I felt compelled to compose this missive this after receiving a weekly “tech tip” from an archery only web-site containing the prominent statement: “Shooting a heavier arrow (shaft + tip) will not necessarily give you more penetration (kinetic energy) over a lighter arrow. Check it for yourself ... take your bow and shoot a heavy arrow and a light arrow through a chronograph, then calculate the kinetic energy. I bet the values aren't much different.” In deference to those espousing (and being led to believe) such an all encompassing statement related to a complex sub-set (archery) in the science of ballistics, I would submit that so much sales hype circulates in the archery market touting arrow speed and really very little discussion time is spent on what I have come to believe is the more critical topic of reliably, humanly dispatching game. After all, the vast majority of shekels spent in the archery industry today are dedicated to deer hunting. Shouldn’t that really be the central issue and not just lauding the ability to launch arrows to 60 yards and beyond? Being able to hit a target at range accurately is important; however, if the pursuit revolves around the ethical killing of game, hitting accurately and killing reliably are not necessarily one and the same topic. Please bear with me if you’ve heard all this before. An arrow’s penetration (or lack thereof) is based on a number of variables. The current rage in archery advertisement centers on velocity. From a simple calculation using an arrow’s weight and it’s velocity at impact, a number, kinetic energy (k.e.) as commonly measured in foot pounds, can be obtained. Basing conclusions about an arrow’s ability to penetrate solely upon velocity, k.e. or a combination of both can be misleading and even cruel. If one were to base their decision on using a particular arrow set up based solely upon k.e., he is missing large parts of the arrow penetration equation. Killing with an arrow has little to do with actual energy transferred to the target (as is commonly found in the firearms industry). If one stops to think about it, were the arrow to actually drop all of its retained energy into the target at point of impact, the arrow would not penetrate at all (as in the case of a small game “blunt” type arrow). An arrow actually performs better when less of its retained energy is shed in the target and penetration is affected by the slicing action provided by a well designed broadhead that maintains its shape and sharpness while performing its duties of destroying the vital circulatory and/or respiratory systems. Two of the most overlooked factors in arrow choice for maximizing penetration are inertia and friction imparted to the arrow combination as it passes through a given target.. Inertia is a body’s propensity to maintain speed and direction based primarily upon its mass. Yes, it takes more energy to start a massive projectile moving but it also requires more effort to change its direction or to stop that travel. In other words: We absolutely want that broadhead to penetrate as far as possible into and beyond (if possible) the target. The arrow’s “impact” has little or nothing to do with its intended purpose. More massive projectiles may or may not strike with more kinetic energy but they tend to retain more of their initial velocity while in flight and during encounters with the target. Friction related penetration is also affected by: 1. Diameter of the shaft (smaller shaft diameter equals less surface area drag and resistance while inside the target thus greater penetration) 2. Number and angle of cutting edges of broadhead (i.e. a more gradual angle to the cutting edge provides less resistance and better penetration, two cutting edges require less energy to penetrate than three edges, three edges require less than four edges) 3. Smooth transition from broadhead ferrule to arrow shaft promotes penetration (a larger ferrule with smaller O. D. shaft penetrates better than same sized shaft and ferrule while a larger shaft than ferrule penetrates more poorly than either of the above) 4. Stiffer shaft penetrates better than a more flexible shaft (less energy is consumed in shaft flexing and increased lateral friction after impact and more energy is retained for forward movement) Of course, taking any one of the above factors outlined above to an extreme (i.e. very heavy shaft but too slow to even find the target) does our goal of successfully harvesting game no good. My admonition to everyone is to be aware of the decisions you are making when choosing an arrow/bow combination. Be careful to filter the advertising propaganda possibly spread by the counter salesperson and television/magazine/catalog ads from the physics of what you actually need to do. There is no free lunch and the current focus on speed and kinetic energy as the end-all be-all to our archery problems is short sighted. While desirable for the 3-D course, that intense commercial focus on speed alone has actually produced a dramatically increased level of struck and wounded game escaping because of inadequate penetration. Merely being able to hit our target is insufficient if we can not reliably bring our intended quarry to ground in an ethical and humanely quick fashion. Not to put too fine a point on it (all puns aside) but the broadhead needs to make it all the way through those vitals and hopefully out the other side producing a wound channel that allows maximum loss of vital fluids and/or gasses. On deer that can be reliably done at 200 feet per second at 20 yards with a sharp broadhead and a reasonably stiff, heavy arrow every time the mark is hit. Hitting a foam target is not the same as hitting one of God’s creatures. I hope this gives some food for thought.
Everybody wants to be The Syntax Police. “In common usage the term "inertia" may refer to an object's "amount of resistance to change in velocity" (which is quantified by its mass), or sometimes to its momentum, depending on the context. The term "inertia" is more properly understood as shorthand for "the principle of inertia" as described by Newton in his First Law of Motion; that an object not subject to any net external force moves at a constant velocity. Thus an object will continue moving at its current velocity until some force causes its speed or direction to change.” Feel better now?
Very well written. I really liked the part of basing kinetic energy as the striking force of the intial hit and nothing more(if I understood the translation correctly). Makes it a lot easier to explain the importance of momentum after impact to a potential customer/friend/etc... Sent from my ADR6350 using Tapatalk 2
A couple of thoughts and this is not to say I disagree with your post: The leverage obtained with the cam(s) of a compound bow come at the expense of distance. That is to say, you need to pull the string with less effort at a greater distance to cause the limbs to flex a relatively small amount. Naturally, the opposite is also true when you release the arrow. Meaning (and this is no great mystery to anyone) a compound will fling an arrow faster than a traditional bow. Because Hoyt, Mathews and a number of other manufactures warrantee their bows for an extended period of time, they would be foolish to recommend shooting an arrow that so light as to damage the cams and limbs. I guess I’m saying that is it’s safe to shoot and you are pulling 55-70 LBS with a modern high energy bow, you have more than enough Momentum to pass through a deer with a proper shot. So if 200 ft/sec will do the job, so will 286 with a properly spined arrow that meets the manufactures weight requirements. Choosing to shoot a heavier arrow with a compound is tradeoff. Heavier equates to: less noise, better penetration and perhaps less wear and tear on your bow. Lighter equates to greater speed and a flatter shot. Perhaps in the end, it is a matter of personal preference and what really matters is proper arrow placement.
The benefit of momentum is experienced when there is improper arrow placement and that is also when faster and flatter get exposed for the fools gold that they are. Just look at the many threads that say " 5 inches of penetration " around here. That isn't because they are shooting a heavy arrow out of a well tuned bow/arrow combination. When you combine a good FOC with a heavier arrow you have a lot of something called "forgiveness" and that comes in real handy on less than ideal shots. If everyone could always hit the "sweet spot" then we could shoot pencils with BH's and kill deer.
I am curious about this: Obviously less noise, better penetration and maybe less wear and tear are beneficial. What is beneficial about greater speed and a flatter shot?
I agree with "momentum" that is what you arelooking for. If you want great blood trails even on marginal shots you need anexit hole. Without an exit hole the blood pools in the deer and does on comeout until the pool reaches the entry hole. Most of us shoot from trees, so thisentry hole is very high on the deer’s body. I will take an arrow that drives completethrough an animal every time. And it ismuch easier to do this with a heaver projectile. A heaver projectile will also do a better jobwhen hitting bones and will keep driving.
throw a peanut at a window 50 yards away it's going to bounce off. it won't even break the glass at 20 yards. If you throw a baseball at the same window it might fall short at 50 yards, but at 20 yards its going to shatter the window.
What is "longer effective range"? If I can hit the X at 50 yards with a heavy arrow how does a lighter, flatter arrow become more effective? A heavy arrow can hit any spot a lighter arrow can hit. I can use a 605 grain arrow at 50 yards, for an example of heavy.
Bruce beat me to the punch on this, but I am anxious to hear the elaboration of this. Specifically, if a given effective hunting distance of "x" is set... Both arrows are still hitting the same mark.
Don't guess your a fan of my GT Velocity's traveling at 310 fps, with a 2" expandable on the end?? I mean how far in the ground should it stick after passing through? As you can see, shoulder bone was not excused from this shot. Stuck into the ground apx. 4" Don't get me wrong, I agree with what you are saying, it's true, but we are hunting deer here, not cape buffalo. According to calculators I'm pushing 71 ftlbs of k.e. But, that's out of the barrel, I know it will not retain that at further distances, but in practical bowhunting situations.... why should I reconsider my set-up? Honest question.
I wouldn't suggest you reconsider your setup. I don't think I have suggested anyone reconsider their setup. I am correcting misconceptions. Now, honest question for you: Do you think your setup, and the results, are the average that we see in these kill threads or the small minority?
You got me. I replied to Konrad, before ever reading your original reply, I agree with you 100%, and wasn't meaning to come off as "My set up is fine and no one should worry about their huge bh's and light arrows". I questioned my set-up myself this year, thought about "going heavy", But for me, I've honestly not had any bad results due to my light, fast, set-up. My total arrow weight is 335gr. , that is light I know, but it get's the job done everytime.... for me. And no it's not the average results, I'm sorry to say.
What is your total arrow weight? Nobody ever said your setup will not work, because obviously it does. But basing arrow effectiveness on a pass through and how far it stuck into the ground is highly dismissible IMHO. Last year I shot a buck at 35 yards, broadside. My setup was a 420 grain arrow traveling at 266fps tipped with a 100grain SlickTrick Mag (not highly conducive to penetration). The arrow took the buck through the back edge of the near shoulder blade and exited through the joint of the off shoulder and continued to bury into the ground up the the fletch's behind him. Basically what I am getting at is that my arrow was generating 65ft/lbs of energy, less than yours, yet still penetrated more/heavier bone and managed to bury deeper into the ground. It's a non issue. I am not going to try to negate you from your setup or convince you it is not deadly. I would feel comfortable shooting it. I will simply state my reasons for shooting a heavy, high FOC arrow. I did switch arrows this year too, now shooting 440grn@17% FOC 1. Heavier arrows are easier to broadhead tune 2. Heavier arrows with high FOC are more forgiving to form issues 3. Heavier arrows are quieter, thus more efficient in energy transfer from bow to arrow 4. Heavier arrows will provide extra "push" when encountering heavy bone/tissue 5. Heavier arrows will not deviate as easily from original course from contact (Shoulder, ribs, branches, etc...) All of these points, plus the fact that I have a LRF to range for me point to absolutely zero positives for a lighter faster arrow for my setup. I think if given the opportunity to experiment, you would begin to see the benefits.
