The father of compound bows

The history of compound bows doesn't go back as far as the discovery of the first simple bows. In the early 1960's, Holless Wilbur Allen of Kansas City, Missouri (USA) was intrigued with the idea of constructing the first compound bow that would have an advantage over the more established recurve bows. Allen was the American inventor of the first compound bow, which he patented on June 23, 1966. The patent was granted to him as a U.S. Patent 3.486.495 in December 1969.

It's hard to imagine any other invention having such an impact on the sport as Allen's on archery. But Wilbur Allen's new Holless bow design has done just that. It revolutionized archery and bowhunting. The invention was not born easily.

Allen:  "All I was trying to develop was about hitting the deer with an arrow at 10 to 25 yards (9.14 to 22.86 meters) before it moves."

To accomplish this, Allen gradually modified his traditional bow. He made various experiments - he shortened the bow's limbs, played with the weight of the arrows, he wanted to make use of the ancient invention of the wheel, and had the brilliant idea of putting a cam on the bow. He was not successful at first, which is also why he studied a lot about kinetic energy. He experimented with different cams and their arrangement.

Force multiplication mechanism using cams and cables

Allen spent hours thinking of a bow that would be faster. One evening in 1966, he had a brilliant idea while studying his compound bow. "What if," he thought, "I placed the swivel cams off-center?" That was it! Within two days he constructed another compound bow. The bow was clunky, the cams were wooden, the bow handle was made of pine boards, the core of the limbs was oak flooring, covered with fiberglass rods, all held together with just epoxy resin, nails, a few screws, and a bit of glue. But his principle was brilliant, Allen drew on physics and applied the mechanism of force multiplication using cams and cables. He achieved a significant increase in arrow speed over a traditional bow with the same draw weight, a 15% relaxation of the draw weight, and the ability to use lighter arrows than traditional bows used. The design of his bow delivered impressive performance.

He approached unsuccessfully several bow manufacturers for the production of his idea. As a marketing slogan he used: Allen's compound bow - an archery bow with cams to multiply the power. However, his compound bow was not that popular with the industrial public and sales were poor. It gave the impression of being home-made and was often ridiculed by bow dealers. He slowly staggered until he finally faded out altogether.     

Eventually, however, Tom Jenings, editor of the well-known contemporary magazine "Archery world", otherwise the current sister magazine of "Bowhunting world", became enthusiastic about the idea. Allen sent Tom his first prototype. He published it under review in the magazine in May 1967 with high rating. He described it with the terms, "reduced maximum draw weight", "more stable than recurve bows", or "the first truly new concept to come to bow design in a thousand years". In addition to writing, Tom also made simple recurve bows with his company, and eventually he and Allen went on to manufacture, develop, and market compound bows. They had the first official production of compound bows in the world. From then on, the archery world has never been the same. A new era had begun!

In 1972, only two companies - Carroll Archery Products and Olympus - made compound bows. By 1974, eight companies were selling them to an expanding market. And that was the year Tom Jennings revolutionized the industry when he introduced his own legendary Model-T, a dual cam bow with tip-to-tip looped cables. To give you an idea, the first compound bows followed Allen's basic design - 4 or 6 cams, which resulted in an uncomfortable feeling from using such a bulky bow. However, sales of the improved Model-T bow caused a furor and a boom. Tom's double cam bow was much lighter and easier to shoot. The first compound bows were too long, usually measuring over 40" (101.6 cm) and imagine shooters had to cock them with their fingers - without a string release.

After the first string releases hit the market in the early 1970s, manufacturers began producing shorter bows.

In the late 1970s, several archery companies, including Precision Shooting Equipment (PSE), Bear Archery, Darton, Martin Archery, Browning, Ben Pearson Archery, and Hoyt faced Allen and Jennings' new market for compound bows. By 1976, all states except Georgia legalized their use during hunting season.  Around that time, the Pope & Young Club began keeping records of the killing of deer with compound bows. In 1977, Archery Digest listed over 100 different models of compound bows, compared to 50 different versions of recurve bows. It took less than 10 years before compound bows became a dominant force in the archery field. In the mid-1980s, when Allen's 17-year patent expired, a wave of production of compound bows by other manufacturers was triggered, followed by an evolution of compound bows that continues to this day. Of the five bow companies that retained the right to produce compound bows using Allen's design and patent, PSE (Precision Shooting Equipment) is the only survivor.

Sadly, Allen died in 1979 in a car accident and did not live to see the events as his compound bow forever changed the dynamics of bowhunting. Modern compound bows have continued to evolve hand-in-hand in both design and equipment of the bow, such as the arrow rest (drop-in), or in the way they shoot (using string releases and D-loops) and what arrows they shoot (small-diameter carbon tubes). We owe it all to a man who loved to fish and whose love of machines and desire to know how they worked set the stage for the modern bowhunting revolution - Holless Wilbur Allen.

By today's standards, the first compound bows were heavy, clunky and expensive. However, they had a big advantage, they shot arrows much faster and consistently more accurate with a flat flight path compared to reflex bows. Compound bows had another advantage that was not immediately obvious to archers - they were made of separate parts and therefore could be tinkered with - further refined, scaled down and camouflaged, unlike the carefully crafted traditional bows. In modern archery today, these bows achieve a let-off of up to 90% at 340 fps (arrow speed of 103.63 m/s).  

The transition from wooden risers to aluminum and carbon

Other advances include the transition from wooden risers (handles) to aluminum and carbon. Some companies in the 1990s also produced risers with an admixture of magnesium, which ignited easily when machined, but soon found it safer and easier to reduce the weight of the gun by machining out the section in aluminum riser. It was also necessary to make the original solid and wooden grips smaller and more suited to the physical characteristics of a person's hands. Such massive grips often produced too much torque. Competing shooters quickly recognized this problem and replaced or modified them. Today's slim grips eliminate torque. The attachment of the limbs to the riser has also undergone a change; in the past, the limbs pivoted from left to right. Today's limbs are fixed and are force adjustable. You can easily adjust the draw weight of the bow.

So much for the discovery and development of compound bows, and in conclusion, perhaps the only thing left is the actual definition of a compound bow: a compound bow is a modern type of bow used in archery for sporting and hunting purposes (the inventor's idea was primarily for deer hunting). Asymmetrical cams are placed at both ends of the bow to form a cam system. These cams distribute the draw weight unevenly over the length of the stringing (the greatest increase in force at the beginning, at the end a decrease in the so-called let off, indicated by a number in %), this increases the speed and range of the arrow and, above all, because of the decrease in the draw weight at the end of the stringing, and thus less recoil, improves the aiming and stability of the shot. With a compound bow, you have the greatest load at the beginning or somewhere in the ½ to ¾ of the draw, and at the end of the draw you feel a draw weight of maybe 17 - 20 lbs. with a max bow setup of approx. 70 lbs. of draw weight. The riser or handle of the bow (center of the bow) is usually duralumin or polymer, the limbs are most often made of fiberglass, polymer or carbon fiber composite. Such compound bows have sophisticated sights with fiber optic and spirit level, additional illumination and a quick-setting system. In various countries these bows are used for modern hunting. Apart from hunting, compound bows are used for sporting purposes and they are also used for World Championship competitions.

Picture source: archeryhalloffame.com/Allen.html, bow-international.com, patentimages.storage.googleapis.com