PZL.37 Łoś
| PZL-37B Łoś | ||
|---|---|---|
PZL.37 Łoś - the second prototype | ||
| Description | ||
| Role | Medium bomber | |
| Crew | 4 | |
| First Flight | June 1936 | |
| Entered Service | 1938 | |
| Manufacturer | PZL | |
| Dimensions | ||
| Length | 12.92 m | 42 ft 5 in |
| Wingspan | 17.93 m | 58 ft 10 in |
| Height | 5.1 m | 16 ft 9 in |
| Wing area | 53.5 m² | 576 ft² |
| Weights | ||
| Empty | 4,935 kg | 10,880 lb |
| Loaded | 8,880 kg | 19,580 lb |
| Maximum takeoff | 9,105 kg | 20,070 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 | 256 mph |
| Combat range | 1,000 km (with max. bombs) | 620 mi |
| Ferry range | 2,600 km | 4,200 mi |
| Service ceiling | 7,000 m | 23,000 ft |
| Rate of climb | 4.7 m/s | 925 ft/min |
| Wing loading | 166 kg/m² (with bombs) | 34 lb/ft² |
| Power/Mass | hp/lb | kW/kg |
| Armament | ||
| Guns | 3 x 7.92 mm machine guns: 1 in nose 1 in rear upper station 1 in underbelly station | |
| Bombs | 2580 kg | 5690 lb |
The PZL-37 Łoś (Polish: 'moose') was a 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.
Development
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 on December 13, 1936. The second prototype PZL-37/II, with a double tail fin and other improvements, was accepted for a production. The first 10 serial aircraft were produced in 1938 as the PZL-37A variant with a single tail fin, however. The next 19 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 (or: Łoś II), 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. During the initial period of PZL-37 service, there were 2 crashes of prototypes and 6 crashes of serial planes, caused by technical problems. After some structural changes, the PZL-37B became a fully reliable aircraft. By the outbreak of World War II, about 92 PZL-37s had been produced and given to the Air Force, further 31 were in different phases of production.
Before the war, the PZL-37B Łoś was one of the world's most modern bombers. It was able to carry heavier bomb load than comparable aircraft, for example the Vickers Wellington. Smaller than most contemporary medium bombers, it was relatively fast and easy to handle. Thanks to a landing gear with double wheels, it could operate from rough fields or meadows. Typically for the late 1930s, its defensive armament consisted of only 3 machine guns, which proved too weak against enemy fighters.
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
The Polish Air Force started to receive the PZL-37B in the spring of 1939. On September 1, 1939, the Polish Air Force had about 86 PZL-37s in total, but less than a half were used in combat. 36 PZL-37Bs were in 4 bomber escadres of a Bomber Brigade: the 11th, 12th, 16th and 17th escadres (two escadres with 9 aircraft each, constituted a group, in Polish: dywizjon; the PZL-37 were in groups X and XV). The rest of the Bomber Brigade aircraft were PZL-23 Karas. About 50 remaining PZL-37s were in the reserve XX group, training units or in repairs.
Only the PZL-37s of the Bomber Brigade took part in combat. By September 1, they had been deployed to country improvised airfields, so they were not destroyed on the ground by the Germans in their initial attack on the main Polish airbases. During the Polish September Campaign, from September 4 onward the planes of the Bomber Brigade were attacking German armoured columns in day attacks, forced by the desperate situation to perform this mission for which they were not designed (the original plans to bomb targets inside Germany were quickly abandoned). Most notably, they hampered the advance of the 16th Armoured Corps near Czestochowa and Radomsko. They suffered heavy losses due to lack of fighter protection, especially, that they usually acted in no more, than three aircraft at a time. Last combat flights took place on September 16. During the campaign, the combat units were reinforced with several other aircraft, and about 46 PZL-37s were used in combat. Of Bomber Brigade, 10 PZL-37s were shot down by fighters, 5 shot down by enemy artillery, two bombed on the ground and a further 10 lost in other ways. A number of not fully completed, training or reserve PZL-37s were also destroyed on airfields and in factories (18 PZL-37s were bombed in a reserve base in Malaszewicze and in a factory in Warsaw - Okęcie).
27 PZL-37s (17 from the Bomber Brigade and 10 training ones) were withdrawn in 1939 to Romania. 22 of them were next used by the Romanian airforce against the USSR from June 1941, armed with German MG 15 machine guns, in the 4th Group, consisting of the 76th and 77th bomber escadres. Amnong others, they were bombing Kiev and Odessa. Due to lack of spares, they were withdrawn from the front in October 1941 and used for training. In 1944, the 76th escadre returned to combat. After the war, several remaining aircraft were dedicated to gunnery target towing and used until mid 1950s.
Captured planes were also tested in Germany and the USSR. Not many PZL-37s, however, fell into German hands (probably only two), because Polish workers scrapped about 30 PZL-37s remaining in factories in Okecie and Mielec in October 1939, under pretext of cleaning up the area, before the competent German authorities were able to reconnoitre. There are no surviving PZL.37 aircraft currently.
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 two-section bomb bay in the fuselage and 8 bomb bays in the central section of the wings. The maximum load was 2,580 kg (2 × 300 kg and 18 × 110 kg). Apart from two 300 kg bombs, it could not carry larger bombs, than 110 kg.
Sometimes the plane is called "PZL P-37", but the letter "P" was generally reserved for fighters of Pulawski's design (see PZL P-11).
Operators
- Poland, Romania,
| 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 |
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