During the Second World War, the armed forces of Nazi Germany had a significant number of anti-aircraft machine gun installations. But the main role in providing air defense in the frontal zone was played by 20-37-mm rapid-fire towed and self-propelled anti-aircraft guns.
Work on the creation of rapid-fire small-caliber anti-aircraft guns was carried out in Germany long before the Nazis came to power. Back in 1914, the German designer Reinhold Becker presented a prototype of a 20 mm cannon for a 20x70 mm projectile. The principle of operation of the weapon's automation was based on the recoil of the free bolt and the advance ignition of the primer until the cartridge was fully discharged. This scheme of automatic operation made the weapon quite simple, but limited the power of the ammunition and the muzzle velocity of the projectile was within 500 m / s. Food was supplied from a detachable magazine for 12 shells. With a length of 1370 mm, the weight of the 20 mm cannon was only 30 kg, which made it possible to install it on aircraft. In this regard, a small number of "Becker guns" were installed on Gotha G1 bombers. In total, the military department of imperial Germany in 1916 ordered 120 20-mm cannons. There were plans to launch a mass production of automatic cannons, including the anti-aircraft version, but it never came to the mass production of 20-mm anti-aircraft guns before Germany's surrender.
After the defeat of the Germans in the war, all rights to these weapons were transferred to the Swiss company Werkzeugmaschinenfabrik Oerlikon. In 1927, Oerlikon specialists brought the model to serial production, which later became known as 1S. Unlike the "Becker cannon", the new 20-mm machine gun was created for a more powerful cartridge of 20 × 110 mm, with an initial velocity of a projectile weighing 117 g - 830 m / s. The mass of the gun without the machine is 68 kg. The rate of fire was 450 rds / min. In the advertising brochures of the "Oerlikon" company it was indicated that the reach in height was 3 km, in range - 4, 4 km. The real capabilities of the anti-aircraft "Erlikon" were much more modest.
In the Wehrmacht, this anti-aircraft gun received the designation 2.0 cm Flak 28, and in the Luftwaffe it was called the 2.0 cm VKPL vz. 36. In total, between 1940 and 1944, Oerlikon supplied 7,013 20-mm assault rifles, 14.76 million rounds, 12,520 spare barrels and 40,000 ammunition boxes to Germany, Italy and Romania. Several hundred of these anti-aircraft guns were captured by German troops in Belgium, Holland and Norway.
20-mm anti-aircraft "Erlikons" supplied to the fleet were mounted on pedestal carriages, to provide air defense of mobile units, there were options with a tripod machine and a detachable wheel drive. However, this rule was not always observed. Pillar mounts were often mounted at stationary positions in fortified areas, and anti-aircraft guns on tripods were placed on various floating crafts, or used in air defense of naval bases.
Although the combat rate of fire of 2, 0 cm Flak 28, due to the low rate of fire and the use of box magazines for 15 and drum magazines for 30 rounds, was relatively small, in general, due to a simple and reliable design and acceptable weight and size characteristics, it was quite an effective weapon with an effective firing range for air targets - up to 1.5 km. Subsequently, during the war years, we called all 20-mm anti-aircraft guns "erlikons", although there were not so many of them against the background of other German anti-aircraft guns of the same caliber. According to German data, the Wehrmacht, Luftwaffe and Kringsmarin had just over 3,000 2, 0 cm Flak 28 installations.
Structurally, the 2, 0 cm Flak 28 anti-aircraft gun had a lot in common with the 20-mm MG-FF aircraft gun developed in 1936 by the German company Ikaria Werke Berlin on the basis of the Swiss automatic cannon Oerlikon FF. The main difference between the aviation MG-FF and the 2, 0 cm Flak 28 anti-aircraft gun was the use of a much weaker 20x80 mm ammunition. Compared to the Swiss Oerlikon FF, the barrel length and reloading system have been increased by 60 mm. To power the aircraft cannon, 15 horn magazines or drums for 30, 45 and 100 shells were used. The projectile weighing 117 g, left the barrel 820 mm long with an initial speed of 580 m / s. The rate of fire did not exceed 540 rds / min.
In order to somehow compensate for the low penetration ability of an armor-piercing projectile and the weak high-explosive effect of a fragmentation projectile at the end of 1940, specialists from the Institute of Ballistics of the Technical Academy of the Luftwaffe created a thin-walled high-explosive projectile with a high coefficient of filling with explosives. The thinner shell of the projectile was made by deep drawing from special alloy steel and hardened by quenching. Compared with the previous fragmentation projectile equipped with 3 g of pentrite, the filling ratio has increased from 4 to 20%. The new 20-mm projectile, designated Minengeschoss (German shell-mine), contained a plastic explosive based on hexogen with the addition of aluminum powder. This explosive, which was approximately 2 times more powerful than TNT, was characterized by an increased high-explosive and incendiary effect. New lightweight delayed action fuses made it possible to explode a projectile inside the aircraft structure, causing serious damage not to the skin, but to the airframe's power set. So when a new high-explosive projectile hits the base of the fighter's wing, it tore off in most cases. Since the new projectile contained less metal, its mass decreased from 117 to 94 g, which, in turn, affected the recoil force of the cannon's free bolt. To preserve the operability of the automation, it was necessary to significantly lighten the shutter and reduce the force of the return spring.
The new modification of the gun was assigned the MG-FF / M index. At the same time, the ammunition for the old versions of the MG-FF and the new MG-FF / M were not interchangeable. Changes made to the design of the weapon were minimal and a significant number of MG-FF cannons fired by replacing the bolt and return spring were upgraded in the field workshops to the level of MG-FF / M. Although the introduction of a new high-explosive projectile increased the effectiveness of firing at air targets, the aimed firing range even at very large and low-maneuverable aircraft did not exceed 500 m.
By the end of 1941, the MG-FF cannon had already ceased to meet the requirements of modern warfare. Its low weight and technological simplicity were not compensated for by significant drawbacks: a low rate of fire, a low muzzle velocity and a bulky drum magazine. The adoption of the new aircraft gun MG.151 / 20 with a belt-fed ammunition, although much more complex and heavy, but also much more rapid-fire and accurate, gradually led to the withdrawal of the aircraft "Erlikon" from service.
In the second half of the war, many of the 20-mm cannons in warehouses repeated the fate of the 7, 92-mm MG.15 / 17 and 13-mm MG.131 machine guns removed from the aircraft. Several hundred aircraft cannons were installed on pivot mounts, which were used for air defense of airfields and for armament of small displacement ships. However, the "grounded" MG-FFs in terms of range and accuracy of fire were much inferior to specialized 20-mm anti-aircraft guns, which were originally created for much more powerful ammunition. So the maximum effective slant firing range of the MG-FF anti-aircraft version was 800 m.
The main military air defense system of the Germans in wartime was the 20-mm anti-aircraft guns 2.0 cm FlaK 30 and 2.0 cm Flak 38, differing from each other in some details. As follows, their designations are 2, 0 cm FlaK 30 (German.2, 0 cm Flugzeugabwehrkanone 30 - 20-mm anti-aircraft gun of the 1930 model) was developed by Rheinmetall in 1930 and officially entered service in 1934. In addition to Germany, these 20-mm anti-aircraft guns were officially in service in Bulgaria, Holland, Lithuania, China and Finland. The advantages of the Flak 30 anti-aircraft gun were: simplicity of design, the ability to quickly disassemble and assemble, and a relatively low weight.
The principle of operation of the automation of the 20-mm anti-aircraft gun was based on the use of recoil force with a short barrel stroke. The installation had a recoil device and ammunition supply from a carob magazine for 20 shells. Rate of fire 240 rds / min.
During transportation, the gun was placed on a two-wheel drive and secured with two brackets and a connecting pin. It took only a few seconds to remove the pin, after which the clamps loosened, and the system, along with the gun carriage, could be lowered to the ground. The carriage provided the possibility of circular fire with the greatest elevation angle of 90 °.
The automatic building sight generated vertical and lateral lead. Data were entered into the sight manually and determined visually, except for the range, which was measured by a stereo range finder.
Since 20-mm anti-aircraft guns were often used for fire support of ground units, starting in 1940, some of them were released with an anti-fragmentation shield. The weight of 2, 0 cm FlaK 30 with a wheel travel without a shield was about 740 kg, in a combat position - 450 kg.
For firing from 2, 0 cm FlaK 30 ammunition was used 20 × 138 mm, with a higher muzzle energy than projectiles 20 × 110 mm, designed for anti-aircraft guns of the company "Oerlikon" 2, 0 cm Flak 28. Fragment-tracer projectile weighing 115 g left barrel FlaK 30 with a speed of 900 m / s. Also, the ammunition load included armor-piercing incendiary tracer and armor-piercing tracer shells. The latter weighed 140 g and, at an initial speed of 830 m / s, at a distance of 300 m, it pierced 20 mm armor. Theoretically, the 20-mm anti-aircraft gun could hit targets at an altitude of more than 3000 m, the maximum firing range was up to 4800 m. However, the effective fire zone was about half as much.
In addition to the main version intended for use in the air defense of the ground forces, two more serial modifications were created: the 2.0 cm FlaK C / 30 and the G-Wagen I (E) leichte FlaK.
An anti-aircraft gun on a C / 35 pedestal carriage with a 20-round drum magazine was intended to arm warships, but it was often used in permanent, engineering-protected positions. There were many such antiaircraft guns in the fortifications of the Atlantic Wall. The G-Wagen I (E) leichte FlaK anti-aircraft gun had a purely railway specificity, it was equipped with mobile anti-aircraft batteries designed to protect large railway junctions, and this modification was also installed on armored trains.
The baptism of fire of German 20-mm anti-aircraft guns took place in Spain. In general, the anti-aircraft gun has proven itself positively, it turned out to be equally effective against bombers and light tanks available to the Republicans. Based on the results of the combat use of 2, 0 cm Flak 30 in Spain, Mauser modernized the anti-aircraft gun. The upgraded model was named 2.0 cm Flak 38. The new anti-aircraft machine gun used the same ammunition, the ballistic characteristics also remained the same.
The operating principle of the 2.0 cm Flak 38 automation has not changed compared to the 2.0 cm Flak 30. But thanks to a decrease in the mass of moving parts and an increase in their speeds, the rate of fire was increased almost 2 times - up to 420-480 rds / min. The introduction of a copy space accelerator made it possible to combine the opening of the shutter with the transfer of kinetic energy to it. To compensate for the increased shock loads, special shock absorbers were introduced. The changes made to the carriage design turned out to be minimal, in particular, a second speed was introduced in manual guidance drives. Mass deliveries of 2, 0 cm Flak 38 to the troops began in the first half of 1941.
Very often, 2, 0 cm Flak 38 were installed on various mobile platforms: half-track SdKfz 10/4 tractors, Sd. Kfz armored personnel carriers. 251, Czech-made light tanks Pz. Kpfw. 38 (t), German Pz. Kpfw. I and Opel Blitz trucks. Self-propelled anti-aircraft guns were attracted to escort the columns, covered the places of concentration, and often operating in the same battle formations with other armored vehicles fired at ground targets.
Also for Kringsmarine, a column mount 2, 0 cm FlaK C / 38 and a spark 2, 0 cm FlaK-Zwilling 38 were produced. By order of the mountain infantry units, an anti-aircraft gun 2, 0 cm Gebirgs-FlaK 38 was developed and since 1942 was mass-produced - on a lightweight carriage, providing transportation of the gun in a "pack" way. Its assembled weight was 360 kg. Weight of individual parts in packs: from 31 to 57 kg. The ballistic characteristics and rate of fire of the mountain anti-aircraft gun remained at the level of 2.0 cm Flak 38. In the firing position, in the case of an anti-splinter shield, the weight of the gun increased to 406 kg, on a wheel drive - 468 kg.
In the first half of 1939, each Wehrmacht infantry division in the state was supposed to have 12 20-mm anti-aircraft guns. The same number of Flak-30 / 38s were in the anti-aircraft division attached to the tank and motorized divisions. The scale of the use of 20-mm in the German armed forces can be judged by the statistics collected by the Ministry of Armaments. As of May 1944, the Wehrmacht and the SS troops had 6,355 Flak-30/38 anti-aircraft guns, and the Luftwaffe units providing German air defense had more than 20,000 20-mm cannons. Several thousand more 20-mm anti-aircraft guns were installed on the decks of warships and transport ships, as well as in the vicinity of naval bases.
German automatic cannons 2, 0 cm Flak 38 and 2, 0 cm Flak 30 at the time of their creation in terms of a complex of service, operational and combat characteristics in their caliber were perhaps the best anti-aircraft guns in the world. However, the magazine supply of ammunition severely limited the combat rate of fire. In this regard, specialists from the weapons company Mauser, based on the 2, 0 cm Flak 38 machine gun, created a 20-mm quad anti-aircraft gun 2, 0 cm Vierlings-Flugabwehrkanone 38 (German 2-cm quad anti-aircraft gun). In the army, this system was usually called - 2, 0 cm Flakvierling 38.
The mass of the quad 20-mm anti-aircraft gun in the combat position exceeded 1.5 tons. The carriage allowed firing in any direction with elevation angles from −10 ° to + 100 °. The rate of fire was 1800 rds / min, which significantly increased the likelihood of hitting the target. At the same time, the number of the calculation in comparison with single-barreled 20-mm assault rifles doubled and amounted to 8 people. Serial production of the Flakvierling 38 continued until March 1945, with a total of 3,768 units transferred to the troops.
Since the mass and dimensions of the quad unit were very significant, they were very often placed in stationary, well-prepared positions in engineering and installed on railway platforms. In this case, the calculation in front was covered with an anti-splinter shield.
Like the 2.0 cm Flak 38, the 2.0 cm Flakvierling 38 quad anti-aircraft gun was used to create self-propelled anti-aircraft guns on the chassis of half-track tractors, armored personnel carriers and tanks.
Perhaps the most famous and advanced SPAAG, which used quadruple 20 mm assault rifles, was the Flakpanzer IV "Wirbelwind" (German: Anti-aircraft tank IV "Smerch"), created on the basis of the PzKpfw IV medium tank.
The first SPAAG was built in May 1944 at the Ostbau Werke plant in Sagan (Silesia, now the territory of Poland). For this, the chassis of the PzKpfw IV tank damaged in battles and returned for overhaul was used. Instead of the standard tower, a new one was installed - a nine-sided open-top, which housed a quad 20-mm anti-aircraft artillery mount. The lack of a roof was explained by the need to monitor the air situation, in addition, when firing from four barrels, a large amount of powder gases was emitted, which could cause a deterioration in the well-being of the calculation in a closed volume. A solid ammunition load of 3200 20-mm shells was placed inside the tank hull.
The deliveries of the ZSU Flakpanzer IV to the troops began in August 1944. Until February 1945, a total of 122 installations were built, of which 100 were assembled on the chassis of linear tanks received for repair. Most of the anti-aircraft "Smerchi" were sent to the Eastern Front. The combination of sufficiently strong armor protection, maneuverability and mobility at the level of the base chassis, as well as the high rate of fire of the quad gun mount made the Flakpanzer IV an effective means of anti-aircraft cover for tank units, and provided the ability to fight not only air, but also ground lightly armored targets and manpower.
In general, the 20-mm machine guns available to the German anti-aircraft gunners were a very effective means of air defense in the near zone, capable of inflicting heavy losses on ground attack aircraft and front-line bombers. The weight and dimensions made it possible to place single-barreled and quadruple units on various, including armored self-propelled chassis. The inclusion of ZSU with rapid-fire 20-mm anti-aircraft guns in the transport and military convoys, as well as their placement on railway platforms, significantly reduced the effectiveness of the actions of Soviet Il-2 attack aircraft and forced the allocation of a special group consisting of experienced pilots who suppressed the fire of the MZA.
In the memoir literature, you can find a mention of how 20-mm anti-aircraft shells ricocheted from the armored hull of attack aircraft. Of course, when a small-caliber armor-piercing projectile is encountered, even with relatively thin armor at a high angle, a ricochet is quite possible. But it should be admitted that 20-mm armor-piercing incendiary and fragmentation shells posed a mortal danger to the IL-2.
Our assault aircraft suffered very significant losses from the fire of the MZA. As the experience of combat operations and control shooting at the range showed, the Il-2 armored box in most cases did not protect against the destructive effect of 20-mm fragmentation and armor-piercing shells. To lose the performance of the propeller-driven group of the attack aircraft, it was often enough to hit one 20-mm fragmentation projectile in any part of the engine. The dimensions of the holes in the armored hull in some cases reached 160 mm in diameter. The cockpit armor also did not provide adequate protection against the action of 20-mm shells. When hitting the fuselage to disable the IL-2, it was necessary to provide an average of 6-8 hits of 20-mm fragmentation shells. The dimensions of the holes in the fuselage skin ranged from 120 to 130 mm. At the same time, the likelihood that shell fragments would break the attack aircraft's rudder control cables was very high. According to static data, the share of the control system (rudders, ailerons and control wiring) accounted for 22.6% of all defeats. In 57% of cases, when 20-mm fragmentation shells hit the Il-2 fuselage, rudder control cables were interrupted and 7% of hits resulted in partial damage to the elevator rods. The hit of 2-3 explosive shells of German cannons of 20 mm caliber in the keel, stabilizer, rudder or height was quite enough to disable the Il-2.
