Crossbows

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Crossbow

Design Although some crossbows (ancient or modern) are drawn using only the unassisted arm strength of the archer, more powerful crossbows required some sort of mechanical device to draw the string. These drawing mechanisms were of many different forms, using levers, ratchets and pulleys in various ways, allowing to use weapons with a draw force far in excess of a bow.

The mechanism that holds the drawn bowstring, called a nut, was usually made of bone, ivory or metal, and the trigger mechanism of metal. Sophisticated bronze triggers with safety notches are known to have been used on crossbows from ancient China. Complicated iron triggers are known in Europe from the early 1400s. As a result crossbows could be kept cocked and ready to shoot for some time with little effort, allowing crossbowmen to aim better.

The bow (called the "prod" or "lath" on a crossbow) of early crossbows were made of a single piece of wood, usually ash or yew. The Saracen introduced composite bows, made from layers of different material—often wood, horn and sinew—glued together and bound with animal tendon. These composite bows could be much more powerful than wooden bows. As steel became more widely available in Europe around the 14th century, spring steel prods came into use. The crossbow prod is very short compared to ordinary bows, resulting in a short draw length. The resulting thick prods are less efficient at releasing energy, but more energy can be stored. A recurve crossbow is a bow that has tips curving away from the archer. The recurve bow's bent limbs allow for a draw length with the same limb length and less hand shock. A compound crossbow is a modern crossbow similar to the compound bow that has pulleys or cams at the end of each limb through which the bow string passes. As the bow is pulled back (drawn) the pulleys or cams turn which, in turn, reduce the amount of force needed to completely draw the bow. Traditionally the prod was often lashed to the stock with rope, whipcord, or other strong cording. This cording is called the bridle of the crossbow.

The strings for a crossbow are typically made of strong fibers that would not tend to fray. Whipcord was very common; however linen, hemp, and sinew were used as well. In wet conditions, twisted mulberry root was occasionally used.

The problem when handling crossbows was the comparably short draw length and the great amount of energy needed. Very light crossbows could be drawn by hand, but for others the help of devices was needed to increase the power. The simplest version was a hook attached to a belt and drawing the bow by straightening the legs. Other devices were different levers, ratchets and windlasses. The later could also be stationary devices for the use by several crossbows.

Variants Remains of an ancient Chinese pistol crossbow, 2nd century BC.Crossbows were utilized in different versions. The smallest are pistol crossbows. Others are simple long stocks with the crossbow mounted on them. These could be shot from under the arm. The next step in development was rifle shaped stocks that allowed better aiming.

The repeating crossbow automized the separate actions of stringing the bow, placing the projectile and shooting. This way the task can be accomplished with a simple one-handed movement, while keeping the weapon stationary. As a result, it is possible to shoot at a faster rate compared to unmodified version. The Chinese repeating crossbow, Chu Ko Nu, accomplishes the task with a magazine containing a number of bolts on top and the mechanism is worked by moving a rectangular lever forward and backward.

The weapon could also be increased in power. The arbalest was a heavy crossbow which required special systems for pulling the sinew and windlasses. For siege warfare the size of crossbows was further increased to hurl large projectiles such as rocks at fortications. The required crossbows needed a massive base frame and powerful windlass devices. Such devices include the oxybeles. The ballista has torsion springs replacing the elastic prod.[2] "Ballista" is still the root word for crossbow in Romance languages such as Italian (balestra).

Multiple bow systems (for example a Chuangzi Nu) have a special system of pulling the sinew via several bows. The workings can be compared to a modern compound bow system. The weapon uses several different bows instead of one bow with a tackle system to achieve a higher acceleration of the sinew via the multiplication with each bow's pulling effect.

Bowguns are a type of handheld crossbow which rather than arrows or bolts shoots spherical projectiles such as stones, clay or lead. The simplest version has sinew with a loop for the projectile or more sophisticated version have a barrel.

Projectiles
Modern crossbow bolt and 1 cent(€) coinThe arrow-like projectiles of a crossbow are called bolts. These are much shorter than arrows, but can be several times heavier. There is an optimum weight for bolts to achieve maximum kinetic energy, which varies depending on the strength and characteristics of the crossbow. In ancient times the bolts of strong crossbow were usually several times heavier than arrows. Modern bolts are stamped with a proof mark to ensure their consistent weight. Bolts typically have three fletches, commonly seen on arrows. Crossbow bolts can be fitted with a variety of heads, some with sickle-shaped heads to cut rope or rigging; but the most common today is a four-sided point called a quarrel. A highly specialized type of bolt can be employed to collect blubber biopsy samples used in biology research.

Crossbows could be adapted to also shoot stones or lead bullets. Primarily used for hunting wildfowl, these had a double string with a pouch between the strings to hold the projectile.

Accessories
The reticles of modern crossbow telescopic sights often allow the shooter to adjust for different rangesThe ancient crossbow often included a metal grid serving as iron sights. Modern crossbow sights often use similar technology to modern firearm sights such red dot sights and telescopic sights. Many crossbow scopes feature multiple crosshairs to compensate for the significant effects of gravity over different ranges.

Quivers can be mounted to hold ammunition. These are often made from plastic and usually hold the bolts in fixed positions along the structure. A popular detachable design consists of a main arm that is attached to the weapon, a plate on one end that secures four or more individual bolts at a point on their shafts and at the other end a cover that secures their heads. This kind of quiver is attached under the front of the crossbow, parallel to the string and is designed to be quickly detached and reattached. Other designs hold bolts underneath the crossbow parallel to the stock, sometimes on either side of the crossbow.

A major cause of the sound of firing a crossbow is vibration of various components. Crossbow silencers are multiple components placed on high vibration parts such as the string and limbs to dampen vibration and suppress the sound of loosing.

History
Main article: History of crossbows

First evidence It is not clear exactly where and when the crossbow originated, but there is evidence that it was used for military purposes from the second half of the 4th century BC onwards.

“ Throughout the southeastern Asia the crossbow is still used by primitive and tribal peoples both for hunting and war, from the Assamese mountains through Burma, Siam and to the confines of Indo-China. The peoples of the northeastern Asia possess it also, both as weapon and toy, but use it mainly in the form of unattended traps; this is true of the Yakut, Tungus, and Chukchi, even of the Ainu in the east. There seems to be no way of answering the question whether it first arose among the barbaric forefathers of these Asian peoples before the rise of the Chinese culture in their midst, and then underwent its technical development only therein, or whether it spread outwards from China to all the environing peoples. The former seems the more probable hypothesis, given the further linguistic evidence in its support.[3] ”

The earliest documention of a Chinese crossbow is in scripts from the 4th–3rd century BC attributed to the followers of Mozi. This source refers the use of a giant crossbow catapult to the 6th to 5th century BC, corresponding to the late Spring and Autumn Period. Sun Tzu's influential book The Art of War (first appearance dated in between 500 BC to 300 BC[4]) refers in chapter V to the traits and in XII to the use of crossbows.[5] One of the earliest reliable records of this weapon in warfare is from an ambush, the Battle of Ma-Ling in 341 BC. By the 200s BC, the crossbow (nu, ?) was well developed and quite widely used in China. Several remains of them have been found among the soldiers of the Terracotta Army in the tomb of Emperor Qin Shi Huang (260-210 BC).[6]

The earliest date for the crossbow is from the 5th century BC,[7] from the Greek world. This was called the gastraphetes, which could store more energy than the Greek bows, and was used in the Siege of Motya in 397 BC. This was a key Carthaginian stronghold in Sicily, as described in the 1st century AD by Heron of Alexandria in his book Belopoeica.[8] This date for the introduction of the crossbow in the Mediterranean is not accepted without doubt because of the temporal difference between writer and event and the lack of other sources stating the same. At least Alexander's siege of Tyre in 332 BC provides reliable sources for the use of these weapons by the Greek besiegers.[9]

The efficiency of the gastraphetes was improved by introducing the ballista. Its application in sieges and against rigid infantry formations featured more and more powerful projectiles, leading to technical improvements and larger ballistae. The smaller sniper version was often called Scorpio.[10] An example for the importance of ballistae in Hellenistic warfare is the Helepolis, a siege tower employed by Demetrius during the Siege of Rhodes in 305 BC. At each level of the moveable tower were several ballistae. The large ballistae at the bottom level were designed to destroy the parapet and clear it of any hostile troop concentrations while the small armorbreaking scorpios at the top level sniped at the besieged. This suppressive shooting would allow them to mount the wall with ladders more safely.[11]

Europe
A Medieval crossbowman drawing his bow behind his pavise. A hook on the end of a strap on his belt engages the bowstring. Holding the crossbow down by putting his foot through the stirrup, he draws the bow by straightening his legsThe use of crossbows in European warfare dates back to Roman times and is again evident from the battle of Hastings until about 1500 AD. They almost completely superseded hand bows in many European armies in the twelfth century for a number of reasons. Although a longbow had greater range, could achieve comparable accuracy and faster shooting rate than an average crossbow, crossbows could release more kinetic energy and be used effectively after a week of training, while a comparable single-shot skill with a longbow could take years of practice.

In the armies of Europe,[12] mounted and unmounted crossbowmen, often mixed with javeliners and archers, occupied a central position in battle formations. Usually they engaged the enemy in offensive skirmishes before an assault of mounted knights. Crossbowmen were also valuable in counterattacks to protect their infantry. The rank of commanding officer of the crossbowmen corps was one of the highest positions in any army of this time. Along with polearm weapons made from farming equipment, the crossbow was also a weapon of choice for insurgent peasants such as the Taborites.

Mounted knights armed with lances proved ineffective against formations of pikemen combined with crossbowmen whose weapons could penetrate most knights' armor. The invention of pushlever and ratchet drawing mechanisms enabled the use of crossbows on horseback., leading to the development of new cavalry tactics. Knights and mercenaries deployed in triangular formations, with the most heavily armored knights at the front. Some of these riders would carry small, powerful all-metal crossbows of their own. Crossbows were eventually replaced in warfare by gunpowder weapons, although early guns had slower rates of fire and much worse accuracy than contemporary crossbows. Later, similar competing tactics would feature harquebusiers or musketeers in formation with pikemen, pitted against cavalry firing pistols or carbines.

Elsewhere
Wheelmounted and elephantmounted double-bow-arcuballistas of the Champa kingdom.In Asia, crossbows were used as antipersonnel and siege weapons. The Chinese developed the repeating crossbow with an automatic reloading system.

The Saracens called the crossbow qaws Ferengi, or "Frankish bow", as the Crusaders used the crossbow against the Arab and Turkoman horsemen with remarkable success. The adapted crossbow was used by the Islamic armies in defence of their castles. Later footstrapped version become very popular among the Muslim armies in Spain. During the Crusades, Europeans were exposed to Saracen composite bows, made from layers of different material—often wood, horn and sinew—glued together and bound with animal tendon. These composite bows could be much more powerful than wooden bows, and were adopted for crossbow prods across Europe.

In Western Africa, crossbows served as a scout weapon and for hunting, with enslaved Africans bringing the technology to America.[13] In the American south, the crossbow was used for hunting when firearms or gunpowder were unavailable because of economic hardships or isolation.[14] Light hunting crossbows were traditionally used by the Inuit in Northern America.

Use of crossbows today
A whale shot by a modified crossbow bolt for a blubber biopsy sample.Crossbows are mostly used for target shooting in modern archery.

In some countries they are still used for hunting, such as in a few states within the USA, parts of Asia and Australia or Africa. Other uses with special projectiles are in whale research to take blubber biopsy samples without harming the whales. [15] Few modern military units are equipped with crossbows as even lower noise alternatives to suppressed firearms.

Comparison to regular bows
With a crossbow archers could release a draw force far in excess of what they could have handled with a bow. Moreover, crossbows could be kept cocked and ready to shoot for some time with little effort, allowing crossbowmen to aim better. The disadvantage is the higher weight and clumsiness compared to a bow, as well as the slower rate of fire and the lower efficiency of the acceleration system.