3.7 cm Flak 18/36/37/43

The 3.7 cm Flak 18/36/37/43 were series of anti-aircraft cannon produced by Nazi Germany, 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.^[2] 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.

Development

The original 37 mm gun was developed by Rheinmetall 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 4,800 m (15,700 ft) effective ceiling.^[1] 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.^[1] 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 1,750 kg (3,900 lb), and complete for transport, including the wheeled mount, 3,560 kg (7,800 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 1,550 kg (3,400 lb) in combat and 2,400 kg (5,300 lb) in transport.^[1] Gun's ballistic characteristics were not changed, although the practical rate of fire raised to 120 rpm.^[1] A new sighting system introduced the next year produced the 3.7 cm Flak 37, otherwise an identical gun.^[1] The Flak 37 was known as 37 ITK 37 in Finland.

The Flak 36/37 were the most produced variants of the weapon.

Flak 43

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,^[1] while at the same time dropping in weight to 1,250 kg (2,800 lb) in combat, and mere 2,000 kg (4,400 lb) in transport.^[1] The barrel was shortened to 89 calibers. It was also produced in a twin-gun mount, the 3.7 cm Flakzwilling 43,^[1] although this version was considered somewhat unwieldy and top-heavy.^[3]

The Flak 37 could be found in some numbers mounted to the ubiquitous Sd.Kfz. 7 or later the schwere Wehrmachtschlepper (sWS), but the newer Flak 43 was almost always used in a mobile mounting. Most famous of these were the converted Panzer IV's, first the "interim" Möbelwagen, and later the Ostwind, 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).^[4]

3.7 cm Flak 43 M43U

The 3.7 cm Flak 43 M43U was the marine version of the 3.7 cm Flak 43 used by the Kriegsmarine on Type VII and Type IX U-boats. It was mounted on the LM42U mount.

Notes

References

• Gander, Terry and Chamberlain, Peter. Weapons of the Third Reich: An Encyclopedic Survey of All Small Arms, Artillery and Special Weapons of the German Land Forces 1939-1945. New York: Doubleday, 1979 ISBN 0-385-15090-3
• Hogg, Ian V. German Artillery of World War Two. 2nd corrected edition. Mechanicsville, PA: Stackpole Books, 1997 ISBN 1-85367-480-X

External links

• 3.7 cm Flak 43 in U.S. Ordnance Catalog