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.
Mortar Information
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, 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]
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
o The Blacker Bombard and PIAT antitank launcher used by Britain in
WW 2 utilized a spigot mortar type launcher.
* Anti-submarine launchers
o 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 retriever dog training dummy
launchers. Small caliber spigot mortars are used as a launcher for
small caliber, lightweight low velocity foam dummy targets used for
training retriever hunting dogs for hunters who hunt birds.
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.
History
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).
Coehoorn mortars were used by both sides during the American Civil
War culminating with 13 inch railroad mortars. During the
Russo-Japanese War of 1904–1905, 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).