perdurabo
07-29-2004, 09:53 AM
My thread dedicated to my favourite plane.
PZL 37 "Łoś" (eng. "Elk")
HISTORY
In 1934 The Aeronautics Department of the Ministry of Defense commissioned, at the PZL, a concept of two engine medium bomber. The initial design was completed by Eng. Jerzy Dąbrowski with the help of Eng. Piotr Kubicki in the summer of 1935. The work to build the first prototype started shortly afterwards, and it was ready for initial taxing trials in May of 1936. The plane had designation P37/I, and it was powered by two Pegasus XIIB engines rated at 873 HP each. The airplane was first flown by test pilot Jerzy Widawski at the end of June. The prototype passed extensive tests at the Institute of Aviation Technique, and based on the results of these tests a second prototype was built. The P37/II was first flown in the spring of 1937. It had more powerful engines, the Bristol Pegasus XX, each having 918 HP. One of the main modifications was a replacement of two strut single wheel landing gears with a single leg double wheel chassis. The twin wheels were independently suspended, according to the patented PZL design. The prototype performance was very good so the Department of Aeronautics ordered 30 planes, which were named the PZL-37 Łoś-A (Elk-A). After building 10 Elks-A there was another significant modification, a double fin tail was introduced to improve the rear gunner shooting view. This version was named the Łoś-Abis (Elk-Abis). In 1938 the PZL factory received an order for the next 100 Łoś-B that were equipped with new engines, the Pegaz XXA. They were manufactured at the PZL-WS1 engine division under license from Bristol. 94 Elks were manufactured before the World War II broke out. Only 45 of them took part in combat with Germans, since the rest were not fully equipped. They performed very well in action, bombing German armored units, but their total number was too small to have a significant impact.
CONSTRUCTION
The Elk was of an all-metal construction low wing monoplane. The fuselage was an elliptical cross section stress skin structure. The nose of the plane was extensively glazed on a frame made of steel tubes. The airplane was manned by a crew of four. Commander/ Bomb-aimer was sitting in the nose. The pilot was behind him on the left side of the fuselage. A radio operator was located behind the pilot. He also manned the lower machine gun. A rear gunner was sitting in a cut-out, partly screened by a canopy made of organic glass. The wing was built in three parts. A two beam center section was bolted to the fuselage. It had hard points to attach engine bearer struts and landing gears. The outer wings were built as a load carrying box of sandwich skin. They were invented by Eng. F.Misztal and patented by the PZL. All bombs were carried internally in bomb bays located in the lower part of the fuselage and the center section between the main beams. The twin fin and rudder tail unit was a cantilever all-metal structure. Rudders and elevators were aerodynamically balanced. A single leg landing gear was carrying twin wheels, flexibly suspended according to the patented PZL design. The undercarriage retracted into the engine nacelles and the apertures were fully closed by doors. The engines were driving three-blade variable pitch propellers.
SOME COMPARISONS
The PZL-37 Łoś is considered one of the best Polish aircraft designs with reference to the period it was conceived. A table below comparing the Łoś with other contemporary planes shows it’s excellence. It was not only matching each one of them but rather exceeded their performance. Only the range was shorter because it was such a requirement from the air force. The range could be increased to 1750 km by installing additional fuel tank and reducing the bomb load to 1774 kG, which was still very high. The B25A was a little bit faster but at the expense of smaller bomb load and by using almost two times more powerful engines than that used by the Elks.
It was the most optimal aircraft. The lightest, the smallest, with the lowest engine power, but with the highest bomb load. The Elk’s planned advanced version the Miś (Teddy Bear) would have a maximum speed of 520 km/h and a range of 3000 km. The Elk design had a couple of advanced design features. These were landing gears designed by Eng. Kubicki. They work well on uneven grass airfields and the wheels of smaller diameters were easier to hide after retraction. Very advanced was the sandwich structure of the wings. This technology allowed to build them very light with high strength to weight ratio. The “Misztal Wing” did not become popular because it was too expensive and complicated, but it can be considered a pioneer of sandwich structures, like for example honeycomb panels. They are commonly used today in satellites where a mass reduction is of prime importance.
Romanian service
In September 1939, 22 (according to Romanian sources) or 27 (Polish sources) took refuge in Romania in front of the advancing German and Soviet forces. The airplanes were interned and 19 of them were armed and assigned to the 4th Bomber Group.
The group participated in operations from very first day of Barbarossa, when two were lost to Soviet AAA. Until the end of the campaign only one P.37 was shot down. but the lack of spare parts meant that few were serviceable. The PZLs claimed 4 VVS fighters shot down and 25 destroyed on the ground.
The P.37s were retreated from active duty, but in 1944, as the front reached Romania, all available forces were mobilized in a desperate attempt to stop the Red Army. Only one P.37B equipped squadron could be raised: the 76th, which was subordinated to the 4th Bomber Group.
After 23 August 1944, the remaining P.37Bs were again retreated, but this time for good
First prototype 37/I
http://www.sampol.de/Fotos/Los/prototyp.1.jpg
first batch 37A
http://www.sampol.de/Fotos/Los/1seria_2.2.jpg
http://www.sampol.de/Fotos/Los/1seria.1.jpg
http://www.sampol.de/Fotos/Los/SeriaA.jpg
http://www.sampol.de/Fotos/Los/SeriaA_2.jpg
sec. prototype 37/II
http://www.sampol.de/Fotos/Los/prot_2_2zd.jpg
http://www.sampol.de/Fotos/Los/2prot_3zd.jpg
http://www.sampol.de/Fotos/Los/protot_2_1zd.jpg
second batch 37A-bis (only diffrence from A is twin tail)
http://www.sampol.de/Fotos/Los/por_Kozka.jpg
http://www.sampol.de/Fotos/Los/Bseria_proby.1.jpg
Factory demonstrator
http://www.sampol.de/Fotos/Los/SP_BNL_2zd.jpg
http://www.sampol.de/Fotos/Los/SP-BMP.jpg
third bath 37 B had twin tail like A-bis and stronger engine
http://www.makettinfo.hu/makett/makettek/epites/pzl-37/pzl-37_2.gif
http://www.airwar.ru/image/i/bww2/pzl37-i.jpg
rows with Łoś from february 38'
http://www.sampol.de/Fotos/Los/na_lotn_2_zd.jpg
http://www.sampol.de/Fotos/Los/na_lotn_2_zd.jpg
captured elk tested by germans
http://www.luftwaffe-experten.co.uk/mike/German%20PZL%20P-37B.gif
in romanian service
http://www.worldwar2.ro/arr/pzl37b.JPG
Data and pics from site:
http://www.sampol.de/angielski/PZL/pzl_eng2.htm
http://www.luftwaffe-experten.co.uk/pzl.html
http://www.worldwar2.ro/arr/pzl37b.htm
(and 2pics from two other sides one in russian and one in finnish on finnish side was plastic model of 37 painted in finnish cammo! Finish mates your AF used Elks?)
PZL 37 "Łoś" (eng. "Elk")
HISTORY
In 1934 The Aeronautics Department of the Ministry of Defense commissioned, at the PZL, a concept of two engine medium bomber. The initial design was completed by Eng. Jerzy Dąbrowski with the help of Eng. Piotr Kubicki in the summer of 1935. The work to build the first prototype started shortly afterwards, and it was ready for initial taxing trials in May of 1936. The plane had designation P37/I, and it was powered by two Pegasus XIIB engines rated at 873 HP each. The airplane was first flown by test pilot Jerzy Widawski at the end of June. The prototype passed extensive tests at the Institute of Aviation Technique, and based on the results of these tests a second prototype was built. The P37/II was first flown in the spring of 1937. It had more powerful engines, the Bristol Pegasus XX, each having 918 HP. One of the main modifications was a replacement of two strut single wheel landing gears with a single leg double wheel chassis. The twin wheels were independently suspended, according to the patented PZL design. The prototype performance was very good so the Department of Aeronautics ordered 30 planes, which were named the PZL-37 Łoś-A (Elk-A). After building 10 Elks-A there was another significant modification, a double fin tail was introduced to improve the rear gunner shooting view. This version was named the Łoś-Abis (Elk-Abis). In 1938 the PZL factory received an order for the next 100 Łoś-B that were equipped with new engines, the Pegaz XXA. They were manufactured at the PZL-WS1 engine division under license from Bristol. 94 Elks were manufactured before the World War II broke out. Only 45 of them took part in combat with Germans, since the rest were not fully equipped. They performed very well in action, bombing German armored units, but their total number was too small to have a significant impact.
CONSTRUCTION
The Elk was of an all-metal construction low wing monoplane. The fuselage was an elliptical cross section stress skin structure. The nose of the plane was extensively glazed on a frame made of steel tubes. The airplane was manned by a crew of four. Commander/ Bomb-aimer was sitting in the nose. The pilot was behind him on the left side of the fuselage. A radio operator was located behind the pilot. He also manned the lower machine gun. A rear gunner was sitting in a cut-out, partly screened by a canopy made of organic glass. The wing was built in three parts. A two beam center section was bolted to the fuselage. It had hard points to attach engine bearer struts and landing gears. The outer wings were built as a load carrying box of sandwich skin. They were invented by Eng. F.Misztal and patented by the PZL. All bombs were carried internally in bomb bays located in the lower part of the fuselage and the center section between the main beams. The twin fin and rudder tail unit was a cantilever all-metal structure. Rudders and elevators were aerodynamically balanced. A single leg landing gear was carrying twin wheels, flexibly suspended according to the patented PZL design. The undercarriage retracted into the engine nacelles and the apertures were fully closed by doors. The engines were driving three-blade variable pitch propellers.
SOME COMPARISONS
The PZL-37 Łoś is considered one of the best Polish aircraft designs with reference to the period it was conceived. A table below comparing the Łoś with other contemporary planes shows it’s excellence. It was not only matching each one of them but rather exceeded their performance. Only the range was shorter because it was such a requirement from the air force. The range could be increased to 1750 km by installing additional fuel tank and reducing the bomb load to 1774 kG, which was still very high. The B25A was a little bit faster but at the expense of smaller bomb load and by using almost two times more powerful engines than that used by the Elks.
It was the most optimal aircraft. The lightest, the smallest, with the lowest engine power, but with the highest bomb load. The Elk’s planned advanced version the Miś (Teddy Bear) would have a maximum speed of 520 km/h and a range of 3000 km. The Elk design had a couple of advanced design features. These were landing gears designed by Eng. Kubicki. They work well on uneven grass airfields and the wheels of smaller diameters were easier to hide after retraction. Very advanced was the sandwich structure of the wings. This technology allowed to build them very light with high strength to weight ratio. The “Misztal Wing” did not become popular because it was too expensive and complicated, but it can be considered a pioneer of sandwich structures, like for example honeycomb panels. They are commonly used today in satellites where a mass reduction is of prime importance.
Romanian service
In September 1939, 22 (according to Romanian sources) or 27 (Polish sources) took refuge in Romania in front of the advancing German and Soviet forces. The airplanes were interned and 19 of them were armed and assigned to the 4th Bomber Group.
The group participated in operations from very first day of Barbarossa, when two were lost to Soviet AAA. Until the end of the campaign only one P.37 was shot down. but the lack of spare parts meant that few were serviceable. The PZLs claimed 4 VVS fighters shot down and 25 destroyed on the ground.
The P.37s were retreated from active duty, but in 1944, as the front reached Romania, all available forces were mobilized in a desperate attempt to stop the Red Army. Only one P.37B equipped squadron could be raised: the 76th, which was subordinated to the 4th Bomber Group.
After 23 August 1944, the remaining P.37Bs were again retreated, but this time for good
First prototype 37/I
http://www.sampol.de/Fotos/Los/prototyp.1.jpg
first batch 37A
http://www.sampol.de/Fotos/Los/1seria_2.2.jpg
http://www.sampol.de/Fotos/Los/1seria.1.jpg
http://www.sampol.de/Fotos/Los/SeriaA.jpg
http://www.sampol.de/Fotos/Los/SeriaA_2.jpg
sec. prototype 37/II
http://www.sampol.de/Fotos/Los/prot_2_2zd.jpg
http://www.sampol.de/Fotos/Los/2prot_3zd.jpg
http://www.sampol.de/Fotos/Los/protot_2_1zd.jpg
second batch 37A-bis (only diffrence from A is twin tail)
http://www.sampol.de/Fotos/Los/por_Kozka.jpg
http://www.sampol.de/Fotos/Los/Bseria_proby.1.jpg
Factory demonstrator
http://www.sampol.de/Fotos/Los/SP_BNL_2zd.jpg
http://www.sampol.de/Fotos/Los/SP-BMP.jpg
third bath 37 B had twin tail like A-bis and stronger engine
http://www.makettinfo.hu/makett/makettek/epites/pzl-37/pzl-37_2.gif
http://www.airwar.ru/image/i/bww2/pzl37-i.jpg
rows with Łoś from february 38'
http://www.sampol.de/Fotos/Los/na_lotn_2_zd.jpg
http://www.sampol.de/Fotos/Los/na_lotn_2_zd.jpg
captured elk tested by germans
http://www.luftwaffe-experten.co.uk/mike/German%20PZL%20P-37B.gif
in romanian service
http://www.worldwar2.ro/arr/pzl37b.JPG
Data and pics from site:
http://www.sampol.de/angielski/PZL/pzl_eng2.htm
http://www.luftwaffe-experten.co.uk/pzl.html
http://www.worldwar2.ro/arr/pzl37b.htm
(and 2pics from two other sides one in russian and one in finnish on finnish side was plastic model of 37 painted in finnish cammo! Finish mates your AF used Elks?)