45 mm anti-aircraft gun (21-K)
Encyclopedia
The 45 mm anti-aircraft gun (21-K) was a Soviet design adapted from the 45 mm anti-tank gun M1937 (53-K). This was a copy of a 3.7 cm (1.5 in) German weapon designed by Rheinmetall
that was sold to the Soviets before Hitler
came to power in 1933 that had been enlarged to 45 mm (1.8 in) in increase its penetrating power. It was used by the Soviet Navy
to equip almost all of their ships from 1934 as its primary light anti-aircraft gun
until replaced by the fully automatic 37 mm 70-K gun from 1942 to 1943. It was used in World War II
and during the Cold War
as the Soviets exported their World War II-era ships to their friends and allies. However it was not very effective as its slow rate of fire and lack of a time fuze required a direct hit to damage targets.
automatically ejected the cartridge case and locked open, ready for the next round. This was less than ideal for an anti-aircraft weapon that relied on its rate of fire to inflict damage on aircraft because every round had to be hand-loaded. Fully automatic weapons of roughly this caliber like the 40 mm Bofors typically used 4-5 round clips of ammunition to produce rates of fire four times as high.
Early production guns had a built-up barrel, but later ones used a monobloc. There were problems with the breech mechanism early in the production run and a number of the first year's production run lacked the semi-automatic breech entirely.
special powered turrets were developed for use on river monitor
s. The 40-K was a single gun turret that weighed 2000 kg (4,409.2 lb) and the 41-K was a twin-gun turret that weighed 2600 kg (5,732 lb). Both turrets could elevate between -5° and +85° at a rate of 8 degrees per second and could traverse a full 360° at a rate between 4.8 to 9.8 degrees per second.
that would detonate the shell at a specified distance from the gun. This meant that only a direct hit would damage its target.
Rheinmetall
Rheinmetall AG is a German automotive and defence company with factories in Düsseldorf, Kassel and Unterlüß. The company has a long tradition of making guns and artillery pieces...
that was sold to the Soviets before Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...
came to power in 1933 that had been enlarged to 45 mm (1.8 in) in increase its penetrating power. It was used by the Soviet Navy
Soviet Navy
The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy would have played an instrumental role in a Warsaw Pact war with NATO, where it would have attempted to prevent naval convoys from bringing reinforcements across the Atlantic Ocean...
to equip almost all of their ships from 1934 as its primary light anti-aircraft gun
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...
until replaced by the fully automatic 37 mm 70-K gun from 1942 to 1943. It was used in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
and during the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
as the Soviets exported their World War II-era ships to their friends and allies. However it was not very effective as its slow rate of fire and lack of a time fuze required a direct hit to damage targets.
Design
The 46-caliber21-K was a very minimal adaptation of the 53-K anti-tank gun that was created by taking the latter's barrel and mounting it on a simple pedestal mount. Its semi-automatic breechBreech-loading weapon
A breech-loading weapon is a firearm in which the cartridge or shell is inserted or loaded into a chamber integral to the rear portion of a barrel....
automatically ejected the cartridge case and locked open, ready for the next round. This was less than ideal for an anti-aircraft weapon that relied on its rate of fire to inflict damage on aircraft because every round had to be hand-loaded. Fully automatic weapons of roughly this caliber like the 40 mm Bofors typically used 4-5 round clips of ammunition to produce rates of fire four times as high.
Early production guns had a built-up barrel, but later ones used a monobloc. There were problems with the breech mechanism early in the production run and a number of the first year's production run lacked the semi-automatic breech entirely.
Description
The 21-K, complete with its pedestal, weighed 507 kg (1,117.7 lb). It was manually operated and could elevate between -10° and +85° at a rate between 10 and 20 degrees per second. It could traverse a full 360° at a rate between 10 to 18 degrees per second, although this was practically limited by its actual location on ship. In the mid-1930s1930s
File:1930s decade montage.png|From left, clockwise: Dorothea Lange's photo of the homeless Florence Thompson show the effects of the Great Depression; Due to the economic collapse, the farms become dry and the Dust Bowl spreads through America; The Battle of Wuhan during the Second Sino-Japanese...
special powered turrets were developed for use on river monitor
River monitor
River monitors were heavily armored, and normally mounted the largest guns of all riverine warships. The name originated from the US Navy's Brown Water Navy's USS Monitor, which made her first appearance in the American Civil War, and being distinguished by a single revolving turret.On 18 December...
s. The 40-K was a single gun turret that weighed 2000 kg (4,409.2 lb) and the 41-K was a twin-gun turret that weighed 2600 kg (5,732 lb). Both turrets could elevate between -5° and +85° at a rate of 8 degrees per second and could traverse a full 360° at a rate between 4.8 to 9.8 degrees per second.
Ammunition
The 21-K used the same ammunition as the 45 mm anti-tank gun M1937 (53-K). The biggest problem in its role as an anti-aircraft gun was that it wasn't provided with a time fuzeFuse (explosives)
In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...
that would detonate the shell at a specified distance from the gun. This meant that only a direct hit would damage its target.
| Shell name | Type | Weight | Filling Weight | Muzzle velocity |
|---|---|---|---|---|
| BR-240 | armor-piercing Armor-piercing shot and shell An armor-piercing shell is a type of ammunition designed to penetrate armor. From the 1860s to 1950s, a major application of armor-piercing projectiles was to defeat the thick armor carried on many warships. From the 1920s onwards, armor-piercing weapons were required for anti-tank missions... |
1.42 kg (3.1 lb) | 18 g (0.634931317892015 oz) | 760 m/s (2,493.4 ft/s) |
| OT-033 | Fragmentation Fragmentation (weaponry) Fragmentation is the process by which the casing of an artillery shell, bomb, grenade, etc. is shattered by the detonating high explosive filling. The correct technical terminology for these casing pieces is fragments , although shards or splinters can be used for non-preformed fragments... -tracer Tracer ammunition Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye... |
1.065 kg (2.3 lb) | 52 g (1.8 oz) | 880 m/s (2,887.1 ft/s) |
| OR-73A | Fragmentation Fragmentation (weaponry) Fragmentation is the process by which the casing of an artillery shell, bomb, grenade, etc. is shattered by the detonating high explosive filling. The correct technical terminology for these casing pieces is fragments , although shards or splinters can be used for non-preformed fragments... -tracer Tracer ammunition Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye... |
1.41 kg (3.1 lb) | 37 g (1.3 oz) | 760 m/s (2,493.4 ft/s) |
| F-73 | High-explosive | 1.41 kg (3.1 lb) | 74 g (2.6 oz) | 760 m/s (2,493.4 ft/s) |
| O-240 | High-explosive | 2.14 kg (4.7 lb) | 118 g (4.2 oz) | 335 m/s (1,099.1 ft/s) |