Development by B.G. Shpitalny in various modifications is known under the designations Sh-37, ShFK-37, MPSh-37, K-37.

Back in 1933 B.G. Shpitalny, several projects of an automatic cannon with a gas-operated principle of automation were proposed for different calibers from 20 to 50 mm. At first, the young head of the newly created OKB-15 was busy fine-tuning his ShKAS and ShVAK machine guns, but apparently Shpitalny's proposals were deposited in the heads of the country's leadership.

In 1935, by the Decree of the Labor and Defense Council and the plant them. Kalinin was instructed to develop a 37-mm automatic cannon by the end of the year. In 1936, a group of OKB-15 consisting of E.V. Charnko, I.A. Komaritsky, L.V. Lyuliev and V.I. Shelkov under the general guidance of B.G. The spit-gun was developed by an automatic cannon. For the implementation and manufacture of prototypes of the gun, the project was transferred to OKB-2 in Kovrov. By the fall of 1937, a prototype gun was manufactured.

The automatics of the OKB-2 37-mm automatic cannon operated using the energy of the gases discharged from the barrel. Automation provided a technical rate of fire up to 300 rds / min. The machine was powered from a drum-type magazine with a capacity of 6 new unitary "flangeless" cartridges 37 × 252. Later, the magazine capacity was reduced to 5 rounds. The gun had a quick-detachable monoblock barrel with a screw-on breech. One of the design features of this gun was a very powerful active slot brake. Thanks to this brake solution, the designers were able to abandon the rollback brake, leaving only the outer knurler.

Sh-37 on IL-2 . The large overall dimensions of the ShFK-37 cannons and store food determined their placement in fairings under the wing of the Il-2 attack aircraft. Due to the installation of a large store on the cannon, it had to be strongly lowered down relative to the wing plane. which not only complicated the design of attaching the gun to the wing (the gun was mounted on a shock absorber and moved with the magazine when firing), but also required making for it bulky fairings with a large cross-section.

IL-2 Nr 1861704 with 37-mm Sh-37 cannons on field tests of the NIP AV Air Force, September 1941.

State tests have shown that the flight data of the Il-2 with large-caliber air cannons ShFK-37, compared to the usual serial single-seat Il-2 with cannons ShVAK or VYa, significantly decreased. The aircraft has become more inert and more difficult to fly, especially in turns and turns at low altitude. Maneuverability deteriorated at high speeds. The pilots complained about significant loads on the rudders when performing maneuvers. Nevertheless, the results of flight tests of the new attack aircraft were generally found to be satisfactory.

Cannon installation Sh-37 on IL-2 AM-38 No. 1861704

During the entire time of military tests, the ShFK-37 guns worked unreliable - the average percentage of ammunition shot per failure was only 54%. That is, almost every second sortie on an IL-2 combat mission with ShFK-37 cannons was accompanied by the failure of at least one of the guns. Conducting aimed fire from one gun was almost impossible. In addition, the small margin of longitudinal stability and the complication of the technique of piloting the Il-2 aircraft with the ShFK-37 cannons, combined with the insufficient rigidity of the wing cannon installations and the strong recoil of the cannons themselves when firing, led to the fact that combat pilots in one sighting sequence could use no more than 2-3 shells. The maximum bomb load of the attack aircraft was only 200 kg. All this significantly reduced the combat value of the new attack aircraft. As a result, the installation of ShFK-37 cannons on the Il-2 aircraft did not find support from most of the combat pilots.

Sh-37 on LaGG-3 . In the process of completing the first LaGG-3 fighter with the Shpitalny cannon, it turned out that the first gun was not linked to the M-105 engine and was not assembled on the plane. With the second prototype it was easier, but it also allowed only temporary fastening, not designed for a large number of shots. And there is nothing to say about the ammunition, it was possible to shove only 21 rounds into the fighter instead of 50 according to the assignment, for which it was necessary to completely redo the cannon magazine, "stretching" it horizontally. They also had to abandon the muzzle brake in order to shorten the length of the barrel sticking out of the nose by half a meter.

Installation diagram of the Sh-37 cannon in the collapse of the M-105P engine blocks

The first cannon fighter was rebuilt from the car of factory # 23. By June 1941, 58 flights were performed on it, 54 of them with cannon firing. Until the end of 1941, plant No.21 built 20 LaGG-3s with Sh-37 guns, designated K-37, and intended for military trials. It seems that it was the K-37 unit that was first used in battles in the Moscow direction in October 1941 as part of the 43rd Air Division.

Then the powerful armament of these machines could not be fully used due to the numerous design and manufacturing defects of the artillery mount. Nevertheless, Shpitalny believed that the use of the new weapon was successful, and reported to Stalin about the destruction of five medium tanks, but kept silent that in the same month the link of fighters ceased to exist.

The total number of series 34 LaGGs with Sh-37 cannons produced was 85 vehicles. In March 1942, they took part in battles as part of the 42nd IAP on the Bryansk front, then on the West. Also LaGGs with 37-mm Shpitalny cannons was equipped with the 188th IAP, several machines were part of the 21 IAP.

In April 1942, a series of 22 Yak-7 fighters armed with a 37-mm Sh-37 cannon was produced. The Yak-7-37 passed military trials on the Northern Front at 42 IAP 240 IAD and, in any case, according to reports, proved to be quite good in air battles. 10 enemy aircraft were shot down with the loss of 7 of our own.

The production of the Sh-37 gun did not last long. Plant No. 74 in Izhevsk in 1941 produced 40 Sh-37 guns, and in 1942 another 196. After that, the production of Sh-37 was curtailed due to the adoption of the NS-37, which, although it was not devoid of shortcomings, was 100 kg lighter, used loose metal tape instead of a bulky store, had a significantly higher rate of fire.

Bibliography

• The history of air armament. /Alexander Shirokorad/
• Anti-tank armament of the KA Air Force in 1941-45: the complicated history of 37-mm aircraft cannons. /O.V. Rastrenin/