3.7 cm Flak M42

The 3.7 cm Flak M42 was the marine version of the 3.7-centimetre (1.5 in) Flak 36/37 and used by the Kriegsmarine on surface ships and as the M42U on Type VII and Type IX U-boats. The 3.7 cm Flak M42U used several types of mounts and entered service in autumn 1943.

3.7 cm/69 Flak M42
A single 3.7 cm Flak M42U gun on the LM 42U mount.
Type	Anti-aircraft gun
Place of origin	Nazi Germany
Service history
In service	1943–1945
Used by	Kriegsmarine
Wars	World War II
Production history
Designed	1942
Manufacturer	Rheinmetal-Borsig
Produced	1943–1945
Specifications (3.7 cm Flak M42)
Mass	109 kg (240 lb)
Barrel length	2.56 cm (1.01 in) bore (69 calibers)
Crew	3–4
Shell	37 × 249R
Shell weight	635–700 g (1.400–1.543 lb)
Caliber	37 mm (1.5 in)
Action	Recoil-operated
Breech	sliding breech block
Elevation	-10° to +90°
Traverse	360°
Rate of fire	250 rounds per minute (cyclic)
Muzzle velocity	815–865 m/s (2,670–2,840 ft/s)
Effective firing range	4,800 m (5,200 yd) at 85° elevation 6,400 m (7,000 yd) at 45° elevation
Feed system	5-round clips

3.7 cm Flak M42

The 3.7 cm Flak M42 was a longer caliber version of the Wehrmacht's 3.7 cm Flak 36, 69 caliber as opposed to 57 caliber. It replaced the older 3.7 cm SK C/30 that had been designed in 1930. The gun was loaded with a five-round ammunition clip, giving it a rate of fire of 250 rounds per minute, unlike the SK C/30 which was single-shot with a rate of 30 rounds per minute. The M42 was also about 134 kg (295 lb) lighter than the SK C/30 and had gun shields.

LM 42U Mount

The LM 42U mount was developed specifically for the 3.7 cm Flak M42U. It was manned by a 3-man crew, with a fourth man operating as the loader.

DLM 42U Mount

The twin mount was based on the LM 42U design, in which the 3.7 cm Flak M42U guns were mounted side by side.

LM 43U Mount

The LM 43U mount was the final design of mount used on U-boats. It was a further improvement on the LM 42U. The LM 43U was only known to be installed on these U-boats (U-249, U-826, U-977, U-1023, U-1171, U-1305 and U-1306).

Gallery

• 
  3.7 cm Flak M42U used on U-boats.
• 
  A single 3.7 cm Flak M42U gun on the LM 42U mount.
• 
  A single 3.7 cm Flak M42U gun on the LM 43U mount.
• 
  Twin 3.7 cm Flak M42U guns on the DLM 42U mount.

Bibliography

• Campbell, John (1985). Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-459-4.
• DiGiulian, Tony (30 November 2016). "Germany 3.7 cm/69 (1.5") Flak M42". NavWeaps. Retrieved 23 September 2017.
• DiGiulian, Tony (30 April 2017). "Germany 3.7 cm/83 SK C/30". NavWeaps. Retrieved 23 September 2017.
• Skwiot, Miroslaw (2011). German Naval Guns 1939–1945. Annapolis, Maryland: Naval Institute Press. ISBN 978-1-59114-311-6.
• Williams, Tony G. (2000). Rapid Fire: The Development of Automatic Cannon, Heavy Machine Guns and Their Ammunition for Armies, Navies and Air Forces. Shrewsbury, UK: Airlife Publishing. ISBN 1-84037-122-6.

Further reading

• Williams, Anthony G. (2022). Autocannon: A History of Automatic Cannon and Ammunition. Ramsbury, UK: The Crowood Press. ISBN 978-1-78500-920-4.