Military vehicles are commonly
armoured (or armored;
see spelling differences) to withstand the impact of
shrapnel,
bullets,
shells,
rockets, and
missiles, protecting the personnel inside from enemy fire. Such vehicles include
armoured fighting vehicles like
tanks,
aircraft, and
ships.
Civilian vehicles may also be armoured. These vehicles include cars used by
officials (e.g.,
presidential limousines),
reporters and others in conflict zones or where violent crime is common. Civilian
armoured cars are also routinely used by security firms to carry money or valuables to reduce the risk of
highway robbery or the
hijacking
Hijacking may refer to:
Common usage
Computing and technology
* Bluejacking, the unsolicited transmission of data via Bluetooth
* Brandjacking, the unauthorized use of a company's brand
* Browser hijacking
* Clickjacking (including ''like ...
of the cargo.
Armour may also be used in vehicles to protect from threats other than a deliberate attack. Some
spacecraft are equipped with specialised armour to protect them against impacts from
micrometeoroids or fragments of
space debris. Modern aircraft powered by
jet engines usually have them fitted with a sort of armour in the form of an
aramid composite
Composite or compositing may refer to:
Materials
* Composite material, a material that is made from several different substances
** Metal matrix composite, composed of metal and other parts
** Cermet, a composite of ceramic and metallic materials ...
kevlar bandage around the fan casing or debris containment walls built into the casing of their
gas turbine engines to prevent injuries or
airframe damage should the fan, compressor, or
turbine blades break free.
The
design 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 is a thin sheet made from an aggregate of carbon nanotubes or carbon nanotube grid paper. The nanotubes are approximately 50,000 times thinner than a human hair. Originally, it was fabricated as a way to handle carbon nanotubes, but i ...
, and
aluminium foam
Regular foamed aluminium
A metal foam is a cellular structure consisting of a solid metal (frequently aluminium) with gas-filled pores comprising a large portion of the volume. The pores can be sealed (closed-cell foam) or interconnected (open-c ...
armour plates.
Materials
Metals
Steel
''
Rolled homogeneous armour'' is strong, hard, and tough (does not shatter when struck with a fast, hard blow). Steel with these characteristics are 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'' is used when light weight is a necessity. It is most commonly used on
APCs and
armoured cars. While certainly not the strongest metal, it is cheap, lightweight, and tough enough that it can serve as easy armour.
Iron
Wrought ''
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
'' was used on
ironclad warships. Early European iron armour consisted of 10 to 12.5 cm of wrought iron backed by up to one meter of solid
wood. It has since been supplemented by steel due to steel being significantly stronger.
Titanium
Titanium has almost twice the density of aluminium, but can have a yield strength similar to high strength steels, giving it a high specific strength. It also has a high specific resilience and specific toughness. So, despite being more expensive, it finds an application in areas where weight is a concern, such as
personal armour and
military aviation. Some notable examples of its use include the
USAF A-10 Thunderbolt II and the Soviet/Russian-built
Sukhoi Su-25 ground-attack aircraft, utilising a bathtub-shaped titanium enclosure for the pilot, as well as the Soviet/Russian
Mil Mi-24 attack helicopter.
Uranium
Because of its high density,
depleted uranium can also be used in tank armour, sandwiched between sheets of steel armour plate. For instance, some late-production
M1A1HA and M1A2 Abrams 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 of half-inch size, 43% of
limestone mineral, and 7% of
bitumen. It was typically applied in a layer two inches thick and backed by half an inch of
steel.
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.
Some main battle tank (MBT) armour utilises polymers, for example polyurethane as used in the "BDD" applique armour applied to modernized
T-62 and
T-55.
Glass
Bulletproof glass is a colloquial term for
glass that is particularly resistant to being penetrated when struck by
bullets. 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 thermoplastic or by using layers of
laminated glass. The desired result is a material with the appearance and light-transmitting behaviour of standard glass, which offers varying degrees of protection from
small arms fire.
The polycarbonate layer, usually consisting of products such as Armormax,
Makroclear
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transpa ...
, Cyrolon,
Lexan 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 (or PVB) is a resin mostly 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 majo ...
,
polyurethane or
ethylene-vinyl acetate. This type of bullet-resistant glass has been in regular use on
combat vehicles since
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
; it is typically about 100–120 mm (3.9–4.7 in) thick and is usually extremely heavy.
Newer materials are being developed. One such,
aluminium oxynitride, is much lighter but at US$10–15 per square inch is much more costly.
Ceramic
Ceramic's precise mechanism for defeating
HEAT 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. Ceramic layers can also be used as part of composite armour solutions. The high hardness of some ceramic materials serves as a disruptor that shatters and spreads the
kinetic energy of projectiles.
Composite
Composite armour is armour consisting of layers of two or more materials with significantly different physical properties;
steel and
ceramics are the most common types of material in composite armour.
Composite
Composite or compositing may refer to:
Materials
* Composite material, a material that is made from several different substances
** Metal matrix composite, composed of metal and other parts
** Cermet, a composite of ceramic and metallic materials ...
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. Composite armour's effectiveness depends on its composition and may be effective against
kinetic energy penetrators as well as
shaped charge munitions;
heavy metals are sometimes included specifically for protection from kinetic energy penetrators.
Composite armour used on modern Western and Israeli main battle tanks largely consists of non-explosive reactive armour (NERA) elements - a type of
Reactive armour. These elements are often a laminate consisting of two hard plates (usually high hardness steel) with some low density interlayer material between them. Upon impact, the interlayer swells and moves the plates, disrupting heat 'jets' and possibly degrading kinetic energy projectiles. Behind these elements will be some backing element designed to stop the degraded jet or projectile element, which may be of high hardness steel, or some composite of steel and ceramic or possibly uranium.
Soviet main battle tanks from the
T-64 onward utilised composite armour which often consisted of some low density filler between relatively thick steel plates or castings, for example
Combination K. For example, the T-64 turret front and cheek was originally filled with aluminum, and then ceramic balls and aluminum, whilst some models of the
T-72 features a glass filler called "Kvartz". The tank
glacis was often a sandwich of steel and some low density filler, either textolite (a
fibreglass reinforced polymer) or ceramic plates. Later T-80 and T-72 turrets contained NERA elements, similar to those discussed above.
Ships
Belt armour is a layer of armour-plating outside the
hull (watercraft) of warships, typically on
battleships,
battlecruisers,
cruisers and some
aircraft carriers.
Typically, the belt covers from the deck down someway below the
waterline of the ship. If built within the hull, rather than forming the outer hull, it can be fitted at an inclined angle to improve the protection.
When struck by a
shell or
torpedo, 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 either projectile. Often, the main belt armour was supplemented with a
torpedo bulkhead 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. Several wartime vessels had belt armour that was thinner or shallower than was desirable, to speed production and conserve resources.
''Deck armour'' on aircraft carriers is usually at the
flight deck level, but on some early carriers was at the
hangar deck. (See
armoured flight deck.)
Aircraft
Armour plating is not common on aircraft, which generally rely on their speed and manoeuvrability to avoid attacks from enemy aircraft and ground fire, rather than trying to resist impacts. Additionally, any armour capable of stopping large-calibre anti-aircraft fire or missile fragments would result in an unacceptable weight penalty. So, only the vital parts of an aircraft, such as the
ejection seat and engines, are usually armoured. This is one area where titanium is used extensively as armour plating. For example, in the American
Fairchild Republic A-10 Thunderbolt II and the Soviet-built
Sukhoi Su-25 ground attack aircraft, as well as the
Mil Mi-24 Hind ground-attack helicopter, the pilot sits in a titanium enclosure known as the "bathtub" for its shape. In addition, the windscreens of larger aircraft are generally made of impact-resistant,
laminated materials, even on civilian craft, to prevent damage from
bird strikes or other debris.
Armoured fighting vehicles
The most heavily armoured vehicles today are the
main battle tank
A main battle tank (MBT), also known as a battle tank or universal tank, is a tank that fills the role of armor-protected direct fire and maneuver in many modern armies. Cold War-era development of more powerful engines, better suspension sys ...
s, which are the spearhead of the ground forces, and are designed to withstand
anti-tank guided missiles,
kinetic energy penetrators,
high-explosive anti-tank weapons,
NBC threats and in some tanks even steep-trajectory shells. The
Israeli
Merkava tanks were designed in a way that each tank component functions as added back-up armour to protect the crew. Outer armour is modular and enables quickly replacing damaged parts.
Layout
For efficiency, the heaviest armour on an
armoured fighting vehicle (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 operations.
Sloping and curving armour can both increase its protection. Given a fixed thickness of armour plate, a projectile striking at an
angle must penetrate more armour than one impacting
perpendicularly. An angled surface also increases the chance of deflecting a projectile. This can be seen on
v-hull
The V-hull is a type of vehicle armor design used on wheeled armored personnel carriers (APCs), infantry mobility vehicles, infantry fighting vehicles (IFVs) and MRAPs. The design originated in the 1970s with vehicles such as the iconic Cassp ...
designs, which direct the force of an
Improvised explosive device or
landmine
A land mine is an explosive device concealed under or on the ground and designed to destroy or disable enemy targets, ranging from combatants to vehicles and tanks, as they pass over or near it. Such a device is typically detonated automati ...
away from the crew compartment, increasing crew
survivability.
Spall liners
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 (HESH) in British terminology, or high explosive plastic/plasticized (HEP) in American terminology, is a type of explosive projectile which uses a plastic explosive that conforms to the surface of a target before detona ...
warheads. Spall liners are made of
Kevlar,
Dyneema,
Spectra Shield Spectra Shield is a composite material (specifically, an ultra-high-molecular-weight polyethylene (UHMWPE) fiber) used in bulletproof vests and vehicle armour. It is manufactured by Honeywell.
Other popular fibers with similar uses are aramid (Ke ...
, or similar materials.
Appliqué
Appliqué armour, or add-on 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 that can penetrate the original armour of the vehicle.
An advantage of appliqué armour is the possibility to tailor a vehicle's protection level to a specific threat scenario.
Improvised
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 or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, British, Canadian and Polish tank crews welded spare strips of tank track to the hulls of their
Sherman tanks.
[Moran, Michael]
"Frantically, the Army tries to armour Humvees: Soft-skinned workhorses turning into death traps,"
''MSNBC'', April 15, 2004. U.S. tank crews often added sand bags in the hull and turrets on Sherman tanks, often in an elaborate cage made of girders. Some Sherman tanks were up-armoured in the field with glacis plates and other armour cut from knocked-out tanks to create ''Improvised Jumbos'', named after the heavily armoured
M4A3E2 assault tank. In the
Vietnam War, U.S. "
gun trucks" were armoured with sandbags and locally fabricated
steel armour plate.
[Gardiner, Paul S]
"Gun Trucks: Genuine Examples of American Ingenuity,"
''Army Logistician'', PB 700-03-4, Vol. 35, No. 4, July–August 2003, Army Combined Arms Support Command, Fort Lee, Virginia. More recently,
U.S. troops in Iraq armoured
Humvees and various military transport vehicles with scrap materials: this came to be known as "
hillbilly armour" or "haji armour" by the Americans.
Moreover, there was the
Killdozer incident, with the modified bulldozer being armoured with steel and concrete composite, which proved to be highly resistant to small arms.
Spaced
Armour with two or more plates spaced a distance apart, called spaced armour, has been in use since the
First World War
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
, where it was used on the
Schneider CA1 and
Saint-Chamond St Chamond may refer to:
* Saint Chamond otherwise Annemund, bishop of Lyon
* Saint-Chamond, Loire, a French town named after him
* Saint-Chamond (manufacturer), informal name for the ''Compagnie des forges et aciéries de la marine et d'Homécou ...
tanks. Spaced armour can be advantageous in several situations. For example, it can reduce the effectiveness of
kinetic energy penetrators because the interaction with each plate can cause the round to tumble, deflect, deform, or disintegrate. This effect can be enhanced when the armour is
sloped. Spaced armour can also offer increased protection against
HEAT projectiles. This occurs because the
shaped charge warhead can detonate prematurely (at the first surface), so that the metal jet that is produced loses its coherence before reaching the main armour and impacting over a broader area. 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. Taken to the extreme, relatively thin armour plates, metal mesh, or
slatted plates, much lighter than fully protective armour, can be attached as side skirts or turret skirts to provide additional protection against such weapons. This can be seen in
middle and late-World War II German tanks, as well as many modern
AFVs. Taken as a whole, spaced armour can provide significantly increased protection while saving weight.
The analogous
Whipple shield uses the principle of spaced armour to protect spacecraft from the impacts of very fast
micrometeoroids. 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
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
''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 and pushes the steel plates into the warhead, disrupting the flow of the charge's liquid metal penetrator (usually
copper at around 500 degrees Celsius; it can be made to flow like water by sufficient pressure). Traditional "light" ERA is less effective against kinetic penetrators. "Heavy" reactive armour, however, offers better protection. The only example currently in widespread service is Russian
Kontakt-5. Explosive 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 systems'' use a sensor to detect an incoming projectile and explosively launch a counter-projectile into its path.
Slat
Slat armour is designed to protect against
anti-tank rocket and missile attacks, where the warhead is a
shaped charge. The slats are spaced so that the warhead is either partially deformed before detonating, or the fuzing mechanism is damaged, thereby preventing detonation entirely. As shaped charges rely on very specific structure to create a jet of hot metal, any disruption to this structure greatly reduces the effectiveness of the warhead.
Slat armour can be defeated by
tandem-charge designs such as the
RPG-27 and
RPG-29.
Electric armour
Electric armour
Electric armour or electromagnetic armour is a type of reactive armour proposed for the protection of ships and armoured fighting vehicles from shaped charge and possibly kinetic weapons using a strong electric current, complementing or replacing ...
is a recent development in the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
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
electric 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. The developers of the
Future Rapid Effect System (FRES) series of armoured vehicles are considering this technology.
See also
*
Active protection system
*
Armoured fighting vehicle
*
Armoured forces
*
Main battle tank
A main battle tank (MBT), also known as a battle tank or universal tank, is a tank that fills the role of armor-protected direct fire and maneuver in many modern armies. Cold War-era development of more powerful engines, better suspension sys ...
*
Non-military armoured vehicles
*
Personal armour
*
Plastic armour
References
External links
Electrically charged armourModern armoured vehicles
{{DEFAULTSORT:Vehicle armour
Armoured warfare
History of the tank