PZL.23 Karaś - WikiHQ

The PZL.23 Karaś (crucian carp) was a Polish light bomber and reconnaissance aircraft designed in the mid-1930s by PZL in Warsaw.

During the interwar period, the Polish High Command had placed considerable emphasis upon the role of armed aerial reconnaissance aircraft. To meet this interest, during 1931, PZL decided to embark on the development of a new combat aircraft to meet this role. An earlier proposal for a fast single-engine passenger airliner, designated the PZL.13, was adopted as the basis of the new design. The new aircraft, which was designated as the PZL.23, a relatively modern design, which integrated features such as an all-metal body and unconventional wing construction. As the British Bristol Pegasus radial engine was licensed for use in Poland only, export aircraft were instead equipped with the Gnome-Rhône 14N engine. Powered as such and along with some airframe changes, the PZL.23 became the PZL.43.

It was the primary Polish reconnaissance bomber in use during the invasion of Poland. On 2 September 1939, a single PZL.23B of the 21st Escadrille was responsible for the bombing of a factory in Ohlau, inside Germany; the attack represented the first bombing raid to be conducted against a target in territory within the Third Reich. During the following days, the PZL.23 bomber escadrilles were deployed to attack several advancing German armoured columns; they often conducted these attacks at low altitudes, which made them vulnerable to anti-aircraft fire. By the end of 1939, around 120 PZL.23s (86 per cent of the Polish Air Force's inventory of the type) were destroyed; however, of these, only 67 had been lost as a direct result of enemy actions.

Development

Background

As a result of wartime experiences acquired by the Polish armed forces during the 1919-1921 Polish–Soviet War, during the 1920s and 1930s (now known as the interwar period), a great emphasis was placed upon the role of armed aerial reconnaissance aircraft.

During the late 1920s, it had become increasingly obvious that the existing types used for the aerial reconnaissance role would need to be replaced, which led to the Ministry of War's Aviation Department defining a set of a broad performance requirements desired in an aircraft to fulfil the role.

Into flight

On 1 April 1934, the P.23/I first prototype conducted its maiden flight; it was quickly followed by the second P.23/II prototype.

During the following year, the third P.23/III prototype was completed; on this aircraft, various further refinements were included, such as the pilot's seat having been raised into a new fully glazed canopy arrangement and the engine being positioned lowered down, giving the aircraft a characteristic hump-nose, as to improve the pilot's external field of vision.

During mid-1935, the second prototype was lost in a crash shortly after a take-off conducted at the maximum loading weight, killing the crew on board. However, since this engine proved to be unreliable during testing, the final variant, which was designated PZL.23B, was fitted with the newer Pegasus VIII model, which was capable of generating a maximum of 720 hp (537 kW) of thrust.

Further development

The Bristol engines were licensed for use in Poland only, so for export purposes the Gnome-Rhône engines were used in a variety of PZL designs. A development of the PZL.23 was the PZL.43 light bomber powered by a Gnome-Rhône 14N engine, with significant changes in the fuselage structure compared to its predecessor. The final export variant to be developed was PZL.43A; it was furnished with a single 1,020 hp Gnome-Rhône 14N-01 engine. 52 PZL.43s were made in total, all for Bulgaria only. The new engine improved the aircraft's performance considerably, resulting in the maximum speed being increased to 365 km/h.

The aircraft were equipped with one of the following engines: Bristol Pegasus IIM2 normal: 570 hp (425 kW), maximum: 670 hp (500 kW) - PZL.23A; Pegasus VIII normal: 650 hp (485 kW), maximum: 720 (537 kW) - PZL.23B.

One of the more unusual features of the PZL.23 was the design of its three-piece low-mounted wing. In order to produce a wing that was both light and strong, Prauss had opted to use a relatively new wing structure which had been recently designed by Polish engineer Fraciszek Misztal.

The fuselage of the PZL.23 had an oval-section structure, composed of a mixture of duralumin frames and stringers, which were strengthened via several struts on the middle section.

Operational history

thumb|right|PZL.23A of the production series

thumb|right|PZL.23A Karaś at the Warsaw Airport. Note lines of [[PZL P.11 or PZL P.7 fighters in the background]]

During late 1936, a batch of 40 PZL.23As were delivered to the Polish Air Force. Due to engine faults, these aircraft were initially flown with a limited service ceiling and they were used exclusively in the training role, being fitted with dual controls to fit this usage. From 1937, a total of 210 PZL.23Bs were delivered to the Air Force. Around this time, the type became the main armament of Polish bomber and reconnaissance "line squadrons", having replaced the majority of Breguet 19, Potez 25 and Potez 27 biplanes. By August 1939, there had been 23 reported crashes involving the type, which was deemed to have been an average safety result.

However, due to rapid advances in the field of aviation during the late 1930s, by 1939 the aircraft was considered to be approaching obsolescence. There were increasing questions over the validity of prior air doctrine, leading to a major reorganisation of the PZL.23 squadrons during 1938–1939. Some PZL.23s were also used in wartime improvised units with 114 PZL.23Bs deployed in combat units (a further 75 PZL.23B and 35 PZL.23A were in air schools, held in reserve or under repair). In total, the PZL.23B were operational with five bomber escadrilles (Eskadra Bombowa) of the Bomber Brigade and seven Army reconnaissance escadrilles, each of which equipped with ten aircraft. In Bomber Brigade there existed also bigger units (Dywizjon Bombowy), consisting of two escadrilles each, and traditionally translated as squadron (two other squadrons of the Bomber Brigade were equipped with the PZL.37 Łoś bomber). In addition, a pair of PZL.43A bombers that had been produced for the Bulgarian order were impressed into Polish service in the 41st Escadrille. The five escadrilles of the Bomber Brigade delivered about 52-60 tons of bombs during the campaign, while the Army escadrilles were responsible for the deployment of roughly another dozen tons.

Due to the plane's low speed, light armour and, perhaps most importantly, a lack of supporting protection from friendly fighter aircraft, the PZL.23 suffered heavy combat losses. Many were shot down by German fighter aircraft, but they were also able to fight back and were responsible for shooting down several in return. Despite the lack of protective armour, Polish aircrews often conducted attacks upon German columns while flying at low altitudes, which made their aircraft particularly vulnerable to anti-aircraft fire. Reportedly, around twenty aircraft were lost in crash landings on the improvised and rough airfields. During 1939, around 120 PZL.23s (86 per cent of the Polish Air Force's inventory) were destroyed. However, only 67 of these had been due to direct enemy action. Additionally, only a small number of PZL.23s were destroyed on the ground at various airfields; the only large-scale Luftwaffe success of this type occurred on 14 September, at Hutniki airfield, against the PZL.23Bs of the Bomber Brigade.

During late 1939, at least 21 PZL.23s were evacuated to Romania,

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Bulgarian Air Force

Specifications (PZL.23B)

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References

Citations

Bibliography

External links

PZL.23 Karas at Ugolok Neba (translated)