164:. It first flew on 10 December 1964. It competed at the highest levels into the late 1980s. Unfortunately, the Kobuz 3 was not immune to accidents and one high-profile fatal accident, at the world glider aerobatic championships at Hockenheim in Germany, highlighted problems with condensation soaking highly stressed wooden parts causing structural failure. The pilot, Krzysztof Wyskiel, was carrying out his competition routine with high accuracy until the penultimate manoeuvre when the wings failed, clapping hands above the fuselage which shot straight down to the ground like an arrow, killing Krzysztof Wyskiel instantly. The three remaining Kobuz 3's in the competition were grounded and remained so until the aircraft were cleared for limited manoeuvres only, curtailing their aerobatic competition careers.
29:
156:
at the controls, but the results were disappointing prompting a re-build as the SZD-21-2A, with a completely revised fuselage, landing gear, canopy and differential ailerons. Flight tests resumed on in May 1962, but serious problems with the pitch and roll stability at high speed as well as flutter
157:
in a certain speed range prompted a further round of modifications. The resulting SZD-21-2AZ (still registered as SP-1990) continued the test program until 20 April 1963, when the aircraft broke up in flight during flutter testing, killing the pilot Sławomir
Makaruk.
149:), than SZD-21-2 Kobuz. The new SZD-21-2 retained the overall shape of the original project, but was constructed with wood throughout, using multiple spars for the wings. Design team was headed by Jerzy Trzeciak, later joined by M. Gracz in Kobuz 3 constructing.
171:
had been finished, based on the Kobuz 3 design (the wings of the first production series of the Swift glider had been manufactured using the wings of Kobus 3 as molds).
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The final version, the SZD-21-2B Kobuz 3, which was of all wood construction with very stiff wings to resist bending and flutter, was produced in small numbers in
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143:, but due to problems with the flying surfaces and a wood metal sandwich, a construction of the design was restarted as the SZD-21 Kobuz (
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207:– The final version of the Kobuz, first flight 10 December 1964, which proved acceptable and a small production batch were completed.
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189:– The initial prototype version, (reg'n SP-1990), which proved unsatisfactory, modified to Kobuz 2A.
195:– The second version of the prototype, (reg'n SP-1990), again disappointing, modified to SZD-21-2AZ
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https://web.archive.org/web/20090916142935/http://www.szdjezow.com.pl/ofirmie_eng.html
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http://www.abpic.co.uk/search.php?q=PZL-Bielsko%20SZD-21%20Kobuz%203&u=type
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396:(Polish aerospace industry 1945-197). Warsaw: Wydawnictwo MON, 1974, p. 126
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http://www.flightglobal.com/pdfarchive/view/1962/1962%20-%200017.html
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http://www.flightglobal.com/pdfarchive/view/1962/1962%20-%200016.html
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In 1991 the design of a new (composite build) aerobatic glider,
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Flight testing of the SZD-21 Kobuz began on 3 June 1961 with
183:– The original designation of the project as begun in 1958.
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Aircraft of comparable role, configuration, and era
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0.90 m/s (177 ft/min) at 100 km/h (62 kn)
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30:1 (19:1 inverted) at 100 km/h (54 kts / 62 mph)
473:http://www.sagach.ch/Deutsch/Flugzeuge/Kobuz.htm
508:
458:http://luftfahrtmuseum.org/htmi/itf/szd21.htm
392:Babiejczuk, Janusz and Grzegorzewski, Jerzy.
8:
488:https://www.youtube.com/watch?v=DjwNOoqf0WM
308:250 km/h (154.3 mph, 189 kn)
139:. Development began in January 1958 as the
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493:
463:http://www.piotrp.de/SZYBOWCE/dszd212b.htm
220:http://www.piotrp.de/SZYBOWCE/dszd212b.htm
16:Polish single-seat aerobatic glider, 1961
586:/ PZL Bielsko-Biała / Allstar PZL Glider
468:http://www.piotrp.de/SZYBOWCE/dszd21.htm
437:, WKiŁ, Warsaw, p. 124–126 (Polish)
320:+7 / −5 as built – (+4 / −1.5 post 1989)
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314:73 km/h (45 mph, 39 kn)
18:
430:. Studio Editions: London. p. 29
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383:
381:
379:
7:
435:Konstrukcje lotnicze Polski Ludowej
259:13.5 m (145.3 sq ft)
394:Polski przemysł lotniczy 1945–1973
253:1.9 m (6 ft 2.8 in)
241:7.25 m (23 ft 9 in)
135:The SZD-21 was a successor to the
14:
247:14 m (45 ft 11 in)
27:
583:Szybowcowy Zakład Doświadczalny
428:Jane's Encyclopedia of Aviation
212:Specifications (SZD-21 Kobuz 3)
123:(Glider Experimental Works) in
121:Szybowcowy Zakład Doświadczalny
418:Segel-Kunstflugzeuge Swift S-1
1:
83:Jerzy Trzeciak, Marian Gracz
949:Aircraft first flown in 1961
408:Glass, A. (1965), p. 124-126
111:was a single-seat aerobatic
433:Glass, Andrzej (ed) (1965)
287:311 kg (685.6 lb)
965:
426:Taylor, J. H. (ed) (1989)
913:PZL Krosno KR-03 Puchatek
881:Margański & Mysłowski
293:401 kg (884 lb)
36:SZD-21-2B Kobuz 3 in the
35:
26:
21:
523:Polish post-1945 gliders
939:1960s Polish sailplanes
843:Politechnika Warszawska
226:General characteristics
154:Stanisław Skrzydlewski
115:designed and built in
38:Polish Aviation Museum
530:Instytut Szybownictwa
324:Maximum glide ratio:
363:PZL Bielsko SZD-59
193:SZD-21-2A Kobuz 2A
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205:SZD-21-2B Kobuz 3
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88:First flight
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22:SZD-21 Kobuz
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944:SZD aircraft
934:PZL aircraft
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312:Stall speed:
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264:Aspect ratio
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181:SZD-21 Sokół
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141:SZD-21 Sokół
140:
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109:SZD-21 Kobuz
108:
106:
97:Number built
91:3 June 1961
390:(in Polish)
348:Vogt Lo-100
299:Performance
131:Development
127:from 1958.
928:Categories
371:References
257:Wing area:
199:SZD-21-2AZ
894:Swift S-1
889:MDM-1 Fox
358:MDM-1 Fox
353:Swift S-1
318:g limits:
245:Wingspan:
217:Data from
169:S-1 Swift
80:Designer
337:See also
175:Variants
277:NACA 64
273:Airfoil
251:Height:
239:Length:
162:Wrocław
74:Wrocław
906:Krosno
833:SZD-59
828:SZD-56
823:SZD-55
818:SZD-54
813:SZD-52
808:SZD-51
803:SZD-50
798:SZD-49
793:SZD-48
788:SZD-45
783:SZD-43
778:SZD-42
773:SZD-41
768:SZD-40
763:SZD-39
758:SZD-38
753:SZD-37
748:SZD-36
743:SZD-35
738:SZD-34
733:SZD-33
728:SZD-32
723:SZD-31
718:SZD-30
713:SZD-29
708:SZD-28
703:SZD-27
698:SZD-26
693:SZD-25
688:SZD-24
683:SZD-23
678:SZD-22
673:SZD-21
668:SZD-20
663:SZD-19
658:SZD-18
653:SZD-17
648:SZD-16
643:SZD-15
638:SZD-14
633:SZD-13
628:SZD-12
623:SZD-11
618:SZD-10
268:14.5:1
117:Poland
113:glider
63:Poland
48:Glider
613:SZD-9
608:SZD-8
603:SZD-7
598:SZD-6
593:SZD-C
233:Crew:
44:Role
871:PW-6
866:PW-5
861:PW-4
856:PW-3
851:PW-2
573:IS-C
568:IS-B
563:IS-A
558:IS-5
553:IS-4
548:IS-3
543:IS-2
538:IS-1
107:The
904:PZL
281:412
119:at
101:30
930::
401:^
378:^
516:e
509:t
502:v
279:1
275::
266::
235:1
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