Compound Bow Details

by Rob Daniels

Undoubtedly one of the biggest advances in the last two decades has been the development of the compound bow. The Compound bow is the latest major development in the search for power and accuracy.

Wilbur Allen, a Missouri bow hunter, is credited with the invention of the compound bow. He holds the patent for the compound bow that he built in 1966. He stopped making recurve bows, took out a license under the Allen patent, and concentrated all his efforts on the compound bow. As compared to the "compound bow'' invented by Allen, all early bow types of bows could be reasonably approximated by Hooke's law.

A compound bow is usually a composite recurve bow coupled with pulleys known as eccentric cams. Compound bows are much more technically sophisticated than the recurve, the bow employing wheels or cams at the tip of the limbs. For the compound bow, however, restoring force and draw (string displacement from equilibrium) are far from being proportional to one another. The width of the wheel tracks and design of the compound bows can make a difference. Modern compound bows optimize this relation by a complex system of pulleys which ensure a minimum force at the maximum draw. Consequently, mechanically advantaged compound bows have been developed which allow the archer to deliver high levels of thrust to the arrow. Many bow manufacturers advertise speed ratings for compound bows in excess of 300 feet per second.

The compound bow, on the other hand, has a pulley and cable system that makes holding weight much easier. A compound bow is simply a machine that stores energy, supplied by the shooter, then releases that energy into an arrow.

The compound bow uses very stiff limbs that can operate with greater energy efficiency than less stiff limbs. The high amount of stored energy in a compound bow could cause a wooden arrow to blow up upon release. Because of the power of compound bows, only modern arrows made from materials capable of withstanding the forces of a compound bow should be used when shooting.

Also, a Compound bow is built for a particular draw length, which is slightly difficult to change. When a compound bow is initially purchased, it must be adjusted so that its draw length is correct for the archer. Growing bodies will grow out of compound bows swiftly in the teen years.

A compound bow has a fixed draw length. In other words, you draw it back to a certain point and it stops. A compound bow must be adjusted so that its draw length is correct for the archer. It is recognized that variations in draw length and/or draw weight can affect the percent of let-off on compound bows. Some compound bows incorporate a "spirit level" which tells the archer if his or her bow is tilted.

Today, compound bows are usually preferred for hunting, although recurve bows are not uncommon and usually legal. Recurve bows and longbows are more traditional and usually a lot less expensive than compound bows. The compound bow can do most anything if you point it in the right direction.

Traditional bows are a simple design that has been around for centuries whereas compounds have only been around for about 40 years. It's main competitor is the modern compound bow that many consider necessary for the continued evolution of bow design and the sport.

From an instruction aspect, the compound bow should not be used; ideally only recurve bows should be used for teaching the basics of archery. A recurve bow is much simpler in function than the compound bow. Traditional bows tend to be substantially longer than compound bows, but they usually weigh a lot less. This means that the arrow of the recurve must be stiffer and therefor heavier than arrow for an equivalent compound bow. Consequently scoring systems are often different for compound shooters, and they rarely compete against recurve bows directly.

About the Author
Rob Daniels writes educational material for http://www.archery-target.com and http://www.kayak-escape.com two of his favorite lifelong sports.