladed propellers were mounted on four wings and synchronized through a wave-interconnection system, were connected to fourgas turbines which, in turn, were mounted in pairs on the rear wings. Maneuvering was achieved by tilting the propeller blades in combination with control surfaces (elevators andailerons), which were located in thethrust stream of the propellers.
The maiden flight of the prototype occurred on 17 March 1966. In contrast to other tilt-rotor craft (such as theBell XV-3), transitions between hovering and horizontal flight succeeded nearly immediately. However, interest increased more towards VTOL and V/STOL properties, not the specific design of the prototype.
Due to failure of a propeller control, described by test pilot Stanley Kakol as the only non-redundant component in the power chain, the prototype crashed on 8 August 1966 and technicians stripped it for components in order to make the second prototype flight capable. Thefuselage was still used as asimulator for some time afterwards.
The second X-22 first flew on 26 August 1967. Early that year, it was equipped with a variable flight control and stabilizer system fromCornell Aeronautical Laboratory, which improved flight performance. Although the X-22 was considered to be the best aircraft of its type at the time, the program was canceled. The required maximum speed of 525 km/h was never reached. The second prototype was moved to Cornell Aeronautical Laboratory for further testing; the last flight occurred in 1988.
Although not on display, the remaining craft, 151521, is currently stored by theNiagara Aerospace Museum,New York.[3]
According to the employees at the Museum, the craft was held onto after being debated for scrapping by the Navy.
General characteristics
Performance
Aircraft of comparable role, configuration, and era
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