2 cm C/30, 2 cm Flak 30 The Germans fielded the unrelated early 2 cm Flak 28 just after World War I, but the
Treaty of Versailles outlawed these weapons and they were sold to Switzerland. , France, August 1944 The original Flak 30 design was developed from the
Solothurn ST-5 as a project for the
Kriegsmarine, which produced the
2 cm C/30. The gun fired the "Long Solothurn", a 20 × 138 mm belted cartridge that had been developed for the ST-5 and was one of the more powerful 20 mm rounds. The C/30, featuring a barrel length of 65
calibres, had a fire rate of about 120 rounds per minute. It proved to have feeding problems and would often jam, which was offset to some degree by its undersized 20 round-magazine which tended to make reloading a frequent necessity. Nevertheless, the C/30 became the primary shipborne light AA weapon and equipped a large variety of German ships. The
MG C/30L variant was also used experimentally as an aircraft weapon, notably on the
Heinkel He 112, where its high power allowed it to penetrate
armoured cars and the light tanks of the era during the
Spanish Civil War.
Rheinmetall then started an adaptation of the C/30 for Army use, producing the
2 cm Flak 30. Generally similar to the C/30, the main areas of development were the mount, which was fairly compact. Set-up could be accomplished by dropping the gun off its two-wheeled trailer, "Sonderanhänger 51" (trailer 51) and levelling the gun using hand cranks. The result was a triangular base that permitted fire in all directions.
2 cm Flak 38, 2 cm GebFlak 38, 2 cm C/38 But the main problem with the design remained unsolved. The rate of fire of 120 RPM (rounds per minute) was not particularly fast for a weapon of this calibre. Rheinmetall responded with the
2 cm Flak 38, which was otherwise similar but increased the rate of fire by 220 RPM and slightly lowered overall weight to 420 kg. The Flak 38 was accepted as the standard Army gun in 1939, and by the Kriegsmarine as the
2 cm C/38. In order to provide airborne and mountain troops with an AA capability,
Mauser was contracted to produce a lighter version of the Flak 38, which they introduced as the
2 cm Gebirgsflak 38 (
2 cm GebFlak 38). It featured a dramatically simplified mount using a tripod that raised the entire gun off the ground, with the additional benefit of allowing the weapon to be set up on an uneven surface. These changes reduced the overall weight of the gun to 276.0 kg. Production started in 1941 and it entered service in 1942.
2 cm Flakvierling 38 Even as the Flak 30 was entering service, the Luftwaffe and
Heer (army) branches of the
Wehrmacht had doubts about its effectiveness, given the ever-increasing speeds of low-altitude
fighter-bombers and attack aircraft. The Army in particular felt the proper solution was the introduction of the
37 mm calibre weapons they had been developing since the 1920s, which had a rate of fire about the same as the Flak 38 but fired a round with almost eight times the weight. This not only made the rounds deadlier on impact, but their higher energy and
ballistic coefficient allowed them to travel much longer distances, allowing the gun to engage targets at longer ranges. This meant it could keep enemy aircraft under fire over longer time spans. The 20 mm weapons had always had weak development perspectives, often being reconfigured or redesigned just enough to allow the weapons to find a use. Indeed, it came as a surprise when Rheinmetall introduced the
2 cm Flakvierling 38, which improved the weapon just enough to make it competitive again. The term
Vierling literally translates to "quadruplet" and refers to the four 20 mm autocannon constituting the design. The
Flakvierling weapon consisted of quad-mounted 2 cm Flak 38 AA guns with collapsing seats, folding handles, and
ammunition racks. The mount had a triangular base with a jack at each leg for levelling the gun. The tracker traversed and elevated the mount manually using two handwheels. When raised, the weapon measured 307 cm (10 feet 1 inch) high. Each of the four guns had a separate magazine that held only 20 rounds. This meant that a maximum combined rate of fire of 1,400 rounds per minute was reduced practically to 800 rounds per minute for combat use – which would still require that an emptied magazine be replaced every six seconds, on each of the four guns. This is the
attainable rate of fire; the sustained rate of fire is significantly lower due to heat buildup and barrel erosion. Automatic weapons are typically limited to roughly 100 rounds per minute per barrel to give time for the heat to dissipate, although this can be exceeded for short periods if the firing window is brief. The gun was fired by two pedals – each of which fired two diametrically opposite barrels – in either semi-automatic or automatic mode. The effective vertical range was 2,200 metres. It was also used just as effectively against ground targets as it was against low-flying aircraft. ==Mounting versatility==