Hiller X-18

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The X-18 was an experimental cargo transport aircraft designed to be the first testbed for tiltwing and STOVL (short take off and vertical landing) technology.

Image:X-18 tilting its wing bw.jpg

[edit] Development

Design work started in 1955 by Stanley Hiller Jr and Hiller Aircraft Corporation received a manufacturing contract and funding from the U.S. Air Force to build the only X-18 ever produced.

To speed up construction and conserve money the plane was constructed from scavenged parts including a Chase C-122 Avitruc fuselage and the turboprops came from the Lockheed XFV-1 and Convair XFY-1 Pogo experimental airplanes program. The tri-bladed counter-rotating propellers were a giant 16 ft (4.8 m) 4.8 m across. The Westinghouse turbojet engine had its exhaust diverted upwards and downwards at the tail to give the plane pitch control at low speeds.

[edit] Service history

The first test flight wasn't until November 24, 1959, ultimately recording 20 flights out of Edwards AFB. A number of problems plagued the X-18 including being susceptible to wind gusts when the wing rotated, acting like a sail. In addition the turboprop engines were not cross-linked, so the failure of one engine meant the airplane would crash.

On the 20th and final flight in July 1961, the X-18 had a propeller pitch control problem when attempting to hover at 10,000 ft and went into a spin. The crew regained control and landed but the X-18 never flew again, however ground testing of the tiltwing concepts continued. Eventually a test stand that the plane was mounted on failed and the plane was severely damaged in the fall. The program was cancelled January 18, 1964 and the X-18 was cut up for scrap.

[edit] The X-18 in Fiction

In the japanese animation series "Ghost in the Shell: Standalone Complex", a craft of a similar design is used as an airborne mobile armour transport craft.

[edit] Specifications (X-18)

[edit] General characteristics

Crew: 2-3
Capacity:
Length: 63 ft 0 in (19.2 m)
Wingspan: 48 ft 0 in (14.6 m)
Height: 24 ft 7 in (7.5 m)
Wing area: ft² m²
Empty: 26,786 lb (12,150 kg)
Loaded: lb ( kg)
Maximum takeoff: 33,000 lb (14,850 kg)
Powerplant:
- 2x Allison T40-A-14 turboprop, 5,500 hp (4,100 kW) each
- 1x Westinghouse J34 turbojet for pitch control, 3,400 lbf (15.2 kN) thrust