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.
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[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] 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
[edit] Performance
- Maximum speed: 253 mph (407 km/h)
- Range: miles ( km)
- Service ceiling: 35,300 ft (10,800 m)
- Rate of climb: ft/min ( m/min)
- Wing loading: lb/ft² ( kg/m²)
- Power/mass:
[edit] External links
[edit] Related content
Comparable aircraft
Designation sequence
Related lists
See also
X-1 · X-2 · X-3 · X-4 · X-5 · X-6 · X-7 · X-8 · X-9 · X-10 · X-11 · X-12 · X-13 · X-14 · X-15 · X-16 · X-17 · X-18 · X-19 · X-20 · X-21 · X-22 · X-23 · X-24 · X-25 · X-26 · X-27 · X-28 · X-29 · X-30 · X-31 · X-32 · X-33 · X-34 · X-35 · X-36 · X-37 · X-38 · X-39 · X-40 · X-41 · X-42 · X-43 · X-44 · X-45 · X-46 · X-47 · X-48 · X-49 · X-50 · X-51
See also List of experimental aircraft
