Avia BH-33

{{Short description|Czechoslovak fighter aircraft}} {{More footnotes needed|date=July 2010}}  {{Infobox aircraft |name=BH-33 |image= File:Avia BH-33.jpg |caption= |type= Fighter |manufacturer=Avia, PWS (under licence), Ikarus (under licence) |designer= Miroslav Hajn and Pavel Beneš |first_flight= 21 October 1927 |introduction= |retired= |status= |primary_user= Czechoslovak Air Force |more_users= Polish Air Force<br />Yugoslav Royal Air Force |produced=Ca. 110, plus 50 licence-built in Poland and 22 in Yugoslavia |number_built= |developed_from = Avia BH-21 |variants= }} right|thumb|Avia BH-33 with engine Walter-Jupiter 480–600 HP

The '''Avia BH-33''' was a biplane fighter aircraft built in Czechoslovakia in 1927. It was based on the BH-21J which demonstrated promising results by combining the original BH-21 airframe with a licence-built Bristol Jupiter radial engine. Other than the peculiar Avia hallmark of having an upper wing with a shorter span than the lower, it was utterly conventional, even featuring a tail fin for the first time in a Pavel Beneš and Miroslav Hajn design (previous aircraft had a rudder but no fin).

==Design and development== Initial tests of the first prototype were disappointing, displaying performance only marginally better than the BH-21, even when fitted with a more powerful version of the Jupiter. Two further prototypes followed, both designated '''BH-33-1''', each with an increasingly powerful Jupiter variant – one a Jupiter VI, the other a Jupiter VII. The performance of the latter example was finally acceptable for the Czechoslovak defence ministry to order a small production run of only five aircraft.

Three examples were sold to Belgium, where there were plans to build the type under licence, but this did not occur. Licence production was undertaken, however, in Poland, where a single example was sold, along with a licence to build 50 aircraft. These were designated '''PWS-A''' and put into service with the Polish Air Force in 1930.<ref name="Belcarz, p.6">Belcarz 2005, p. 6.</ref>

Development continued with an almost total redesign of the fuselage, replacing the wooden, slab-sided structure with one of oval cross-section, built up from welded steel tubes. Designated '''BH-33E''', this was a world-class fighter for its time. Nevertheless, the response from the Czechoslovak military was lukewarm (although two were bought for the national aerobatics team), and Avia again looked abroad for customers, this time selling 20 aircraft to the Kingdom of Yugoslavia, along with a licence to produce another 24. Two or three examples were also bought by Soviet Union for evaluation.<ref>Taylor 1989, p. 86.</ref>

thumb|Avia BH-33L

In late 1929, a further development was flown as the '''BH-33L''', featuring longer-span wings, and a Škoda L W-block engine. This version finally brought the company the domestic sales that it had been hoping for, with 80 aircraft ordered by the Czechoslovak Air Force. These became standard equipment with some air regiments up to the outbreak of World War II.<ref>Taylor and Alexander 1969, p. 58.</ref>

A single, final variant with a BMW-built Pratt & Whitney Hornet engine was built as the '''BH-33H''' (later redesignation '''BH-133''') in 1930, but this did not lead to production.

==Operational history== Following the outbreak of the Spanish Civil War, a single BH-33 was covertly purchased in Belgium in August 1936 on behalf of the Spanish Republican Air Force. While it was delivered to Spain, the aircraft's machine guns had been removed when the aircraft and pilot was briefly detained in France before being released.<ref>Howson 1999, p. 88</ref> The planes were used by Spanish Republican Air Force during Spanish-Civil War.<ref>{{cite web |url=http://www.zi.ku.dk/personal/drnash/model/Spain/did.html |title=Spanish Civil War Aircraft |website=www.zi.ku.dk |access-date=1 August 2022 |archive-url=https://web.archive.org/web/20150205085135/http://www.zi.ku.dk/personal/drnash/model/Spain/did.html |archive-date=5 February 2015 |url-status=dead}}</ref> Czechoslovak BH-33s never saw combat, and Poland's examples had long been replaced in service by the time of the German invasion. Two Yugoslavian machines did, however see combat against ''Luftwaffe'' Messerschmitt Bf 109s, but were both destroyed and their pilots killed.

==Variants== ;BH-33 :First prototype. ;;BH-33-1 :Two prototypes powered by Jupiter VI (second) and Jupiter VII (third) engines plus five serial built aircraft with Jupiter VII engine. ;BH-33E :Rebuilt fuselage ;BH-33E-SHS :Yugoslav Version powered by IAM K9 engine, 22 built.<ref>{{cite web|url=http://vazduhoplovnetradicijesrbije.rs/index.php/istorija/248-avia-bh-33 |title=Авиа BH-33 |access-date=2014-04-07 |url-status=dead |archive-url=https://web.archive.org/web/20140407191654/http://vazduhoplovnetradicijesrbije.rs/index.php/istorija/248-avia-bh-33 |archive-date=2014-04-07 }}</ref> ;BH-33L :Version with longer-span wings, powered by a Škoda L engine, 80 built. ;BH-33H (BH-133) :Version powered by Pratt & Whitney Hornet engine, one built. ;P.W.S.A :Polish license-built variant of the BH-33 with minor modifications,<ref name="Belcarz, p.6" /> 50 built between 1929 and 1932.

==Operators== ;{{BEL}} *Belgian Air Force received three BH-33-1 aircraft. ;{{flag|Independent State of Croatia}} *Air Force of the Independent State of Croatia ;{{CZS}} *Czechoslovak Air Force *Czechoslovak National Security Guard ;{{GRE}} *Hellenic Air Force acquired five Yugoslav-produced BH-33s, during the 1935 ''coup'', when Greece was a republic. ;{{POL}} *Polish Air Force received one BH-33 and 50 PWS-A license-built variant. ;{{flag|Slovakia|1938}} *Slovak Air Force (1939–1945) ;{{USSR}} *Soviet Air Force bought two or three BH-33Es for tests. ;{{flag|Spanish Republic}} * Spanish Republican Air Force ;{{flagcountry|Kingdom of Yugoslavia}} *Yugoslav Royal Air Force

==Specifications (BH-33L)== thumb|Avia BH-33 {{Aircraft specs |prime units? = met |crew=one, pilot |ref=Jane's all the World's Aircraft 1928,<ref name=JAWA1928>{{cite book |title=Jane's all the World's Aircraft 1928 |editor1-last=Grey |editor1-first=C.G. |year=1928 |publisher=Sampson Low, Marston & company, ltd |location=London |page=77c}}</ref> Combat aircraft of the world<ref name=Taylor>{{cite book|last1=Taylor|first1=John W. R. |last2=Alexander |first2=Jean |display-authors=et al |title=Combat aircraft of the world |date=1969 |publisher=Ebury P.; Michael Joseph |location=London |isbn=0-71810-564-8 |page=58}}</ref> |length m=7.22 |length ft=23 |length in=8 |span m=8.90 |span ft=29 |span in=2 |height m=3.13 |height ft=10 |height in=3 |wing area sqm=25.5 |wing area sqft=274 |empty weight kg=1,117 |empty weight lb=2,463 |gross weight kg=1,560 |gross weight lb=3,439 |eng1 number=1 |eng1 name=Škoda L |eng1 kw=430 |eng1 hp=580 |max speed kmh=298 |max speed mph=186 |cruise speed kmh=280 |cruise speed mph=174 |range km=450 |range miles=280 |ceiling m=8,000 |ceiling ft=26,247 |climb rate ms=9.9 |climb rate ftmin=1,940 |armament = *2 × fixed, forward-firing 7.7 mm (.303 in) Vickers machine guns *2 × fixed, forward-firing 7.92mm vz.28 machine gun<ref>{{Cite web|url=http://www.airwar.ru/enc/fww1/bh33.html|title=Avia BH-33}}</ref> }}

==See also== {{Portal|Aviation}} {{Aircontent  |related= *BH-17 *BH-21 *BH-22 *BH-23 |similar aircraft= |lists= *List of Interwar military aircraft |see also= }}

==References== {{Reflist}}

===Bibliography=== * {{cite book |last=Howson |first=Gerald |title=Arms for Spain: The Untold Story of the Spanish Civil War |year=1999 |location=New York |publisher=St. Martin's Press |isbn=0-312-24177-1}} * {{cite book|last1=Kopański|first1=Tomasz J.|last2=Belcarz|first2=Bartłomiej|title=Avia BH 33 (PWS A), PWS 10, PZL P.7a|date=2005|publisher=Wydawnictwo Stratus|location=Sandomierz|isbn=83-89450-36-4|language=cs}} * {{cite book|last1=Němeček|first1=Vaclav|title=Československá letadla|date=1968|publisher=Naše Vojsko|location=Praha |language=cs}} * {{cite book|last1=Taylor|first1=John W. R. |last2=Alexander |first2=Jean |display-authors=et al |title=Combat aircraft of the world |date=1969 |publisher=Ebury P.; Michael Joseph |location=London |isbn=0-71810-564-8 |page=58}} * {{cite book|last1=Taylor|first1=Michael J.H.|last2=Gunston|first2=Bill|display-authors=et al|title=Jane's encyclopedia of aviation|date=1989|publisher=Portland House|location=New York|isbn=0-517-69186-8}} *{{cite journal |last1=Wauthy|first1=Jean-Luc|last2=de Neve|first2=Florian|name-list-style=amp|title=Les aéronefs de la Force Aérienne Belge, deuxième partie 1919–1935|journal=Le Fana de l'Aviation |date=June 1995 |issue=305 |pages=28–33 |issn=0757-4169|language=fr|trans-title=Aircraft of the Belgian Air Force}}

==Further reading==

*''World Aircraft Information Files.'' London: Bright Star Publishing, File 889 Sheet 86.

==External links== {{Commons category|Avia BH-33}} * [http://www.airwar.ru/enc/fww1/bh33.html airwar.ru] (in Russian)

{{DEFAULTSORT:Avia Bh-33}} Category:Single-engined tractor aircraft Category:Biplanes Category:1920s Czechoslovak fighter aircraft BH-33 Category:Aircraft first flown in 1927