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Chinese repeating crossbow

A repeating crossbow or Chu-ko-nu (Chinese: 連弩) is a crossbow where the separate actions of stringing the bow, placing the bolt and firing it can be accomplished with a simple one-handed movement, all the while keeping the crossbow stationary. This allows the bow to fire at a faster rate compared to a normal crossbow. A magazine containing a number of bolts is present on top of the bow and the mechanism is worked by moving a rectangular lever forward and backward.

Repeating crossbows have a long history, with the oldest accurate written record dating back to the Han Dynasty (ca. 200 BC-220 AD) in China. The repeating crossbow (Chinese: 諸葛弩; pinyin: Zhūgě nǔ; Wade-Giles: Chu-ke nu; literally "Zhuge crossbow"; sometimes mistranscribed as Chu-ko-nu) is an extremely simple piece of equipment. It is claimed to have been invented by Chinese strategist Zhuge Liang (181-234 A.D.), which is arguable since the earliest drawings of the weapon have been found from the buried library of Chu, dating all the way back to 250 B.C. It is more likely that during the Ming Dynasty historians confused it with Zhuge Liang's invention of the lian-nu which shot two to three bolts at once and was used in massed formations. The repeating crossbow saw its last serious action in the China-Japan war of 1894-1895, where photographs show repeating crossbows as common weapons among Manchurian troops. The basic construction of this weapon has remained very much unchanged since its invention, making it one of the longest-lived mechanical weapons.

The repeating crossbow was introduced in Korea by King Sejong, who during a trip to China saw the weapon and was impressed by its mechanism. In Korean it was called sunogung (Hangul: 수노궁; Hanja: 手弩弓).^[1]

Chinese Chu-ko-nu

Part of a Naval Battle Scroll from the Imjin War

The chu-ko-nu was a very simple and rugged design. This weapon was extremely easy to manufacture and use, and, in the hands of a trained soldier, could easily launch ten bolts in fifteen seconds. In comparison, a standard arbalest could barely shoot one in that time. The chu-ko-nu, however, had neither the power nor the accuracy of a common crossbow. This gave it a shorter range, compensated for by using lightweight bolts instead of the heavy bolts of single-shot crossbows. Thus, the chu-ko-nu was not very useful against more heavily armored troops unless poison was smeared on bolts, in which case even a small wound could be fatal. Since a chu-ko-nu was shot from the hip, the accuracy was poor but could be adjusted very swiftly since the next shot was only a second away.

The chu-ko-nu was operated by moving a lever forwards and backwards. In that movement, a bolt would be dropped in place, the string would be strung, then the bolt would be shot and another one would be ready to take its place.

This put the weapon's string under heavy wear since it had forces straining it from above and below, and lifting of the magazine especially added serious pressure to the string. Chu-ko-nu strings were therefore often reinforced with quills of birds, preferably swan or duck.

Alterations of chu-ko-nu included mountable siege crossbows with bigger bolts and greater power which required two men to operate: sighter and operator. There was also a heavy version using two magazines, thus doubling the number of bolts discharged. The latter was used in extreme close-quarter combat because they had extremely short range, and the bigger version which required two hands to operate was mounted on wall tops. They proved to be effective in defending gates and doorways of castles. It can be considered as a kind of predecessor to modern automatic weapons, though it is much closer to the hand-operated rapid fire firearms of the 19th century (see Gatling Gun).

• Crossbow
• Polybolos

• Crossbow Plans - How to build a repeating crossbow.
• CHU-KO-NU - The Chinese Repeating Crossbow
• The Chinese Repeating Crossbow - From Ralph Payne-Gallwey's work