Shell (projectile) - History

History

Solid cannonballs (“shot”) did not need a fuze, but hollow balls (“shells”) filled with something, such as gunpowder to fragment the ball needed a fuze, either impact (percussion) or time. Percussion fuzes with a spherical projectile presented a challenge because there was no way of ensuring that the impact mechanism hit the target. Therefore shells needed a time fuze that was ignited before or during firing and burnt until the shell reached its target. Early reports of shells include Venetian use at Jadra in 1376 and shells with fuzes at the 1421 siege of St Boniface in Corsica. These were two hollowed hemispheres of stone or bronze held together by an iron hoop. Written evidence for early explosive shells in China appears in the early Ming Dynasty (1368–1644) Chinese military manual Huolongjing, compiled by Jiao Yu (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 iron.

Yi jang-son made Bigyukjincheonroi in the reign of Seonjo of Joseon. (WP:CIRCULAR and WP:RSUE) Bigyukjincheonroi is a time shell that consisted of wooden tube wound with time fuze made of thread, iron scrap and cap. Its time fuze can be set the time by length of thread. It was used in Japanese invasions of Korea. They were usually fired from the family of wan-gu (Hangul: 완구; Hanja: 碗口; literally "bowl-mouth") mortars.

An early problem was that until 1672 there was no means of measuring the time precisely enough—clockwork fuzes did not yet exist. The burning time of the powder fuze was subject to considerable trial and error. Early powder burning fuzes had to be loaded fuze down to be ignited by firing or a portfire put down the barrel to light the fuze. Other shells were wrapped in bitumen cloth which would ignite during the firing and in turn ignite a powder fuse. However, by the 18th Century it was discovered that the fuze towards the muzzle could be lit by the flash through the windage between shell and barrel. Nevertheless, shells came into regular use in the 16th Century, for example a 1543 English mortar shell filled with 'wildfire'. About 1700 shells began to be employed for horizontal fire from howitzers with a small propelling charge and in 1779 experiments demonstrated that they could be used from guns with heavier charges. They became usual with field artillery early in the 19th Century. By this time shells were usually cast iron, but bronze, lead, brass and even glass were tried.

See the article on Artillery fuze for more information.

Cast-iron spherical common shell (so named because they were used against "common" targets) were in use up to 1871. Typically the thickness of the metal body was about 1/6 their diameter and they were about 2/3s the weight of solid shot of the same calibre. In order to ensure that shells were loaded with their fuzes towards the muzzle they were attached to wooden bottoms called 'sabots'. In 1819 a committee of British artillery officers recognised that they were essential stores and in 1830 Britain standardised sabot thickness as half inch. The sabot also intended to reduce jamming during loading and the rebounding of the shell as it traveled along the bore on discharge. Mortar shells were not fitted with sabots.

Rifling was invented by Jaspard Zoller, a Viennese gun maker at the end of the 15th Century, and it was realised that twisted rifling to spin an elongated projectile would greatly improve its accuracy. This was known to artillerists but its application to artillery was beyond the available technology until around the mid 19th Century. English inventor notable Armstrong, Whitworth and Lancaster and the latter's rifled guns were used in the Crimean War. Armstrong's rifled breech-loading cannon was a key innovation and adopted for British service in 1859. Also in the 1850s rifled guns were developed by Major Cavelli in Italy, Baron Wahrendorff and Krupp in Germany and the Wiard gun in the United States. However, rifled barrels required some means of engaging the shell with the rifling. Lead coated shells were used with Armstrong guns, but were not satisfactory so studded projectiles were adopted. However these did not seal the gap between shell and barrel. Wads at the shell base were tried, without success, in 1878 the British adopted a copper 'gas-check' at the base of their studded projectiles, and in 1879 tried a rotating gas check to replace the studs, leading to the 1881 automatic gas-check. This was soon followed by the Vavaseur copper driving band as part of the projectile. The driving band rotated the projectile, centred it in the bore and prevented gas escaping forwards. A driving band has to be soft but tough enough to prevent stripping by rotational and engraving stresses. Copper is generally most suitable but cupro nickel or gilding metal are also used.

The first pointed armour piercing shell was introduced by Major Palliser in 1863, it was made of chilled cast iron with an ogival head of 11⁄₂ calibres radius. However, during 1880–1890 steel shells and armour began to appear and it was realised that steel bodies for explosive filled shells had advantages - better fragmentation and resistance to the stresses of firing. These were cast and forged steel.

Shells have never been limited to an explosive filling. An incendiary shell was invented by Valturio in 1460. The carcass was invented in 1672 by a gunner serving Christoph van Galen, Prince Bishop of Munster, initially oblong in an iron frame or carcass (with poor ballistic properties) it evolved into a spherical shell. Their use continued well into the 19th Century. In 1857 the British introduced an incendiary shell (Martin's) filled with molten iron, which replaced red hot shot used against ships, most notably at Gibraltar in 1782. Two patterns of incendiary shell were used by the British in World War 1, one designed for use against Zeppelins.

Similar to incendiary shells were star shells, designed for illumination rather than arson. Sometimes called lightballs they were in use from the 17th Century onwards. The British adopted parachute lightballs in 1866 for 10, 8 and 51⁄₂ inch calibres. The 10-inch wasn't officially declared obsolete until 1920!

Smoke balls also date back to the 17th Century, British ones contained a mix of saltpetre, coal, pitch, tar, resin, sawdust, crude antimony and sulphur. They produced a 'noisome smoke in abundance that is impossible to bear'. In the 19th Century British service they were made of concentric paper with thickness about 1/15th of total diameter and filled with powder, saltpetre, pitch, coal and tallow. They were used to 'suffocate or expel the enemy in casemates, mines or between decks; for concealing operations; and as signals.

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 helmets 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.