Trebuchet
Overview
 
A trebuchet is a siege engine
Siege engine
A siege engine is a device that is designed to break or circumvent city walls and other fortifications in siege warfare. Some have been operated close to the fortifications, while others have been used to attack from a distance. From antiquity, siege engines were constructed largely of wood and...

 that was employed in the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

. It is sometimes called a "counterweight trebuchet" or "counterpoise trebuchet" in order to distinguish it from an earlier weapon that has come to be called the "traction trebuchet", the original version with pulling men instead of a counterweight.
The counterweight trebuchet appeared in both Christian and Muslim lands around the Mediterranean in the twelfth century.
Encyclopedia
A trebuchet is a siege engine
Siege engine
A siege engine is a device that is designed to break or circumvent city walls and other fortifications in siege warfare. Some have been operated close to the fortifications, while others have been used to attack from a distance. From antiquity, siege engines were constructed largely of wood and...

 that was employed in the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

. It is sometimes called a "counterweight trebuchet" or "counterpoise trebuchet" in order to distinguish it from an earlier weapon that has come to be called the "traction trebuchet", the original version with pulling men instead of a counterweight.
The counterweight trebuchet appeared in both Christian and Muslim lands around the Mediterranean in the twelfth century. It could fling projectiles of up to three hundred and fifty pounds (140 kg) at high speeds into enemy fortifications.

The trebuchet did not become obsolete until the 15th century, well after the introduction of gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

, which appeared in Europe in second half of 13th century.

Basic design

A trebuchet is a type of catapult
Catapult
A catapult is a device used to throw or hurl a projectile a great distance without the aid of explosive devices—particularly various types of ancient and medieval siege engines. Although the catapult has been used since ancient times, it has proven to be one of the most effective mechanisms during...

 that works by using the energy of a raised counterweight to throw the projectile. Initially, the sling, which has a pouch containing the projectile, is placed in a trough below the axle, which supports the beam. Upon releasing the trigger, the sling and the beam swing around toward the vertical position, where one end of the sling releases, opening the pouch and propelling the projectile towards the target. The efficiency of the transfer of the stored energy of the counterweight to the projectile can be quite high, even without, for example, restraining the path of the counterweight.

Modern-day enthusiasts have varied the original design, especially to control the path of the counterweight.

The three chief distinguishing characteristics of a trebuchet are:

~ A ) The machine is powered exclusively by gravity; most often directly by means of a counterweight, though sometimes indirectly (such as in a traction trebuchet).

~ B ) Such force rotates a throwing arm - usually four to six times the length of the counterweight arm - to multiply the speed of the arm and, eventually, the projectile.

~ C ) The machine utilizes a sling affixed to the end of the throwing arm, acting as a secondary fulcrum, to further multiply the speed of the projectile.

Trebuchets versus torsion

The trebuchet is often confused with the earlier torsion siege engines. The main difference is that a torsion siege engine (examples of which include the onager
Onager (siege weapon)
The onager was a Roman siege engine, which derived its name from the kicking action of the machine, similar to that of an onager , it was created as a simpler, cheaper version of the ballista. The Onager is a type of catapult that uses torsional pressure, generally from twisted rope, to store...

  and ballista
Ballista
The ballista , plural ballistae, was an ancient missile weapon which launched a large projectile at a distant target....

) uses a twisted rope or twine to provide power, whereas a trebuchet uses a counterweight, usually much closer to the fulcrum than the payload for mechanical advantage
Mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...

, though this is not necessary. A trebuchet also has a sling
Sling (weapon)
A sling is a projectile weapon typically used to throw a blunt projectile such as a stone or lead "sling-bullet". It is also known as the shepherd's sling....

 holding the projectile (although the Roman onager
Onager (siege weapon)
The onager was a Roman siege engine, which derived its name from the kicking action of the machine, similar to that of an onager , it was created as a simpler, cheaper version of the ballista. The Onager is a type of catapult that uses torsional pressure, generally from twisted rope, to store...

 often had a sling as well), and a means for releasing it at the right moment for maximum range.

Traction trebuchet

The trebuchet derives from the ancient sling
Sling (weapon)
A sling is a projectile weapon typically used to throw a blunt projectile such as a stone or lead "sling-bullet". It is also known as the shepherd's sling....

. A variation of the sling, called staff sling (Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

: fustibalus), contained a short piece of wood to extend the arm and provide greater leverage. This evolved into the traction trebuchet in which a number of people pull on ropes attached to the short arm of a lever that has a sling on the long arm. This type of trebuchet is smaller and has a shorter range, but is a more portable machine and has a faster rate of fire than larger, counterweight-powered types. The smallest traction trebuchets could be powered by the weight and pulling strength of one person using a single rope, but most were designed and sized for between 15 and 45 men, generally two per rope. These teams would sometimes be local citizens helping in the siege or in the defense of their town. Traction trebuchets had a range of 100 to 200 ft (30.5 to 61 ) when casting weights up to 250 pounds (113.4 kg). It is believed that the first traction trebuchets were used by the Mohists in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 as early as in the 5th century BC descriptions of which can be found in the Mojing
Mozi
Mozi |Lat.]] as Micius, ca. 470 BC – ca. 391 BC), original name Mo Di , was a Chinese philosopher during the Hundred Schools of Thought period . Born in Tengzhou, Shandong Province, China, he founded the school of Mohism, and argued strongly against Confucianism and Daoism...

 (compiled in the 4th century BC). The Chinese named the later counterweight trebuchet Huihui Pao (Muslim Weapons, "huihui" means Muslim) or Xiangyang Pao (襄陽砲), where Pao means bombard.

The traction trebuchet next appeared in Byzantium
Byzantium
Byzantium was an ancient Greek city, founded by Greek colonists from Megara in 667 BC and named after their king Byzas . The name Byzantium is a Latinization of the original name Byzantion...

. The Strategikon
Strategikon
The Strategicon or Strategikon is a manual of war by written in the late 6th century and usually attributed to Byzantine Emperor Maurice; it is moreover a practical manual, "a rather modest elementary handbook," in the words of its introduction, "for those devoting themselves to generalship."The...

of Emperor Maurice, composed in the late 6th century, calls for "ballistae revolving in both directions," (Βαλλίστρας έκατηρωθεν στρεφόμενας), probably traction trebuchets (Dennis 1998, p. 99). The Miracles of St. Demetrius, composed by John I, archbishop of Thessalonike, clearly describe traction trebuchets in the Avaro-Slav artillery: "Hanging from the back sides of these pieces of timber were slings and from the front strong ropes, by which, pulling down and releasing the sling, they propel the stones up high and with a loud noise." (John I 597 1:154, ed. Lemerle 1979)

They were also used with great effect by the Islamic armies during the Muslim conquests
Muslim conquests
Muslim conquests also referred to as the Islamic conquests or Arab conquests, began with the Islamic prophet Muhammad. He established a new unified polity in the Arabian Peninsula which under the subsequent Rashidun and Umayyad Caliphates saw a century of rapid expansion of Muslim power.They...

. A surviving Arab technical treatise on these machines is Kitab Aniq fi al-Manajaniq ( كتاب أنيق في المنجنيق, An Elegant Book on Trebuchets), written in 1462 by Yusuf ibn Urunbugha al-Zaradkash. It provides detailed construction and operating information.

There is some doubt as to the exact period in which traction trebuchets, or knowledge of them, reached Scandinavia. The Vikings may have known of them at a very early stage, as the monk Abbo de St. Germain reports on the siege of Paris in his epic De bello Parisiaco dated about 890 that engines of war were used. Another source mentions that Nordic people or "the Norsemen" used engines of war at the siege of Angers as early as 873.

Hand-trebuchet

The hand-trebuchet was a staff sling mounted on a pole using a lever
Lever
In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...

 mechanism to propel projectiles. Basically a portable trebuchet which could be operated by a single man, it was used by emperor Nikephoros II Phokas around 965 to disrupt enemy formations in the open field. It was also mentioned in the Taktika of general Nikephoros Ouranos
Nikephoros Ouranos
Nikephoros Ouranos was a high-ranking Byzantine official and general during the reign of Emperor Basil II. One of the emperor's closest associates, he was active in Europe in the wars against the Bulgarians, scoring a major victory at Spercheios, and against the Arabs in Syria, where he held...

 (ca. 1000), and listed in the Anonymus De obsidione toleranda as a form of artillery.

Counterweight trebuchet

The earliest written record of the counterweight trebuchet, much more powerful than the traction version, appears in the work of the 12th century Byzantine
Byzantine
Byzantine usually refers to the Roman Empire during the Middle Ages.Byzantine may also refer to:* A citizen of the Byzantine Empire, or native Greek during the Middle Ages...

 historian Niketas Choniates. Niketas describes a trebuchet used by Andronikos I Komnenos
Andronikos I Komnenos
Andronikos I Komnenos was Byzantine Emperor from 1183 to 1185). He was the son of Isaac Komnenos and grandson of Emperor Alexios I Komnenos.-Early years:...

, future Byzantine emperor, at the siege of Zevgminon in 1165 which was equipped with a windlass
Windlass
The windlass is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder , which is rotated by the turn of a crank or belt...

, an apparatus which was required neither for traction nor hybrid trebuchets to launch missiles. Chevedden dates the invention of the new artillery type back to the Siege of Nicaea
Siege of Nicaea
The Siege of Nicaea took place from May 14 to June 19, 1097, during the First Crusade.-Background:Nicaea , located on the eastern shore of Lake İznik, had been captured from the Byzantine Empire by the Seljuk Turks in 1081, and formed the capital of the Sultanate of Rüm...

 in 1097 when the Byzantine emperor Alexios I Komnenos
Alexios I Komnenos
Alexios I Komnenos, Latinized as Alexius I Comnenus , was Byzantine emperor from 1081 to 1118, and although he was not the founder of the Komnenian dynasty, it was during his reign that the Komnenos family came to full power. The title 'Nobilissimus' was given to senior army commanders,...

, an ally of the besieging crusaders
Crusades
The Crusades were a series of religious wars, blessed by the Pope and the Catholic Church with the main goal of restoring Christian access to the holy places in and near Jerusalem...

, was reported to have invented new pieces of heavy artillery which deviated from the conventional design and made a deep impression on everyone.

The dramatic increase in military performance is for the first time reflected in historical records on the occasion of the second siege of Tyre in 1124, when the crusaders reportedly made use of "great trebuchets". By the 1120–30s, the counterweight trebuchet had diffused not only to the crusaders states, but probably also westwards to the Normans of Sicily and eastwards to the Great Seljuqs. The military use of the new gravity-powered artillery culminated in the 12th century during the Siege of Acre (1189–91) which saw the kings Richard I of England
Richard I of England
Richard I was King of England from 6 July 1189 until his death. He also ruled as Duke of Normandy, Duke of Aquitaine, Duke of Gascony, Lord of Cyprus, Count of Anjou, Count of Maine, Count of Nantes, and Overlord of Brittany at various times during the same period...

 and Philip II of France
Philip II of France
Philip II Augustus was the King of France from 1180 until his death. A member of the House of Capet, Philip Augustus was born at Gonesse in the Val-d'Oise, the son of Louis VII and his third wife, Adela of Champagne...

 wrestle for control of the city with Saladin
Saladin
Ṣalāḥ ad-Dīn Yūsuf ibn Ayyūb , better known in the Western world as Saladin, was an Arabized Kurdish Muslim, who became the first Sultan of Egypt and Syria, and founded the Ayyubid dynasty. He led Muslim and Arab opposition to the Franks and other European Crusaders in the Levant...

's forces.

The only pictorial evidence of a counterweight trebuchet in the 12th century comes from an Islamic scholar, Mardi bin Ali al-Tarsusi
Mardi bin Ali al-Tarsusi
Mardi bin Ali al-Tarsusi was a 12th century Ayyubid writer and expert on military matters. He wrote a number of treatises, including a military manual for Saladin in 1187...

, who wrote a military manual for Saladin
Saladin
Ṣalāḥ ad-Dīn Yūsuf ibn Ayyūb , better known in the Western world as Saladin, was an Arabized Kurdish Muslim, who became the first Sultan of Egypt and Syria, and founded the Ayyubid dynasty. He led Muslim and Arab opposition to the Franks and other European Crusaders in the Levant...

 circa 1187. He describes a hybrid trebuchet that he said had the same hurling power as a traction machine pulled by fifty men due to "the constant force [of gravity], whereas men differ in their pulling force." (Showing his mechanical proficiency, Tarsusi designed his trebuchet so that as it was fired it cocked a supplementary crossbow, probably to protect the engineers from attack.) He allegedly wrote "Trebuchets are machines invented by unbelieving devils." (Al-Tarsusi, Bodleian MS 264). This suggests that by the time of Saladin, Muslims were acquainted with counterweight engines, but did not believe that they had invented these machines.

During the Crusades
Crusades
The Crusades were a series of religious wars, blessed by the Pope and the Catholic Church with the main goal of restoring Christian access to the holy places in and near Jerusalem...

, Philip II of France
Philip II of France
Philip II Augustus was the King of France from 1180 until his death. A member of the House of Capet, Philip Augustus was born at Gonesse in the Val-d'Oise, the son of Louis VII and his third wife, Adela of Champagne...

 named two of the trebuchets he used in the Siege of Acre in 1191 "God's Stone-Thrower" and "Bad Neighbor." During a siege of Stirling Castle
Stirling Castle
Stirling Castle, located in Stirling, is one of the largest and most important castles, both historically and architecturally, in Scotland. The castle sits atop Castle Hill, an intrusive crag, which forms part of the Stirling Sill geological formation. It is surrounded on three sides by steep...

 in 1304, Edward Longshanks
Edward I of England
Edward I , also known as Edward Longshanks and the Hammer of the Scots, was King of England from 1272 to 1307. The first son of Henry III, Edward was involved early in the political intrigues of his father's reign, which included an outright rebellion by the English barons...

 ordered his engineers to make a giant trebuchet for the English army, named "Warwolf
Warwolf
The Warwolf, or War Wolf or Ludgar , is believed to be the largest Trebuchet ever made. It was created in Scotland by order of King Edward Longshanks of England, during the siege of Stirling Castle, as part of the Scottish Wars of Independence.When disassembled, the weapon would fill 30 wagons...

". Range and size of the weapons varied. In 1421 the future Charles VII of France
Charles VII of France
Charles VII , called the Victorious or the Well-Served , was King of France from 1422 to his death, though he was initially opposed by Henry VI of England, whose Regent, the Duke of Bedford, ruled much of France including the capital, Paris...

 commissioned a trebuchet (coyllar) that could shoot a stone of 800 kg, while in 1188 at Ashyun, rocks up to 1,500 kg were used. Average weight of the projectiles was probably around 50–100 kg, with a range of ca. 300 meters. Rate of fire could be noteworthy: at the siege of Lisbon
Siege of Lisbon
The Siege of Lisbon, from July 1 to October 25, 1147, was the military action that brought the city of Lisbon under definitive Portuguese control and expelled its Moorish overlords. The Siege of Lisbon was one of the few Christian victories of the Second Crusade—it was "the only success of the...

 (1147), two engines were capable of launching a stone every 15 seconds. Also human corpses could be used in special occasion: in 1422 Prince Korybut
Sigismund Korybut
Sigismund Korybut was a duke from the Gediminid dynasty, best known as a military commander of the Hussite army and a governor of Bohemia and Prague during the Hussite Wars....

, for example, in the siege of Karlštejn Castle shot men and manure within the enemy walls, apparently managing to spread infection among the defenders. The largest trebuchets needed exceptional quantities of timber: at the Siege of Damietta
Siege of Damietta
The Siege of Damietta of 1218 was part of the Fifth Crusade. The city, under the control of the Ayyubid Al-Kamil, was besieged by and taken by the Crusaders in 1219....

, in 1249, Louis IX of France
Louis IX of France
Louis IX , commonly Saint Louis, was King of France from 1226 until his death. He was also styled Louis II, Count of Artois from 1226 to 1237. Born at Poissy, near Paris, he was an eighth-generation descendant of Hugh Capet, and thus a member of the House of Capet, and the son of Louis VIII and...

 was able to build a stockade for the whole Crusade camp with the wood from 24 captured Egyptian trebuchets.

Counterweight trebuchets do not appear with certainty in Chinese historical records until about 1268, when the Mongols laid siege to Fancheng and Xiangyang. At the Siege of Fancheng and Xiangyang
Battle of Xiangyang
The Battle of Xiangyang also known as the Battle of Xiangfan was a six-year battle between invading Yuan Dynasty armies founded by the Mongols and Southern Song forces between AD 1267 and 1273. After the battle, the victorious Yuan forces pushed farther into the Song heartland...

, the Mongol army, unable to capture the cities despite besieging the Song
Song Dynasty
The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...

 defenders for years, brought in two Persian engineers who built hinged counterweight trebuchets and soon reduced the cities to rubble, forcing the surrender of the garrison. These engines were called by the Chinese historians the Huihui Pao (回回砲)("huihui" means Muslim) or Xiangyang Pao (襄陽砲), because they were first encountered in that battle. Recent research by Paul E. Chevedden indicates that the hui-hui pao was actually a European design, a double-counterweight engine that had been introduced to the Levant
Levant
The Levant or ) is the geographic region and culture zone of the "eastern Mediterranean littoral between Anatolia and Egypt" . The Levant includes most of modern Lebanon, Syria, Jordan, Israel, the Palestinian territories, and sometimes parts of Turkey and Iraq, and corresponds roughly to the...

 by Holy Roman Emperor
Holy Roman Emperor
The Holy Roman Emperor is a term used by historians to denote a medieval ruler who, as German King, had also received the title of "Emperor of the Romans" from the Pope...

 Frederick II
Frederick II, Holy Roman Emperor
Frederick II , was one of the most powerful Holy Roman Emperors of the Middle Ages and head of the House of Hohenstaufen. His political and cultural ambitions, based in Sicily and stretching through Italy to Germany, and even to Jerusalem, were enormous...

 (1210–1250) only shortly before. The Muslim historian Rashid-al-Din Hamadani (1247?–1318) refers in his universal history
Universal history
Universal history is basic to the Western tradition of historiography, especially the Abrahamic wellspring of that tradition. Simply stated, universal history is the presentation of the history of humankind as a whole, as a coherent unit.-Ancient authors:...

 to the Mongol trebuchets used at the Song cities as "Frankish" or "European trebuchets" ("manjaniq ifranji" or "manjaniq firanji"):

Before that there had not been any large Frankish catapult in Cathay [i.e. China], but Talib, a catapult-maker from this land, had gone to Baalbek and Damascus, and his sons Abubakr, Ibrahim, and Muhammad, and his employees made seven large catapults and set out to conquer the city [Sayan Fu or Hsiang-yang fu = modern Xiangfan].


With the introduction of gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

, the trebuchet lost its place as the siege engine of choice to the cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents 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,...

. Trebuchets were used both at the siege of Burgos
Siege of Burgos
At the Siege of Burgos, from 19 September to 21 October 1812, the Anglo-Portuguese Army led by General Arthur Wellesley, Marquess of Wellington tried to capture the castle of Burgos from its French garrison under the command of General of Brigade Jean-Louis Dubreton. The French repulsed every...

 (1475–1476) and siege of Rhodes
Siege of Rhodes (1480)
In 1480 the small Knights Hospitaller garrison of Rhodes withstood an attack of the Ottoman Empire.-Preparation:In 1470, the island of Tilos was evacuated to Rhodes because they were susceptible to attacks from the Ottoman Empire...

 (1480). One of the last recorded military uses was by Hernán Cortés
Hernán Cortés
Hernán Cortés de Monroy y Pizarro, 1st Marquis of the Valley of Oaxaca was a Spanish Conquistador who led an expedition that caused the fall of the Aztec Empire and brought large portions of mainland Mexico under the rule of the King of Castile in the early 16th century...

, at the 1521 siege of the Aztec capital Tenochtitlán. Accounts of the attack note that its use was motivated by the limited supply of gunpowder. The attempt was reportedly unsuccessful: the first projectile landed on the trebuchet itself, destroying it.

In 1779, British forces defending Gibraltar
Gibraltar
Gibraltar is a British overseas territory located on the southern end of the Iberian Peninsula at the entrance of the Mediterranean. A peninsula with an area of , it has a northern border with Andalusia, Spain. The Rock of Gibraltar is the major landmark of the region...

, finding that their cannons were unable to fire far enough for some purposes, constructed a trebuchet. It is unknown how successful this was: the Spanish attackers were eventually defeated, but this was largely due to a sortie
Sortie
Sortie is a term for deployment or dispatch of one military unit, be it an aircraft, ship, or troops from a strongpoint. The sortie, whether by one or more aircraft or vessels, usually has a specific mission....

.

Modern recreational use

Trebuchets are popular in modern times in a number of contexts. In particular, traditional models are constructed by historical re-enactment and living history
Living history
Living history is an activity that incorporates historical tools, activities and dress into an interactive presentation that seeks to give observers and participants a sense of stepping back in time. Although it does not necessarily seek to reenact a specific event in history, living history is...

 enthusiasts, and others use the trebuchet as an engineering challenge, or for recreational purposes.

Trebuchets are used to throw pumpkins at the annual pumpkin chunking
Pumpkin chunking
Pumpkin Chucking, or for rhyming purposes Pumpkin Chunking is the sport of hurling or 'chucking' a pumpkin by mechanical means for distance...

 contest held in Sussex County, Delaware
Sussex County, Delaware
Sussex County is a county located in the southern part of the U.S. state of Delaware. As of 2010 the population was 197,145, an increase of 25.9% over the previous decade. The county seat is Georgetown. The Seaford Micropolitan Statistical Area includes all of Sussex County.Sussex County is...

. The record-holder in that contest for trebuchets is the Yankee Siege, which at the 2009 Championship tossed a pumpkin 2034 feet (620 m). The 51 feet (15.5 m), 55000 pounds (24,947.6 kg) trebuchet fires 8 pound pumpkins.

The largest currently-functioning trebuchet in the world is the 22-tonne machine at Warwick Castle, England. It stands 18 metres tall (59 ft) and throws missiles typically 80lbs up to 300 metres.

Modern engineering thought and materials have come up with several non-traditional designs, in particular, several with "floating arms" to increase efficiency.

Fixed-Counterweight (FCW) Trebuchets

The earliest trebuchets most often utilized counterweights affixed directly to the shorter arm. This eliminated the radically unpredictable variable of the traction trebuchet, enabling far more consistent aiming - as well as reducing the manpower required by an individual machine. A trebuchet became a far greater threat to fortifications because it could now fire repeatedly at a specific point with a relatively high degree of accuracy.

The chief liability of this design is that the formidable mass of the counterweight swings through a wide arc and its inertia can readily topple the trebuchet - posing almost as much threat to the attackers as the defenders.

Hinged-Counterweight (HCW) Trebuchets

By suspending the counterweight, rather than being mounted directly, trebuchets gained a primitive form of recoil suppression. Though still travelling through an arc, the fall of the counterweight became closer to vertical and imparts lesser lateral forces against the frame of the siege engine. In addition to greater stability, this also allowed attackers to fire heavier projectiles for greater damage or from further distances to protect the crews.

This style of machine quickly became the de-facto standard for trebuchets, utilized by the overwhelming majority of known machines since its introduction.

Arm-Over-Wheel (AROW) and Arm-Over-Cam (AROC) Trebuchets

Rather than the fixed axles of traditional trebuchets, the center of rotation for these machines move towards the counterweight as it fires - enabling the counterweight to fall almost directly downwards. As with its Hinged-Counterweight forebearers, this design better utilized the energy of its falling counterweight to impart far greater force into the projectile.

Unfortunately, this development came extremely late in the historical use of trebuchets. Much like how steam- and electric-powered cars vanished with the advent of the gasoline-powered internal combustion engine, the widespread use of gunpowder coupled with social upheavals all but eliminated sieges before this technology saw much use.

Floating-Arm (FAT) Trebuchets

A floating-arm trebuchet is an efficient modern variant. Rather than having an axle fixed to the frame, it is mounted on wheels that roll on a track parallel to the ground, and the counterweight is constrained to fall in a direct path downwards upon the release. This increases the proportion of energy transferred to the projectile. This is more sophisticated than the medieval weapon, but previous designs accomplished a similar effect by placing the whole trebuchet on wheels.

Further Refinements

The recreational use of trebuchets, coupled with modern materials and manufacturing, has given birth to designs the ancients would not even recognize as trebuchets. Foremost among these is Merlin, which uses no counterweight whatsoever - the weight of the machine itself is what powers this trebuchet with an efficiency beyond the wildest dreams of medieval engineers.

External links



The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK