PZL.37 Los

From Academic Kids

PZL-37B Łoś

PZL.37 Łoś -the second prototype
RoleMedium bomber
First FlightJune 1936
Entered Service1938
Length12.92 min
Wingspan17.93 min
Height5.1 min
Wing area53.5 m²ft²
Empty4,935 kglb
Loaded8,880 kglb
Maximum takeoff9,105 kglb
Engines 2 xBristol Pegasus
Power 2 xPegasus XX
 600 to 700 kW810 to 940 hp
Maximum speed412 km/hmph
Combat range1,000 km (with bombs)miles
Ferry range2,600 kmmiles
Service ceiling7,000 mft
Rate of climb4.7 m/sft/min
Wing loading166 kg/m² (with bombs)lb/ft²
Guns3 x 7.92 mm or 7.7 mm machine guns:
1 in nose
1 in rear upper station
1 in underbelly station
Bombs2580 kg5645 lb

The PZL-37 Los (in Polish: Łoś) was the Polish twin-engine medium bomber, used in the Polish September Campaign in 1939. It was one of the most modern bombers in the world before the Second World War.


It was designed in the mid-1930s in the PZL factory in Warsaw by Jerzy Dąbrowski. The first prototype with a single tail fin flew in June 1936. The second prototype PZL-37/II, with a double tail fin and other improvements, was accepted for a production, with a name Łoś (in Polish - the moose). The first 10 serial aircraft were produced in 1938 as the PZL-37A variant with a single tail fin, however. The next 20 interim aircraft were built as PZL-37A bis, with a double tail fin. They all were powered by Bristol Pegasus XII B radial engines produced in Poland under licence. The main production variant, the PZL-37B, was fitted with the double tail fin and newer Pegasus XX engines. Production of PZL-37B for the Polish Air Force started in autumn 1938.

Before the war, the PZL-37B Łoś was one of the world's most modern and outstanding bombers. Smaller than most contemporary medium bombers, it was still able to carry a heavier bomb load than comparable aircraft, including the famous Vickers Wellington. It was relatively fast and easy to handle. Thanks to a landing gear with double wheels, it could operate from rough fields or meadows. The only drawback was its relatively weak defensive armament, consisting of 3 machine guns. Its range was also limited, but the Łoś was not meant to be a long range bomber.

Starting with a presentation at a salon in Belgrade in June 1938 and in Paris in November, the PZL-37 met with a huge interest. For export purposes, new variants were developed: the PZL-37C with Gnome-Rhone 14N-0/1 engines of 970 hp (720 kW), maximum speed 445 km/h and the PZL-37D with 14N-20/21 (1050 hp (780 kW), maximum speed 460 km/h). In 1939, 20 PZL-37Cs were ordered by Yugoslavia, 15 by Bulgaria, 30 PZL-37D by Romania and 25 by Turkey. The outbreak of the war prevented the production of these aircraft. At that time, PZL developed the next variant for the Polish airforce, the PZL-49 Miś, but this was not completed before the war. Having slightly bigger dimensions, Miś ("Bear") was to be fitted with Bristol Hercules II engines (1350 hp (1,000 kW), maximum speed 520 km/h) and an upper turret.

Combat use

During the initial period of PZL-37 service, several crashes were caused by technical problems or crew inexperience. After some structural changes, the PZL-37B became extremely reliable. The Polish Air Force started to receive the PZL-37B in the spring of 1939. By the outbreak of World War II, about 105 PZL-37s had been produced, but not all were completed. On September 1, 1939, the Polish Airforce had 70 PZL-37s. 36 PZL-37Bs were in 4 bomber escadres of a Bomber Brigade (two escadres with 9 aircraft each, constituted a group, in Polish: dywizjon; PZL-37 were in groups X and XV). The rest of the Bomber Brigade aircrafts were PZL-23 Karas. The further 34 PZL-37As and Bs were in training units.

Only the PZL-37s of the Bomber Brigade took part in combat. By September 1, they had been deployed to field airfields, so they were not bombed by the Germans. During the campaign, from September 4 the planes were attacking German armoured columns in day attacks, most notably the 16th Armoured Corps near Czestochowa and Radomsko. They suffered losses due to lack of armour and fighter protection. During the campaign, the combat units were supplemented with several other aircraft, so about 45 PZL-37s were used. 14 PZL-37Bs were shot down, and a further 12 were lost in other ways. A number of not fully completed or training PZL-37s were also destroyed on airfields and in factories.

About 19 PZL-37Bs from the Bomber Brigade and 27 training ones were withdrawn in 1939 to Romania and then used by the Romanian airforce against the USSR from 1941, armed with German MG 15 machine guns. Captured planes were also tested in Germany and the USSR.

Technical design

The aircraft was conventional in layout, all metal, metal-covered, with low wings. The crew consisted of four: pilot, commander-bombardier, radio operator and a rear gunner. The bombardier was accommodated in the glazed nose, with a forward machine gun. The radio operator sat inside the fuselage, above the bomb bay, and he also operated an underbelly rear machine gun. The main undercarriage retracted into the engine nacelles. The undercarriage was double-wheeled, with an independent suspension for each wheel. The plane was powered by two Bristol Pegasus radial engines . The PZL-37A had Pegasus XII B engines (normal power: 860 hp (640 kW), maximum: 970 hp (720 kW) - other data: 873 hp (650 kW)), The PZL-37B had Pegasus XX engines (normal power: 840 hp (630 kW), maximum: 940 hp (700 kW) - other data 918 hp (680 kW)). The bombs were carried in bomb bays in the fuselage and in the central section of the wings. The maximum load was 2,580 kg (2 × 300 kg and 18 × 110 kg).

Sometimes the plane is called called "PZL P-37", but the letter "P" was generally reserved for fighters of Pulawski's design (see PZL P-11).

Related content
Related Development PZL-49 Miś
Similar Aircraft Handley Page Hampden - Heinkel He 111 - Dornier Do 17 - Ilyushin Il-4
Designation Series

PZL-26 - PZL-27 - PZL-30 - PZL-37 - PZL-38 - PZL-43 - PZL-44

Related Lists

List of bomber aircraft

Lists of Aircraft | Aircraft manufacturers | Aircraft engines | Aircraft engine manufacturers

Airports | Airlines | Air forces | Aircraft weapons | Missiles | Timeline of aviation

pl:PZL.37 Łoś

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