You may already know that recurve bows or longbows are quite easier to understand. Their limbs save the energy that pushes the arrow as the archer lets go of the string. On the other hand, But how does a compound bow work?
A compound bow works through the levering system consisting of pulleys and cables that bends its limbs. This is due to the many improvements in compound bows over conventional bows. These improvements are mainly in the bows’ accuracy, speed, and distance.
This article will break down the operational process of a compound bow and the parts that make it up. Furthermore, you will understand the benefits of possessing one of these compound bows.
What is Compound Bow in Archery?
A compound bow comes with stiffer limbs and relies on its levering system to work. Usually, the system consists of pulleys and cables for limb bending, which makes compound bows efficient for target practicing.
Archers get a mechanical advantage via the pulley or cam system. This explains why a compound bow has stiffer limbs than a recurve or longbow. This rigidity advantage is the reason compound bows possess more energy efficient than other types of bows. A compound bow aids better accuracy and is not sensitive to different temperatures and humidity.
Archers view images via a magnifying glass (scope). When they engage the release aid, the energy from the limbs and cables moves to the arrow, forcing it out of the bow to their targets. In archery, archers need a push weight of 28 kg (61.7 pounds), even though at full draw, the weight drops down to around 6 kg (13.2 pounds). Also, the speed of an arrow shot from a compound bow can get above 350 km/h. Thanks to the double system strings.
The Parts of a Compound Bow
The compound bow is not so much like the recurve or longbow because of its several moving parts, making it daunting for beginners. However, knowing the different parts of a compound bow gives you a good idea of what you want to purchase.
The following are the different parts that make up a typical compound bow:
- Limbs: This is the part of the bow that creates its actual shape. The limbs store energy build-up when an archer draws the string. They support the idler wheel or cam at one end of the bow and are fixed to the riser at another end.
- Riser: This is the junction of all accessories and limbs and the part that aids grip. But always ensure that the bow has no dents or cracks, as this may result in vibration at the shot.
- String: The string is the most important part of the bow. It extends from one cam to another in a bow having a two-cam system. The bowstring does not go beyond the cam on a one-cam system, but the main string continues to the idler wheel on top.
- Berger hole: The Berger hole is the part of the bow that houses the arrow rest. The arrow should always rest at the center of the Berger hole upon setting up the bow.
- Arrows:Technically speaking, they are not part of the bow anatomy, but it is also important to add them to the list. They are carbon or aluminum made, but mostly carbon. Carbon arrows maintain their shape and are more durable than aluminum ones.
- Bow sling: The bow sling goes side by side with a stabilizer upon installation. It helps the archer to maintain hold of the bow after a shot.
- Bow sight: The bow sight is located at the front of the bow within the riser’s sight window. It helps for accurate vision when an archer aims.
- Cable slide: The cable slide holds the cables and strings to sustain the direction of your shot. The cable guard attaches with the cable slide to make this feasible.
- Cables: The cables of a compound bow look similar to the bowstring and also stretch from one cam to another. The cam and cables work together in the course of taking a shot.
- Peep sights: The peep sights comprise a metal piece or round plastic placed in the bowstring. It helps the archer get precise aim and set up the arrow’s trajectory with the front view.
- Arrow rest: This part keeps the arrow in place when the archer draws the bow. Just like several components of a compound bow have substitute names, this is also called the arrow shelf.
- Stabilizer: A stabilizer offers a counterbalance in the bow’s weight by reducing every feeling of vibration when an archer takes a shot. There can be more than 28 of these components in indoor target practice.
How does a Compound Bow work?
A compound bow transfer the power the archer puts into the string as he draws it back, directly to the arrow. Drawing back the bowstrings causes the limbs to bend. At this point, the limbs store the shooting power, awaiting the release from the archer. Once the archer releases the arrow, the limbs turn the potential energy to kinetic, forcing the arrow through the bow and return to its initial state.
Every mechanical system has losses. Meaning the total energy the archer used at full draw is not equal to the one the limbs exerted on the arrow. The idea behind the construction of compound bows is to reduce this phenomenon. The more the applied energy, the faster the arrow, and a flatter bow arc signifies more speed.
The following points explain in detail how a compound bow works:
Energy (Force x Distance) –
This formula also applies in the way an archer shoots a compound bow. The distance the arrow will cover is a determinant of the force the archer applies on the string plus that aided by the bow. This explains the energy of the shot. A simple draw-force curve will display distance on the x-axis and the applied force on the y-axis.
How a Compound Bow produces more shot speed –
A conventional bow shoots an arrow at a speed lesser than or equal to 185 Ft. /s. But coming to compound bows, they propel arrows at a speed of 370 Ft. /s, which is twice the speed a traditional bow generates. How is this possible?
Compound bows do not have a linear draw cycle. As the archer draws the bowstring back, he exerts force to it until near the string’s peak. At this point, the bow lets off, giving the archer relief. This then aids a better aim and speed of the shot.
Using a simple block and tackle system, the archer exerts tension on the outer wheels that cut across the inner wheels. As the outer wheel goes further backward, the inner wheels continue to generate more force.
This is just a simple block and tackle system that compound bows provide – multiplying input force over a distance.
How Compound Bows shoot easier
A compound bow works with noncircular cams to help the archer achieve a variable draw weight. This is what’s responsible for the change in force as an archer completes a draw cycle (let-off).
But the sad truth is no compound bow has 100% efficiency. The reason is that the total energy stored by the limbs, as the archer pulls the string, is not equal to that which the arrow receives. This is a result of noise and friction around and on the bowstrings.
How Cams (Wheels) affect the Draw Cycle
Usually, compound bows come with an oval-shaped outer cam, and in most cases, the inner cam also has this same shape. To measure the ratio between both radii, designers take facts from the point where the bowstring and cable meet the cams during a draw cycle. When designers change the radii, they alter the ratio of the gear.
When an archer draws back the string at first instance, the cams start rotating, and the radius of the outer cam starts out very small. This is the point where the draw weight gets tough and requires more force from the archer. For humans, our ability to pull is best when the arm is extendable and not contracted. When the string is at full draw, the archer is already close to having a contracted arm.
As you multiply the energy in your arm, the gear ratio of the cam maximizes it towards the end of the draw cycle. This is what’s responsible for the let-off that archers experience. When a compound bow is at full draw, it creates a ‘rare wall’ that prevents the archers from drawing back the string any further.
Is a Compound Bow better than a Regular Bow?
Due to the mechanical advantage and extra efficiency of compound bows, they seem to provide more energy than regular bows. As a result, an equal draw weight from a compound bow and a regular bow will not produce the same energy on the arrow.
Some archers consider compound bows as an improvement on recurve bows because their design allows better shots with power and precision. These and several more points are why a compound bow is better than a recurve bow.
Benefits of using a Compound Bow
Compound bows offer certain benefits that most people consider very important and helpful. In your experience using a compound bow, you will notice the following:
- Reduced upper body power
- More distance from goal or target
- Greater precision and power
- Extra add-ons and customization
Final Thoughts
How a compound bow works are dependent on the winch existence of two systems, the string and the cables. It is important to get familiar with this operation, as it will also help tackle problems with your bow.
The information in this article is based on experiments carried out on a compound bow. We hope the article gives you the right answers to the question; how does a compound bow work?