Hiller X-18

Last updated
X-18
Hiller X-18 testplatformLarge.jpg
Ground testing the X-18 tiltwing
General information
TypeExperimental prototype
Manufacturer Hiller Aircraft
Designer
StatusAircraft scrapped 1964
Number built1
History
First flight24 November 1959
Developed from Chase YC-122 Avitruc

The Hiller X-18 was an experimental cargo transport aircraft designed to be the first testbed for tiltwing and V/STOL (vertical/short takeoff and landing) technology.

Contents

Development

The X-18 showing its elaborate engine configuration 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 United States Air Force to build the only X-18 built, serialized 57-3078. [1]

To speed up construction and conserve money, the plane was constructed from scavenged parts including a Chase YC-122C Avitruc fuselage, 49-2883, [1] and turboprops from the Lockheed XFV-1 and Convair XFY-1 Pogo experimental fighter programs. 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. Hiller nicknamed their X-18 the Propelloplane for public relations purposes. [2]

Service history

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

Preliminary testing occurred at Moffett Field Naval Air Station, CA. The first flight (hop) was on 11/20/1959 followed by the first real flight on 11/24/1959 with Hiller test pilots George Bright and Bruce Jones. [3] Further test flights were held at Edwards AFB, ultimately recording 20 flights. 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. Thrust control was through throttle changes, which were too slow for acceptable height and roll control.

On the 20th and final flight in July 1961, the X-18 had a propeller pitch control problem when attempting to convert to a hover at 10,000 ft (3,000 m) 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 VTOL Test Stand was built on which the X-18's vertical takeoff and landing and hover control was to be tested. One engine run was successfully conducted to the full 15-foot (4.6 m) wheel height on the VTOL Test Stand. The program was canceled on January 18, 1964, before further VTOL Test Stand testing could be conducted, and the X-18 was cut up for scrap.

The program proved several things that contributed to further tilt-wing VSTOL technology programs:

  1. cross-shafting between the engines was necessary in order to avoid loss of control in the event of an engine failure.
  2. direct propeller pitch control was necessary for precise height and lateral control during VTOL and hover.

This knowledge was employed in the successful development and flight tests of the Tri-Service XC-142A tilt-wing VSTOL transport.

Specifications (X-18)

3-view line drawing of the Hiller X-18 Hiller X-18 3-view line drawing.png
3-view line drawing of the Hiller X-18

Data from Jane's All the World's Aircraft 1961-62, [4] The X-planes : X-1 to X-29 [5]

General characteristics

Performance

See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

Related Research Articles

<span class="mw-page-title-main">VTOL</span> Aircraft takeoff and landing done vertically

A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wing aircraft and other hybrid aircraft with powered rotors such as cyclogyros/cyclocopters and gyrodynes.

<span class="mw-page-title-main">Tiltrotor</span> Aircraft type

A tiltrotor is an aircraft that generates lift and propulsion by way of one or more powered rotors mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a transverse rotor design, with a few exceptions that use other multirotor layouts.

<span class="mw-page-title-main">V/STOL</span> Aircraft takeoff and landing class

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<span class="mw-page-title-main">Tiltwing</span>

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<span class="mw-page-title-main">Tail-sitter</span> Type of VTOL aircraft

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<span class="mw-page-title-main">Bell X-22</span> 1960s American V/STOL aircraft

The Bell X-22 is an American V/STOL X-plane with four tilting ducted fans. Takeoff 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 takeoff troop transporters such as the preceding Hiller X-18 and the X-22's successor, the Bell XV-15. Another program requirement was a true airspeed in level flight of at least 525 km/h.

<span class="mw-page-title-main">Ryan X-13 Vertijet</span> Experimental vertical take-off and landing (VTOL) jet aircraft

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<span class="mw-page-title-main">Curtiss-Wright X-19</span> Experimental VTOL tiltrotor quadcopter airplane

The Curtiss-Wright X-19, company designation Model 200, was an American experimental tiltrotor aircraft of the early 1960s. It was noteworthy for being the last aircraft of any kind manufactured by Curtiss-Wright.

<span class="mw-page-title-main">Canadair CL-84 Dynavert</span> Canadian experimental tiltwing VSTOL aircraft

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<span class="mw-page-title-main">Lockheed XFV</span>

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<span class="mw-page-title-main">LTV XC-142</span> Experimental military tilt-wing aircraft

The Ling-Temco-Vought (LTV) XC-142 is a tiltwing experimental aircraft designed to investigate the operational suitability of vertical/short takeoff and landing (V/STOL) transports. An XC-142A first flew conventionally on 29 September 1964, and completed its first transitional flight on 11 January 1965 by taking off vertically, changing to forward flight, and finally landing vertically. Its service sponsors pulled out of the program one by one, and it eventually ended due to a lack of interest after demonstrating its capabilities successfully.

<span class="mw-page-title-main">Powered lift</span> VTOL capable fixed-wing aircraft

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<span class="mw-page-title-main">Doak VZ-4</span> Type of aircraft

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<span class="mw-page-title-main">Dassault Balzac V</span> Type of aircraft

The Dassault Balzac V was a French vertical takeoff and landing (VTOL) testbed of the early 1960s. It was built by Dassault Aviation from a prototype Mirage III aircraft to test the configuration for the Mirage IIIV. The sole example was involved in two major accidents that killed the aircraft's pilot, and was not repaired after the second crash.

<span class="mw-page-title-main">Tiltjet</span>

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<span class="mw-page-title-main">VTOL X-Plane</span> American experimental aircraft

The Vertical Take-Off and Landing Experimental Aircraft program was an American research project sponsored by the Defense Advanced Research Projects Agency (DARPA). The goal of the program was to demonstrate a VTOL aircraft design that can take off vertically and efficiently hover, while flying faster than conventional rotorcraft. There have been many previous attempts, most of them unsuccessful as of 2015.

<span class="mw-page-title-main">NASA GL-10 Greased Lightning</span> American unmanned aircraft

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<span class="mw-page-title-main">Kaman K-16B</span> Type of aircraft

The Kaman K-16B was an experimental vertical-takeoff-and-landing aircraft that was constructed by Kaman Aircraft for the United States Navy in 1959 to evaluate the tiltwing concept. Converted from a Grumman Goose amphibian, the K-16B underwent extensive wind tunnel and tethered testing, but was not flown before the project was terminated in 1962.

References

  1. 1 2 "1957 USAF Serial Numbers". joebaugher.com. Retrieved 19 February 2016.
  2. "Hiller's Tiltwing Transport if Largest VTOL Transport." Popular Mechanics, March 1959, p. 107.
  3. "The X-Planes" . Retrieved 5 September 2016.
  4. Taylor, John W.R., ed. (1961). Jane's All the World's Aircraft 1961-62. London: Sampson Low, Marston & Co. p. 265.
  5. Miller, Jay (1983). The X-planes : X-1 to X-29. Marine on St. Croix: Speciality. pp. 124–127. ISBN   0933424353.
  6. Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.