PZL.37 Los Development Combat Use Technical Design

PZL-37B Los
PZL.37 Los -the second prototype
Description
Role	Medium bomber
Crew	4
First Flight	June 1936
Entered Service	1938
Manufacturer	PZL
Dimensions
Length	12.92 m	in
Wingspan	17.93 m	in
Height	5.1 m	in
Wing area	53.5 m²	ft²
Weights
Empty	4,935 kg	lb
Loaded	8,880 kg	lb
Maximum takeoff	9,105 kg	lb
Powerplant
Engines 2 x	Bristol Pegasus
Power 2 x	Pegasus XX
	600 to 700 kW	810 to 940 hp
Performance
Maximum speed	412 km/h	mph
Combat range	1,000 km (with bombs)	miles
Ferry range	2,600 km	miles
Service ceiling	7,000 m	ft
Rate of climb	4.7 m/s	ft/min
Wing loading	166 kg/m² (with bombs)	lb/ft²
Power/Mass	hp/lb	kW/kg
Armament
Guns	3 x 7.92 mm or 7.7 mm machine guns: 1 in nose 1 in rear upper station 1 in underbelly station
Bombs	2580 kg	5645 lb

It was designed in the mid-1930s in the PZL factory in Warsaw by Jerzy Dabrowski . 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 Los (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 Los 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 WellingtonThe Vickers Wellington was a twin-engine, medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs' Chief Designer, R. It was widely used in the first two years of World War II, before being replaced as a bomber by. 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 Los was not meant to be a long range bomber.

Starting with a presentation at a salon in BelgradeFor other uses see Belgrade (disambiguation Belgrade ( Serbian, Beograd , (population in Belgrade region 1,711,800 by census of 2002) is the capital of Serbia (since 1403) and Serbia and Montenegro (since 2003) and Yugoslavia ( 1918- 2003). The city lies 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 14 NO1 engines (970 hp (720 kW), maximum speed 445 km/h) and the PZL-37D with Gnome-Rhone 14N21 (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 Mis, but this was not completed before the war. Having slightly bigger dimensions, Mis ("Bear") was to be fitted with Bristol Hercules II engines (1350 hp (1,000 kW), maximum speed 520 km/h) and an upper turret.

2 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.

3 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 Mis
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

Polish bomber aircraft 1930-1939 World War II Polish medium bombers

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