40-mm anti-aircraft gun Bofors L / 60
After the end of World War I, many countries in service had 37-mm Maxim-Nordenfeldt automatic anti-aircraft guns and 40-mm Vickers automatic anti-aircraft guns.
Both systems had a similar pattern of operation of automation on the principle of using the recoil energy in the short course of the barrel.
The world's first 37-mm automatic cannon was created by the American H. S. Maxim in 1883. In general, in its design, it was an enlarged version of the widely known machine gun.
All mechanisms 37-mm machine mounted in the casing and box. The casing guided the barrel when firing and was a reservoir for the coolant, and the spring was pressed into the same fluid. The excess recoil energy is absorbed by the hydropneumatic buffer.
Used for the supply of cloth tape on 25 shells. The weight of the projectile is about 500 g. A cast-iron grenade with a ground impact tube, a canister having a 31 bullet or a remote grenade with an 8-second tube were used as projectiles. Firing Rate — 250-300 rds / min.
The Vickers machine gun was a lightweight and somewhat simplified Maxim machine with water-cooled barrel. The changes made it possible to reduce the size of the box and the weight of the machine compared to Maxim.
40-mm Vickers automatic gun
Tools of both types were used mainly in navy, which was due to the need weapons in clear water for cooling stems, significant weight (400-600 kg) and design complexity.
These machines have proven to be a very effective means Defense. The relatively powerful projectile had a good destructive effect, often the damaged aircraft fell apart in the air. Automatic fire allowed for a sufficient density of fire and sharply increased the probability of hitting the target.
Common drawbacks of automata were: the complexity and high cost of manufacture, complex cleaning and preparation for shooting, the use of cloth tape and the long path of the cartridge when feeding from the tape, low reliability.
Soon due to rapid development aviation These weapons no longer met the military's demands. More reliable and long-range weapons were needed to fire at air targets.
In the summer of 1930, Sweden began testing a new 40-mm automatic gun, which was developed by Viktor Hammar and Emmanuel Jansson, designers of the Bofors plant.
Automatic guns based on the use of recoil force according to the scheme with a short recoil of the barrel. All actions necessary for firing a shot (opening the bolt after the shot, extracting the liner, cocking the drummer, feeding the cartridges into the chamber, closing the bolt and lowering the hammer) are performed automatically. Manually carried out the aiming, pointing guns and feed clips with ammunition in the store.
The Swedish Navy showed interest in the new system. Official trials for the Swedish Navy began on March 21, 1932. Upon completion of the trials, it was named Bofors 40 mm L/60, although the barrel was actually 56,25 calibers long, not 60 as the name suggests. The 900 g high-explosive shell (40x311R) left the barrel at a speed of 850 m/s. The rate of fire was about 120 rounds/min, which increased slightly when the gun did not have high elevation angles. This was due to the fact that gravity assisted the ammunition feed mechanism. That is, the shells' own weight assisted the reloading mechanism.
The practical rate of fire was 80-100 rounds/min. The shells were loaded with 4-round clips, which were inserted manually. The gun had a practical ceiling of about 3800 m, with a range of over 7000 m.
The automatic gun was equipped with a modern sighting system for that time. The horizontal and vertical gunners had reflex sights, the third member of the crew was behind them and worked with a mechanical computer. The sight was powered by a 6V battery.
However, the recognition of the new system, as is often the case, did not happen at home. Swedish naval sailors believed that 20-25-mm were the optimal calibers for anti-aircraft guns, so they were in no hurry to order less rapid-fire 40-mm anti-aircraft guns.
The first customer of the L60 anti-aircraft guns was the Dutch fleet, which installed 5 twin installations of this type on the De Ruyter light cruiser.
Light cruiser "De Ruyter"
Later, the Dutch navy purchased several more batches of anti-aircraft guns to arm ships. The guns were mounted on a special stabilized mount developed by the Dutch company Hazemeyer. In the late 1930s, this mount was the most advanced short-range anti-aircraft weapon in the world.
The gun entered service with the Swedish Navy after testing and trial operation only in 1936. The first versions of the 40 mm guns were used on submarines. The barrel was shortened to 42 calibers, which reduced the muzzle velocity of the projectile to 700 m/s. When not in use, the barrel was raised and the gun was retracted into a watertight cylindrical case. The shortened gun was used on Sjölejonet-class submarines, where it was the only deck gun powerful enough to provide effective fire against small vessels.
In 1935, a land version of this gun appeared. It was mounted on a four-wheeled towed "cart". In case of urgent need, shooting could be conducted directly from the gun carriage, i.e. "from the wheels" without additional procedures, but with less accuracy. In normal mode, the gun carriage frame was lowered to the ground for greater stability. The transition from the "marching" position to the "combat" position took about 1 minute.
With an installation weight of about 2000 kg, its towing was possible with an ordinary truck. Calculation and ammunition while located in the back.
The gun was popular with foreign customers. The first buyer of the anti-aircraft gun was Belgium. The countries that purchased Bofors L60 anti-aircraft guns in the late 30s included: Argentina, Belgium, China, Denmark, Egypt, Estonia, Finland, France, Greece, Norway, Latvia, the Netherlands, Portugal, Great Britain, Thailand and Yugoslavia.
The Bofors L60 was produced under license in Belgium, Finland, France, Hungary, Norway, Poland and the United Kingdom. The Bofors L60 was also produced in significant quantities in Canada and the United States. More than 100 Bofors 40mm anti-aircraft guns had been manufactured worldwide by the end of World War II.
Anti-aircraft 40-mm guns produced in different countries were adapted to local conditions of production and use. Components and parts of guns of different "nationalities" were often not interchangeable.
The greatest difference from the "original" was in the British-made anti-aircraft guns. The British did a great job of simplifying and reducing the cost of the guns. To speed up targeting of fast-moving and diving aircraft, the British used the mechanical analog computer of Major Kerrison (AV Kerrison), which became the first automatic anti-aircraft fire control system.
Kerrison Mechanical Analog Calculator
Kerrison's device was a mechanical calculating and solving device that allowed the gun's aiming angles to be determined based on data on the target's position and movement, the ballistic parameters of the gun and ammunition, as well as wind speed and other external conditions. The resulting aiming angles were automatically transmitted to the gun's aiming mechanisms using servomotors.
A three-man crew, receiving data from this device, aimed the gun quite easily and with good accuracy. When using this device, the computer controlled the gun's aiming, and the crew only had to load the gun and fire. The original reflector sights were replaced by simpler ring anti-aircraft sights, which were used as backups.
In this modification, the QF 40 mm Mark III gun became the army's standard light anti-aircraft gun. This British 40 mm anti-aircraft gun had the most advanced sighting devices of the entire Bofors family.
However, in combat it was discovered that the use of the Kerrison device in some situations was not always possible, and in addition, it required a supply of fuel, which was used to power the electric generator. Because of this, in most cases, when shooting, only conventional ring sights were most often used, without using any target designation and calculations of corrections for lead, which greatly reduced the accuracy of shooting. Taking into account combat experience, in 1943 a simple trapezoidal device Stiffkey was developed, which moved the ring sights to introduce corrections during shooting and was controlled by one of the anti-aircraft gunners.
The British and Americans using the Bofors L60 created a series of ZSU. Open turret anti-aircraft guns mounted on a chassis tank Crusader. This self-propelled anti-aircraft gun was called Crusader III AA Mark I.
ZSU Crusader III AA Mark I
However, the most widespread British 40mm ZSU was the "Carrier, SP, 4x4 40mm, AA 30cwt", created by mounting an anti-aircraft gun on the chassis of a regular four-wheeled Morris truck.
Self-propelled gun "Carrier, SP, 4x4 40 mm, AA 30cwt"
In the USA, Bofors were mounted on modified 2,5 t GMC CCKW-353 truck chassis.
These self-propelled units were used to support the ground forces and provide quick protection against air attacks without the need for stationary installation on the ground and deployment of the system into a combat position.
After the fall of Holland in 1940, part of the Dutch fleet went to the UK, and the British had the opportunity to familiarize themselves in detail with the Hazmeyer marine installations. 40-mm Hazmemeier Dutch naval anti-aircraft installations differed favorably in combat and service performance from the British 40-mm "pom-pom" company "Vikkers".
Firing 40-mm Vickers anti-aircraft guns
In 1942, Great Britain began its own production of such installations. Unlike "land" anti-aircraft guns, most naval guns were water-cooled.
For the American and British fleets, a large number of one, two, four, and six-barreled anti-aircraft guns, including radar-guided ones, were developed.
In the US Navy, this weapon is considered to be the best anti-aircraft gun of the Second World War, 40-mm anti-aircraft guns were the most effective against Japanese kamikaze aircraft. As a rule, one direct hit of an 40-mm fragmentation projectile was enough to destroy any Japanese aircraft used as a “flying bomb”.
The effective range of 40-mm anti-aircraft guns was twice as high as that of 12,7-mm machine guns and 20-mm anti-aircraft guns.
By the end of the war, the Bofors had almost completely replaced the 20mm Oerlikon automatic cannons on large warships.
Despite the fact that Germany had its own anti-aircraft 37-mm automatic machine "Rheinmetall", 40-mm Bofors L60 were actively used in the armed forces of Germany and its allies.
Captured Bofors tanks captured in Poland, Norway, Denmark and France were used by the Germans under the designation 4-cm/56 Flak 28.
Abandoned Polish 40-mm Bofors L60 anti-aircraft gun against the background of a crushed column
A number of these Norwegian-made guns were used on submarines and on the cruisers Admiral Hipper and Prinz Eugen.
In Finland and Hungary, these tools were manufactured under license and used throughout the war.
Finnish 40mm Bofors L60 automatic anti-aircraft gun on an armored train
In Japan, an attempt was made to launch the Bofors L60 into serial production after several British air-cooled installations were captured in Singapore. The Japanese anti-aircraft gun was designated 4 cm / 60 Type 5, but it was not produced in significant quantities due to the weakness of the production base.
But the most massive copy of the Bofors L60 was the Soviet "37-mm automatic anti-aircraft gun mod. 1939 G. ”also known as 61-K.
After the failure of an attempt to launch mass serial production at the Kalinin Plant (No. 8) near Moscow of the German 37-mm automatic anti-aircraft gun "Rheinmetall", due to the urgent need for such an anti-aircraft gun, it was decided at the highest level to create an anti-aircraft machine gun based on the Swedish system, which by that time had received worldwide recognition.
37-mm automatic anti-aircraft gun obr. 1939
The gun was created under the supervision of M. N. Loginov and in 1939 was accepted into service under the official designation "37-mm automatic anti-aircraft gun mod. 1939".
According to the gun service manual, its main task was recognized as combating air targets at ranges of up to 4 km and at altitudes of up to 3 km. If necessary, the gun can also be used to fire at ground targets, including tanks and armored vehicles.
Its introduction into production was accompanied by great difficulties, the percentage of defects was high. Before the war, about 1500 37-mm anti-aircraft guns were manufactured. However, their quality left much to be desired, delays and failures during firing were very frequent.
On 22 June 1941, the Red Army had an 1214 "37-mm automatic anti-aircraft guns arr. 1939 g. During the 1941 battle of the year, anti-aircraft guns suffered significant losses - until 1 September 1941, the 841 gun was lost, and in just 1941 a year - 1204 guns. Huge losses were hardly compensated by production - on 1 January 1942, there was about 1600 37-mm 61-K anti-aircraft guns available.
In the initial period of the war, 37-mm anti-aircraft guns were supplied to artillery anti-tank defense brigades and anti-tank regiments as a standard weapon for fighting tanks. In 1941, 320 37-mm anti-aircraft guns were sent to fighter-anti-tank units. In 1942, anti-aircraft guns were removed from anti-tank artillery.
A significant amount of 61-K was captured as trophies by German troops. In the Wehrmacht, these guns got the 3,7 cm Flak 39 (r) index and were used in battles - so, by January 1944, the troops had 390 of such guns.
37-mm automatic anti-aircraft gun 61-К captured by the Germans
During the war, the USSR was supplied with 40 mm Bofors L60 by the Allies in large quantities. In terms of its ballistic characteristics, the 40 mm Bofors gun was slightly superior to the 61-K - it fired a slightly heavier projectile at a similar muzzle velocity. In 1940, comparative tests of the Bofors and 61-K were conducted in the USSR, and based on their results, the commission noted the approximate equivalence of the guns.
61-K during the Great Patriotic War were the main means of air defense of the Soviet troops in the front line. The tactical and technical characteristics of the gun allowed it to effectively deal with the enemy’s front-line aviation, but until 1944, the troops experienced an acute shortage of automatic anti-aircraft guns. Only at the end of the war our troops were adequately covered from air strikes. On 1, January 1945, there were about 19 800 61-K guns and Bofors L60.
After the end of World War II, 37-mm anti-aircraft guns 61-K and 40-mm Bofors L60 participated in many armed conflicts, in a number of countries they are still in service.
In the US, the Bofors L40 60-mm assault rifle is used on Lockheed AC-130 "ganships" for firing at ground targets.
Reloading 40-mm Bofors L60 guns on board AC-130
These anti-aircraft guns became the most "belligerent" they for all the years of use were shot down more aircraft than all the other combined anti-aircraft guns.
A further development of the Bofors L60 system was the 40 mm Bofors L70 anti-aircraft mount, which uses a more powerful 40 × 364R round with a slightly lighter projectile weighing 870 g, which increased the muzzle velocity to 1030 m/s.
40-mm Bofors L70
In addition, the gun carriage and recoil mechanism was redone. The first copy of the new weapon was made in 1947 year. In November, 1953, this gun was adopted as a standard NATO anti-aircraft gun, and soon it began to be produced in thousands of series.
Over the years of production, several versions of this anti-aircraft gun were created, which differed in the power supply scheme and sighting devices. The latest modifications of this gun had a rate of fire of 330 rounds per minute.
In addition to the towed anti-aircraft gun itself, the Bofors L70 was used in the self-propelled anti-aircraft units: VEAK-4062 and M247 Sergeant York.
Over the years of production, several versions of this anti-aircraft gun were created, which differed in the power supply scheme and sighting devices. The latest modifications of this gun had a rate of fire of 330 rounds per minute.
In addition to the towed anti-aircraft gun itself, the Bofors L70 was used in the self-propelled anti-aircraft units: VEAK-4062 and M247 Sergeant York.
ZSU M247 Sergeant York
In the Swedish army, this weapon is armed with the CV9040 infantry fighting vehicle, in order to place it in the tower it was necessary to turn the weapon "upside down". Under this weapon, developed new ammunition, including: subcaliber and fragmentation with remote blasting.
BMP CV9040
The Bofors L/70 is used as the main gun on the South Korean K21 IFV.
BMP K21
The Bofors L/70 gun is also still used in various naval installations to arm patrol and missile boats and combat vessels of small displacement.
The most modern of those using the L/70 artillery unit is the Italian Dardo anti-missile and anti-aircraft defense system (manufactured by Oto Melara), designed for ship anti-missile and anti-aircraft defense.
High-explosive fragmentation projectiles with ready striking elements in the form of 600 tungsten balls and a non-contact fuse are used for firing at PKR.
Many years later, the technical solutions implemented in the 40-mm gun of the Swedish company Bofors in the 30s are still being used effectively today. There is no doubt that this system will celebrate its centenary in service.
Information sources:
http://www.thetankmaster.com/artilleryr.asp
http://www.navweaps.com/Weapons/WNUS_4cm-56_mk12.htm
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