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.]] A trebuchet (, or ), also sometimes called a '''trebucket''' () is a Medieval Siege Engine , a weapon employed either to batter Masonry or to throw Projectile s over Wall s. The trebuchet is thought to have been invented in China between the 5th and 3rd Centuries BC . The counterweight trebuchet was a development of the Chinese traction trebuchet, in which a crew of men pulled down on ropes attached to a levered sling to propel the missile. The device reached Europe around 500 AD. It was also used during the middle ages to throw people who had died from the Black Plague over castle walls, in an attempt to infect the people under siege. ACTION OF THE TREBUCHET A trebuchet is powered by a falling Counterweight acting through a beam acting as a Lever . The fulcrum of the beam (usually an axle) is placed at the top of a high strutted vertical frame and the counterweight is normally freely suspended from the end of the short arm of the beam. The sling has a captive end attached to the long arm of the beam, and a free end with a loop that slips from a hook projecting from the end of the beam. The trebuchet is cocked by raising the counterweight, usually with a winch. A trigger mechanism holds the counterweight up. The sling is arranged horizontally in a trough parallel to the beam, toward the counterweight, and the projectile placed in its pouch. When the trigger is released, the counterweight falls and the beam pulls the sling, at first horizontally along the trough in the base of the frame. Soon after, the sling lifts off and whips in an arc upwards. When the projectile moves close to the point where the taut sling makes about a 45° angle with the horizontal, the free end of the sling slips from the hook, and the missile flies free toward its target. The dimensions of each of the components of the trebuchet determine how well the trebuchet functions. The beam is particularly critical. It must be as light as possible, yet strong enough not to break when fired. The ratio of the length of the long to the short end of the beam, and to the sling length, are important factors in determining the range of the projectile. The object of a good design is to transfer as much of the potential energy of the hanging counterweight into kinetic energy of the projectile. If the transfer is a perfect 100%, and friction is neglected, the maximum range, , of the projectile can be shown to be , where is the distance the counterweight falls, and and are the mass of the counterweight and projectile, respectively. The efficiency of a real trebuchet is then easily determined as the ratio of the actual range achieved to the calculated maximum range. Designs were probably carried out by making variations on a scale model, and were, no doubt, empirically determined. There are no really detailed descriptions of medieval (or earlier) trebuchets that give, for example the dimensions or shape of the beam, the ratio of its long arm to its short arm, and so on. No examples, nor models, from medieval times survive. The few extant contemporary drawings of them are highly schematic and even sometimes show physically impossible proportions. Methods used for optimizing their performance and design were apparently closely held military secrets, and are not available to present-day re-constructors. Emplacing and aiming the trebuchet was also, no doubt, done by empirical trials. Small adjustments can be made by changing the angle of the hook holding the free end of the sling, a process which requires a heated forge on a full-scale engine. For larger, quicker adjustments, the length of the sling can be altered. Small adjustments from side-to-side can also be made by moving the channel in which the missile and sling slide in the base of the frame. The trebuchet itself could be moved as well, but with larger trebuchets, this would have been difficult-the largest trebuchets could weigh many tons. Because of the time required to load the sling and to raise the counterweight, a large trebuchet's rate of fire is slow, often not more than a couple of shots an hour. Smaller trebuchets can fire a couple of times a minute. The payload of a trebuchet was usually a large rounded stone, although other projectiles were occasionally used: dead animals, beehives, the severed heads of captured enemies, small stones burned into clay balls which would explode on impact like grapeshot, barrels of burning tar or oil, Greek Fire , or even unsuccessful negotiators, prisoners of war, and spies catapulted alive. Trebuchets were formidably powerful weapons, with a range of up to about 300 Yard s. Castle designers often built their fortifications with trebuchets in mind; for instance, Caerphilly Castle in Wales was surrounded by artificial lakes to keep besiegers and their siege weapons at a distance. The range of many trebuchets was in fact shorter than that of an English Longbow in skilled hands, making it somewhat dangerous to be a trebuchet operator during a siege. This meant that sieges could be long drawn-out affairs, sometimes lasting for years at a time. A trebuchet can increase its efficiency (and hence either range or payload) by allowing the counterweight to take the straightest possible downward path. This maximises the transfer of the counterweight's potential energy to the projectile rather than to stressing the frame. Mounting the counterweight on a pivot straightens the path of its fall, increasing its effectiveness. A fixed counterweight trebuchet in particular can therefore be made more efficient by the addition of wheels to allow the frame to move freely back and forth. The addition of wheels also makes the trebuchet more stable as part of the forward momentum of the falling counterweight is transferred to the forward motion of the trebuchet instead of a tilting action of the vertical frame, possibly tipping over of the machine or severely damaging the structure. The velocity of the trebuchet frame is added to that of the item being thrown, increasing its velocity and range by up to 33 percent. The wheeled trebuchet can effectively employ a fixed counterweight, mounted to the short end of the throwing arm, rather than the pendulum weight described above. Such weights are believed to have been made from Lead , evidenced in at least one case by requisitions for the lead used as roofing material in churches. HISTORY AND FIRST USES The invention of the trebuchet derives, no doubt, from the ancient Sling . A variant of it, the staff sling, involved using 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, has a shorter range and is a more portable machine, but has a faster rate of fire than a larger counterweight powered one. 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 to utilize from 20 to 100 men, generally two per rope. These teams would sometimes be local citizens assisting in the siege or in the defense of their town. Traction trebuchets had a range of from 200 to well over 300 feet (60 to 100+ meters) when casting weights up to 130 pounds (60kg). It is believed that the first traction trebuchets were used in China as early as in the 5th century BC, descriptions of which can be found in the 5th century B.C. Mozi . Chinese counterweight trebuchets were called the Huihui Pao (回回砲) or Xiangyang Pao (襄陽砲). ("huihui" means muslim) because they were first encountered in China at the siege cities of Fancheng and Xiangyang when the Mongol army, unable to capture the cities despite besieging the Song defenders for years, brought in two Persian engineers who built hinged counterweight trebuchets and soon reduced the cities to rubble and forcing the surrender of the garrison. The trebuchet spread westwards and reached the Arab countries through Persia and Byzantium . The first trebuchets - or the art of building trebuchets - arrived in the Nordic countries by way of Northern Germany, where engines of war are regularly mentioned in the books of the Hanseatic League . There is some doubt as to the exact period in which these devices or knowledge of them reached Scandinavia. The Vikings may have known them at a very early stage, as the monk Abbo de St. Germain reports on the Siege Of Paris in his epic "De belle Parisiato" dated about 890 A.D. 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 A.D. Trebuchets were first used in Italy at the end of the 12th Century , and were introduced to England in 1216 during the Siege Of Dover . The forces of Simon de Montfort built a massive trebuchet nicknamed La Malvoisine ("Bad Neighbour") for their siege of the pro-heretic town of Minerve during the Albigensian Crusade (1210).(During the siege of Stirling Castle in 1304, Edward Longshanks ordered his engineers to make a giant trebuchet for the English army, named "Warwolf." No details of its design survive. With the introduction of Gunpowder , the trebuchet lost its place as the siege engine of choice to the Cannon . The last recorded military use was by Hernán Cortés , 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 . TREBUCHETS TODAY Today, many hobbyists build and experiment with trebuchets and it is used in classrooms to illustrate mechanical and physical principles. The trebuchets range in size from table-top to huge machines weighing many tons. Recent modern developments include: the ''floating arm trebuchet'' where the counterweight is constrained to drop down vertically, while the fixed axle is replaced by rollers; a variation is the ''F2K trebuchet''. Other variations are the "scissor-jack" [http://www.siege-engine.com/ScissorTreb.shtml , "whipper" [http://www.thehurl.org/tiki-browse_image.php?galleryId=1&imageId=1396]. Modern hobbyist trebuchets sometimes replace the counterweight with banks of Spring s. Another notable variation on the classical trebuchet involves one that props the counterweight in its initial configuration. Since the center of mass is higher than the conventional one in which the counterweight hangs from the end of the short end of the beam, more energy is available for throwing the projectile. This is a little more complex, though, and few have been built. King Arthur, a propped counterweight trebuchet built by the team led by Christopher Gerow, was a Punkin Chunkin champion for four years running. Its reign was ended in 2004 by the huge Yankee Siege {Link without Title} , with a record throw of 1394 feet. Another trebuchet is a MRT, or multi-rotational trebuchet. It is less efficient than a Floating arm trebuchet, but more efficient than a traditional trebuchet. Its arm makes one or more full rotations before launching the projectile. A United States organization, Science Olympiad , hosts a "Storm the Castle" event for middle and high school students involving the trebuchet. The competitors build a small trebuchet (maximum one meter long, 75 cm wide, 75 cm high) and fire projectiles at targets of varying distances. ETYMOLOGY Trebuchet is Old French , from ''trebucher'' "to throw over" < ''tres'' "over, beyond" and ''buc'' " Torso " < Latin ''trans'' and a Germanic word. Trebuchets are often referred to as a variety of Catapult , though this word is today generally reserved for a device powered by elastic energy. Other names for counterweight (or counterpoise) trebuchets include ''bricole'' or ''brigola'', which translates as ''two-testicle'' and refers to trebuchets with a split counterweight, and ''couillard'', which translates as ''testicle'' and refers to a trebuchet with a single counterweight. Descriptive terms, such as a "witch with ropes for hair" were used by some sources to describe how a traction trebuchet looks. The "HollyWood catapult" is a trebuchet without a sling--the projectile is placed in a cup at the end of the long arm of a beam . It is a very poorly performing trebuchet. There is no evidence that it was actually used in warfare. POP CULTURE TRIVIA Recent depictions of trebuchets in pop culture include:
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