Avro VZ-9 Avro CarIn 1952, a Canadian firm, A. V. Roe Aircraft Limited, launched a project to develop a supersonic fighter-bomber that could take off and land vertically, cruise at low altitudes on a cushion of air, and accelerate to high speeds at higher altitudes. Its circular shape gave it the appearance of a "flying saucer" out of science fiction movies of the period. A.V. Roe (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 turborotor 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. The Canadian government eventually abandoned funding for the project because of cost.
The U.S. military then became interested, and in July 1954, the US government awarded A. V. Roe two contracts, worth nearly $2 million to continue the study. Avro offered the project to the U.S. government, and the U.S. Army and U.S. Air Force took it over in 1958. Each service had different requirements. The Army was looking for a subsonic, all-terrain reconnaissance and troop-transport vehicle that was rugged and adaptable. The Army wanted to replace their light observation aircraft and helicopters. They hoped the Avro Car would have the capability to carry up to 1,000 pounds, and fly at 30 mph for at least 30 minutes. The Air Force wanted a VTOL that could hover beneath enemy radar and then rocket into the stratosphere at supersonic speeds. Avro's designers believed they could satisfy both services, but these two sets of requirements differed too much. The blue print for the Avro Car promised hovering take-off and landing, and upward speeds of 300 mph at an altitude of 10,000 feet.
Although the project remained in Canada, it was owned and controlled by the United States, designated the VZ-9AV Avrocar ("VZ" stood for "experimental vertical flight," "9" for the ninth concept proposal, and "AV" for Avro). The Avro/Canada VZ-9 AvroCar was a buried fan concept of the early 1960s which was a not entirely successful attempt at using ground effect for motion. This aircraft used a large ducted fan for generation of vertical lift in VTOL and in translation driven by three Continental J69 turbojets. 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.
Unfortunately, the Avro Car was unable to perform as engineers had hoped. The first prototype was sent to the National Aeronautics and Space Administration (NASA) Ames Research Center at Moffett Field, Calif. There, wind tunnel tests proved that the aircraft had insufficient control for high speed flight and was aerodynamically unstable. Tests with scale models 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 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 mph, and all attempts to end the hubcapping failed. During flight tests, the Avro Car reached speeds of 35 mph, but became increasingly unstable at altitudes of more than a few feet. Test pilots related that any air bleedoff for direction changes tended to dip one side of the disc, so precise maneuvering over uneven terrain was a challenge. The aircraft exhibited excellent hover efficiency, however.
The project was cancelled in December 1961. The second prototype aircraft went to the U.S. Army Transportation Museum at Fort Eustis, Va., and the first prototype Avrocar came to the National Museum of the United States Air Force in 2007.
|Join the GlobalSecurity.org mailing list|