The PZL P.37 Los medium bomber formed part of the failed defense of Poland during the German invasion of September 1939.
Authored By: Staff Writer | Last Edited:
Credit: Image from the Public Domain.
The nation of Poland was not without an aero-industry in the period leading up to World War 2 (1939-1945). In fact, PZL was a dominant player for the Polish Air Force from 1928 until 1939 and several of its products were used in the defense of Poland during the German invasion of September 1939. One contributor to the failed mission became the PZL P.37 Los ('Moose'), a medium bomber design of twin-engine configuration. Over 120 of the type were produced and a portion of these saw active combat against Axis forces in the ensuing battles of the early phases of world War 2. Production spanned from 1938 until 1939. Captured examples were later taken on by the Romanian Air Force and these were used into 1944. Two captured specimens were also tested by the Germans and three evaluated by the Soviets.
The medium bomber gained prominence prior to World War 2 for its ability to deliver viable bomb loads over range at serviceable speeds. The Poles understood this and invested in the type as did other air powers of the day. The P.37 emerged from work began in the middle part of the 1930s under the direction of Jerzy Dabrowski. A prototype was made ready for a first-flight as soon as December 13th, 1936. At the time of its service introduction in 1938, the P.37 was hailed as one of the more advanced bombing platforms anywhere in the world.
The aircraft's profile was traditional with a stepped, heavily-glazed and streamlined nose section at the front - offering exception views of the terrain ahead. The tubular fuselage tapered to the rear to which a split-fin tail unit was fitted. The wings were straight and low-mounted along the sides of the fuselage with curved wing tips. The undercarriage was of a tail-dragger design with double-wheeled main legs. The engines were housed in nacelles at each wing mainplane leading edge and drove three-bladed propeller units. The crew numbered four and included the pilot, bombardier / navigator and several machine gunners. Dimensions included a length of 42,4 feet, a wingspan of 58.9 feet and a height of 16.8 feet. The aircraft held an empty weight of 9,436lb against a Maximum Take-Off Weight (MTOW) of 20,070lb.
The aircraft was defensed by a 7.92mm machine gun at the nose, another 7.92mm machine gun fitted to a dorsal station and yet-another 7.92mm machine gun installed in a ventral position. Internally, the bomber could carry up to 5,690lb of conventional drop ordnance.
Performance specifications of the P.37 included a maximum speed of 256 miles per hour, a range out to 1,615 miles and a service ceiling up to 23,000 feet. Rate-of-climb was 925 feet-per-minute.
Variants were led by the P.37/I prototype and this differed in having a single-finned tail unit. The P.37/II was another prototype incorporating various improvements as well as introducing the twin-finned tail arrangement. The first ten aircraft of the series were designated P.37bis and carried the single-finned tail unit of the first prototype as well as 2 x Bristol Pegasus XIIB series engines. The P.37Abis followed through a batch of nineteen aircraft and had twin-finned tails.
The definitive production model became P.37B (I/II) and carried twin-finned tails as well as in-house PZL Pegaz XX series air-cooled radial piston engines of 970 horsepower output (each).
P.37C and P.37D were proposed versions with Gnome-Rhone 14N-01 and 14N-21 engines respectively - neither were produced. The P.49 Mis was another proposed bomber variant based on the P.37 but only a single incomplete prototype was made as the German invasion halted its development.
During the war, the bomber operated with the 10th and 15th Bomber Squadrons of the Polish Air Force. Deliveries began in early-1938 but a limited supply of engines meant that operating strength was slow to achieve. At the time of the German invasion of Poland in September of 1939, about 86 were on hand to defend though, in the subsequent fighting, fewer than 50% of the stock were actually pressed into service. When used in bombing sorties, the bombers were sent airborne with less than the intended bomb load due to operating from unprepared airfields which limited their tactical and strategic value. As the invasion pressed on, losses of the series mounted as no fighter escorts were provided - making these large targets juicy pickings for German pilots. Before the end, about 25 of the stock were flown to Romanian where they were interred by local authorities (and reconstituted for service in the Romanian Air Force and used until mid-1944). Some 30 P.37 bombers were destroyed by the Poles before they could be captured by the Germans.
Planned pre-war customers for the P.37 included Belgium, Bulgaria, Greece, Spain, Turkey and Yugoslavia.
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