The 3.7 cm Flak 18/36/37/43
were series of anti-aircraft cannon produced by Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...
, which saw widespread service in the Second World War. The cannon was fully automatic and effective against aircraft flying at altitudes up to 4200 meters. The cannon was produced in both towed and self-propelled versions. Having a flexible doctrine, the Germans used their anti-aircraft pieces in ground support roles as well, and 37 mm caliber guns were no exception to that. With Germany's defeat, production ceased, and overall, 37 mm caliber anti-aircraft cannon fell into gradual disuse, being replaced by the Bofors 40 mm gun, and later, 35-mm anti-aircraft pieces produced by Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
The original 37 mm gun was developed by Rheinmetall
Rheinmetall AG is a German automotive and defence company with factories in Düsseldorf, Kassel and Unterlüß. The company has a long tradition of making guns and artillery pieces...
in 1935 as the 3.7 cm Flak 18
. It had a barrel length of 98 calibers (hence the additional designation L/98), which allowed 4800 m (15,748 ft) effective ceiling. The armor penetration was considerable when using dedicated ammunition, at 100 m distance it could penetrate 36 mm of a 60°-sloped armor, and at 800 m distance correspondingly 24 mm. It used a mechanical bolt for automatic fire, featuring a practical rate of fire of about 80 rounds per minute (rpm). The gun emplaced for combat weighed 1750 kg (3,858.1 lb), and complete for transport, including the wheeled mount, 3560 kg (7,848.5 lb).
The Flak 18 was produced only in small numbers, and production had already ended in 1936. Development continued, focusing on replacement of the existing cumbersome dual-axle mount with a lighter single-axle one, resulting in a 3.7 cm Flak 36
that cut the complete weight to 1550 kg (3,417.2 lb) in combat and 2400 kg (5,291.1 lb) in transport. Gun's ballistic characteristics were not changed, although the practical rate of fire raised to 120 rpm. A new sighting system introduced the next year produced the 3.7 cm Flak 37
, otherwise an identical gun. The Flak 37 was known as 37 ITK 37
The Flak 36/37 were the most produced variants of the weapon.
The new 3.7 cm Flak 43
was a dramatic improvement over the older models. A new gas-operated breech improved the practical firing rate to 150 RPM, while at the same time dropping in weight to 1250 kg (2,755.8 lb) in combat, and mere 2000 kg (4,409.2 lb) in transport. The barrel was shortened to 89 calibers. It was also produced in a twin-gun mount, the 3.7 cm Flakzwilling 43
, although this version was considered somewhat unwieldy and top-heavy.
The Flak 37 could be found in some numbers mounted to the ubiquitous Sd.Kfz. 7 or later the schwere Wehrmachtschlepper
The Schwerer Wehrmachtschlepper , or sWS for short, was a German World War II half-track flat-bed cargo vehicle used in various roles between 1943 and 1945. The unarmored models were used as supply vehicles and as tractors to haul things...
), but the newer Flak 43 was almost always used in a mobile mounting. Most famous of these were the converted Panzer IV
The Panzerkampfwagen IV , commonly known as the Panzer IV, was a medium tank developed in Nazi Germany in the late 1930s and used extensively during the Second World War. Its ordnance inventory designation was Sd.Kfz...
's, first the "interim" Möbelwagen
The 3.7cm FlaK auf Fahrgestell Panzerkampfwagen IV , nicknamed Möbelwagen because of its boxy turret , was a self-propelled anti-aircraft gun built from the chassis of the Panzer IV tank...
, and later the Ostwind
The Flakpanzer IV "Ostwind" was a self-propelled anti-aircraft gun based on the Panzer IV tank. It was developed in 1944 as a successor to the earlier self-propelled anti-aircraft gun Wirbelwind....
, which was considered particularly deadly.
Compared to its closest Allied counterpart, the 40 mm Bofors, the Flak 43 had a slightly superior rate of fire and was both notably lighter & more compact; to the Bofors credit it was a significantly more powerful weapon (with greater range, ceiling & a shorter projectile flight time) which fired a more destructive shell. Large-scale production did not start until 1944 and about 7,216 were produced by end of the war (Zwillings
included, each counted as two guns).