The Hiller VZ-1 Pawnee (U.S. Army designation; earlier Army designation: HO-1) is a unique direct-lift rotor aircraft, using contra-rotating

ducted fan In aeronautics, a ducted fan is a thrust-generating mechanical fan or Propeller (aeronautics), propeller mounted within a cylindrical wiktionary:duct, duct or shroud. Other terms include ducted propeller or shrouded propeller. When used in vertic ...

s for lift inside a flying 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 The Office of Naval Research (ONR) is an organization within the United States Department of the Navy responsible for the science and technology programs of the U.S. Navy and Marine Corps. Established by Congress in 1946, its mission is to plan ...

(ONR) contract to

Hiller Aircraft Hiller Aircraft Corporation is an American private aerospace company, based in Firebaugh, California. It was founded in 1942 as Hiller Industries by Stanley Hiller to develop helicopters. History Stanley Hiller, then seventeen, established t ...

, and flew successfully beginning in 1955.

Design and development

The original concept had been developed by Charles H. Zimmerman in the late 1940s. Further development followed, both by Hiller Aircraft 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. The smaller ONR model used two Nelson H-59 piston engines, coupled to the propellers by a modified helicopter transmission built by the Industrial Power Division of

Hall-Scott Hall-Scott Motor Car Company was an American manufacturing company based in Berkeley, California. It was among the most significant builders of water-cooled aircraft engines before World War I. History 1910–21 The company was founded in 1910 ...

. The larger Pawnee model used three of those engines 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.

Testing and evaluation

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, 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. 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 The National Air and Space Museum (NASM) of the Smithsonian Institution is a museum in Washington, D.C., in the United States, dedicated to history of aviation, human flight and space exploration. Established in 1946 as the National Air Museum, ...

Udvar-Hazy Center The Steven F. Udvar-Hazy Center, also called the Udvar-Hazy Center, is the Smithsonian Institution, Smithsonian National Air and Space Museum (NASM)'s annex at Dulles International Airport in the Chantilly, Virginia, Chantilly area of Fairfax C ...

in Chantilly, Virginia."Hiller Model 1031-A-1 Flying Platform."
''Smithsonian National Air and Space Museum''. Retrieved: 2 November 2011. The latter platform was formerly on loan to the

Pima Air & Space Museum The Pima Air & Space Museum is an aerospace museum in Tucson, Arizona, US. It features a display of nearly 400 aircraft spread out over on a campus occupying . It has also been the home to the Arizona Aviation Hall of Fame since 1991. Overv ...

. A replica of the 1031 platform is on display at the Evergreen Aviation & Space Museum.

Gallery

File:Hiller Flying Platform Udvar-Hazy Center.jpg, Hiller 1031-A-1 at

File:Hiller 1031.jpg, Reproduction of the Hiller 1031 Flying Platform, built by Ken Spence of Bend, Oregon in 2006. File:Hiller info.pdf, Placard describing the reproduction of the Hiller 1031 on display at the Evergreen Aircraft Museum.

Specifications (Model 1031-A-1)

References

;Notes ;Bibliography * * * *

External links