A
shell is a payload-carrying
projectileA projectile is any object propelled through space by the exertion of a force which ceases after launch. Although a thrown baseball could be considered a projectile, the word more often refers to a weapon...
, which, as opposed to
shotRound shot is an obsolete solid projectile without explosive charge, fired from a cannon. As the name implies, round shot is spherical; its diameter is slightly less than the bore of the gun it is fired from.Round shot was made in early times from dressed stone, but by the 17th century, from iron...
, contains an explosive or other filling, though modern usage includes large solid projectiles previously termed
shot (AP, APCR, APCNR, APDS, APFSDS and proof shot). Solid shot may contain a pyrotechnic compound if a
tracerTracer ammunition are special bullets that are modified to accept a small pyrotechnic charge in their base. Ignited upon firing, the composition burns very brightly, making the projectile visible to the naked eye...
or spotting charge is used.
Shells are usually large rounds fired by
artilleryArtillery is a military combat Arm that employs weapons capable of discharging large projectiles in combat. They are generally capable of adding considerable fire power to the military capability of an armed force...
, armored fighting vehicles (including
tankA tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility and tactical offensive and defensive capabilities...
s), and
warshipA warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way than merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuverable than merchant ships...
s.
Shells usually have the shape of a
cylinderA cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given straight line, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...
topped by an
ogiveAn ogive is the roundly tapered end of a two-dimensional or three-dimensional object.-Applied physical science and engineering:In ballistics or aerodynamics, an ogive is a pointed, curved surface mainly used to form the approximately streamlined nose of a bullet or other projectile.The traditional...
-shaped nose for good aerodynamic performance, possibly with a tapering base; but some specialised types are quite different.
History
Written evidence for the first explosive shells appears in the early
Ming DynastyThe Ming Dynasty , or Empire of the Great Ming , was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history," was the last dynasty in China ruled by ethnic...
(1368–1644)
ChineseChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
military manual
HuolongjingThe Huolongjing is a 14th century military treatise that was compiled and edited by Jiao Yu and Liu Ji of the early Ming Dynasty in China...
, compiled by
Jiao YuJiao Yu was a Chinese military officer loyal to Zhu Yuanzhang , the founder of the Ming Dynasty . He was entrusted by Emperor Hongwu as a leading artillery officer for the rebel army that overthrew the Mongol Yuan Dynasty, and established the Ming Dynasty...
(fl. 14th to early 15th century) and Liu Ji (1311–1375) sometime before the latter's death, a preface added by Jiao in 1412. As described in their book, these hollow, gunpowder-packed shells were made of
cast ironCast iron usually refers to grey iron, but also identifies a large group of ferrous alloys, which solidify with a eutectic. The colour of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due to its carbide impurities which...
.
Explosive shells in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
do not appear to have been in general use before the middle of the 16th century, when hollow balls (i.e., hollow
shells in the ordinary sense) of stone or cast iron were filled with
gunpowderGunpowder, also called black powder, is a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing volumes of hot solids and gases which can be used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any...
and a slow-burning composition to act as fuze and detonate the charge, and were fired from
mortarA mortar is a muzzle-loading indirect fire weapon that fires shells at low velocities, short ranges, and high-arcing ballistic trajectories. It typically has a barrel length less than 15 times its caliber.- Function :...
s. The flash from the discharge of the gun was supposed to ignite the fuze which would burn through and detonate the gunpowder after a certain time.
In practice the flash did not always ignite the fuze, and the amount of fuze compound to burn for the right time before detonation could not be determined reliably.
Later shells were fitted with a hollow forged iron or copper plug, filled with slow-burning powder. While firing the gun might ignite the fuze, it was more reliable to ignite the fuze manually and then fire. This required that the muzzle-loading barrel be short enough for the gunner to readily reach in, ignite the fuze, and get out of the way before the gun fired. The short barrel produced low
muzzle velocitiesA gun's muzzle velocity is the speed at which the projectile leaves the muzzle of the gun. Muzzle velocities range from subsonic for some pistols to more than 1,800 m/s for tank guns firing kinetic energy penetrator ammunition. The latter velocity is close to the limit achievable with chemical...
which required high trajectories; the guns were mortars or howitzers.
In 1823, the first guns to fire explosive shells with the flat trajectory of
cannonA cannon is any tubular piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
s were invented by the French General
Henri-Joseph PaixhansHenri-Joseph Paixhans was a French artillery officer of the beginning of the 19th century.Henri-Joseph Paixhans graduated from the École Polytechnique...
. The guns were adopted by various navies from the 1840s, thereby triggering the demise of wooden ships, and the iron-
hullA hull is the watertight body of a ship or boat. Above the hull comes the superstructure and deckhouse. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...
revolution in
shipbuildingShipbuilding is the construction of ships. It normally takes place in a specialized facility known as a shipyard. Shipbuilders, also called shipwrights, follow a specialized occupation that traces its roots to before recorded history....
. Cast-iron spherical common shell (so named because they were used against "common" [usual] targets) were in use up to 1871. Towards the end of this period they were fitted with a wooden disc called a
sabotA sabot is a device used in a firearm or cannon to fire a projectile, such as a bullet, that is smaller than the bore diameter, or which must be held in a precise position...
, attached by a copper
rivetA rivet is a permanent mechanical fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole. Then the tail is "upset" A rivet is a...
, intended to keep the fuze centered when loading. The sabot was also supposed to reduce the rebounding tendency of the shell as it traveled along the bore on discharge. Mortar shells were not fitted with
sabotA sabot is a device used in a firearm or cannon to fire a projectile, such as a bullet, that is smaller than the bore diameter, or which must be held in a precise position...
s.
Cast ironCast iron usually refers to grey iron, but also identifies a large group of ferrous alloys, which solidify with a eutectic. The colour of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due to its carbide impurities which...
was used for projectiles until the end of the 19th century, when
steelSteel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten...
came into use, first for projectiles intended for piercing armor, and later for use in high-velocity guns where the shock of discharge was too severe for cast iron.
During the First World War, shrapnel shells and explosive shells inflicted terrible casualties on infantry, accounting for nearly 70% of all war casualties and leading to the adoption of steel
helmetA helmet is a form of protective gear worn on the head to protect it from injuries, a variation of the hat. The oldest known use of helmets was by Assyrian soldiers in 900BC, who wore thick leather or bronze helmets to protect the head from sword blows and arrows...
s on both sides. Shells filled with poison gas were used from 1917 onwards. Frequent problems with shells led to many military disasters when shells failed to explode, most notably during the 1916 Battle of the Somme.
Sizes
The calibre of a shell is its
diameterIn geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
. Depending on the historical period and national preferences, this may be specified in
millimetreThe millimetre is a unit of length in the metric system, equal to one thousandth of a metre, which is the current SI base unit of length.Equal to 1000 micrometres.Equal to 1000000 nanometres....
s,
centimetreA centimetre is a unit of length in the metric system, equal to one hundredth of a metre, which is the current SI base unit of length. Centi is the SI prefix for a factor of...
s, or
inchAn inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
es. The length of gun barrels for large cartridges and shells (naval) is frequently quoted in terms of calibre. [1] Some guns, mainly British, were specified by the weight of their shells (see below).
Due to manufacturing difficulties the smallest shells commonly used are around 20 mm calibre, used in aircraft cannon and on armoured vehicles. Smaller shells are only rarely used as they are difficult to manufacture and can only have a small explosive charge. The largest shells ever fired were those from the German super-
railway gunA railway gun, also called a railroad gun, is a large artillery piece, designed to be placed on rail tracks. Many countries have built railway guns, but the best known are the large Krupp-built pieces used by Germany in World War I and World War II...
s,
Gustav and DoraSchwerer Gustav and Dora were the names of the German 80 cm K railway guns. They were developed in the 1930s by Krupp in order to destroy heavily fortified positions. They weighed nearly 1,350 tonnes, and could fire shells weighing seven tonnes to a range of 37 kilometers...
, which were 800 mm (31.5") in calibre. Very large shells have been replaced by
rocketA rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust by the reaction of the rocket to the ejection of a jet of fast moving fluid exhaust from a rocket engine. Chemical rockets create their exhaust by the combustion of rocket propellant...
s,
guided missileGuided Missile is a London based independent record label set up by Paul Kearney in 1994.Guided Missile has always focused on 'the underground', preferring to put out a steady flow of considered and quality releases and developing the numerous and now essential GMevents around London and...
, and bombs, and today the largest shells in use are 203 mm (8 inches). Guns of that size are uncommon; 155 mm (6.1 inches) is the largest calibre in common use.
Gun calibres have standardized around a few common sizes, especially in the larger range, mainly due to the uniformity required for efficient military logistics. Shells of 105, 120, and 155 mm diameter are common for NATO forces' artillery and
tank gunA 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:...
s. Artillery shells of 122, 130 and 152 mm, and tank gun ammunition of 100, 115, or 125 mm calibre remain in use in Eastern Europe and China. Most common calibres have been in use for many years, since it is
logisticallyLogistics is the management of the flow of goods, information and other resources, including energy and people, between the point of origin and the point of consumption in order to meet the requirements of consumers...
complex to change the calibre of all guns and ammunition stores.
The weight of shells increases by and large with calibre. A typical 150 mm (5.9") shell weighs about 50 kg, a common 203 mm (8") shell about 100 kg, a concrete demolition 203 mm (8") shell 146 kg, a 280 mm (11") battleship shell about 300 kg, and a 460 mm (18") battleship shell over 1500 kg. The
Schwerer GustavSchwerer Gustav and Dora were the names of the German 80 cm K railway guns. They were developed in the 1930s by Krupp in order to destroy heavily fortified positions. They weighed nearly 1,350 tonnes, and could fire shells weighing seven tonnes to a range of 37 kilometers...
supergunA supergun is an extraordinarily large cannon with an extremely high muzzle velocity and large bore. They are used to bombard an enemy from extremely long range and destroy heavy fortifications.- Late Middle Ages :...
fired 4.8 and 7.1 tonne shells.
Old-style British classification by weight
During the 19th Century the British adopted a particular form of designating artillery. Guns were designated by nominal standard projectile weight while Howitizers were designated by barrel calibre. British Guns and their ammunition were designated in
poundThe pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement...
s, e.g., as "two-pounder" shortened to "2-pr" or "2-pdr". Usually this refered to the actual weight of the standard projectile (shot, shrapnel or HE), but, confusingly, this was not always the case. Some were named after the weights of obsolete projectile types of the same calibre, or even obsolete types that were considered to have been functionally equivalent. Also, projectiles fired from the same gun, but of non-standard weight, took their name from the gun. Thus, conversion from "pounds" to an actual barrel diameter requires consulting a historical reference. Since the creation of NATO new British guns are designated by calibre.
High-explosive (HE)
The most common shell type is high explosive, commonly referred to simply as HE. They have a strong
steelSteel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten...
case, a bursting charge, and a fuze. The fuse detonates the bursting charge which shatters the case and scatters hot, sharp case pieces (
fragments,
splinters) at high velocity. Most of the damage to soft targets such as unprotected personnel is caused by shell pieces rather than by the blast. The term "shrapnel" is sometimes incorrectly used to describe the shell pieces, but shrapnel shells functioned very differently and are long obsolete. Depending on the type of fuze used the HE shell can be set to burst on the ground (percussion), in the air above the ground (time or proximity), or after penetrating a short distance into the ground (percussion with delay, either to transmit more ground shock to covered positions, or to reduce the spread of fragments).
Early high explosives used before and during
World War IWorld War I , also known as the First World War, the Great War, and the War to End All Wars, was a global military conflict which involved most of the world's great powers, assembled in two opposing alliances: the Triple Entente and the Triple Alliance...
in HE shells were Lyddite (picric acid),
PETNPentaerythritol tetranitrate , is one of the most powerful high explosives known, with a relative effectiveness factor of 1.66....
,
TNTTrinitrotoluene , or more specifically, 2,4,6-trinitrotoluene, is a chemical compound with the formula C
6H
23CH
3. This yellow-coloured solid is a reagent in chemistry but is best known as a useful explosive material with convenient handling properties...
. However, pure TNT was expensive to produce and most nations made some use of mixtures using cruder TNT and ammonium nitrate, some with other compounds included. These fills included Ammonal, Schneiderite and
AmatolNot to be confused with the barbiturate Amytal.Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Amatol was used extensively during World War I and World War II...
. The latter was still in wide use in
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
.
From 1944-5
RDXCyclotrimethylenetrinitramine, also known as RDX, cyclonite, hexogen, and T4, is an explosive nitroamine widely used in military and industrial applications. Nomenclature variants include cyclotrimethylene-trinitramine and cyclotrimethylene trinitramine.In its pure, synthesized state RDX is a...
and TNT mixtures became standard. Notably "
Composition B" (cyclotol)Composition B, colloquially "comp B", is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades and various other munitions...
. The introduction of 'insensitive munition' requirements, agreements and regulations in the 1990s caused modern western designs to use various types of plastic bonded explosives (PBX) based on RDX.
The percentage of shell weight taken up by its explosive fill increased steadily throughout the 20th Century. Less than 10% was usual in the first few decades, by World War 2 leading designs were around 15%. However, British researchers in that war identified 25% as being the optimal design for anti-personnel purposes, based on recognition that far smaller fragments that hitherto would give the required effects. This was achieved by 1960s designed 155mm L15 shell developed as part of the FH70 program. The key requirement for increasing the HE content without increasing shell weight was to reduce the thickness of shell walls, this required improvements in high tensile steel.
Mine shell
The
mine shell is a particular form of HE shell developed for use in small caliber weapons such as 20 mm to 30 mm cannon. Small HE shells of conventional design can contain only a limited amount of explosive. By using a thin-walled steel casing of high tensile strength, a larger explosive charge can be used. Most commonly the explosive charge also was a more expensive but higher-detonation-energy type. The
mine shell concept was invented by the Germans in the Second World War primarily for use in aircraft guns intended to be fired at opposing aircraft. Mine shells produced relatively little damage due to fragments, but a much more powerful blast. The aluminum structures and skins of Second World War aircraft were readily damaged by this greater level of blast.
Armor-piercing (AP)
The earliest naval and anti-tank shells had to withstand the extreme shock of punching through armor plate. Shells designed for this purpose sometimes had a greatly strengthened case with a small bursting charge, and sometimes were solid metal, i.e.
shotShot may refer to:* Shot , a part of a film between two cuts* Shot glass, a liquor measure* Lead shot, small balls of shot generally used as weights or as firearms projectiles* Round shot, a solid projectile used in muzzle-loading cannon...
. In either case, they almost always had a specially hardened and shaped nose to facilitate penetration.
A further refinement of such designs improved penetration by adding a softer metal cap to the penetrating nose giving
APC (Armour piercing - capped). The softer cap dampens the initial shock that would otherwise shatter the round. The best profile for the cap is not the most aerodynamic; this can be remedied by adding a further hollow cap of suitable shape:
APCBC (APC + Ballistic Cap).
AP shells with a bursting charge were sometimes distinguished by appending the suffix "HE". At the beginning of the Second World War, solid shot AP projectiles were common. As the war progressed, ordnance design evolved so that APHE became the more common design approach for anti-tank shells of 75 mm caliber and larger, and more common in naval shell design as well. In modern ordnance, most full caliber AP shells are APHE designs.
Armour-piercing, discarding-sabot (APDS)
APDS was developed by engineers working for the
FrenchFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
Edgar BrandtEdgar William Brandt was a French ironworker, prolific weapons designer and head of a company that designed 60mm, 81mm and 120mm mortars that were very widely copied throughout and subsequent to World War II...
company, and was fielded in two calibers (75 mm/57 mm for the Mle1897/33 75 mm anti-tank
cannonA cannon is any tubular piece of artillery that uses gunpowder or other usually explosive-based propellants to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
, 37 mm/25 mm for several 37 mm gun types) just before the French-German armistice of 1940. The
Edgar BrandtEdgar William Brandt was a French ironworker, prolific weapons designer and head of a company that designed 60mm, 81mm and 120mm mortars that were very widely copied throughout and subsequent to World War II...
engineers, having been evacuated to the
United KingdomThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
, joined ongoing APDS development efforts there, culminating in significant improvements to the concept and its realization. British APDS ordnance for their
QF 6 pdrThe Ordnance QF 6-pounder 7 cwt, or just 6 pounder, was a British 57 mm gun, their primary anti-tank gun during the middle of World War II, as well as the main armament for a number of armoured fighting vehicles...
and 17 pdr anti-tank guns was fielded in March 1944.
The armor-piercing concept calls for more penetration capability than the target's armour thickness. Generally, the penetration capability of an armor piercing round is proportional to the projectile's kinetic energy. Thus an efficient means of achieving increased penetrating power is increased velocity for the projectile. However, projectile impact against armour at higher velocity causes greater levels of shock. Materials have characteristic maximum levels of shock capacity, beyond which they may shatter on impact. At relatively high impact velocities, steel is no longer an adequate material for armor piercing rounds due to shatter. Tungsten and tungsten alloys are suitable for use in even higher velocity armour piercing rounds due to their very high shock tolerance and shatter resistance. However, tungsten is very dense, and tungsten rounds of full-caliber design are too massive to be accelerated to an efficient velocity for maximized kinetic energy. This is overcome by using a reduced-diameter tungsten shot, surrounded by a lightweight outer carrier, the
sabot (a French word for a wooden shoe). This combination allows the firing of a smaller diameter (thus lower mass/aerodynamic resistance/penetration resistance) projectile with a larger area of expanding-propellant "push", thus a greater propelling force/acceleration/resulting kinetic energy.
Once outside the barrel, the sabot is stripped off by a combination of
centrifugal forceIn classical mechanics, centrifugal force is an outward force associated with curved motion, that is, rotation about some center...
and aerodynamic force, giving the shot low drag in flight. For a given caliber the use of APDS ammunition can effectively double the anti-tank performance of a gun.
Armour-piercing, fin-stabilized, discarding-sabot (APFSDS)
An Armour-Piercing, Fin-Stabilised, Discarding Sabot (
APFSDSA kinetic energy penetrator is a type of ammunition which, like a bullet, does not contain explosives and uses kinetic energy to penetrate the target....
) projectile uses the sabot principle with fin (drag) stabilisation. A long, thin sub-projectile has increased sectional
densityThe density of a material is defined as its mass per unit volume. The symbol of density is ρ .- Formula :Mathematically:where: is the density, is the mass, is the volume....
and thus penetration potential. However, once a projectile has a length-to-diameter ratio greater than 10 (less for higher density projectiles), spin stabilisation becomes ineffective. Instead, drag stabilisation is used, by means of fins attached to the base of the sub-projectile, making it look like a large metal arrow.
Large calibre APFSDS projectiles are usually fired from smooth-bore (unrifled) barrels, though they can be and often are fired from rifled guns. This is especially true when fired from small to medium calibre weapon systems. APFSDS projectiles are usually made from high-density metal alloys such as
tungstenTungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A steel-gray metal, tungsten is found in several ores, including wolframite and scheelite...
heavy alloys (WHA) or
depleted uraniumDepleted uranium is uranium primarily composed of the isotope uranium-238 . Natural uranium is about 99.27 percent U-238, 0.72 percent U-235, and 0.0055 percent U-234. U-235 is used for fission in nuclear reactors and nuclear weapons. Uranium is enriched in U-235 by separating the isotopes by mass...
(DU);
maraging steelMaraging steels are iron alloys which are known for possessing superior strength and toughness without losing malleability. These steels are a special class of low carbon ultra-high strength steels which derive their strength not from carbon, but from precipitation of inter-metallic compounds. The...
was used for some early Soviet projectiles. DU alloys are cheaper and have better penetration than others as they are denser and self-sharpening, but they present radiological and toxic hazards that remain on the battlefield. The less toxic WHAs are preferred in most countries except the USA, UK, and
RussiaRussia , officially known as both Russia and the Russian Federation , is a country in northern Eurasia . It is a semi-presidential republic, comprising 83 federal subjects...
.
Armour-piercing, composite rigid (APCR)
Armour-Piercing, Composite Rigid is a British term, the US term for the design is
High Velocity Armour Piercing (HVAP) and German,
Hartkernmunition. The APCR projectile is a core of a high-density hard material such as
tungsten carbideTungsten carbide, WC is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
surrounded by a full-bore shell of a lighter material (e.g. an
aluminiumAluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13. It is not soluble in water under normal circumstances....
alloy). Most APCR projectiles are shaped like the standard APCBC shot (although some of the German Pzgr. 40 and some Soviet designs resemble a stubby arrow), but the projectile is lighter: up to half the weight of a standard AP shot of the same calibre. The lighter weight allows a higher velocity. The kinetic energy of the shot is concentrated in the core and hence on a smaller impact area, improving the penetration of the target armour. To prevent shattering on impact, a shock-buffering cap is placed between the core and the outer ballistic shell as with APC rounds. However, because the shot is lighter but still the same overall size it has poorer ballistic qualities, and loses velocity and accuracy at longer ranges. The APCR was superseded by the APDS which dispensed with the outer light alloy shell once the shot had left the barrel.
The Germans used an APCR round, the
Panzergranate 40 (Pzgr.40) "arrowhead" shot, for their 5 cm Pak 38 antitank guns in 1942, and it was also developed for their 75 and 88 mm antitank and tank guns, and for anti-tank guns mounted in German aircraft. Shortages of the key component, tungsten, led to the Germans dropping the use of APCR during late World War II because it was more efficiently used in industrial applications such as machine tools.
Armour-piercing, composite non-rigid (APCNR)
Armour-Piercing, Composite Non-Rigid (APCNR), the British term, is based on the same projectile design as the APCR - a high density core within a shell of soft iron or other alloy, but it is fired by a gun with a tapered barrel, either a taper in a fixed barrel (
Gerlich design in German use; original development efforts in the late 1930s in Germany, Denmark and France) or a final added section as in the British "squeeze -bore" (
Littlejohn adaptorThe Littlejohn adaptor was a device that could be added to the British QF 2 pounder anti-tank gun. It was used to extend the service life of the 2-pounder during the Second World War by converting it to squeeze bore operation. "Littlejohn" came from the literal anglicization of the name of Mr...
). The projectile is initially full-bore, but the outer shell is deformed as it passes through the taper. Flanges or studs are swaged down in the tapered section, so that as it leaves the muzzle the projectile has a smaller overall cross-section. This gives it better flight characteristics with a higher sectional density and the projectile retains velocity better at longer ranges than an undeformed shell of the same weight. As with the APCR the kinetic energy of the round is concentrated at the core on impact. The initial velocity of the round is greatly increased by the decrease of barrel cross-sectional area toward the muzzle, resulting in a commensurate increase in velocity of the expanding propellant gases.
The Germans deployed their
Schwere Panzerbüchse 412.8 cm schwere Panzerbüchse 41 or "Panzerbuchse 41" was a German anti-tank weapon working on the squeeze bore principle. Officially classified as heavy anti-tank rifle , it would be better described, and is widely referred to, as a light anti-tank gun.-Description:Although the sPzB 41 was...
, their initial tapered barrel design, as a light anti-tank weapon early in the Second World War, but although HE projectiles were designed and put into service, the limiting of the shell diameter to the muzzle bore reduced their mass to only 85 grams and hence reduced their effectiveness. The British used the Littlejohn squeeze-bore adaptor which could be attached or removed as necessary, to extended the usefulness of their
QF 2 pdrThe Ordnance QF 2-pounder was a 40 mm British anti-tank and vehicle-mounted gun, employed in the Second World War. It was actively used in the Battle of France, and during the North Africa campaign...
gun in armoured cars and light tanks which could not take a larger gun. Although a full range of shells and shot could be used, changing the adaptor in the heat of battle was highly impractical. The APCNR was superseded by the APDS design which was compatible with non-tapered barrels.
High-explosive, anti-tank (HEAT)
HEATHigh explosive anti-tank warheads are made of an explosive shaped charge that uses the Neumann effect to create a very high-velocity jet of metal in a state of superplasticity that can punch through solid armor.The jet moves at hypersonic speeds in solid material and therefore erodes...
shells are a type of
shaped chargeA 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, initiate nuclear weapons, and penetrate armor...
used to defeat armoured vehicles. They are extremely efficient at defeating plain steel armour but less so against later composite and
reactive armourReactive armour is a type of vehicle armour that reacts in some way to the impact of a weapon to reduce the damage done to the vehicle being protected. It is most effective in protecting against shaped charges and specially hardened long rod penetrators...
. The effectiveness of the shell is independent of its velocity, and hence the range: it is as effective at 1000 metres as at 100 metres. The speed can even be zero in the case where a soldier simply slaps a magnetic mine onto a tank's armor plate. A HEAT charge is most effective when detonated at a certain, optimal, distance in front of the target and HEAT shells are usually distinguished by a long, thin nose probe sticking out in front of the rest of the shell and detonating it at the correct distance, e.g.,
PIATThe Projector, Infantry, Anti Tank was a British anti-tank weapon developed during the Second World War. The PIAT was designed in response to the British Army's need for a hand-held infantry anti-tank weapon that was more effective than the current weapons it possessed...
bomb. HEAT shells are less effective if spun (i.e., fired from a rifled gun).
Discarding-sabot shell (DSS)
In principle the same as the APDS shot but applied to High Explosive Shells. It is a means to deliver a shell to a greater range. The design of the sub-projectile carried inside the sabot can be optimised for aerodynamic properties and the sabot can be built for best performance within the barrel of the gun. The principle was developed by a Frenchman,
Edgar BrandtEdgar William Brandt was a French ironworker, prolific weapons designer and head of a company that designed 60mm, 81mm and 120mm mortars that were very widely copied throughout and subsequent to World War II...
, in the 1930s. With the occupation of France, the Germans took the idea for application to anti-aircraft guns—a DSS projectile could be fired at a higher muzzle velocity and reach the target altitude more quickly, simplifying aiming and allowing the target aircraft less time to change course.
High-explosive, squash-head (HESH) or high-explosive plastic (HEP)
HESH is another anti-tank shell based on the use of explosive. Developed by the
BritishThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
inventor Sir
Charles Dennistoun BurneySir Charles Dennistoun Burney, 2nd Baronet was an English aeronautical engineer, private inventor and Conservative Party politician....
in World War II for use against fortifications. A thin-walled shell case contains a large charge of a
plastic explosivePlastic explosive is a specialised form of explosive material. It is soft and hand moldable solid material. Plastic explosives are properly known as Putty explosives within the field of explosives engineering....
. On impact the explosive flattens, without detonating, against the face of the armour, and is then detonated by the fuze. Energy is transferred through the armour plate: when the compressive shock reflects off the air/metal interface on the inner face of the armour, it is transformed into a tension wave which
spallSpall are flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure...
s a "scab" of metal off into the tank damaging the equipment and crew without actually penetrating the armour.
HESH is completely defeated by
spaced armourArmour with two or more plates spaced a distance apart, called spaced armour. When sloped it 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 it increases anyway the protection offered by...
, so long as the plates are individually able to withstand the explosion. It is still considered useful as not all vehicles are equipped with spaced armour, and it is also the most effective munition for demolishing brick and concrete. HESH shells, unlike HEAT shells, are best fired from rifled guns.
Proof shot
A proof shot is not used in combat but to confirm that a new gun barrel can withstand operational stresses. The proof shot is heavier than a normal shot or shell, and an oversize propelling charge is used, subjecting the barrel to greater than normal stress. The proof shot is inert (no explosive or functioning filling) and is often a solid unit, although water, sand or iron powder filled versions may be used for testing the gun mounting. Although the proof shot resembles a functioning shell (of whatever sort) so that it behaves as a real shell in the barrel, it is not aerodynamic as its job is over once it has left the muzzle of the gun. Consequently it travels a much shorter distance and are usually stopped by an earth bank for safety measures.
The gun, operated remotely for safety in case it fails, fires the proof shot, and is then inspected for damage. If the barrel passes the examination "proof marks" are added to the barrel. The gun can be expected to handle normal ammunition, which subjects it to less stress than the proof shot, without being damaged.
Shrapnel shells
Shrapnel shells were an early (1784) anti-personnel munition which delivered large numbers of bullets at ranges far greater than rifles or machine guns could attain - up to 6,500 yards by 1914. A typical shrapnel shell as used in
World War IWorld War I , also known as the First World War, the Great War, and the War to End All Wars, was a global military conflict which involved most of the world's great powers, assembled in two opposing alliances: the Triple Entente and the Triple Alliance...
was streamlined, 75 mm (3 inch) in diameter and contained approximately 300 lead-antimony balls (bullets), each approximately 1/2 inch in diameter. Shrapnel used the principle that the bullets encountered much less air resistance if they travelled most of their journey packed together in a single streamlined shell than they would if they travelled individually, and could hence attain a far greater range.
The gunner set the shell's fuze so that it was timed to burst as it was angling down towards the ground just before it reached its target (ideally about 150 yards before, and 60-100 feet above the ground). The fuze then ignited a small "bursting charge" in the base of the shell which fired the balls forward out of the front of the shell case, adding approximately 200 - 250 ft/second to the existing velocity of 1200 - 750 ft/second. The shell case dropped to the ground and the bullets continued in an expanding cone shape before striking the ground over an area approximately 250 yards x 30 yards in the case of the US 3 inch shell. The effect was of a large shotgun blast just in front of and above the target, and was deadly against troops in the open. A trained gun team could fire 20 such shells per minute, with a total of 6,000 balls, which compared very favourably with rifles and machine-guns.
However, shrapnel's relatively flat trajectory (it depended mainly on the shell's velocity for its lethality, and was only lethal in a forward direction) meant that it could not strike trained troops who avoided open spaces and instead used dead ground (dips), shelters, trenches, buildings, and trees for cover. It was of no use in destroying buildings or shelters. Hence it was replaced during
World War IWorld War I , also known as the First World War, the Great War, and the War to End All Wars, was a global military conflict which involved most of the world's great powers, assembled in two opposing alliances: the Triple Entente and the Triple Alliance...
by the high-explosive shell which exploded its fragments in all directions and could be fired by high-angle weapons such as howitzers, hence far more difficult to avoid.
Cluster shells
Cluster shells are a type of carrier shell or cargo munition. Like
cluster bombCluster munitions or cluster bombs are air-dropped or ground-launched explosive weapons that eject smaller submunitions: a cluster of bomblets. The most common types are designed to kill enemy personnel and destroy vehicles...
s, an artillery shell may be used to scatter smaller submunitions, including anti-personnel grenades, anti-tank top-attack munitions, and
landminesA land mine is a target triggered explosive weapon. Their non-explosive predecessors have been used on the battlefield since ancient times. Landmines were designed to be used to deter, channel, delay and kill an enemy. They have been used in various formats, for centuries and have featured in all...
. These are generally far more lethal against both
armorAn armoured fighting vehicle is a military vehicle, protected by armour and armed with weapons. AFV's can be wheeled or tracked.Armoured fighting vehicles are classified according to their intended role on the battlefield and characteristics. This classification is not absolute; at different times...
and
infantryInfantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of the Combat Arms they are the backbone of armies...
than simple high-explosive shells, since the multiple munitions create a larger kill zone and increase the chance of achieving the direct hit necessary to kill armor. Most modern armies make significant use of cluster munitions in their artillery batteries.
However, in operational use submunitions have demonstrated a far higher mulfunction rate than previously claimed, including those that have self-destruct mechanisms. This problem, the 'dirty battlefield", led to the
Ottawa TreatyThe Ottawa Treaty or the Mine Ban Treaty, formally the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, bans completely all anti-personnel landmines . , there were 156 States Parties to the treaty. Two states have...
.
Artillery-scattered mines allow for the quick deployment of minefields into the path of the enemy without placing engineering units at risk, but artillery delivery may lead to an irregular and unpredictable minefield with more unexploded ordnance than if mines were individually placed.
Signatories of the
Ottawa TreatyThe Ottawa Treaty or the Mine Ban Treaty, formally the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, bans completely all anti-personnel landmines . , there were 156 States Parties to the treaty. Two states have...
have renounced the use of cluster munitions of all types where the carrier contains more than ten submunitions.
Chemical
Chemical shells contain just a small explosive charge to burst the shell, and a larger quantity of a chemical agent such as a poison gas. Signatories of the
Chemical Weapons ConventionThe Chemical Weapons Convention is an arms control agreement which outlaws the production, stockpiling and use of chemical weapons...
have renounced such shells.
Non-lethal shells
Not all shells are designed to kill or destroy. The following types are designed to achieve particular non-lethal effects. They are not completely harmless: smoke and illumination shells can accidentally start fires, and impact by the discarded carrier of all three types can wound or kill personnel, or cause minor damage to property.
Smoke
The smoke shell is designed to create a smokescreen. The main types are bursting (those filled with white
phosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks. Elemental phosphorus exists in two major forms - white phosphorus and red phosphorus...
WP and a small HE bursting charge are best known) and base ejection (delivering three or four smoke cannisters, or material impregnated white phosphorus). Base ejection shells are a type of carrier shell or cargo munition.
Base ejection smoke is usually white, however, coloured smoke has been used for marking purposes. The original cannisters were non-burning, being filled with a compound that created smoke when it reacted with atmospheric moisture, modern ones use red phosphorus because of its multi-spectral properties. However, other compounds have been used, in World War 2 Germany used oleum (fuming sulphuric acid) and pumice.
Illumination
Modern illuminating shells are a type of carrier shell or cargo munition. Those used in World War 1 were shrapnel pattern shells ejecting small burning 'pots'.
A modern illumination shell has a fuze which ejects the "candle" (a
pyrotechnicPyrotechnics is the science of materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...
flare emitting white or
infraredInfrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves...
light) at a calculated altitude, where it slowly drifts down beneath a heat resistant
parachuteA parachute is a device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are made out of cloth, most commonly nylon....
, illuminating the area below. These are also known as
starshell or
star shell.
Coloured flare shells have also been used for target marking purposes.
Carrier
The carrier shell is simply a hollow carrier equipped with a fuze which ejects the contents at a calculated time. They are often filled with
propagandaPropaganda is communication aimed at influencing the attitude of a community toward some cause or position. As opposed to impartially providing information, propaganda in its most basic sense, presents information primarily to influence an audience...
leaflets (see external links), but can be filled with anything that meets the weight restrictions and is able to withstand the shock of firing. Famously, on Christmas Day 1899 during the
siege of LadysmithThe Siege of Ladysmith was a protracted engagement in the Second Boer War, taking place between 30 October 1899 and 28 February 1900 at Ladysmith, Natal.-Background:...
, the
BoerAfrikaners are White Afrikaans speakers who have been established in Southern Africa since the 17th century. They are mainly of northwestern European descent , but their native tongue is Afrikaans, a purported close relative of Dutch...
s fired into Ladysmith a carrier shell without fuze, which contained a
Christmas puddingChristmas pudding is the dessert traditionally served on Christmas day. It has its origins in England, and is sometimes known as plum pudding, though this can also refer to other kinds of boiled pudding involving a lot of dried fruit.-History:...
, two
Union FlagThe Union Flag, also known as the Union Jack, is the flag of the United Kingdom of Great Britain and Northern Ireland. It retains an official or semi-official status in some Commonwealth Realms; for example, it is known as the Royal Union Flag in Canada...
s and the message "compliments of the season". The shell is still kept in the museum at Ladysmith.
Fireworks
Aerial firework bursts are created by shells. In the United States, consumer firework shells may not exceed 1.75
inchAn inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
es in diameter.
Unexploded shells
The fuze of a shell has to keep the shell safe from accidental functioning during storage, due to (possibly) rough handling, fire, etc, it also has to survive the violent launch through the barrel, then reliably function at the correct time. To do this it has a number of arming mechanisms, which are successively enabled under the influence of the firing sequence.
Sometimes, one or more of these arming mechanisms fails, and if the fuze is installed on an HE shell, it fails to detonate on impact. More worrying and potentially far more hazardous are fully armed shells on which the fuze fails to initiate the HE firing. This may be due to shallow, low velocity or soft impact conditions. Whatever the reason for failure, such a shell is called a
blind or
unexploded ordnance (UXO). The older term, "dud", is discouraged because it implies that the shell
cannot detonate. Blind shells often litter old battlefields and depending on the impact velocity may be buried some distance into the earth, all remain potentially hazardous. For example, antitank ammunition with a piezoelectric fuze can be detonated by relatively light impact to the piezoelectric element, and others, depending on the type of fuze used can be detonated by even a small movement. The battlefields of the First World War still claim casualties today from leftover munitions. Thankfully modern electrical and mechanical fuzes are highly reliable, if they do not arm correctly they keep the initiation train out of line, or if electrical in nature, discharge any stored electrical energy.
If a blind shell is discovered, it should be avoided, other people warned of its presence, and it should be reported to the local
policeA police service is a public force empowered to enforce the law and provide security through the legitimized use of force.The term is most commonly associated with police services of a state that are authorized to exercise the police power of that state within a defined legal or territorial area of...
or
armed forcesThe armed forces of a country are its government-sponsored defense, fighting forces, and organizations. They exist to further the foreign and domestic policies of their governing body, and to defend that body and the nation it represents from external and internal aggressors. In some countries...
for safe destruction.
Range enhancing technologies
Shells may be modified into
RAPA Rocket Assisted Projectile is an artillery or cannon round incorporating a rocket motor for independent propulsion. This grants the projectile both greater speed and range than an ordinary shell, which is propelled only by the ballistic force of the gun's exploding charge. Some forms of Rocket...
and
Base bleedBase bleed is a system used on some artillery shells to increase their range, typically by about 30%.Most of the drag on an artillery shell comes from the nose of the shell, as it pushes the air out of its way at supersonic speeds. Shaping the shell properly can reduce this greatly. However,...
rounds to increase range.
External links