PZL P.23 Karas
PZL P.23 Karas was the most numerous type of aircraft in service with the Polish Air Force in September 1939. It saw extensive action in the first two weeks of the war, and suffered heavy losses, only 15% of the planes from first-line units making their escape to Romania. However, the plane's role in World War 2 was not finished. Impressed for Romanian service, P.23s flew missions against the USSR till the summer of 1943, and the Bulgarian PZL 43 Tchaikas - the export derivative of the P.23 - were withdrawn from first-line units only in September 1944.
PZL P.23 Karas (crucian carp) was developed in the early 1930s
in response to the Polish Air Force's need to replace its ageing biplane
Potez 25 and Potez 27 light bomber/reconnaissance aircraft. The specification
presented to PZL in 1931 (Panstwowe Zaklady Lotnicze - the State
Aviation Works) called for an all-metal light bomber plane powered by a
Bristol Pegasus air-cooled radial engine, which should carry a minimum
600 kg (1330 lb) bomb-load, and whose maximum speed should reach 300 km/h
(186 mph). Another requirement was the ability to operate from improvised
airfields. It was soon decided that the new plane's design would be based
on the PZL 13 fast passenger/transport airplane project by Stanislaw Prauss,
which had been abandoned in early 1931.
Necessary changes to the project, apart from fuselage redesign, included the addition of wing flaps, and the provision for weapons mountings. The wing was designed by Franciszek Misztal, based on his original stressed-skin main spar concept, which had earlier been only tested on the PZL 19 high-performance touring airplane. Serious problems with the wing's construction caused delays, and the first prototype, powered by the Bristol Pegasus II M2 engine made its maiden flight in August 1934.
The first prototype revealed many problems, which were overcome by the
second and third prototypes. The fuselage was redesigned, with internal
bomb bay removed to provide more space for the crew, and engine installation
lowered for better visibility. The wing's mechanization was redesigned
with automatic slats added on the leading edge, and the wing root fairings
significantly enlarged. After additional changes to the engine fairing
and the exhaust, the airplane was accepted by the Lotnictwo Wojskowe
and given the designation PZL P.23A Karas. An order for 200 aircraft
was placed with the PZL.
The production started in the end of 1935 but its pace suffered because of frequent problems with the Pegasus II M2 engines, license-built by the Polish Skoda works (this engine variant was never produced by Bristol). In addition, the leading-edge slats proved unreliable, and were consequently removed. Only 40 P.23As were built and assigned to training duties, pending the availability of the P.23B variant fitted with the more powerful Bristol Pegasus VIII engine, whose production commenced in the summer of 1936. In February 1937 the production reached the pace of 20 aircraft per month, and the original order for 200 P.23s was fulfilled in September 1937. Additional 50 aircraft were ordered, and the production of the P.23B variant concluded in February 1938.
Meanwhile, an effort was being made to adapt the P.23 for the dive-bombing
role, which resulted in a prototype designated PZL P.42. Although the plane's
dive-bombing capabilities proved poor, it became the basis for the more
successful PZL 46 Sum horizontal bomber which was supposed to replace
P.23s in first-line units starting form March 1940.
In early 1936 Bulgaria placed an order for 12 P.23s, with the additional
requirement of a more powerful engine and an additional forward-firing
machine gun. The fuselage was thus redesigned to accept the Gnome-Rhone
14N-01 engine, and the plane was given the designation PZL 43A Tchaika
(sea gull in Bulgarian). Because of delays in engine shipments from France,
this first series was eventually fitted with Gnome-Rhone 14kfs engines,
while additional 42 planes ordered by Bulgaria, designated PZL 43B, received
the intended GR 14N-01 engine. At the outbreak of war nine of these aircraft
were still at the Warsaw Okecie airfield, and five of them saw combat in
the Polish Campaign.
During the September campaign 114 P.23s were flown by first-line units,
and additional 11 (including the five PZL 43s) were received as replacements.
Of these, only 17 reached Romania on September 17. Such a high attrition
rate was caused in most part by the inability to repair the aircraft, so
a large proportion of the planes was abandoned after receiving combat damage.
Still, used for attacks on heavily defended German motorized and Panzer
columns, flying without fighter escort, many planes were lost in combat.
After the collapse of Poland, about 30 P.23s from both first-line and training units reached Romania. After receiving a major overhaul, 19 of these aircraft were impressed for local service, and saw combat on the eastern front, flying reconnaissance and bombing missions over the Crimea and Don river, and were withdrawn from the front in January 1943, following the collapse of the Axis troops at Stalingrad. From the summer of 1943 the remaining Romanian P.23s were relegated to training duties.
The PZL 43 equipped units of the Bulgarian air force never saw front line combat, and were used locally against communist guerillas throughout 1943 and 1944. In September 1944, after Bulgaria switched sides and joined the Allies, the Tchaikas were finally replaced by aircraft of indigenous design.
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