File:Avro Canada VZ-9AV Avrocar 6.jpg

English: (National Museum of the United States Air Force collection, Wright-Patterson Air Force Base, Dayton, Ohio, USA)

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From exhibit signage:

Avro Canada VZ-9AV Avrocar

The Avrocar was the result of a Canadian effort to develop a supersonic, vertical takeoff and landing (VTOL) fighter-bomber in the early 1950s. However, its circular shape gave it the appearance of a "flying saucer" out of science fiction movies of the period.

A.V. Rose (Avro) Aircraft Limited (later Avro Canada) based its design concept for the Avrocar on using the exhaust from turbojet engines to drive a circular "turborotor" which produced thrust. By directing this thrust downward, the turboroto would create a cushion of air (also known as "ground effect") upon which the aircraft would float at low altitude. When the thrust was directed toward the rear, the aircraft would accelerate and gain altitude.

In 1952, the Canadian government provided initial funding but dropped the project when it became too expensive. Avro offered the project to the United States government, and the United States Army and the United States Air Force took it over in 1958. Each service had different requirements: the Army wanted to use it as a subsonic, all-terrain troop transport and reconnaissance craft, but the United States Air Force wanted a vertical takeoff and landing aircraft that could hover below enemy radar then zoom up to supersonic speed.

Avro's designers believed they could satisfy both services, but these two sets of requirements differed too much.

Research data originally indicated that a circular wing might satisfy both the Army's and Air Force's requirements, and Avro built two small test vehicles to prove the concept. Designated the VZ-9AV Avrocar ("VZ" stood for "experimental vertical flight", "9" for the ninth concept proposal, and "AV" for Avro).

Tests with scale models at Wright-Patterson Air Force Base, Ohio indicated that the cushion of air under the Avrocar would become unstable just a few feet off the ground. The aircraft would be incapable of reaching supersonic speeds, but the testing went ahead to determine if a suitable aircraft could be developed for the Army. The first prototype, the Avrocar on display (serial number 58-7055) was sent to the National Aeronautics and Space Administration (NASA) Ames Research Center at Moffett Field, California. There, wind tunnel tests proved that the aircraft had insufficient control for high speed flight and was aerodynamically unstable.

The second Avrocar prototype underwent flight tests that validated the wind tunnel tests. If it flew more than three feet above the ground, the Avrocar displayed uncontrollable pitch and roll motions, which the Avro engineers called "hubcapping". The Avrocar= could only reach a maximum speed of 35 miles per hour, and all attempts to end the hubcapping failed. The project was cancelled in December 1961.

The second prototype aircraft went to the United States Army Transportation Museum at Fort Eustis, Virginia, and the first prototype Avrocar came to the National Museum of the United States Air Force in 2007.

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