3.7 cm FlaK 43

Germany produced a series of 37 mm guns prior to and during World War II as their primary medium-caliber anti-aircraft gun. Unlike other nations, the German forces generally did not see much need for this class of weapon, and the 37 mm series remained fairly rare until the end of the war.

Earlier guns

The original 37 mm gun was developed by Rheinmetall in 1935 as the 3.7 cm Flugzeugabwehrkanone 18. It was essentially an enlarged version of the 2 cm FlaK 30 firing a standard-caliber 37 mm from an L/89 barrel. Like the Flak 30, it used a mechanical bolt for automatic fire, but nevertheless featured a fairly good rate of fire, about 160 RPM (2.7 Hz). The complete gun, including wheeled mount, weighed 1757 kg.

The Flak 18 was produced only in small numbers, and production had already ended in 1936 in favor of well known 2 cm Flakvierling 38, a four-barrel development of the Flak 30. Some development continued, however, resulting in a lighter two-wheel mount produced as the 3.7 Flak 36 that cut the complete weight to 1544 kg. A new sighting system introduced the next year produced the 3.7 Flak 37 that was otherwise similar. It appears existing weapons were brought up to the Flak 37 standard, while new production started in 1942 and produced 1178 before production ended in 1944. The Flak 37 was known as 37 ITK 37 in Finland.

FlaK 43

As Allied air power grew dramatically during the mid-period of the war, the 20 mm quad-mount proved to have too little power and the 37 mm was turned to as its replacement. Not content with the existing versions, Rheinmetall-Borsig and Krupp were asked to produce a new version that was less expensive.

Krupp initially won the contract, but at the last moment the Krupp design developed weaknesses and Rheinmetall-Borsig got the award. This immediately resulted in the factional wrangling in the Nazi party that often beset German wartime industrial production, so by the time Rheinmetall-Borsig was actually able to go ahead well over a year had passed. The design partially able to made up for the delay, however, as it was produced with stampings, welding and simple components in the same way as submachine guns. The production time for a gun was cut by a factor of four. [http://books.google.com/books?id=MuGsf0psjvcC&pg=PA168&dq=3.7+cm+FlaK+43&sig=dH2TpdNv7E3zd-3q73BwyIPfG_c#PPA168,M1 3.7-cm Flak 43 and Flakzwilling 43] , "The Encyclopedia of Weapons of World War II", Chris Bishop, pp. 168] ]

The new 3.7 Flak 43 was a dramatic improvement over the older models. A new gas-operated breech improved the firing rate to 250 RPM, while at the same time dropping in weight to 1247 kg. 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 ubiquidous SdKfz 7 or (later) the sWS. 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 over double the firing rate, could set up in much smaller spaces, and was considerably lighter when considering the gun and mount together. Luckily for Allied aircrews, this fearsome weapon was put into production far too late to have any real effect on the war effort. Apparently this was due to some political wrangling, and although the weapon was complete in 1942, production did not start until 1944. About 928 single and 185 double versions were produced by end of the war. [ [http://www.feldgrau.com/weaprod.html Production Stats on German Tube-fired Weapons 1939-1945] , by Jason Long]

Note

Some sources claim the gun had an L/89 barrel, as stated above, while others claim it was a L/60. It is not clear if this refers to a change for the Flak 43.

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