Military vehicle

Military vehicle

A military vehicle is a vehicle that includes all land combat and transportation vehicles, which are designed for or are in significant use by military forces throughout the world. Vehicles that are armored or intended for combat are often referred to as armoured fighting vehicles....

s are commonly armoured (or armored) to withstand the impact of shrapnel

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...

, bullet

Bullet

A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

s, missile

Missile

Though a missile may be any thrown or launched object, it colloquially almost always refers to a self-propelled guided weapon system.-Etymology:The word missile comes from the Latin verb mittere, meaning "to send"...

s, or shell

Shell (projectile)

A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

s, protecting the personnel inside from enemy fire. Such vehicles include tank

Tank

A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

s, aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

, and ships.

Civilian vehicles may also be armoured. These vehicles include cars used by reporters, official

Official

An official is someone who holds an office in an organization or government and participates in the exercise of authority .A government official or functionary is an official who is involved in public...

s and others in conflict zones or where violent crime is common, and president

President

A president is a leader of an organization, company, trade union, university, or country.Etymologically, a president is one who presides, who sits in leadership...

ial limousine

Limousine

A limousine is a luxury sedan or saloon car, especially one with a lengthened wheelbase or driven by a chauffeur. The chassis of a limousine may have been extended by the manufacturer or by an independent coachbuilder. These are called "stretch" limousines and are traditionally black or white....

s. Armoured car

Armored car (valuables)

A common meaning of armored car is as an armored van or truck, used in transporting valuables, such as large quantities of money . The armored car is a multifunctional vehicle designed to protect and ensure the well being of the transported individuals and/or contents...

s are also routinely used by security firms to carry money or valuables to reduce the risk of highway

Highway

A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...

 robbery

Robbery

Robbery is the crime of taking or attempting to take something of value by force or threat of force or by putting the victim in fear. At common law, robbery is defined as taking the property of another, with the intent to permanently deprive the person of that property, by means of force or fear....

 or the hijacking

Carjacking

Carjacking is a form of hijacking, where the crime is of stealing a motor vehicle and so also armed assault when the vehicle is occupied. Historically, such as in the rash of semi-trailer truck hijackings during the 1960s, the general term hijacking was used for that type of vehicle abduction,...

 of the cargo.

Armour may also be used in vehicles to protect from threats other than a deliberate attack. Some spacecraft

Spacecraft

A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

 are equipped with specialised armour to protect them against impacts from micrometeoroid

Micrometeoroid

A micrometeoroid is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram. A micrometeor or micrometeorite is such a particle that enters the Earth's atmosphere or falls to Earth.-Scientific interest:...

s or fragments of space junk. Modern aircraft powered by turbine engines usually have them fitted with a sort of armour in the form of an aramid composite kevlar

Kevlar

Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...

 bandage around the fan casing or of debris containment walls built into the casing of their gas turbine

Gas turbine

A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....

 engines to prevent injuries or airframe

Airframe

The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...

 damage should the fan/compressor/turbine wheel disintegrate.

The design

Design

Design as a noun informally refers to a plan or convention for the construction of an object or a system while “to design” refers to making this plan...

 and purpose of the vehicle determines the amount of armour plating carried, as the plating is often very heavy and excessive amounts of armour restrict mobility. In order to decrease this problem, some new materials (nanomaterials) and material compositions are being researched which include buckypaper

Buckypaper

Buckypaper is a thin sheet made from an aggregate of carbon nanotubes. The nanotubes are approximately 50,000 times thinner than a human hair. Originally, it was fabricated as a way to handle carbon nanotubes, but it is also being studied and developed into applications by several research groups,...

, aluminium foam armour plates, ...

Steel

Rolled homogeneous armour

Rolled homogeneous armour

Rolled homogeneous armour is a type of steel which is used to armour vehicles.-Composition:Armoured steel must be hard yet impervious to shock in order to resist high velocity metal projectiles. Steel with these characteristics is produced by processing cast steel billets of appropriate size and...

is strong, hard, and tough (does not shatter when struck with a fast, hard blow). Steel with these characteristics is produced by processing cast steel billets of appropriate size and then rolling them into plates of required thickness. Rolling and forging (hammering the steel when it is red hot) irons out the grain structure in the steel, removing imperfections which would reduce the strength of the steel. Rolling also elongates the grain structure in the steel to form long lines, which enable the stress the steel is placed under when loaded to flow throughout the metal, and not be concentrated in one area.

Aluminium

Aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

is used when light weight is a necessity. It is most commonly used on APCs and armoured cars.

Iron

Wrought iron

Iron armour

Iron armour was a type of armour used on ironclad warships. The earliest material available in sufficient quantities for armouring ships was iron, wrought or cast. The use of iron gave rise to the term ironclad as a reference to a ship 'clad' in iron....

was used on ironclad warship

Ironclad warship

An ironclad was a steam-propelled warship in the early part of the second half of the 19th century, protected by iron or steel armor plates. The ironclad was developed as a result of the vulnerability of wooden warships to explosive or incendiary shells. The first ironclad battleship, La Gloire,...

s. Early European iron armour consisted of 10 to 13 cm of wrought iron backed by up to one meter of solid wood

Wood

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

.

Titanium

Titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

has not seen much use due to its expense. It is however considered to be superior to most other metal armour types. However, some notable examples of its use include USAF A-10 Thunderbolt II

A-10 Thunderbolt II

The Fairchild Republic A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support for ground forces by attacking tanks,...

 and the Soviet/Russian-built Sukhoi Su-25

Sukhoi Su-25

The Sukhoi Su-25 is a single-seat, twin-engine jet aircraft developed in the Soviet Union by the Sukhoi Design Bureau. It was designed to provide close air support for the Soviet Ground Forces. The first prototype made its maiden flight on 22 February 1975...

 ground-attack aircraft, utilizing a bathtub-shaped titanium enclosure for the pilot, as well as the Soviet/Russian Mil Mi-24

Mil Mi-24

The Mil Mi-24 is a large helicopter gunship and attack helicopter and low-capacity troop transport with room for 8 passengers. It is produced by Mil Moscow Helicopter Plant and operated since 1972 by the Soviet Air Force, its successors, and by over thirty other nations.In NATO circles the export...

 attack helicopter.

Uranium

Because of its high density, depleted uranium

Depleted uranium

Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...

 can also be used in tank armour, sandwiched between sheets of steel armour plate. For instance, some late-production M1A1HA and M1A2 Abrams

M1 Abrams

The M1 Abrams is a third-generation main battle tank produced in the United States. It is named after General Creighton Abrams, former Army Chief of Staff and Commander of US military forces in Vietnam from 1968 to 1972. The M1 is a well armed, heavily armored, and highly mobile tank designed for...

 tanks built after 1998 have DU reinforcement as part of the armour plating in the front of the hull and the front of the turret, and there is a program to upgrade the rest (see Chobham armour).

Plastic

Plastic metal, was a type of vehicle armour originally developed for merchant ships by the British Admiralty in 1940. The original composition was described as 50% clean granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 of half-inch size, 43% of limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 mineral, and 7% of bitumen. It was typically applied in a layer two inches thick and backed by half an inch of steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

.

Plastic armour was highly effective at stopping armour piercing bullets because the hard granite particles would deflect the bullet which would then lodge between plastic armour and the steel backing plate. Plastic armour could be applied by pouring it into a cavity formed by the steel backing plate and a temporary wooden form.

Glass

Bulletproof glass is a colloquial term for glass

Glass

Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

 that is particularly resistant to being penetrated when struck by bullet

Bullet

A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

s. The industry generally refers to it as bullet-resistant glass or transparent armour.

Bullet-resistant glass is usually constructed using a strong but transparent material such as polycarbonate

Polycarbonate

PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...

 thermoplastic

Thermoplastic

Thermoplastic, also known as a thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently...

 or by using layers of laminated glass

Laminated glass

Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral , between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high...

. The desired result is a material with an appearance and light-transmitting behaviour of standard glass but offers varying degrees of protection from small arms

Small arms

Small arms is a term of art used by armed forces to denote infantry weapons an individual soldier may carry. The description is usually limited to revolvers, pistols, submachine guns, carbines, assault rifles, battle rifles, multiple barrel firearms, sniper rifles, squad automatic weapons, light...

 fire.

The polycarbonate layer, usually consisting of products such as Armormax, Makroclear

Makroclear

Makroclear is a brand of solid polycarbonate plastic sheet ranging from 0.75 to 15 mm thickness.Polycarbonate is seen as the toughest transparent material...

, Cyrolon, Lexan

Lexan

Lexan is a registered trademark for SABIC Innovative Plastics' brand of polycarbonate resin thermoplastic. Polycarbonate polymer is produced by reacting bisphenol A with carbonyl dichloride, also known as phosgene. Lexan is the brand name for polycarbonate sheet and resin in a wide range of grades...

 or Tuffak, is often sandwiched between layers of regular glass. The use of plastic in the laminate provides impact-resistance, such as physical assault with a hammer, an axe, etc. The plastic provides little in the way of bullet-resistance. The glass, which is much harder than plastic, flattens the bullet and thereby prevents penetration. This type of bullet-resistant glass is usually 70–75 mm (2.8–3.0 in) thick.

Bullet-resistant glass constructed of laminated glass layers is built from glass sheets bonded together with polyvinyl butyral

Polyvinyl butyral

Polyvinyl butyral is a resin usually used for applications that require strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility. It is prepared from polyvinyl alcohol by reaction with butyraldehyde. The major application is laminated safety glass for automobile...

, polyurethane

Polyurethane

A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

 or ethylene-vinyl acetate

Ethylene-vinyl acetate

Ethylene vinyl acetate is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene....

. This type of bullet-resistant glass has been in regular use on combat vehicles since 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...

; it is typically about 100–120 mm (3.9–4.7 in) thick and is usually extremely heavy.

Ceramic

Ceramic

Ceramic

A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

's precise mechanism for defeating HEAT

High explosive anti-tank

High explosive anti-tank warheads are made of an explosive shaped charge that uses the Munroe effect to create a very high-velocity partial stream of metal in a state of superplasticity that can punch through solid armor....

 was uncovered in the 1980s. High speed photography showed that the ceramic material shatters as the HEAT round penetrates, the highly energetic fragments destroying the geometry of the metal jet generated by the hollow charge, greatly diminishing the penetration.

Composite

Composite armour is armour consisting of layers of two or more materials with significantly different chemical properties; steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 and ceramic

Ceramic

A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

s are the most common types of material in composite armour. Composite armour was initially developed in the 1940s, although it did not enter service until much later and the early examples are often ignored in the face of newer armour such as Chobham armour

Chobham armour

Chobham armour is the name informally given to a composite armour developed in the 1960s at the British tank research centre on Chobham Common, Surrey, England...

. Composite armour's effectiveness depends on its composition and may be effective against kinetic energy penetrator

Kinetic energy penetrator

A kinetic energy penetrator is a type of ammunition which, like a bullet, does not contain explosives and uses kinetic energy to penetrate the target....

s as well as shaped charge

Shaped charge

A shaped charge is an explosive charge shaped to focus the effect of the explosive's energy. Various types are used to cut and form metal, to initiate nuclear weapons, to penetrate armor, and in the oil and gas industry...

 munitions; heavy metals

Heavy metals

A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...

 are sometimes included specifically for protection from kinetic energy penetrators.

Ships

Belt armour

Belt armor

Belt armor is a layer of heavy metal armor plated on to or within outer hulls of warships, typically on battleships, battlecruisers and cruisers, and on aircraft carriers converted from those types of ships....

 is a layer of armour

Armour

Armour or armor is protective covering used to prevent damage from being inflicted to an object, individual or a vehicle through use of direct contact weapons or projectiles, usually during combat, or from damage caused by a potentially dangerous environment or action...

-plating outside the hull of warships, typically on battleships, battlecruisers, cruiser

Cruiser

A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...

s and some aircraft carrier

Aircraft carrier

An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

s.

Typically the belt covered from the deck down someway below the waterline

Waterline

The term "waterline" generally refers to the line where the hull of a ship meets the water surface. It is also the name of a special marking, also known as the national Load Line or Plimsoll Line, to be positioned amidships, that indicates the draft of the ship and the legal limit to which a ship...

 of the ship. If built within the hull, rather than forming the outer hull it could be fitted at an inclined angle to improve the protection.

When struck by a shell

Shell (projectile)

A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

 or torpedo

Torpedo

The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

, the belt armour is designed to prevent penetration, by either being too thick for the warhead to penetrate, or sloped to a degree that would deflect the shell or torpedo. Often, the main belt armour was supplemented with a torpedo bulkhead

Torpedo bulkhead

A torpedo bulkhead is a type of armor common on the more heavily armored warships, especially battleships and battlecruisers of the early 20th century. It is designed to keep the ship afloat even if the hull was struck underneath the belt armor by a shell or by a torpedo...

 spaced several meters behind the main belt, designed to maintain the ship's watertight integrity even if the main belt were penetrated.

The air-space between the belt and the hull also adds buoyancy

Buoyancy

In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

. Several wartime vessels had belt armour that was thinner or shallower than was desirable, to speed production and conserve resources.

Aircraft

Armour plating is usually not very common on aircraft, which generally rely on their speed and manoeuvrability to avoid ground fire, rather than trying to resist impacts. Additionally, any armour capable of stopping large-calibre antiaircraft fire or missile fragments would be simply too heavy and overtax the powerplant. Still, this is one area where titanium is used extensively as armour plating. For example, in the USAF A-10 Thunderbolt II

A-10 Thunderbolt II

The Fairchild Republic A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support for ground forces by attacking tanks,...

 ground-attack aircraft and the Soviet-built Sukhoi Su-25

Sukhoi Su-25

The Sukhoi Su-25 is a single-seat, twin-engine jet aircraft developed in the Soviet Union by the Sukhoi Design Bureau. It was designed to provide close air support for the Soviet Ground Forces. The first prototype made its maiden flight on 22 February 1975...

 Frogfoot ground attack jet, as well as the Mil Mi-24

Mil Mi-24

The Mil Mi-24 is a large helicopter gunship and attack helicopter and low-capacity troop transport with room for 8 passengers. It is produced by Mil Moscow Helicopter Plant and operated since 1972 by the Soviet Air Force, its successors, and by over thirty other nations.In NATO circles the export...

 Hind ground-attack helicopter, the pilot sits in a titanium enclosure known as the "bathtub" for its shape. In addition, larger aircraft's cockpit glazing is generally made of impact-resistant, laminated materials, even on civilian craft, to prevent damage from striking birds or other debris.

Armoured fighting vehicles

The most heavily armoured vehicles today are the main battle tank

Main battle tank

A main battle tank , also known as a battle tank or universal tank, is a tank that fills the heavy direct fire role of many modern armies. They were originally conceived to replace the light, medium, heavy and super-heavy tanks. Development was spurred onwards in the Cold War with the development...

s, which are the spearhead of the ground forces, and are designed to withstand anti-tank missiles, kinetic energy penetrator

Kinetic energy penetrator

A kinetic energy penetrator is a type of ammunition which, like a bullet, does not contain explosives and uses kinetic energy to penetrate the target....

s, NBC threats and in some tanks even steep-trajectory shells. The Israel

Israel

The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

i Merkava

Merkava

The Merkava is a main battle tank used by the Israel Defense Forces. The tank began development in 1974 and was first introduced in 1978. Four main versions of the tank have been deployed. It was first used extensively in the 1982 Lebanon War...

 tanks were designed in a way that each tank component functions as additional back-up armour to protect the crew. Outer armour is modular and enables quick replacement of damaged armour.

Technologies

For efficiency, the heaviest armour on an armoured fighting vehicle

Armoured fighting vehicle

An armoured fighting vehicle is a combat vehicle, protected by strong armour and armed with weapons. AFVs can be wheeled or tracked....

 (AFV) is placed on its front. Tank tactics require the vehicle to always face the likely direction of enemy fire as much as possible, even in defence or withdrawal

Withdrawal (military)

A withdrawal is a type of military operation, generally meaning retreating forces back while maintaining contact with the enemy. A withdrawal may be undertaken as part of a general retreat, to consolidate forces, to occupy ground that is more easily defended, or to lead the enemy into an ambush...

 operations.

Sloping

Sloped armour

Sloped armour is armour that is neither in a vertical nor a horizontal position. Such "angled" armour is often mounted on tanks and other armoured fighting vehicles...

 and curving armour can both increase its protection. Given a fixed thickness of armour plate, a projectile striking at an angle

Angle

In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...

 must penetrate more armour than one impacting perpendicular

Perpendicular

In geometry, two lines or planes are considered perpendicular to each other if they form congruent adjacent angles . The term may be used as a noun or adjective...

ly. An angled surface also increases the chance of deflecting a projectile. This can be seen on v-hull

V-hull

The V-hull is a type of vehicle armor design used on wheeled armored personnel carriers , infantry mobility vehicles and infantry fighting vehicles...

 designs, which direct the force of an Improvised explosive device

Improvised explosive device

An improvised explosive device , also known as a roadside bomb, is a homemade bomb constructed and deployed in ways other than in conventional military action...

 or landmine away from the crew compartment, increasing crew survivability

Survivability

Survivability is the ability to remain alive or continue to exist. The term has more specific meaning in certain contexts.-Engineering:In engineering, survivability is the quantified ability of a system, subsystem, equipment, process, or procedure to continue to function during and after a natural...

.

Beginning during the Cold War, many AFVs have spall liners inside of the armour, designed to protect crew and equipment inside from fragmentation (spalling) released from the impact of enemy shells, especially high explosive squash head

High explosive squash head

High explosive squash head is a type of explosive ammunition that is effective against buildings and is also used against tank armour. It was fielded chiefly by the British Army as the main explosive round of its main battle tanks during the Cold War...

 warheads. Spall liners are made of Kevlar

Kevlar

Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...

, Dyneema or similar materials.

Appliqué armour

Appliqué armour consists of extra plates mounted onto the hull or turret of an AFV. The plates can be made of any material and are designed to be retrofitted to an AFV to withstand weapons which can penetrate the original armour of the vehicle.

Improvised armour

Vehicle armour is sometimes improvised in the midst of an armed conflict by vehicle crews or individual units. 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...

, U.S. tank crews welded spare strips of tank track to the hulls of their Sherman

M4 Sherman

The M4 Sherman, formally Medium Tank, M4, was the primary tank used by the United States during World War II. Thousands were also distributed to the Allies, including the British Commonwealth and Soviet armies, via lend-lease...

, Lee

M3 Lee

The Medium Tank M3 was an American tank used during World War II. In Britain the tank was called "General Lee", named after Confederate General Robert E. Lee, and the modified version built with a new turret was called the "General Grant", named after U.S. General Ulysses S. Grant.Design commenced...

, and Stuart tank

Stuart tank

The M3 Stuart, formally Light Tank M3, was an American light tank of World War II and supplied to British and Commonwealth forces under lend-lease prior to the entry of the U.S. into the war—and used thereafter by U.S...

s. In the Vietnam War

Vietnam War

The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

, U.S. "gun truck

Gun truck

A military gun truck is an improvised fighting vehicle used by units of regular armies or other official government armed forces, based on a conventional cargo truck, that is able to carry a large weight of weapons and armor...

s" were armoured with sandbags and locally fabricated steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 armour plate. More recently, U.S. troops in Iraq armoured Humvees and various military transport vehicles with scrap materials: this came to be known as "hillbilly armor" or "haji armor" by the Americans.

Spaced armour

Armour with two or more plates spaced a distance apart, called spaced armour, when sloped reduces the penetrating power of bullets and solid shot as after penetrating each plate they tend to tumble, deflect, deform, or disintegrate, when not sloped reduces the protection offered by the armour, and detonates explosive projectiles before they reach the inner plates. It has been in use since the First World War, where it was used on the Schneider CA1

Schneider CA1

The Schneider CA1 was the first French tank. It was inspired by the need to overcome the stalemate of the trench warfare of the Great War.-Caterpillar development:...

 and St Chamond

St Chamond (tank)

The Saint-Chamond was the second French heavy tank of the First World War.Overall an inadequate design born of commercial rivalry, the war ended before it was replaced by British heavy tanks.-Development:...

 tanks. Many middle and late-World War II German tanks had spaced armour in the form of armoured skirts, to make their thinner side armour more effective against anti-tank fire.

The principle of spaced armour protects against high explosive anti-tank

High explosive anti-tank

High explosive anti-tank warheads are made of an explosive shaped charge that uses the Munroe effect to create a very high-velocity partial stream of metal in a state of superplasticity that can punch through solid armor....

 (HEAT) projectiles which create a focus

Focus

Focus, FOCUS, or foci may refer to:In science, mathematics or computing:*Focus , selectively concentrating on one aspect of the environment while ignoring other things...

ed jet of plasticised metal, very effective at the focus point, but much less so beyond there. Relatively thin armour plates or even metal mesh, much lighter than fully protective armour, can be attached as side skirts or turret skirts on tanks and other armoured vehicles. This light armour detonates the warhead prematurely so that the jet of molten metal is focussed well before the main armour, becoming relatively ineffective. Factory-made and improvised stand-off armour was introduced in the Second World War to defend against the new Bazooka

Bazooka

Bazooka is the common name for a man-portable recoilless rocket antitank weapon, widely fielded by the U.S. Army. Also referred to as the "Stovepipe", the innovative bazooka was amongst the first-generation of rocket propelled anti-tank weapons used in infantry combat...

, Panzerfaust

Panzerfaust

The Panzerfaust was an inexpensive, recoilless German anti-tank weapon of World War II. It consisted of a small, disposable preloaded launch tube firing a high explosive anti-tank warhead, operated by a single soldier...

, and other HEAT weapons.

In response to increasingly effective HEAT warheads, integral spaced armour was reintroduced in the 1960s on the German Leopard 1. There are hollow spaces inside this type of armour, increasing the length of travel from the exterior of the vehicle to the interior for a given weight of armour, to reduce the shaped charge's penetrating power. Sometimes the interior surfaces of these hollow cavities are sloped, presenting angles to the anticipated path of the shaped charge's jet in order to further dissipate its power. For example, a given weight of armour can be distributed in 2 layers 15 cm (6 inch) thick instead of a single 30 cm (12 in) layer, giving much better protection against shaped charges.

Adding space between the armour plates increases the total volume covered by the armour, which by the Square-cube law

Square-cube law

The square-cube law is a principle, drawn from the mathematics of proportion, that is applied in engineering and biomechanics. It was first demonstrated in 1638 in Galileo's Two New Sciences...

 increases the amount of armour needed for a given thickness by around the 2/3 power of the total volume. Also thinner sheets of armour can be more subject to damage by kinetic weapons than a single thicker layer of armour would be.

Today light armoured vehicles mount panels of metal rods, known as slat armour or cage armour, and some main battle tanks carry rubber skirts to protect their relatively fragile suspension and front belly armour.

The Whipple shield

Whipple shield

The Whipple shield or Whipple bumper, invented by Fred Whipple, is a type of hypervelocity impact shield used to protect manned and unmanned spacecraft from collisions with micrometeoroids and orbital debris whose velocities generally range between ....

 uses the principle of spaced armour to protect spacecraft from the impacts of very fast micrometeoroid

Micrometeoroid

A micrometeoroid is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram. A micrometeor or micrometeorite is such a particle that enters the Earth's atmosphere or falls to Earth.-Scientific interest:...

s. The impact with the first wall melts or breaks up the incoming particle, causing fragments to be spread over a wider area when striking the subsequent walls.

Sloped armour

Sloped armour is armour that is mounted at a non-vertical and non-horizontal angle, typically on tanks and other armoured fighting vehicles. For a given normal to the surface of the armour, its plate thickness, increasing armour slope improves the armour's level of protection by increasing the thickness measured on a horizontal plane, while for a given area density of the armour the protection can be either increased or reduced by other sloping effects, depending on the armour materials used and the qualities of the projectile hitting it. The increased protection caused by increasing the slope while keeping the plate thickness constant, is due to a proportional increase of area density and thus mass, and thus offers no weight benefit. Therefore the other possible effects of sloping, such as deflection, deforming and ricochet of a projectile, have been the reasons to apply sloped armour in armoured vehicles design. Another motive is the fact that sloping armour is a more efficient way of covering the necessary equipment since it encloses less volume with less material. The sharpest angles are usually seen on the frontal glacis plate, both as it is the hull side most likely to be hit and because there is more room to slope in the longitudinal direction of a vehicle.

Reactive armour

Explosive reactive armour, initially developed by German researcher Manfred Held while working in Israel, uses layers of high explosive sandwiched between steel plates. When a shaped-charge warhead hits, the explosive detonates

Detonation

Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

 and pushes the steel plates into the warhead, disrupting the flow of the charge's liquid metal penetrator (usually copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 at around 500 degrees Celsius; it can be made to flow like water by sufficient pressure). Traditional "soft" ERA is less effective against kinetic penetrators. "Hard" reactive armour, however, offers better protection. The only example currently in widespread service is Russian Kontakt-5

Kontakt-5

Kontakt-5 is a type of third-generation explosive reactive armour originating in the Soviet Union. It is the first type of ERA which is effectively able to defeat modern armour-piercing fin-stabilized discarding sabot rounds....

. Reactive armour poses a threat to friendly troops near the vehicle.

Non-explosive reactive armour is an advanced spaced armour which uses materials which change their geometry so as to increase protection under the stress of impact.

Active protection system

Active protection system

An active protection system is a system designed to prevent sensor-based weapons from acquiring and/or destroying a target....

s use a sensor to detect an incoming projectile and explosively launch a counter-projectile into its path.

Slat armour

Slat armour is designed to protect against anti-tank rocket-propelled grenade (RPG) attacks. It functions by placing a rigid barrier around the vehicle which causes the shaped charge

Shaped charge

A shaped charge is an explosive charge shaped to focus the effect of the explosive's energy. Various types are used to cut and form metal, to initiate nuclear weapons, to penetrate armor, and in the oil and gas industry...

 warhead

Warhead

The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...

, which uses a shaped explosion rather than kinetic energy, to explode at a relatively safe distance. It can be defeated by tandem-charge

Tandem-charge

A tandem-charge weapon is an explosive device or projectile that has two or more stages of detonation. It is effective against cage armor, which is designed to protect an armored vehicle against anti-tank munitions. The first stage of the weapon triggers the reactive armor of the target, limiting...

 designs such as the RPG-27

RPG-27

The RPG-27 is a Soviet disposable rocket launcher.-History:The RPG-27 Tavolga was developed by the State Research and Production Enterprise, Bazalt as a modern anti-tank grenade launcher designed to defeat modern and future tanks with advanced reactive and composite armor as well as fortified...

 and RPG-29

RPG-29

The RPG-29 is a Russian rocket-propelled grenade launcher. Adopted by the Soviet Army in 1989, it was the most recent weapon of its type to be adopted by the Russian military before the fall of the Soviet Union in 1991. The RPG-29 has since been supplemented by other rocket-propelled systems, such...

.

Electrically charged armour

Electrically charged armour is a recent development in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 by the Defence Science and Technology Laboratory. A vehicle is fitted with two thin shells, separated by insulating material. The outer shell holds an enormous electrical charge, while the inner shell is at ground. If an incoming HEAT jet penetrates the outer shell and forms a bridge between the shells, the electrical energy discharges through the jet, disrupting it. Trials have so far been extremely promising, and it is hoped that improved systems could protect against KE penetrators. Developers of the Future Rapid Effect System

Future Rapid Effect System

The Future Rapid Effect System is the British MOD programme to deliver a fleet of more than 4,000 armoured fighting vehicles for the British Army...

 (FRES) series of armoured vehicles are considering this technology.

See also

• Active protection system
  Active protection system
  An active protection system is a system designed to prevent sensor-based weapons from acquiring and/or destroying a target....
  
  
• Armoured fighting vehicle
  Armoured fighting vehicle
  An armoured fighting vehicle is a combat vehicle, protected by strong armour and armed with weapons. AFVs can be wheeled or tracked....
  
  
• Non-military armoured vehicles
  Non-military armored vehicles
  Non-military armored vehicles are armored vehicles used outside of professional armed forces. While primarily invented and used for defense from an equally well armed organized force, armor technology has found a number of other uses outside of this military context.-Internal security...
  
  
• Armoured forces
• Personal armour
  Personal armor
  Personal armor is the whole of protecting clothing, designed to absorb and/or deflect slashing, bludgeoning, and penetrating attacks. They were historically used to protect soldiers, whereas today, they are also used to protect police forces, private citizens and private security guards or...
  
  
• Plastic armour
  Plastic Armour
  Plastic armour was a type of vehicle armour originally developed for merchant ships by Edward Terrell of the British Admiralty in 1940...
  
  
• Main battle tank
  Main battle tank
  A main battle tank , also known as a battle tank or universal tank, is a tank that fills the heavy direct fire role of many modern armies. They were originally conceived to replace the light, medium, heavy and super-heavy tanks. Development was spurred onwards in the Cold War with the development...
  
  

External links

• Electrically charged armour
• Defense Systems - Idaho National Laboratory
• http://www.defense-update.com/products/l/liba.htm - New Light Armor
• Modern armoured vehicles