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Hiller X-18

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Ground testing the X-18 tiltwing
Type Experimental prototype
Manufacturer Hiller Aircraft Corporation
Designed by Stanley Hiller Jr
Maiden flight 24 November Template:Avyear
Status Aircraft scrapped Template:Avyear
Number built One

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.


File:Hiller X-18 front.jpg
The X-18 showing its elaborate engine configuration

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 contra-rotating propellers were a giant 16 ft (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.

Service history

File:Hiller X-18 ground.jpg
The X-18 with partially rotated tiltwings

The first test flight was on 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 finally cancelled on January 18, 1964 and the X-18 was cut up for scrap.

File:X-18 tilting its wing bw.jpg
The Hiller X-18, rotating its tiltwings

Specifications (X-18)

General characteristics

  • Crew: 2-3
  • Length: 63 ft 0 in (19.2 m)
  • Wingspan: 48 ft 0 in (14.6 m)
  • Height: 24 ft 7 in (7.5 m)
  • Empty weight: 26,786 lb (12,150 kg)
  • Max takeoff weight: 33,000 lb (14,850 kg)
  • Powerplant:


See also

Comparable aircraft

Designation sequence

Related lists

See also

External links

Wikimedia Commons has media related to:


de:Hiller X-18 it:Hiller X-18 lv:Hiller X-18 ja:X-18 (航空機) no:Hiller X-18 pl:Hiller X-18

This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article "Hiller X-18".