Shrapnel

From Wikipedia, the free encyclopedia

A sectioned Shrapnel shell displayed at the Canadian War Museum, Ottawa

For other uses, see Shrapnel (disambiguation).

Shrapnel is the term commonly used to describe the metal fragments and debris thrown out by any exploding object, be it a high explosive (HE) filled shell or a homemade bomb wrapped with nails or ball bearings. The word shrapnel is derived from the name of Major-General Henry Shrapnel (1761–1842), an English artillery officer, whose experiments—initially conducted in his own time, and at his own expense—designed a shell specifically for the purpose. The term "Shrapnel" originally referred only to the the spherical shot or musket balls dispersed when a shrapnel shell bursts, and this is still the technical meaning of the term, although it is now used to describe all types of high velocity debris thrown out from an explosion, and makes no differentiation to the process which created or produced the debris. The Oxford English Dictionary documents that the term Shrapnel is often used to describe fragments or shot intentionally included in explosive devices, such as pipe casings, nails, or ball bearings. For shells, bombs or other munitions, the technical term for these particles is fragments, splinters or shards, fragments being the preferred name in scientific documents on the subject. Another term which can be used to describe a particle other than a bullet which causes a wound is "bomb fragment" or "bomb shard". These terms also include items which were not part of the original explosive device, but which are propelled as projectiles by the force of the explosive or impact.

1 The shrapnel shell
2 Later designs
3 World War I era
4 World War II era
5 Vietnam era
6 Modern era
7 Other use of term
8 See also

[edit] The shrapnel shell

In 1784 Lieutenant Shrapnel of the Royal Artillery began the course to develop an anti-personnel weapon. At the time artillery could use "canister shot" or "case-shot" also known as grape shot, to defend themselves from infantry or cavalry attack. Instead of a cannonball, a tin or canvas container filled with small iron or lead balls was loaded. When fired, the container burst open during passage through the bore or at the muzzle, giving the effect of an oversized shotgun shell. At ranges of up to 300 m canister shot was still highly lethal, though at this range the shots’ density was much lower, making a hit on a human target less likely. At longer ranges, solid shot or the common shell — a hollow cast iron sphere filled with black powder — was used, although with more of a concussive than a fragmentation effect, as the pieces of the shell were very large and sparse in number. Shrapnel's innovation was to combine the multi-projectile shotgun effect of canister shot, with a delayed-action fuse to take the effect of canister shot to the enemy at a distance. His shell was a hollow cast-iron sphere filled with a mixture of balls and powder, with a crude time fuse. If the fuse was set correctly then the shell would break open, either in front or above the intended target, releasing its contents (of musket balls). The shrapnel balls would carry on with the "remaining velocity" of the shell. The explosive charge in the shell was to be just enough to break the casing rather than scatter the shot in all directions. As such his invention increased the effective range of canister shot from 300 to about 1100 m. He called his device 'spherical case' shot, but in time it came to be called after him; a position formalised in 1852 by the British Government. Initial designs suffered from the potentially catastrophic problem that friction between the shot and black powder during the high acceleration down the gun bore could sometimes cause premature ignition of the powder. This problem was overcome by placing the powder within a central metal tube, or a separate area within the hollow shell. As a buffer to prevent lead shot deforming, a resin was used as a packing material between the shot. A useful side effect of using the resin was that the combustion also gave a visual reference upon the shell bursting.

It took until 1803 for the British artillery to adopt it, albeit with great enthusiasm when it did. Shrapnel was promoted to Major in the same year. The Duke of Wellington used it beginning in 1808 against Napoleon, including in the Battle of Waterloo, and wrote admiringly of its effectiveness.

The design was improved by Captain E M Boxer RA in the 1840s and crossed over when cylindrical shells for rifled guns were introduced.

[edit] Later designs

For use with cylindrical shells, the design was slightly modified; the new hollow cylindrical shells had a nose mounted time fuse, a central flash channel around which the resin-encased shrapnel balls were placed, and a hollow containing black powder at the base, above which was a plate that was joined in the centre to the flash tube. At a preselected time during flight, the fuse functioned — the flash was directed down the central tube and ignited the rear powder charge. The powder charge was just enough to shear the fuse threads or pins, and force the shrapnel balls out. The vast majority of the balls' velocity came from the terminal velocity of the shell. Once loosed, the shrapnel balls became a hail of spherical bullets following the line of fire, creating an oval pattern upon striking the ground. Though highly effective against unprotected troops, they were useless when the troops are protected by cover, such as in trenches.

[edit] World War I era

During the initial stages of World War I, shrapnel was widely used by all sides to attack massed advancing troops in the open, but later dropped and the high explosive shell became the predominant type of 'explosive' shell used. The dropping of the shrapnel shell from use was due to the advent of trench warfare; the shrapnel was unable to cut the barbed wire entanglements in no man's land, crater the ground, or to defeat troops under cover, all of which were required as a precursor to an attack.

With the advent of relatively insensitive high explosives which could be used as the filling for shells, it was found that the casing of a properly designed high explosive shell fragmented so effectively that additional shot was not required. For example, the detonation of an average 105 mm shell produces several thousand high velocity (1,000 to 1,500 m/s) fragments, a lethal (at close range) blast overpressure and, if a surface or sub-surface burst, a useful cratering and anti-material effect — all in a munition much less complex to make than the later versions of the shrapnel shell.

One item of note is the 'Universal Shell', a type of field gun shell developed by Krupp of Germany in the early 1900s. This shell could function as either a shrapnel shell, or high explosive projectile. The shell had a modified fuse and instead of resin as the packing between the shrapnel balls, TNT was used. When the fuse was set to time, the fuse functioned in the normal way, ejecting the balls and igniting (not detonating) the TNT, the TNT giving a visual puff of black smoke. In impact mode the TNT filling was detonated, so becoming an high explosive shell with a very large amount of low velocity fragmentation and a milder blast. Again due to its complexity, it was dropped in favour of the simple high explosive shell.

[edit] World War II era

By World War II shrapnel shells, in the strict sense of the word, fell out of use, the last recorded use of shrapnel being 60 pdr shells fired in Burma in 1943.

[edit] Vietnam era

Although not strictly shrapnel, a 1960s weapons project produced the Beehive shell. Unlike the shrapnel shells’ balls, the beehive shell contained flechettes. The result was the 105 mm M546 APERS-T, first used in the Vietnam in 1966. The shell consisted of approximately 8,000 half gram flechettes, these arranged in five tiers, a time fuse, body shearing detonators, central flash tube, smokeless propellant charge with a dye marker contained in the base and tracer element. The functioning of the shell was as follows; the time fuse fires, flash sent down the flash tube, shearing detonators fire, and the forward body splits into four pieces, body and first four tiers dispersed by the projectile's spin, last tier and visual marker by the powder charge. The flechettes spread, mainly due to spin, from the point of burst in an ever widening cone along the projectile's previous trajectory prior to burst. The round is a highly effective anti-personnel weapon, but complex to make. It is said that the name beehive was given to the munition type due to the noise of the flechettes moving through the air resembling that of a swam of angry bees.

[edit] Modern era

Soviet shell of 125 mm for tanks

Though shrapnel rounds are now rarely used, there are other modern rounds, apart from the Beehive shell, that use, or have used the shrapnel principle. The DM 111 20 mm cannon round used for close range air defence, the flechette filled 40 mm HVCC (40 x 53 mm HV grenade), the 35 mm cannon (35 × 228 mm) AHEAD ammunition (152 x 3.3 g tungsten cylinders), RWM Schweiz 30 × 173 mm Air-Bursting munition, 5-Inch Shotgun Projectile (KE-ET) and possibility many more. Also many modern armies have canister shot ammunition for tank and artillery guns, the XM1028 round for the 120 mm M256 tank gun being one example (approx 1150 tungsten balls at 1400 m/s).

At least some Anti-Ballistic Missiles (ABMs) use shrapnel like warhead instead of the more common blast/fragmentation (blast/frag) type. As with a blast/frag warhead, the use of this type of warhead does not require a direct body-on-body impact, so greatly reducing tracking and steering accuracy requirements.

At a predetermined distance from the incoming re-entry vehicle (RV) the warhead releases, in the case of the ABM warhead by an explosive expulsion charge, an array of mainly rod-like sub-projectiles into the RV's flight path.

Unlike a blast/frag warhead, the expulsion charge is only needed to release the sub-projectiles from the main warhead, not to accelerate them to high velocity. The velocity required to penetrate the RV's casing comes from the high terminal velocity of the warhead, similar to the shrapnel shell's principle.

The reason for the use of this type of warhead and not a blast/frag is that the fragments produced by a blast/frag warhead cannot guarantee penetration of the RV's casing.

By using rod like sub-projectiles, a much greater thickness of material can be penetrated, greatly increasing the potential for disruption of the incoming RV.