Avro Canada VZ-9AV
| Avro Canada VZ-9AV | |
|---|---|
|
|
| Type: | VTOL - experimental aircraft |
| Design country: | |
| Manufacturer: | |
| First flight: |
November 12, 1959 (unbound) |
| Number of pieces: |
2 |
The Avro Canada VZ-9AV Avrocar was an experimental VTOL aircraft made by the Canadian manufacturer Avro Canada in the 1950s. Because it was designed as a disk plane, its outward appearance resembled the popular idea of a flying saucer at the time and was accordingly nicknamed the Flying Saucer . Initially a Canadian military project, it later became a secret US Air Force project. The aircraft should take off vertically in the ground effect as a hovercraft and then reach high speeds in aerodynamically supported flight. This goal could not be achieved, as excessive dynamic instabilities occurred at hovering heights above 0.9 m.
history
development
Avro Canada began developing the first concepts for disk-shaped aircraft in 1946. In 1954 the Canadian government stopped the program due to cost reasons. The US government then signed a contract with Avro Canada for the financing and further construction. In 1958, the US Army and US Air Force took control of the program, which was now run as Avro Canada VZ-9AV "Avrocar". Two prototypes were made.
The VZ-9 should be able to carry a total payload of 1,000 lbs (450 kg) including the crew; the maximum speed should be 300 mph (483 km / h) and the maximum altitude should be 10,000 feet (3,000 m). The aircraft was equipped with three Continental J69 -T9 turbojets with 417 kp (4.1 kN) thrust each.
Flight testing
The information on the data from first flights is shown in the literature contradicting itself. After Ball, the VZ-9 began its testing in a tied state in a suspension frame on December 5, 1959. It remains unclear whether this was the first or second prototype. According to Baugher, it was probably the second prototype. Other sources give for the first untethered flight of the second prototype (USAF / US Army serial number 59-4975) on November 12, 1959 in Malton . This date is mentioned in a commercial. The first prototype (58-7055) will then for the first time on 17 May 1961 at the Ames Research Center of NASA in Moffett Field near California have flown. According to Baugher, however, this machine was only used for wind tunnel studies. Ball also gives no information about the flight of a second machine.
Between July 1960 and June 1961 a total of 75 flight hours were completed. The Avrocar was flown by Major Walter J. Hodgson. During the flights it was found that the aircraft became unstable from an altitude of 0.9 m. This was due to dynamic, surging effects that were caused by briefly leaving the ground effect and re-diving into part of the aircraft. The problems were not related to the performance of the engines. A maximum of 48 km / h could be reached above the ground. The aircraft was also extremely loud. In December 1961 the program was discontinued. It had cost more than $ 10 million ($ 87,520,000 today). Avro's proposals with new General Electric J85 engines were no longer implemented. In 1975 the National Air and Space Museum received the first prototype Avrocar (58-7055).
.jpg)
construction
Drive principle
Early studies had shown in model tests that disc-shaped aircraft can manage their flight control by changing the direction of the jet outlet. The jet emerges from a gap between the lower and upper surface of the pane. The exhaust gas jet could be deflected upwards or downwards or to the side along the circumference of the pane, whereby the gap size (and position?) Was changed. With a (single?) Fixed gap size, lateral thrust should be generated for level flights. With another precisely set gap size, the beam could be deflected in such a way that a vertical thrust effect was created. The upper part of the gap would be closed for vertical lifting. For level flight, the jet would not be deflected but blown out directly over part of the circumference. The opposite nozzles would be closed, so that there is a thrust to one side.
In the prototypes carried out, the central element of the drive was an encapsulated fan (ducted propeller ) measuring 5.49 m in diameter . With the help of a so-called tip turbine , the fan, which was able to achieve an air mass flow of around 150 kg / s, was driven by exhaust gases from the three jet engines. Directly below the fan, its cold air flow was mixed with the hot exhaust gases from the engines in an air duct. In this duct, the air is guided to nozzles that are arranged along the entire circumference. Since the vehicle was supposed to operate in the ground effect for a longer period of time, the maintenance of a stable flight condition and thus the creation of a stable air cushion under the fuselage was of particular importance. For this purpose, an additional central air jet was generated by the engine exhaust in this flight condition, which was switched off in aerodynamic level flight.
Stabilization and control
Since the vehicle was statically as well as dynamically unstable in aerodynamic flight, relatively complex measures for artificial stabilization were necessary. For this purpose, the nozzles rotating around the outside were automatically controlled via a mechanical connection with the fan in order to generate corrective pitch and roll moments.
The control was initially carried out by two superimposed rows of external circumferential spoilers that formed a double ring. The spoilers, which could be moved up and down, deflected the fan jet, which was guided over convexly curved metal sheets, differently. The beam followed the baffle according to the Coandă principle .
For a vertical take-off, the spoilers directed the air downwards, creating a circular air curtain under the vehicle. For horizontal flight, the spoilers should direct the air to the rear via flaps attached to the "stern", similar to the blown flaps on STOL aircraft.
After some development time, this system was modified to achieve a higher lift in hover flight. The upper row of the nozzle outlets and the spoilers were completely removed. The control was now ensured by a ring around the lower nozzle outlets. The “focusing” ring brought the blower jet under the vehicle to a solid so-called “tree trunk”. When the control ring was moved back, the beam was deflected backwards.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 |
| diameter | 5.5 m |
| height | 1.47 m |
| Empty mass | 2095 kg |
| Flight mass | 2563 kg |
| Top speed | approx. 480 km / h (planned), real approx. 48 km / h |
| Service ceiling | approx. 3000 m (planned) |
| Engines | 3 × Continental J69 -T9 turbo jets with 4.1 kN thrust each |
literature
- Ernest Ball: The (almost) Flying Saucer - Avro Canada Avrocar . In: AIR Enthusiast International June 1974, p. 300 f.
- Randall Whitcomb: Avro Aircraft & Cold War Aviation , Vanwell Publishing, St. Catharines 2002, ISBN 1-55125-082-9
- Bill Zuk: Avrocar: Canada's flying saucer: the story of Avro Canada's secret projects , Mills Pressm, Boston 2001, ISBN 1-55046-359-4
- Desire Francine G. Fedrigo, Ricardo Gobato, Alekssander Gobato: Avrocar: a real flying saucer . 2015, arxiv : 1507.06916 .
- Steve Markman, Bill Holder: Straight up - a history of vertical flight , Schiffer Military History Book, 2000, ISBN 0-7643-1204-9 , pp. 161, 162, 167
Web links
- Photos and films on www.laesiworks.com
- Avro Canada VZ-9AV "Avrocar" on the Avroland Canada website (English)
- Avro Canada VZ-9AV "Avrocar" on the website avroarrow.org with a detailed description of the history (English)
- Video of flight tests
Individual evidence
- ^ Ball, AIR International June 1974, p. 301
- ↑ USAF serial no. 1958
- ↑ Unstable hover due to hubcapping (behavior similar to a tumbling hubcap)
