Bow Design
practice Sharp
The Design of the Archery Bow by Colin Ledsome MEng CEng FIMechE FIED MCMI FBIS MDS
The archery bow is a deceptively simple looking device. The longbow, star of many Robin Hood films, is a bent stick with a string. You put an arrow to the string, pull it back and let it go, what could be complicated about that? Think again. The bow has been in use for at least 40,000 years and has gone through a lot of evolution in that time. The following article is based on research into the design of the recurve bow carried out at Imperial College London by Leo Lang, who I supervised, plus my own 25 years of shooting and coaching experience. This is only a brief introduction.
History We can speculate on a likely chain of historic development. Before the bow, there was the spear, a long sharp pointed stick, perhaps with a flint head, which was thrown at the target, usually a hunted animal. Accuracy needed a lot of practice. Some cultures developed a ‘throwing stick’, usually a grooved stick with a socket for the tail end of the spear, which effectively lengthened
the throwing arm giving more range and speed. (The Australian aboriginal ‘woomera’ is a classic example.) The spear was useful for bringing down smaller animals, but was less effective in the open against larger herd animals. For them, one strategy was to drive the herd through a narrow passage, perhaps between trees or rocks, and use heavier spears at close range.
Perhaps someone bent a stick and tied a piece of string between its ends for some other purpose, a snare or a child’s toy. A twang of the string gave someone an idea, and the bow was born. Short bows could propel a pointed stick harder and more accurately at short range than it could be thrown. As bows and arrows got longer, fletchings of various sorts were added at the tail of the arrows to keep them aligned in flight (arrowdynamics!). The crafts of bowyer and fletcher were established. Where straight tight-grained woods, or similar materials such as bamboo, were available, longer bows gave more range. In other areas, laminates
Perhaps someone bent a stick and tied a piece of string between its ends for some other purpose, a snare or a child’s toy
Fig 1 – Composite bow from Rameses II
of horn, bone and many other materials were developed. Laminates allowed bowyers to experiment with the shape of the bow
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