PZL Bielsko SZD-21
| SZD-21 Kobuz | |
|---|---|
.jpg) SZD-21-2B "Kobuz 3" |
|
| Type: | Glider for aerobatics |
| Design country: | |
| Manufacturer: | |
| First flight: |
June 3, 1961 |
| Commissioning: |
1964/65 |
| Production time: |
1961-1966 |
| Number of pieces: |
32 |
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The PZL Bielsko SZD-21 Kobuz ( German Hobby ) is a Polish aerobatics - Glider . SZD stands for Szybowcowy Zakład Doświadczalny (Glider Development Plant ).
history
Development work for a successor to the IS-4 Jastrząb (Habicht) from 1949 began in 1958 and was carried out by Jerzy Trzeciak under the project name Sokół (Falcon). The first flight of the prototype SZD-21-2 “Kobuz” with the registration number SP – 1990 was carried out by Stanisław Skrzydlewski on June 3, 1961. The unsatisfactory test results resulted in some modifications and the aircraft was tested again as the SZD-21-2A "Kobuz 2" on May 18, 1962. Here came on the wings flutter , which led on April 20, 1963 crash of the prototype in which the test pilot Sławomir Makaruk was killed. The project was then revised by I. Trzeciak and M. Gracz: the structure was completely changed and the fuselage lengthened. In this final form, the type with the registration number SP-2452 was flown in as SZD-21-2B "Kobuz 3" by Skrzydlewski on December 10, 1964 and then put into production. The series comprised a total of 30 copies that were built until 1966.
Jerzy Makula and Marek Szufa took first and third place with the Kobuz 3 at the world championships in glider aerobatics, which took place for the first time in Mautendorf (Austria) in 1985 . In 1987 Makula was able to achieve second place at the German championship in Paderborn with the type, Marian Bednorz came third. At the 1989 world championships there was a fatal accident in Hockenheim , in which Krzysztof Wyskiel, a member of the Polish selection, was killed Life came because the wings of his Kobuz 3 broke off during the compulsory program and the aircraft fell unchecked to the ground from a height of 300 meters. As a result, the Kobuz was no longer admitted to subsequent international competitions.
construction
The Kobuz is a cantilevered middle decker in half-shell wood construction. The front fuselage and the fuselage-wing transitions are made of GRP . The rear fuselage is planked with plywood. The trapezoidal wings with laminar profile and split ailerons also have plywood cladding and are filled with polystyrene . The rudders of the cantilevered normal tail are covered with fabric. The vertical fin is made of wood, the two-spar horizontal fin made of aluminum ribs with plywood planking. The landing gear consists of a bow runner, the retractable, rubber-sprung and brakable main wheel and a tail spur.
Technical specifications
| Parameter | Data (SZD-21-2B Kobuz 3 ) |
|---|---|
| crew | 1 |
| length | 7.25 m |
| span | 14.00 m |
| height | 1.90 m |
| Wing area | 13.50 m² |
| Wing extension | 14.2 |
| Wing loading | maximum 29.50 kg / m² |
| Empty mass | 311 kg |
| Payload | 90 kg |
| Takeoff mass | normal 401 kg maximum 435 kg |
| Top speed | 350 km / h |
| Minimum speed | 73 km / h |
| Glide ratio | 30 at 100 km / h |
| Slightest sinking | 0.9 m / s at 100 km / h |
| Load multiple | +7 / −5 |
| profile | NACA 64-1-412 (wing root) |
See also
literature
- Kazimierz Wojciech Chudzinski: Polish gliders . Volume 1: 1945-1970. Verlag für Technik und Handwerk, Baden-Baden 2014, ISBN 978-3-88180-454-7 .
- Heinz A. F. Schmidt: Airplanes from all over the world. Volume II . 2nd revised edition. Transpress, Berlin, p. 106 .
