Crossbow
An automatic bow: The bow string is tied on a wooden support that holds it. When a trigger is pressed, the wooden support releases the bow string, releasing the arrow. The crossbow require less strength to fire it (but more to load it).
Composite bow
A composite bow is made from different materials laminated together, usually applied under tension.
The Hun and Hungarian bows use horn on rear and with sinew on front. They are recurve bows as the shape curves back on itself and it is this design that gives the bows tremendous power compared with their size.
The English longbow has a natural composite of yew sap wood and heart wood. The heart wood is on the inside of the bow and resists compression and the outer sapwood stretches. This makes a powerful natural spring.
Modern composite bows such as a compound bow use laminated wood, plastic, and fibreglass. These are little affected by changes of temperature and humidity.
Ballista
A ballista is basically an oversized crossbow. It is used as a siege weapon and it's very effective because it only requires two men to fire it. It fires large arrows.
Compound bow
A compound bow is usually a composite recurve bow coupled with pulleys known as eccentric cams. It is little affected by changes of temperature and humidity and gives superior accuracy, velocity, and distance in comparison to the classic longbow. They were first developed and patented by Holless Wilbur Allen in the USA in the 1960s and have become increasingly popular.
A composite bow is made from different materials laminated together, usually applied under tension. Modern composite bows use laminated wood, plastic, and fibreglass. These are little affected by changes of temperature and humidity. With recurve bows, the shape curves back on itself. It is this design that gives the bows tremendous power compared to their size.
With a traditional single string bow as the string is pulled back the tension increases, so the bow must be aimed and released quickly, on release the string rapidly accelerates to its fastest and then decelerates for the rest strings return to stationary. There are mechanical advantages to pulleys:
the draw weight does not increase as the bow is drawn enabling the archer to hold the bow fully drawn and take time to aim;
the pulleys enable the archer to draw a bow with a much higher draw weight than they could manage with a conventional single stringed bow (there are very few people alive today who could shoot accurately with a single string using the draw weights of the longbows found on the Mary Rose);
the string continues to accelerate from the release to rest so imparting more power (and hence speed) to the arrow.
Archers in modern archery competitions usually uses a release aid to hold the string steady. This attaches to the bowstring at a point and permits the archer to release the string with a pull of a trigger.
Arbalest
An arbalest is a crossbow with steel prod (the "bow" part). It was much more powerful than a crossbow with a wood prod.
The arbalest was a late variation of the medieval European crossbow. A larger weapon, the arbalest had a steel prod ("bow"). Since an arbalest was much larger than earlier crossbows, and because of the greater tensile strength of steel, it had a greater force. A skilled arbalestier could shoot two bolts per minute. Arbalests were sometimes considered inhumane or unfair weapons, since an inexperienced crossbowman could use one to kill a knight who had a lifetime of training.
This led to their ban by Pope Innocent II, in whose name Canon 29 of the Second Lateran Council (1139, as translated in Decrees of the Ecumenical Councils, ed. Norman P. Tanner) states "We prohibit under anathema that murderous art of crossbowmen and archers, which is hateful to God, to be employed against Christians and Catholics from now on." Note that the anathema was only on the use of these weapons against "Christians and Catholics." In context, this proscription was probably a very late part of a wider, millennial attempt by the Catholic Church to limit warfare, known as the Peace of God movement.
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