Large-caliber machine guns and the first cannons appeared on board aircraft back in the First World War, but then these were only timid attempts to increase the firepower of the first aircraft. Until the mid-30s of the 20th century, this weapon was used in aviation only sporadically. The real heyday of aviation rapid-fire guns fell on the pre-war years and the years of World War II. In the Soviet Union, one of the most famous aircraft cannons, which was installed on a huge number of aircraft from I-16 to La-7, and as part of the turrets was used on Pe-8 and Er-2 bombers, was the ShVAK 20-mm automatic aviation cannon (Shpitalny -Vladimirov Aviation Large-caliber). Mainly, this gun was used to arm Soviet fighters.
At the same time, none of the Soviet aircraft cannons could boast of such production volumes as the ShVAK. In 1942, a rather difficult year for the whole country, Soviet enterprises were able to produce 34,601 aircraft cannons of this type. The production of ShVAK was launched at the Tula Arms Plant, Kovrov Arms Plant and Izhevsk Machine-Building Plants. In total, in the USSR, taking into account the pre-war production, more than 100 thousand copies of the 20-mm ShVAK aircraft cannon were manufactured. Its slightly modified version was also used to arm light tanks, for example, the mass T-60 tank. Considering the volume of production and use of this artillery system, it is rightly referred to as the "weapon of Victory".
ShVAK is the first Soviet automatic aviation cannon of 20 mm caliber. It was put into service in 1936 and was produced until 1946, when the last 754 guns of this type were assembled. The aircraft cannon was produced in four versions: wing, turret, motor-gun and synchronous. The motor-gun was distinguished by the presence of a longer barrel and a shock absorber. In its structure, the ShVAK was completely similar to the large-caliber 12, 7-mm machine gun of the same name, which was adopted back in 1934. The only difference was in the diameter of the barrel used. Tests of the ShVAK large-caliber machine gun demonstrated to the designers that, thanks to the available margin of safety, the caliber of the system can be increased to 20 mm without changing the dimensions of the moving system, simply by replacing the barrel. The ShVAK gun had a tape feed, the reloading process was carried out mechanically or pneumatically.
Aviation cannon ShVAK
Synchronous ShVAK on La-5 fighter
For the first time, the new cannon was installed on the IP-1 fighter designed by Dmitry Pavlovich Grigorovich. In the summer of 1936, it was presented to the Air Force Research Institute for state tests. At the same time, it took about four years to fine-tune it. Only in 1940, the ShVAK cannon designed by Boris Gavrilovich Shpitalny and Semyon Vladimirovich Vladimirov began to be mounted on Soviet fighters, both in the breakup of the cylinder block of the M-105 aircraft engine (motor-gun) and in the wing. The combat debut of the new Soviet aircraft gun took place in 1939. ShVAK air cannons were on the I-16 fighters, which were used in battles with the Japanese at Khalkhin Gol.
Structurally, the ShVAK 20-mm aircraft cannon repeated the previous models of the ShKAS and ShVAK machine guns (12, 7 mm). The gun's automatics worked on the basis of a gas outlet. The air gun had a fixed barrel, which, when assembled, was connected to the assembled box by means of a locking insert. As in previous developments, in the ShVAK 20-mm aircraft cannon, a highlight of Shpitalny's systems was used - a 10-position drum mechanism for phasing out the cartridge from the tape, thanks to its use, a high rate of fire of the system was ensured. But this scheme of work required the use of its own welted cartridge with a protruding flange-flange, which clinging to the screw groove of the gun drum. For this reason, no other type of cartridge could be used in the Spitalny's weapon.
Today we can safely say that the idea of unifying weapons for different calibers is quite sensible. Many systems in world practice followed the same path; today, in the first quarter of the 21st century, multi-caliber weapons are experiencing a real heyday. However, in the case of Shpitalny's models, everything was not so simple. The thing is that his first project of the ShKAS aircraft machine gun was built around the already existing cartridge of a rifle caliber 7, 62x54R with a rim, which was completely justified for the machine gun to achieve a high rate of fire. But already ShVAKs demanded from the Soviet industry to create fundamentally new ammunition of welted design. In the variant with a 12, 7-mm machine gun, this solution was unsuccessful. This caliber was conceived as universal, it was planned to use it not only in aviation. With the already existing 12.7x108 mm degtyarevsky cartridge, which was more convenient for store food, even the assertiveness that was characteristic of Shpitalny was not enough to push the parallel production of a similar welted cartridge 12.7x108R. Such a cartridge in the USSR was produced for a short time in parallel with the production of a small series of large-caliber machine guns ShVAK. In the end, it was simply discontinued.
Wing ShVAK on I-16 type-17 fighter
But the 20-mm version of the ShVAK was waiting for a much more successful fate. At the time of the development of this aircraft gun, other 20-mm cartridges simply did not exist in the Soviet Union. As a possible option, the production of "Long Soloturn" was considered - a powerful Swiss ammunition of 20x138R caliber, for which the Atsleg AP-20 universal machine gun was created in KB-2, however, in general, the niche of 20-mm ammunition in the USSR was not filled, which completely untied the hands to the creators of the ShVAK air cannon.
To other negative aspects of the unification of the 12, 7-mm and 20-mm versions of the ShVAK, experts attribute the fact that the Vladimirov group, trying to maintain a single design of the nodes of the two aircraft systems, was forced to equalize the geometric dimensions along the length of the two types of cartridges. The length of both cartridges was 147 mm, which ensured a single design of the most labor-intensive system unit in production - the drum feed structure. However, if the 12.7mm cartridge was powerful enough for its class, then the new 20x99R turned out to be one of the weakest 20mm caliber ammunition among its foreign counterparts.
Ultimately, the motor-cannon formed the basis of the armament of the Soviet Yak and LaGG fighters; in the wing version, it also went to the first Il-2 attack aircraft with an ammunition capacity of 200 rounds per barrel. The beginning of the Great Patriotic War spurred both the mass production of 20-mm ShVAK cannons and the introduction of synchronous versions of the gun, which since 1942 began to appear on Lavochkin's fighters, and were installed on individual series of the MiG-3 fighter.
Aviamotor VK-105PF with motor-gun ShVAK
But the turret version of the ShVAK could not boast of a successful fate and did not take root in Soviet aviation. Too heavy and cumbersome, it did not fit into the light turrets of our bombers. Its use was extremely limited. The gun was installed on a flying boat MTB-2 (ANT-44), as well as on an experienced bomber Myasishchev DB-102. Almost the only serial combat aircraft on which the turret version of the ShVAK was regularly installed was the Pe-8 (TB-7) heavy bomber, the production of which was practically piecemeal throughout the war years. And already at the very end of the war, a ShVAK cannon was also installed on the upper turret of the Er-2 bomber.
Thus, the main consumer of ShVAK aircraft guns throughout the entire period of their production was Soviet fighter aircraft. ShVAK were on the I-153P, I-16, I-185, Yak-1, Yak-7B, LaGG-3, La-5, La-7 and Pe-3 fighters. When the I-16 fighter was withdrawn from production, and the Il-2 attack aircraft began to re-equip with the new 23-mm VYa aircraft cannon, the production of the wing version of the ShVAK was almost completely curtailed. In 1943 alone, 158 of these guns were fired for the rearmament of the Lend-Lease Hurricanes, where they were installed instead of 7, 7-mm Browning machine guns. And at the end of the war, the wing-mounted version of the cannon again found its use, becoming the offensive weapon of the Tu-2 twin-engine high-speed bomber.
At the same time, the ShVAK motor-gun, with some design changes in 1941-42, was mounted on light T-30 tanks (modification of the T-40) instead of the 12, 7-mm DShK machine gun, which made it possible to significantly increase the power of their fire effect on the enemy and gave tankers the opportunity to hit lightly armored enemy vehicles (armor penetration - up to 35 mm with a sub-caliber projectile), anti-tank guns, machine-gun nests and enemy manpower. A variant of the gun under the designation ShVAK-tank or TNSh-20 (tank Nudelman-Shpitalny) was serially installed on light tanks T-60.
TNSh-20 cannon in the T-60 light tank
In May 1942, specialists from the Air Force Research Institute came to the conclusion that the ShVAK 20-mm aircraft cannon works flawlessly on the I-16 (in the wing), Yak-1 and LaGG-3 fighters (through the gearbox). The projectile of this cannon is effective against enemy aircraft, armored cars, light tanks and vehicles, and railway fuel tanks. For action against medium and heavy tanks, the shell of the ShVAK cannon is not effective. In general, the ShVAK projectile in terms of weight, and hence the effectiveness of the explosive action, was inferior to the projectile of the German aircraft guns of the same caliber (the ShVAK projectile weighed 91 grams, and the German MG FF aircraft gun - 124 grams). It was also noted that in terms of the effectiveness of action against targets, the ShVAK was significantly inferior to the 23-mm VYa aircraft cannon.
Comparing the Soviet ShVAK with the German MG FF aircraft cannon, you come to the conclusion that the German gun, which used the recoil energy of the free bolt (on the ShVAK - gas outlet), had an advantage only in the weight and breaking strength of the shells used. At the same time, the initial projectile velocity of the German cannon was at least 220 m / s less, but the second salvo for the wing aircraft cannons was practically the same. At the same time, the MG FF was 15 kg lighter, including due to the use of a shorter barrel. At the same time, this advantage of German guns was lost with the appearance in the USSR of the new B-20 aircraft gun.
Today it is rather difficult to objectively assess the value of the ShVAK 20-mm aircraft cannon. Of course, it had a certain bunch of shortcomings - weak ammunition with poor ballistics, operational and technological complexity, which, especially at the initial stage of production, led to the high cost of the gun. At the same time, the first drawback was easily compensated for by the huge rate of fire of the ShVAK, which reached 800 rounds per minute, and the cost reduction was due to the establishment of mass production and adaptation of the industry. It is worth noting that in terms of rate of fire, the ShVAK had no equal among the serially produced aircraft guns of other states. True, the synchronous versions that were installed on the excellent Soviet La-5 and La-7 fighters, depending on the engine operating mode, had a lower rate of fire - 550-750 rounds per minute.
Comparison of the 20x99R cartridge with other ammunition
In any case, we can say that Shpitalny-Vladimirov's air cannon has become one of those iconic samples of the Red Army's weapons that were able to ensure our country victory in the Great Patriotic War. According to the fighter pilots of those years, the power of even the relatively weak 20-mm shells of the ShVAK cannon was enough to fight any Luftwaffe aircraft. Of course, if Germany massively had heavy bombers or Soviet aviation had to collide in the sky with armada of American "flying fortresses", our fighters would have had a hard time, but in reality none of this happened.
It is also important to remember that in the Soviet Union there was no alternative to ShVAK for a long time. The development of the promising B-20 aircraft cannon designed by Mikhail Evgenievich Berezin, also created by him on the basis of a large-caliber machine gun and based on the same principle of operation as the ShVAK, was seriously delayed due to the designer's illness. For this reason, the ShVAK aircraft cannon, despite its "weakness", remained the main weapon of the fighters of the Great Patriotic War.
The training of Soviet pilots, which grew during the war and made it possible to effectively use the weapons at their disposal, also played a significant role. It is no secret that the personnel of the Red Army Air Force, which met the war on June 22, 1941, had extremely low qualifications and an almost complete lack of experience in the combat use of their aircraft. The only exceptions were the command personnel who managed to pass Spain, Khalkhin Gol, the winter war with Finland, but there were few such pilots. And they, in the main, passed on the accumulated experience in accordance with the training course "The course of the combat employment of fighter aircraft." This was confirmed by the consumption of ammunition for air targets, which changed throughout the war from its first months to the last. If at the initial stage of the war, Soviet pilots often opened fire on the enemy from a distance of 300-400 meters, then already in 1942, having gained experience, from a distance of 100-150 meters, and sometimes from 50 meters. This led to an increase in shooting accuracy and a reduction in ammunition consumption. With regard to the ShVAK aircraft cannon, this increased the effectiveness of its shells. When the enemy plane turned into a colander, the lower explosive force of the Soviet cannon shells was no longer significant.
Wing of the German Bf 109 fighter after being hit by 20 mm ShVAK shells
During the pre-war period and the years of World War II, the Soviet industry produced more than 100 thousand ShVAK aircraft cannons, which makes it one of the most massive artillery systems in the history of aviation. The production of ShVAK was discontinued only in 1946. It was replaced by the more advanced B-20 aircraft cannon, which, having similar combat characteristics, was more reliable and lightweight.
The performance characteristics of ShVAK:
Length / weight:
Wing version - 1679 mm / 40 kg.
Turret variant - 1726 mm / 42 kg.
Motor-gun - 2122 mm / 44, 5 kg.
The stroke length of the moving parts is 185 mm.
Rate of fire - 700-800 rds / min.
The muzzle velocity is 815 m / s.
Cartridge - 20x99 mm R.
