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Modern recurve bow
A recurve bow has tips that curve away from the archer when the bow is unstrung. By one technical definition, the difference between recurve and other bows is that the string touches sections of the limbs of recurve bows when the bow is strung. A recurve bow stores more energy than an equivalent straight-limbed bow, potentially giving a greater amount of cast to the arrow. A recurve will permit a shorter bow than the simple bow for a given arrow energy and this form was often preferred by archers in environments where long weapons could be cumbersome, such as in brush and forest terrain, or while on horceback. By contrast, the traditional straight longbow tends to "stack"—that is, the required draw force increases more rapidly per unit of draw length as the string is drawn back.
Recurved limbs also put greater strain on the materials used to make the bow, and they may make more noise with the shot. Extreme recurve may make the bow unstable when being strung. An unstrung recurve bow can have a confusing shape and many Native American weapons, when separated from their original owners and cultures, were incorrectly strung backwards and destroyed when attempts were made to shoot them.
Historical and current use
Recurve bows made out of composite materials were used by, among other groups, the Scythians, Hyksos, Magyars, Huns, Greeks, Turks, Mongols, and Chinese. The recurve bow spread to Egypt and much of Asia in the second millennium BC. Presumably Greek and Phoenician influence would have introduced the recurve form to the rest of the Mediterranean region. The standard weapon of Roman imperial archers was a composite recurve, and the stiffening laths used to form the actual recurved ends have been found on Roman sites throughout the Empire, as far north as Bar Hill on the Antonine Wall in Scotland. During the Middle Ages composite recurve bows were used in the drier European countries; the all-wooden straight longbow was the normal form in wetter areas. Recurved bows depicted in the British Isles (see illustrations in "The Great War Bow") may have been composite weapons, or wooden bows with ends recurved by heat and force, or simply artistic licence. Many North American bows were recurved, especially West Coast bows. Recurve bows went out of widespread use with the availability of effective firearms. Self bows, composite bows, and laminated bows using the recurve form are still made and used by amateur and professional bowyers.
The modern recurve bow
The unqualified phrase "recurve bow" or just "a recurve" in modern archery circles will usually refer to a typical modern recurve bow, as used by archers in the Olympics and many other competitive events. It will employ advanced technologies and materials. The limbs are usually made from multiple layers of fibreglass, carbon and/or wood on a core of carbon foam or wood. The riser (the handle section of the bow) is generally separate and is constructed from wood, carbon, aluminium alloy or magnesium alloy. Several manufacturers produce risers made of carbon fibre (with metal fittings) or aluminium with carbon fibre. Risers for beginners are usually made of wood or plastic. The synthetic materials allow predictable manufacture for consistent performance. The greater mass of a modern bow is itself an aid to stability, and therefore to accuracy.
The modern recurve is the only form of bow permitted in the Olympics (though the Compound bow is permitted in some categories at the Paralympic Games) and is the most widely used by European and Asian sporting archers.
The modern Olympic-style recurve is a development of the American Flat Bow, with rectangular-section limbs that taper towards the limb tips. Most recurves today are "take-down" bows—that is, the limbs can be detached from the riser for ease of transportation and storage, and for interchangeability. Older recurves and some modern hunting recurves are one-piece bows. Hunters often prefer one-piece bows over take-down bows because the limb pockets on take-down bows can be a source of noise while drawing.
Modern recurve bow terminology
- Arrow rest - Where the arrow rests during draw. These may be simple fixed rests or may be spring-loaded or magnetic flip rests.
- Back (of bow) - The face of the bow on the opposite side to the string
- Belly (of bow) - The face of the bow on the same side as the string
- Bow sight - An aiming aid attached to the riser
- Sling - A strap attached to the bow handle, wrist or fingers to stop the bow falling from the hand
- Brace height - The distance between the deepest part of the grip and the string
- Grip - The part of the bow held by the bow hand
- Limbs - The upper and lower working parts of the bow, which come in a variety of different poundages
- Nocking point - The place on the bowstring where the nock (end) of an arrow is fitted
- Riser - The rigid centre section of a bow to which the limbs are attached
- String - The cord that attaches to both limb tips and transforms stored energy from the limbs into kinetic energy in the arrow
- Tab or Thumb ring - A protection for the digits that draw the string. Also provides better release performance. Usually made of leather.
- Tiller - The difference between the limb-string distances measured where the limbs are attached to the riser. Usually the upper distance is slightly more than the bottom one, resulting in a positive tiller. Reflects the power-balance between both limbs.
Recurve archers often have many other pieces of equipment attached to their recurve bows, such as:
- Clicker - a blade or wire device fitted to the riser, positioned to drop off the arrow when the archer has reached optimum draw length. Used correctly, this ensures the same cast-force each time. Many archers train themselves to shoot automatically when the clicker drops off the arrow.
- Kisser - a button or nodule attached to the bowstring. The archer touches the kisser to the same spot on the face each time (usually the mouth) to give a consistent vertical reference.
- Plunger Button - a fine-tuning device consisting of a spring-cushioned tip inside a housing. The plunger button screws through the riser so that the tip emerges above the rest. The side of the arrow is in contact with the tip when the arrow is on the rest. The spring is tuned so that it allows a certain amount of movement of the arrow towards the riser on release, bringing the arrow to the ideal "centre shot" location. The plunger button is used to compensate for the arrow's flex, since the arrow flexes as the string pushes onto it with a very high acceleration, creating what is known as the archer's paradox. The device is also known as a pressure button or Berger button (after its inventor, Vic Berger).
- Stabilizers - weight-bearing rods attached to a recurve bow to balance the bow to the archer's liking, dampen the effect of torque and dissipate vibration.
Outline in frontal view
Bows usually taper from the handle to the tips. Tapering may reduce mass in the outer limb; this increases the speed at which the tips move which propels arrows faster. Shapes may be optimized for various purposes, especially maximum speed of the arrow; the details are the subject of active research.
Narrow bows normally taper uniformly. However, the taper of flat bows varies. The working limbs of “paddle" bows maintain width for almost the entire limb length, “pyramid" bows taper uniformly from the handle to a narrow tip, and “Holmegaard-style" bows remain full width to about two-thirds of the way along the limb, then narrow sharply. “Eiffel tower" bows taper sharply, but smoothly, to a very narrow outer tip.
Cross-section of limbs
The optimal cross-section of the bending section of a bow limb is rectangular and almost all modern bows have such limbs. However, many, perhaps most, traditional bows have had a cross-section closer to circular, with every possible variation being used at some point. Current definitions of the traditional longbow require approximations of a D-shaped cross section.