X-22A

Specifications

Company- Bell Aerospace
Type- Test viability of ducted lift propellers for VTOL aircraft.
Goals- Research dual-tandem-ducted propeller.
Primary Testing Facility Research- Bell, Calspan Test Facilities
Dimensions- Span- 39 ft, 3 in; Length- 39 ft, 7 in; Height: 20 ft, 8 in
Max Speed- 255 MPH
Range- 455 miles
Max Altitude- 27,800 ft
Power Plant- Four General Electric YT58-GE-8D turboshaft engines with 1,267 hp each
Thrust- N/A
Weights- Empty: 10,478 lbs; Maximum: 17,644 lbs
Payload- N/A
Flights- 501
Number of Prototypes Built- 2
Project Tenure- 1966-1984
Project Status- Cancelled

Information

The Bell X-22 was a V/STOL X-plane with four tilting ducted fans. Take-off was to selectively occur either with the propellers tilted vertically upwards, or on a short runway with the nacelles tilted forward at approximately 45�. Additionally, the X-22 was to provide more insight into the tactical application of vertical take-off troop transporters, such as the preceding Hiller X-18 as well as the X-22 successor, the Bell XV-15. Another demand was that, while flying horizontally, a minimum speed of 525 km/h (283 knots; 326 mph) was to be attained.

Triple blade propellers were mounted on four wings and, synchronized through a wave-interconnection system, were connected to four gas turbines which themselves were mounted in pairs to the rear wings. Maneuvering was achieved by tilting the propeller blades in combination with control surfaces (elevators & ailerons), which were located in the thrust stream of the propellers.

In 1962, the US Navy announced their request for two prototype aircraft with V/STOL capability, powered by four ducted fan nacelles. Bell Helicopter already had intensive experience with VTOL 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.

Maiden flight of the prototype occurred on March 17th, 1966. In contrast to other tilt-rotor craft (such as the Bell 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 diminished maintenance, the prototype crashed on August 8th, 1966 and technicians stripped it for components in order to make the second prototype flight capable. The fuselage was still used as a simulator for some time afterwards.

The second X-22 first flew on August 26th 1967. Early that year, it was equipped with a variable flight control and stabilizer system from Cornell 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 cancelled. The required minimum 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. The craft is currently on display in the Niagara Aerospace Museum, New York.

Although the ducted fan propellers were considered usable, they were never utilized again on a US military aircraft.

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