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VZ-1 Pawnee
Hiller VZ-1 Pawnee (2).jpg
Role Direct lift rotor aircraft
Manufacturer Hiller Aircraft Corporation
First flight 20 November 1957
(Model 1031-A-1)
Status Experimental
Primary user United States Army
Number built Six

The Hiller VZ-1 Pawnee (U.S. Army designation; earlier Army designation: HO-1) was a unique direct lift rotor aircraft, using contra-rotating ducted fans for lift inside a platform upon which the single pilot shifted body weight for directional control. The platform was developed starting in 1953 under an Office of Naval Research (ONR) contract to Hiller Aircraft Corporation, and flew successfully, starting in 1955.[1]

Design and developmentEdit

The original concept had been developed by Charles H. Zimmerman in the late 1940s.[2] Further development followed, both by Hiller and the De Lackner Company. There were two main models, the ONR model 1031-A-1 and the somewhat larger VZ-1 Pawnee model produced in 1956 for the U.S. Army. Three of each model were built as prototypes. Neither of the variants was put into production.[3]

The smaller ONR model used two 44 horsepower (33 kW) Nelson H-59 piston engines. The larger Pawnee model used three of the aforementioned engine and had an extended duct area. The Pawnee had ineffective "kinesthetic control" and instead had the operator seated on a platform controlling the flight with conventional helicopter controls.[4]

Testing and evaluationEdit

Due to aerodynamic effects in the duct within which the propellers rotated, the platform was dynamically stable, even though the pilot and center of gravity of the platform were fairly high up. In testing, the prototypes flew well enough, but the U.S. Army judged them to be impractical as combat vehicles as they were small, limited in speed and only barely flew out of the ground cushion effect.[5]

Two of the six prototypes are known to survive; both are ONR 1031-A-1 models. One is located at the Hiller Aviation Museum in San Carlos, California, the other is at the National Air and Space Museum's Udvar-Hazy Center in Chantilly, Virginia.[6] The latter platform was formerly on loan to the Pima Air Museum. A replica of the 1031 platform is on display at the Evergreen Aviation & Space Museum.

Specifications (Model 1031-A-1)Edit


Hiller 1031-A-1 at the Udvar-Hazy Center

Data from National Air and Space Museum[6]

General characteristics
  • Crew: One
  • Length: 8 ft 4 in diameter (2.54 m)
  • Rotor diameter: 7 ft (2.13 m)
  • Height: 7 ft (2.13 m)
  • Empty weight: 370 lb (167.8 kg)
  • Max. takeoff weight: 555 lb (251.7 kg)
  • Powerplant: × 2 × Nelson H-56 piston engines, 40 hp (30 kW) each
  • Propellers: 2 × contra-rotating two-bladed aluminum rotor


  • Maximum speed: 16 mph (26 km/h)
  • Service ceiling: 32.8 ft (10 m)</ul>Armament
  • Standard combat weapons of a U.S. soldier

See alsoEdit


  1. Rogers 1989, pp. 74–78.
  2. Taylor 1999, p. 104.
  3. Rogers 1989, p. 78.
  4. Winchester 2005, pp. 130–131.
  5. Winchester 2005, p. 130.
  6. 6.0 6.1 "Hiller Model 1031-A-1 Flying Platform." Smithsonian National Air and Space Museum. Retrieved: 2 November 2011.
  • Rogers, Mike. VTOL: Military Research Aircraft. New York: Orion Books, 1989. ISBN 0-517-57684-8.
  • Taylor, Michael. The World's Strangest Aircraft. London: Grange Books, 1999. ISBN 1-85627-869-7.
  • Winchester, Jim. The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters. London: Amber Books, 2005. ISBN 1-904687-34-2.

External linksEdit

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