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PZL P.37 Los

Twin-Engine Medium Bomber Aircraft


The PZL P.37 Los medium bomber formed part of the failed defense of Poland during the German invasion of September 1939.

Detailing the development and operational history of the PZL P.37 Los Twin-Engine Medium Bomber Aircraft.  Entry last updated on 4/5/2018. Authored by Staff Writer. Content ©
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.


YEAR: 1938
STATUS: Retired, Out-of-Service
MANUFACTURER(S): Panstwowe Zaklady Lotnicze (PZL) - Poland
LENGTH: 42.49 ft (12.95 m)
WIDTH: 58.89 ft (17.95 m)
HEIGHT: 16.73 ft (5.1 m)
EMPTY WEIGHT: 9,436 lb (4,280 kg)
MTOW: 20,073 lb (9,105 kg)
POWER: 2 x Bristol Pegasus XX air-cooled radial piston engines developing 970 horsepower each and driving three-bladed propeller units.
SPEED: 256 mph (412 kph; 222 kts)
CEILING: 22,966 feet (7,000 m; 4.35 miles)
RANGE: 1,616 miles (2,600 km; 1,404 nm)
RATE-OF-CLIMB: 925 ft/min (282 m/min)
OPERATORS: Nazi Germany (evaluated); Poland; Romania; Soviet Union (evaluated)

1 x 7.92mm machine gun in nose on trainable mounting.
1 x 7.92mm machine gun in dorsal position on trainable mounting.
1 x 7.92mm machine gun in ventral position on trainable mounting.

Up to 5,690lb of conventional drop stores held internally.
Graphical image of an aircraft medium machine gun
Graphical image of an aircraft conventional drop bomb munition
Variants / Models

• P.37 - Base Series Designation
• P.37/I - Initial prototype; single-finned tail unit.
• P.37/II - Second prototype; twin-finned tail unit.
• P.37A - Production model; single-finned tail unit; outfitted with Bristol Pegasus XIIB engines; 10 examples completed.
• P.37Abis - Twin-finned tail unit; 19 examples completed.
• P.37B (I/II) - Twin-finned tail unit; PZL Pegaz XX series engines fitted.
• P.37C - Proposed model with 2 x Gnome-Rhone 14N-01 engines.
• P.37D - Proposed model with 2 x Gnome-Rhone 14N-21 engines.
• P.49 'Mis' - Proposed advanced bomber form; incomplete prototype.

Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

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Relative Maximum Speed
Hi: 300mph
Lo: 150mph
This entry's maximum listed speed (256mph).

Graph average of 225 miles-per-hour.
City-to-City Ranges
Graph showcases the PZL P.37B's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era
Pie graph section
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Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production (120)
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units

  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.

Altitude Visualization
Small airplane graphic
Supported Roles
Ground Attack
Aerial Tanker
A2A=Air-to-Air; UAV=Unmanned; CAS=Close Support; ASW=Anti-Submarine; AEW=Airborne Early Warning; MEDEVAC=Medical Evac; EW=Electronic Warfare; SAR=Search-Rescue
Commitments / Honors
Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for pioneering aircraft
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon representing modern aircraft
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur War
Military lapel ribbon for experimental x-plane aircraft
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.

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