Tank gun

A tank gun is the main armament of a tank. Modern tank guns are large-caliber high-velocity guns, capable of firing kinetic energy penetrators, high explosive anti-tank rounds, and in some cases guided missiles.

Overview

Tank guns are a specific field of weapon design that meet the particular needs of the tank. They must provide accuracy, range, penetration, and rapid fire in a package that is as compact and lightweight as possible, to allow mounting in the cramped confines of an armored turret. As the tank's primary armament, they are almost always employed in a direct-fire mode to defeat a variety of ground targets at all ranges, including dug-in infantry, lightly-armored vehicles, and especially other heavily-armored tanks. They use self-contained ammunition, allowing rapid loading (or use of an autoloader). They often show a bulge in the barrel, which is a bore evacuator, or a device on the muzzle, which is a muzzle brake.

History

World War I

The first tanks were used to break through trench defences in support of infantry actions particularly machine gun positions during the First World War and they were fitted with machine guns or high explosive firing guns of modest calibre. These were naval or field artillery pieces stripped from their carriages and mounted in turrets or sponsons on armored vehicles. The early British Mark I tanks of 1916 utilised naval 57-mm Hotchkiss guns ("6-pounders") mounted at the sides in sponsons. These guns proved too long for use in the British tank designs as they would come into contact with obstacles and the ground on uneven terrain, and the succeeding Mark IV tank of 1917 was equipped with the shortened 6 pounder 6 cwt which can be considered the first specialised tank gun. The first German tank, the A7V, utilized a similar naval gun, the 57-mm Nordenfelt captured from Russia, but mounted at the front. The early French Schneider CA1 mounted a short 75-mm mortar on each side, while the St Chamond mounted a standard 75-mm field gun in the nose. The thin armour of the tanks meant that such weapons were effective against other vehicles, though the Germans fielded few tanks anyway and the Allied tanks concentrated on anti-infantry and infantry support activities.

World War II

This thinking remained pervasive into the dawn of World War II, when most tank guns were still modifications of existing artillery pieces, and were expected to primarily be used against unarmored targets. The larger caliber, shorter range artillery mounting didn't go away however. Tanks intended specifically for infantry support (the infantry tanks) which were expected to take out emplacements and infantry concentrations carried large calibre weapons to fire large high explosive shells -- though these could be quite effective against other vehicles at close ranges.

However, other strategists saw new roles for tanks in war, and wanted more specifically developed guns tailored to these missions. The ability to destroy enemy tanks was foremost on their minds. To this end, the emerging anti-tank gun designs were modified to fit tanks. These weapons fired smaller shells, but at higher velocities with higher accuracy, improving their performance against armor. Such light guns as the QF 2-pounder (40mm) and 37 mm equipped a number of cruiser tanks in the 1930s. These weapons lacked a good high-explosive shell for attacking infantry and fortifications, and were not powerful enough to penetrate the heaviest armor.

World War II saw a leapfrog growth in all areas of military technology. Battlefield experience led to increasingly powerful weapons being adopted. 20-40mm weapons soon gave way to 50, 75, 88 and even 90-millimetre calibre. In 1939, the standard German "panzer" had either a 20mm or 37mm medium-velocity weapon, but by 1945 88mm high-velocity guns were common. Shells were improved to provide better penetration with harder materials and scientific shaping. All of these meant improvements in accuracy and range, although the average tank had to grow as well to carry the ammunition, mounting, and protection for these powerful guns.

Many nations devised tank destroyers during the war, with the Germans re-purposing captured 76.2mm Russian field artillery and Czech tank chassis to form the potent Marder tank destroyer. A typical tank destroyer traded armor weight for a much more powerful primary armament. Some of these lacked turrets, with a limited-traverse weapon mount only.

During the Second World War, the British produced some variants of their tanks with howitzers, notably the Churchill tank which had a hull mounted gun similar to the contemporary French Char B as well as a turret gun. This was dropped as an unworkable idea and the majority of British "Close Support" (CS) tanks had their turret gun replaced with a howitzer or similar as with the Centaur CS with its 95 mm HE firing gun.

After World War II

By the end of the war the variety in tank designs was narrowed and the concept of the main battle tank emerged. After World War II, the race to increase caliber slowed. Slight increases were made between tank generations. In the West, guns of around 90 mm gave way to the ubiquitous 105 mm L7. This lasted a long while with a shift to 120 mm in the 1970s and 80s (the UK changed in the late 60s with their Chieftain tank). In the East, the 85 mm quickly yielded to the 100 mm and 115 mm gun, with the 125 mm caliber now standard. Most of the improvements were instead made in ammunition and fire control systems.

With kinetic energy penetrator rounds, solid shot and armour-piercing shell gave way to armour-piercing discarding sabot (APDS) (a product of 1944), and fin-stabilized (APFSDS) rounds with tungsten or depleted uranium penetrators. Parallel developments brought rounds based on chemical energy; High explosive squash head (HESH), and shaped-charge High explosive anti-tank (HEAT). These had the same penetrating power irrespective of muzzle velocity or range.

Stadiametric range-finders were successively replaced by coincidence and laser rangefinders. Accuracy of modern tank guns is pushed to the limits by computerized fire control systems, wind sensors, and muzzle referencing systems which compensate for barrel warping, wear and temperature. Fighting capability at night, in poor weather and smoke was improved by infrared, light-intensification, and thermal imaging equipment.

Gun technology has had only a few innovations. Throughout the history of tank guns, they have almost exclusively been rifled weapons. Rifling of the barrel imparts spin on the projectile, improving ballistic accuracy. The best traditional antitank weapons have been kinetic energy rounds, whose penetrating power and accuracy decrease with range. For longer ranges, high explosive anti-tank rounds are better, but accuracy still suffers and for extremely long ranges, anti-tank guided missiles (ATGMs) are considered to have a better chance of hitting the target.

The use of autoloaders has been a development favoured by some nations and not others. Some countries adopted it as a means to keep the overall size of the tank down. Interest has also been shown as a means to protect the crew by separating them further from the gun and ammunition.

moothbore guns

In the 1960s smoothbore tank guns were developed by the Soviet Union and by the experimental U.S.–German MBT-70 project. Based on their experience with the gun/missile system of the BMP-1, the Soviets produced the T-64B main battle tank, with an auto-loaded 125 mm smoothbore high-velocity tank gun, capable of firing APFSDS ammunition as well as ATGMs. Similar guns continue to be used in the latest Russian T-90 and Ukrainian T-84 MBTs. The German company Rheinmetall developed a more conventional 120 mm smoothbore tank gun which does not fire missiles, adopted for the Leopard 2, and later the U.S. M1 Abrams. The chief advantages of smoothbore designs are their greater suitability for fin stabilised ammunition and their greatly reduced barrel wear compared with rifled designs.

Future tank guns

The recent Russian Black Eagle prototype, shown at some arms exhibitions, reportedly can be equipped with a 152 mm tank gun.Fact|date=November 2007

The near future of the tank gun does not look likely to hold many revolutionary developments. Whereas, in the past, caliber had been limited by technological issues, now they are as large as reasonable to fit on vehicles in the size class of today's main battle tanks. Instead, the emphasis is on the electronics and the ammunition more than ever. A focus on crew survivability and technology may also lead to more tank guns with autoloaders, mounted in remote controlled turrets or on light vehicles, like the proposed Mobile Gun System.

See also

* Artillery
* Anti-tank guns
* List of artillery#Tank guns

External links

* [http://battlefield.ru/index.php?option=com_content&task=category&sectionid=6&id=33&Itemid=49&lang=en Specification and Armor Penetration Values of Soviet Tank Guns] - up to the end of World War II, at the Russian Battlefield (battlefield.ru).