Archery accessories affect flight, but the arrows themselves provide the greatest potential loss of efficiency in turning bow energy into arrow speed.
At full draw, a broadhead is sitting still at the end of the arrow where it resists moving (called inertia). The arrow bends when the energy from the bow pushes against the nock.
How much an arrow bends depends on three factors:
- Arrow length
- Arrow stiffness
- Broadhead weight
The longer the arrow, the easier it bends. Stiffer (spine) arrows are heavier. The heavier the broadhead, the more it resists moving, which increases the arrow’s tendency to bend. The heavier the arrow and broadhead combination, the slower it will leave the bow.
The arrow’s speed and trajectory will be primarily affected by its initial speed and drag. An arrow has the least drag when it presents the smallest profile to the direction of flight. When the arrow bends, its profile becomes wider and, therefore, slows down.
The bend allowed the arrow to curve around an older bow’s riser (this was called the “archer’s paradox”). This is no longer a concern, because newer bows have larger sight windows, such that the bowstring is located exactly in line with the center of the arrow rest and the broadhead. The stiff arrow bends less and gives a more aerodynamic profile, so stiffer arrows are generally better (except for the greater arrow weight).
Straight arrow flight depends on the bow as well as the arrow. A well-tuned bow sends the arrow straight away in optimal position with minimum fish-tailing or other movement of the arrow that increases drag. Optimal arrow flight only occurs when the arrow rest, nocking point, arrow stiffness, and string force are matched to propel the arrow straight with minimal extraneous motion.
How Heavy?
There has been an enduring debate among bow-hunters regarding arrow weight, which is paralleled by the gun-hunter’s argument about bullet weight.
The gun-hunting argument for heavier, slower bullets goes like this: “Would you rather be hit by a bowling ball or a golf ball?” The argument for lighter, faster bullets goes like this: “Would you rather be hit by a bowling ball at 30 feet per second or a golf ball at 3,000 feet per second?”
Arrows travel much slower than bullets, but there’s still some trade-off between speed and weight. A lighter arrow drops less at 30 yards than a heavier arrow shot from the same bow. However, if two arrows travel at the same speed, the heavier arrow will have more momentum and, hence, better penetration than the lighter arrow. Given that most bow-hunters are not exact in their range estimates, particularly given the excitement of being close to a deer, greater accuracy is probably more valuable than a slight improvement in penetration. On the other hand, the heavier, slower arrow slows the string and limb motion, giving less vibration to the limbs, and less vibration means less noise.
Another advantage to greater arrow speed is less time for the target to move. Most bow-hunters recognize that deer are capable of “jumping the string.” Clearly, the less time required for the arrow to reach the deer, the less movement the target can make. Shots are too hard to come by to miss, or even worse, to hit in the wrong place.
The best test for arrow weight is how well it flies from the bow. A heavy arrow or a light arrow doesn’t really matter if you don’t hit the deer in the right spot.
Getting to the Point
Any hunting broadhead can affect arrow flight, including mechanicals. Anyone over 40 remembers two-bladed broadheads, whose large blades basically acted as another set of fletching. Each blade had the potential to act as a wing, causing the arrow to veer. Those were the worst-case scenarios.
However, the same holds true today, even with the smaller, more streamlined mechanical broadheads. Helical fletching helps fix this problem. Even so, there’s a real need to test broadhead flight, especially if any changes are made to the bow, accessories or arrows.
Broadheads also change arrow weight, which, of course, affects arrow speed, arrow bending and the stiffness needed for optimum flight.
Whenever possible, practice shooting with the same style of broadheads you will be hunting with this fall. Also be aware that numerous companies make practice points that mirror the flight of a regular broadhead/arrow combination. One in particular is the SEVR practice point (shaped like a field point but designed with the same flight characteristics of a hunting head).
Bow Weight
In gun-hunting, the bullet leaves the breech and the rifle recoils in the opposite direction with the same amount of energy. The recoil increases as bullet weight and speed increase, and it decreases as rifle weight increases. Hunting bows are a bit more complicated.
In archery, the shot produces recoil back toward the hunter just as a gun does. The string and limbs also move forward, depending on the angle of the limbs with respect to the riser. However, unlike a gun, the bowstring and limbs then overshoot and rebound back toward the archer. The limbs and string continue to oscillate until all the energy dissipates.
You can visualize that stretchy cables and string add to this rebound effect, hence, the need for a low-stretch string. The heavier the bow, the less this recoil effect, but a heavy bow has other disadvantages. Heavier bows tend to move less, but the heavier the bow, the harder it is to hold steady.
Stabilizers add to the bow’s weight, and this reduces recoil. Long stabilizers, such as those used in target archery, place most of the mass a long distance from the bow, increasing the inertia that reduces movement of the bow limbs forward or backward or turning to the right or left. A bow-mounted quiver increases mass and reduces recoil, but it also means more weight and possibly more vibration (noise).
The shooter’s follow-through technique also affects accuracy.
It’s All About Accuracy
Whatever bow-and-arrow combination you choose, remember: Even slight changes can affect your overall accuracy.
When considering changes to your rig, think about how it might affect arrow flight, friction, string weight, bow weight and shot noise. Always ask yourself: How much will my accuracy improve if I make this change?
The bottom line? Never take anything for granted and constantly check your equipment and arrow performance. Good shot opportunities at good deer don’t happen every day, so we must make the most of our shots by having a good setup … and plenty of practice.
