Onager (siege weapon)

This article is about the siege weapon. For the horse species, see Onager.

Sketch of an Onager, from Antique technology by Diels.

This article is part of the series on: Military of ancient Rome (portal) 753 BC – AD 476
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The onager was a Roman siege engine, which derived its name from the kicking action of the machine, similar to that of an onager (wild ass), 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 energy for the shot. The onager consisted of a large frame placed on the ground to whose front end a vertical frame of solid timber was rigidly fixed; through the vertical frame ran an axle, which had a single stout spoke. On the extremity of the spoke was a sling used to launch a projectile. Some onagers, as depicted in ancient drawings used a bowl-shaped bucket instead of a sling to fire the projectile.

The onager's framework is made out of two beams from oak, which curve into humps. In the middle they have quite large holes in them, in which strong sinew ropes are stretched and twisted. A long arm is then inserted between the bundle of rope, at its end it has a pin and a pouch. It strikes on a huge buffer with a sack stuffed with fine chaff and secured by tight binding. When it comes to combat, a round stone (often clay balls with combustible substance in them, which explode on impact and burst into flames) is put in the pouch and the arm is winched down. Then, the master artilleryman strikes the pin with a hammer, and with a big blow, the stone is launched towards its target.

—Ammianus Marcellinus, a Roman writer.

In action the spoke or arm was forced down, against the tension of twisted ropes or other springs, by a windlass, and then suddenly released. As the weighted sling swung outwards through centrifugal acceleration, one end would release, as with a staff-sling, and the projectile would be hurled forward. The arm would then be caught by a padded beam or bed, whence it could be winched back again.

The onagers of the Roman Empire were mainly used for besieging forts or settlements. They would often be armed with huge stones or rocks that could be covered with a combustible substance and set alight.

In the Middle Ages (recorded from around 1200) a less powerful version of the onager was used that held the projectile in a fixed bowl instead of a sling. This was so that many small projectiles could be thrown, as opposed to one larger one. This engine was sometimes called the mangonel, although the same name may have been used for a variety of siege engines.

See also

Trebuchet

External links

• Onager Physics An analysis of the Onager
• Onager Animation Animated Onager
• Caerphilly Castle's onager firing
• Onager video: http://www.youtube.com/watch?v=1BPa_nOiK4A
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This artillery-related article is a stub. You can help Wikipedia by expanding it.v · Categories: Ancient Rome military stubs Artillery stubs Roman artillery Roman siege engines Medieval siege engines Wikimedia Foundation. 2010. Игры ⚽ Поможем написать реферат 1957 in India 1958 in India Look at other dictionaries: Onager — This article is about the horse species. For the weapon, see Onager (siege weapon). Onager Turkmenian Kulan (Equus hemionus kulan) at Korkeasaari Zoo. Conservation s …   Wikipedia Siege engine — Replica battering ram at Château des Baux, France. 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… …   Wikipedia Roman siege engines — were, for the most part, adapted from Hellenistic siege technology. Relatively small efforts were made to develop the technology; however, the Romans brought an unrelentingly aggressive style to siege warfare [Goldsworthy 2000: 144] . Caesar… …   Wikipedia Sling (weapon) — A sling is a projectile weapon typically used to throw a blunt projectile such as a stone. It is also known as the shepherd s sling.A sling has a small cradle or pouch in the middle of two lengths of cord. The sling stone is placed in the pouch.… …   Wikipedia Mangonel — A simple illustration of an ancient catapult A mangonel (derived from Greco Latin word manganon, meaning engine of war )[1][2] was a type of catapult or siege engine used in the …   Wikipedia Onagre (engin) — Pour les articles homonymes, voir Onagre. L’onagre était un engin de siège de la période romaine post classique qui tire son nom de l analogie de son mouvement avec celui de la ruade d un onagre, sorte d âne sauvage. Il s agit d une sorte de… …   Wikipédia en Français Catapult — A catapult is any one of a number of non handheld mechanical devices used to throw a projectile a great distance without the aid of an explosive substance particularly various types of ancient and medieval siege engines.The name is the Latinized… …   Wikipedia List of established military terms — This is a list of established military terms which have been in use for at least 50 years. Technology has changed so not all of them are in current use, or they may have been superseded by more modern ones. However they are still in current use… …   Wikipedia Sassanid army — The birth of the Sassanid army ( fa. ارتش ساسانيان Artesh e Sāsānīyān , Pahlavi Spâh سپاه, army ) dates back to the rise of Ardashir I (r. 226–241), the founder of the Sassanid dynasty, to the throne. Ardashir aimed at the revival of the Persian… …   Wikipedia Ballista — The ballista (Latin, from Greek βαλλίστρα ballistra , from βάλλω ballō , to throw ), plural ballistae, was a weapon developed from earlier Greek crossbows. It relied upon different mechanics using instead of a prod two levers with torsion springs …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”