3.7 cm Flak 18/36/37

3.7 cm Flak 18/36/37
A 3.7 cm Flak 36/37 in Italy, 1944
Type	Anti-aircraft gun
Place of origin	Nazi Germany
Service history
In service	1936–1945
Used by	Nazi Germany, Romania, Bulgaria
Wars	World War II
Production history
Designer	Rheinmetall
Produced	1936–1945
No. built	20,243[1] (Germany) 360[2] (Romania)
Variants	BK 37 aircraft gun
Specifications (3.7 cm Flak 36/37[3])
Mass	1,550 kg (3,420 lb) (combat) 1,250 kg (2,760 lb) (Flak 43)[1]
Barrel length	2.11 m (83 in) (57 calibers)
Crew	6–7
Shell	37 × 263 mm B
Shell weight	623–659 g (1.373–1.453 lb)
Caliber	37 mm (1.5 in)
Breech	gas-operated bolt
Carriage	three-legged platform
Elevation	-8° to +85°
Traverse	360°
Rate of fire	160 rpm (cyclic)
Muzzle velocity	770–840 m/s (2,500–2,800 ft/s)
Effective firing range	4,200 m (4,600 yd) (anti-aircraft)
Maximum firing range	7,995 m (8,743 yd) (ground range)
Feed system	6-round clips

The 3.7 cm Flak 18/36/37 was a series of anti-aircraft guns produced by Nazi Germany that saw widespread service in the Second World War. The cannon was fully automatic and effective against aircraft flying at altitudes up to 4,200 m.^[4] 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; 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, by 35-mm anti-aircraft pieces produced in Switzerland.