PZL.23 Karaś

The PZL.23 Karaś was a Polish light bomber and reconnaissance aircraft designed in the mid-1930s by PZL in Warsaw. It was the primary Polish reconnaissance bomber in use during the Invasion of Poland.

The aircraft was developed in 1931 to replace Breguet 19 and Potez 25 aircraft in the Polish Air Force. Designer Stanisław Prauss based the new recon bomber on a proposed passenger transport plane that never saw into production, the PZL.13. 

The PZL.23 design was a modern all-metal body with wings built around light closed profiles instead of spars (introduced first in PZL.19). The P.23/I first prototype flew on 1 April 1934, followed by the second P.23/II prototype.

In the third P.23/III prototype of 1935, the pilot's seat was raised and the engine lowered to improve sight lines. This prototype was accepted for production, with the name Karaś (in Polish - the crucian carp). The first series, PZL.23A was fitted with a Bristol Pegasus IIM2 radial engine of 670 hp (500 kW) produced in Poland under licence. Since this engine proved to be unreliable, the final variant PZL.23B was fitted with a newer Pegasus VIII of 720 hp (537 kW).

The aircraft was a low-wing cantilever monoplane of all-metal, metal-covered construction. The crew of three consisted of a pilot, a bombardier, and a rear gunner. The bombardier's combat station was situated in a gondola underneath the hull, where he could also operate an underbelly machine gun. The fixed undercarriage was well spatted, but despite a massive look, it was not suited for rough airfields. Bombs were carried under the wings: the maximum load was 700 kg (1,500 lb) (6 x 100 kg and 2 x 50 kg). 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. Regardless of the engine, the aircraft had a two-blade propeller.

The Bristol engines were licensed for use in Poland only, so for export purposes the Gnome-Rhône 14K was used in a variety of PZL designs. In this case the 14K-powered PZL.23, with some changes to the airframe, became the PZL.43 Karaś. Final export variant was PZL.43A, with 1,020 hp Gnome-Rhone 14N-01 engine. 52 PZL.43s were made in total, all for Bulgaria only. The new engine improved the aircraft's performance considerably, maximum speed increased to 365 km/h.
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PZL.23 Karaś (suom. ruutana) on puolalainen kevyt toisen maailmansodan aikainen pommikone, jota käytettiin myös tiedusteluun ja Puolan armeijan yhteyskoneena. Konetyyppi oli yksimoottorinen alataso, joka kehiteltiin 6-paikkaisesta P.13 -matkustajakoneesta.
Ensimmäinen, noin 40 lentokoneen A-sarja valmistui Bristol IIM2 -moottorilla, jonka teho oli 590 hevosvoimaa.

Koneen aseistuksena oli kolme 7,7 millimetrin konekivääriä, joista yksi ampui kiinteästi eteen, toinen vapaasti liikuteltavana taakse ylös ja kolmas sijaitsi ala-ampumossa, rungon alapuolisessa gondolissa. Pienestä 680 hevosvoiman (507 kW) moottoritehostaan huolimatta tyyppi kykeni kuljettamaan enimmillään 700 kg suuruisen pommikuorman. Niin kutsutun operatiiviseen käyttöön osoitetun B-sarjan PZL.23 käytti Bristol Pegasus VIII -tähtimoottoria voimanlähteenään.

PZL.23 oli hidas ja kömpelö, sen moottori alimitoitettu ja puolustusaseistus heikohkoa. Siten se oli helppo saalis saksalaisten aseille salamasodan aikana. Laskeutumistelineet olivat kiinteätä muotosuojallista mallia. Suurin nopeus oli 300 km/h ja lentomatka 1 400 kilometriä. Lakikorkeus oli 7 300 metriä. 
Konetyyppiä valmistettiin arviolta 250 kappaletta.

Humblen mukaan tyyppi oli Puolan pääasiallinen pommikonetyyppi, sekä kärsi kovimpia menetyksiä taistelutoimissa. Osa tämän tyypin koneista internoitiin Romaniaan Puolan puolustuksen romahtaessa syksyllä 1939.
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n 1936, 40 PZL.23As were produced. Between late 1936 and February 1938, 210 PZL.23Bs were produced with the new engines. They were also known as Karaś A and B or Karaś I and II. All PZL.23s had military numbers from 44.1 to 44.250.Sometimes the aircraft is called the "PZL P.23", but despite an abbreviation P.23 painted on a tail fin, the letter "P" was generally reserved for fighters of Pulawski's design (like PZL P.11). In November 1936, one aircraft was shown at the Paris Air Show, where it was met with interest.

During this period, PZL developed the PZL.46 Sum, a new light bomber, partly based on the PZL.23 design, but only two prototypes were completed in 1938. There was also a single experimental variant of the Karaś, PZL.42, with double tail fins and a modified bombardier gondola, retractable into the fuselage.

Forty PZL.23As were delivered to the Polish Air Force in late 1936. Due to engine faults, their service ceiling was limited and they were used only in the training role, being fitted with dual controls. A total of 210 PZL.23Bs were delivered to the Air Force from 1937. They became the main armament of Polish bomber and reconnaissance "line squadrons", in the 1930s replacing Breguet 19, Potez 25 and Potez 27 biplanes. By August 1939, there had been 23 reported crashes, an average safety result.

By 1939, the aircraft was obsolescent. The main deficiency was its low speed but a lack of maneuverability also proved a problem (the maximum speed of the PZL.23B was 365 km/h, but it was forbidden to exceed 319 km/h due to dangerous flight characteristics). However, at the outbreak of World War II on 1 September 1939, during the invasion of Poland, it remained Poland's primary light bomber and reconnaissance aircraft. 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). 

The PZL.23Bs were operational in five bomber squadrons (Eskadra Bombowa) of the Bomber Brigade and seven Army reconnaissance squadrons, each with 10 aircraft (other squadrons of the Bomber Brigade were equipped with PZL.37 Łoś). In addition two PZL.43A from the Bulgarian order were impressed into the Polish service in the 41st Squadron.

On 2 September 1939, one PZL.23B of the 21st Squadron bombed a factory in Ohlau, the first bomb attack on the German Third Reich. The PZL.23 bomber squadrons also attacked German armoured columns, especially on 3 September 1939, while the main mission of the Army squadrons was reconnaissance. The five squadrons of the Bomber Brigade delivered about 52-60 tons of bombs during the campaign, the Army squadrons added about another dozen tons.

Due to the plane's low speed, light armour and (most importantly) lack of fighter protection, PZL.23s suffered heavy combat losses. Many were shot down by German fighter aircraft, but they also shot down several in return. Despite the lack of armour, crews often attacked German columns from low level, making their aircraft vulnerable to AA fire. Some 20 aircraft were lost in crash landings on the improvised and rough airfields. About 120 PZL.23s (86%) were destroyed in 1939, but only 67 due to direct enemy action. And only a small number were destroyed on airfields, with the only large scale Luftwaffe success of this type occurring on 14 September, at Hutniki airfield, against PZL.23Bs of the Bomber Brigade.

At least 21 PZL.23s were evacuated in 1939 to Romania with 19 used by the Romanian Air Force against the USSR. 50 PZL.43s and PZL.43As (two were delivered by the Germans) were used in Bulgaria for training until 1946, known as the "Chaika". No PZL.23s survived the war.

General characteristics
Crew: 3
Length: 9.68 m (31 ft 9 in)
Wingspan: 13.95 m (45 ft 9 in)
Height: 3.3 m (10 ft 10 in)
Wing area: 26.8 m² (288 ft²)
Empty weight: 1,928 kg (4,251 lb)
Loaded weight: 2,813 kg (6,202 lb)
Max. takeoff weight: 3,428 kg (7,557 lb)
Powerplant: 1 × PZL Bristol Pegasus IIM2 9-cylinder radial engine, 670 hp (500 kW)
Maximum speed: 304 km/h (189 mph)
Cruise speed: 240 km/h (149 mph)
Stall speed: 110 km/h (68 mph)
Range: 1,260 km (783 mi)
Service ceiling: 7,300 m (23,950 ft)
Rate of climb: 6.5 m/s (1,280 ft/min)
Armament: 3 x machine guns:
1 x 7.92 mm PWU wz.33 fixed in nose;
1 x 7.92 mm Vickers F in rear upper station;
1 x 7.92 mm Vickers F in underbelly station;
Bombs: 700 kg (1,543 lb) bombs.