Mortar (weapon)

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Image:Soldier firing M224 60mm mortar.jpg
US soldier loading a M224 60-mm mortar.

A mortar is a muzzle-loading artillery piece that fires indirect shells (bombs in the United Kingdom) at low velocities, short ranges, and high-arcing ballistic trajectories, typically with a barrel length less than 15 times its caliber. These attributes contrast with the mortar's larger siblings, rifled howitzers and field guns, which fire at higher velocities, longer ranges, and flatter arcs. Typically a modern mortar consists of a tube into which is dropped a mortar shell (bomb) onto a firing pin resulting in the detonation of the propellant and the firing of the shell.

In the 19th and early 20th centuries very heavy immobile siege mortars were used, of up to one metre calibre.

A mortar can also be a launcher for fireworks, a hand-held or vehicle-mounted projector for smoke shells or flares, or a large grenade launcher.

Mortars are relatively simple and easy to operate artillery pieces. Light and medium mortars are man-portable, and are usually used by infantry organizations. The chief advantage a mortar section has over an artillery battery is its small size and its mobility. It is able to fire from the protection of a trench or defilade. In these aspects the mortar is an excellent infantry support weapon, as it can travel over any terrain and is not burdened by the logistical support needed for artillery.

There are also heavy mortars of 120 mm to 240 mm calibre. These are usually towed or vehicle-mounted weapons, sometimes breech-loaded, and normally employed by artillery units attached to battalion through division level. Even at this large size, mortars are simpler and less expensive than comparable howitzers or field guns.

A mortar can be carried by one or more people (larger mortars can be broken down into components), or transported in a vehicle. An infantry mortar can usually also be mounted and fired from a mortar-carrier; a purpose-built armoured vehicle with a large roof hatch. A heavy mortar can be mounted on a towed carriage, or permanently vehicle-mounted as a self-propelled mortar.

An unusual support weapon is the Soviet/Russian 2B9 Vasilek 82 mm automatic mortar, also manufactured by the People's Republic of China's Norinco as the Type W99 mortar. This is a fully-automatic weapon, capable of a high rate of fire. It can also be used in a direct fire mode, and can fire a HEAT round for use against light armoured vehicles.

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[edit] Design

Most modern mortar systems consist of three main components: a tube or barrel, a base plate, and a bipod.

Modern mortars normally range in caliber from 60 millimeters (2.36 inches) to 120 millimeters (4.72 inches) however, aberrations both larger and smaller than these specifications have been produced. An example of the smaller scale is the British 51 mm light mortar which is carried by an individual and consists of only a tube and a base plate. Conversely, a large abnormality is the Soviet 2S4 M1975 "Tyulpan" (tulip tree) 240-mm self-propelled mortar.

Smaller mortars (up to 81 mm) are commonly used and transported by infantry based mortar sections as a substitute for, or in addition to, artillery.

Ammunition for mortar systems generally come in two main varieties: fin-stabilized and spin-stabilized. The former have short fins on their posterior portion that control their path in flight. The latter use spin (similar to a thrown American Football) to balance and control the mortar shell. These rounds can either be illumination (infrared or visible illumination), smoke, or high explosive.

Spin-stabilised rounds require a rifled barrel. Since mortars on the whole are top-loaded, the mortar bomb has a pre-engraved band that engages with the rifling of the barrel. The increase in accuracy is at a cost in loading time.

Mortars came in a variety of calibres. The French 81 mm mortar became standard for many countries. The Soviets developed an ingenious tactical advantage based upon this fact. They standardized an 82 mm mortar for their armies. Hence, they could use the ammunition of other countries which they found on the battlefield in their mortars, albeit with less accuracy, while their own would be too large for their opponents. This was made use of during the Vietnam War and at other times. [citation needed]

[edit] Spigot mortar

Spigot Mortars are a particular type of mortar which utilize a (mostly) solid rod barrel or spigot, with a hollow tube in the projectile into which the spigot fits, inverting the normal tube mortar arrangement. At the top of the tube in the projectile, propellant such as gunpowder is stored in a cavity. There is usually a trigger mechanism built into the base of the spigot, with a long firing pin running up the length of the spigot activating a primer inside the projectile and firing the propellant charge.

The advantage of a spigot mortar is that the firing unit (baseplate and spigot) is smaller and lighter than an equivalent payload and ranged conventional mortar is. It is also somewhat simpler to manufacture.

The disadvantage is that additional material is required in the mortar projectile to contain the propellant gases during firing. While most mortar shells have a streamlined shape towards the back that naturally fits a spigot mortar application well, using that space for the spigot mortar tube takes volume and mass away from explosive warhead payload and fragmentation mass of the projectile. If carrying only a few projectiles, the projectile weight disadvantage is not significant. However, if used in large quantities, more weight is added in the heavier and more complex projectiles than is saved in the spigot unit, compared to a conventional mortar.

A near silent mortar can be made using the spigot principle. The round has a close fit but moveable plug in the tube that fits over the spigot. When the round is fired the projectile is pushed off the spigot as normal, but the plug is caught by a narrowing of the tube at the base. This traps the gases from the propelling charge and hence the sound of the firing. Post WW2 the silent Belgium Fly-K spigot-mortar was accepted into French service as the TN-8111.

Spigot mortars are generally out of favor in modern usage, replaced by small conventional mortars.

Military applications of spigot mortars include

  • Anti-tank launchers
    • The Blacker Bombard and PIAT antitank launcher used by Britain in WW 2 utilized a spigot mortar type launcher.
  • Anti-submarine launchers
    • The Hedgehog launcher fired a number of antisubmarine projectiles from the deck of a ship forwards, in a circular pattern. The projectiles would detonate if they struck a submarine while sinking, and the pattern was spaced so that any submarine which was partly underneath the projectile landing zone should be struck one or more times.

Nonmilitary applications include use as dummy launchers for training retriever dogs, whereby small- caliber spigot mortars are used to launch lightweight, low-velocity foam dummy targets used for training retriever hunting dogs for bird hunters. Extremely simple launchers use a separate small primer cap as the sole propellant (similar or identical to the cartridges used in industrial nailguns).

Other Advantages

An additional advantage of the mortar is its ability to place munitions in close proximity to the weapon placement due to the "lobbing" nature of the ballistics. This can also be an advantage if the attacking point of the mortar is at a lower elevation than the target. Imagine attacking a city centre with heavy resistance at 1 km with an elevation disadvantage of 30 meters (100 feet). Regular long-range artillery would not work. The lobbing effect of the mortar is the perfect solution to enemy neutralisation in this scenario.

[edit] History

Image:Edinburgh Castle Great Hall French Mortar.jpg
Georgian-era portable French Mortar.
Image:Mallet's mortar.JPG
Mallet's Mortar with 36 inch shells which would have contained 480 lb (217 kg) of gunpowder.
Image:PaixhansMonsterMortar.gif
An 1832 "Monster Mortar" invented by Henri-Joseph Paixhans.

Mortars have existed for hundreds of years, first finding usage in siege warfare. However, these weapons were huge, heavy, iron monstrosities that could not be easily transported. Simply made, these weapons were no more than an iron bowl truly reminiscent of the mortar wherefrom they drew their name. An early portable mortar was invented by Baron Menno van Coehoorn (Siege of Grave, 1674). Coehorn mortars, of approximately 180 lbs weight, were used by both sides during the American Civil War. During the Russo-Japanese War of 19041905, Leonid Gobyato for the first time applied deflection from closed firing positions in the field and designed together with General Roman Kondratenko the first mortar that fired navy shells. However, it was not until World War I and the Stokes trench mortar devised by Sir Wilfred Stokes in 1915, that the modern, man-portable mortar was born. The Germans also developed a series of trench mortars or Minenwerfer in calibres from 7.58 cm to 25 cm.

Extremely useful in the muddy trenches of Europe, mortars were praised because of their high angle of flight. A mortar round could be aimed to fall directly into trenches where artillery shells, due to their low angle of flight, could not possibly go. Modern mortars have improved upon these designs even more, offering a weapon that is light, adaptable, easy to operate, and yet possesses enough accuracy and firepower to provide the infantry with quality close fire support against soft and hard targets more quickly than any other means.

The largest mortars ever developed were the French "Monster Mortar" (developed by Henri-Joseph Paixhans in 1832), "Mallet's mortar" (developed by Woolwich Arsenal, London in 1857) and the "Little David" (developed in the United States for use in World War II). Each weapon had a caliber of 36 inches (915 mm); only the "Monster Mortar" was used in action (at the Siege of Antwerp in 1832).<ref name=Guiness>Template:Cite web</ref>


[edit] See also

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ar:هاون cs:Minomet da:Mortér de:Mörser (Geschütz) es:Mortero (arma) fr:Mortier (arme) hr:Minobacač it:Mortaio he:מרגמה nl:Mortier (wapen) ja:迫撃砲 no:Bombekaster pl:Moździerz (broń) pt:Morteiro ru:Миномёт sl:Minomet fi:Kranaatinheitin sv:Granatkastare vi:Súng cối zh:迫击炮

Mortar (weapon)

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