The compound bow has a more complicated design than the other bows, it allows for the maximum speed of the arrow using a levering system, usually of cables and pulleys, to bend the limbs. The limbs of a compound bow are much stiffer than those of a recurve bow or longbow. This limb stiffness makes the compound bow more energy-efficient than other bows, in conjunction with the pulley/cams. The compound bow has its string applied to pulleys, and one or both of the pulleys have one or more cables attached to the opposite limb. When the string is drawn back, the string causes the pulleys to turn. These bows are designed with a pulley system of wheels or cams and cables, which help the archer hold a heavier draw weight when at full draw. This weight let off, depending on brand and design of the bow, can be anything from about 60% to 80% of the full draw weight.
The compound bow is little-affected by changes in temperature and humidity and it gives superior accuracy, velocity, and distance in comparison to other bows. The compound bow has become increasingly popular. In the United States, the compound is the dominant form of bow. The heaviest poundage compound bow allowed in competition in Ireland is 60 pounds.
Compound bows have only been around since the mid 1960′s first developed in by Holless Wilbur and are now used by beginners to the more experienced professional archers and bowhunters. That means an archer can draw back and aim a more powerful bow for a longer time when aiming. While the older compound bows and longbows look more like the letter “D” when held sideways, the more modern compound bows, look like the letter “W”. The ultrafast compound bows, with their shorter and more parallel limb have a “bat wing” like shape. When used with archery sights and release aids, the modern compound bow can be very fast and accurate.
– The function of the cam systems is to maximize the energy storage throughout the draw cycle and provide let-off at the end of the cycle (less holding weight at full draw). A traditional recurve bow has a very linear draw weight curve – meaning that as the bow is drawn back, the draw force becomes increasingly heavier with each inch of draw. Therefore, little energy is stored in the first half of the draw, and much more energy at the end where the draw weight is heaviest. The compound bow reaches its peak weight within the first few inches of the draw, and remaining more flat and constant until the end of the cycle where the cams “let-off” and allow a reduced holding weight.
– When a compound bow is drawn, the limbs are pulled in toward each other, by the buss cables, unlike a longbow or recurve where the limbs flex in the direction of the bow string. This difference allows modern compounds to have limbs that are horizontal instead of angled. The horizontal limb configuration minimizes the amount of recoil and vibration felt by the shooter when the arrow is released.
– The bow is resistant to temperature and humidity changes giving the bow superior accuracy, velocity, and distance in comparison to bows made of natural materials.
– The pulley system usually will include some rubber-covered blocks that act as draw-stops. These provide a solid “wall” that the archer can draw against. These draw stops can be adjusted to suit the archer’s optimum draw-length, which helps the archer achieve a consistent anchor point and a consistent amount of force imparted to the arrow on every shot, further increasing accuracy.
– The relatively large number of moving parts requires additional maintenance and creates more points of failure.
– Although no bows are warranted to survive a dry fire, it’s not unusual for numerous parts to be damaged or destroyed after even a single compound dry fire.
– Unlike most recurve bows, replacing the string or making adjustments to let-off or draw length often requires a bow press or a trip to an archery pro shop that has one.
Arrows used with compound bows differ significantly from arrows shot from recurve bows. Recurve bows can safely use wooden shafted arrows, or, alternatively, heavy aluminum shafted arrows, requiring in any case that arrows with more mass be used with recurve bows than with compound bows to avoid damaging recurve bows from experiencing problems from dry-firing the bow.
In contrast, shafts of arrows used with compound bows are usually made of an aluminium alloy, or carbon composite material, or a combination of these materials, and are lighter than arrows intended for use with recurve bows, thereby increasing arrow flight speed for compound bows than possible with similar draw weight recurve bows. Due to the greater forces that a compound bow places on an arrow than a recurve bow, wooden arrows may break when shot from a compound bow, possibly driving a broken arrow shaft into an archer’s arm, or the arrow may shatter because of the higher acceleration forces applied to it during release. Hence, wooden arrows, that would be entirely safe with a recurve bow, are inherently dangerous to use with a compound bow. Likewise, lighter weight arrows of aluminum or carbon composite materials, that would be safe to use with a compound bow, are unsafe to use with a recurve bow. Manufacturers thus produce arrow shafts with different weights (mass), and different stiffnesses (known as spine, more arrow stiffness implying more spine) to be consistent with a bow’s draw weight. Manufacturers also manufacture arrows of different lengths in the same model of shaft to accommodate different draw lengths, matched to archers’ different length arms (sometimes termed wingspan).