The Hiller VZ-1 Pawnee (U.S. Army designation; earlier Army designation: HO-1) was a unique direct-lift

rotor aircraft A Flettner airplane is a type of rotor airplane which uses a Flettner rotor to provide lift. The rotor comprises a spinning cylinder with circular end plates and, in an aircraft, spins about a spanwise horizontal axis. When the aircraft moves ...

, using contra-rotating

ducted fan In aeronautics, a ducted fan is a thrust-generating mechanical fan or propeller mounted within a cylindrical duct or shroud. Other terms include ducted propeller or shrouded propeller. When used in vertical takeoff and landing (VTOL) applicati ...

s 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 Hiller Aircraft Company was founded in 1942 as Hiller Industries by Stanley Hiller to develop helicopters. History Stanley Hiller, then seventeen, established the first helicopter factory on the West Coast of the United States, located in Berkele ...

, 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 Nelson may refer to: Arts and entertainment * ''Nelson'' (1918 film), a historical film directed by Maurice Elvey * ''Nelson'' (1926 film), a historical film directed by Walter Summers * ''Nelson'' (opera), an opera by Lennox Berkeley to a lib ...

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 The Hiller Aviation Museum is an aircraft history museum located at the San Carlos Airport in San Carlos, California. The museum was founded by Stanley Hiller in June 1998. and is endowed by members of the Hiller family. It specializes in Nor ...

in San Carlos, California, the other is at the National Air and Space Museum's

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

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, located in Tucson, Arizona, is one of the world's largest non-government funded aerospace museums. The museum features a display of nearly 300 aircraft spread out over 80 acres (320,000 m²) on a campus oc ...

. A replica of the 1031 platform is on display at the

Evergreen Aviation & Space Museum The Evergreen Aviation & Space Museum is an aviation museum in McMinnville, Oregon. Its exhibits include the Hughes H-4 Hercules (''Spruce Goose'') and more than fifty military and civilian aircraft, unmanned aerial vehicles (drones), and spac ...

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