Arrow Build Recommendations from an Engineer: Video 10 archery education series. 

Thank you! 🙏

@@johnbottone4996 I was unaware they coined the phrase. Thanks for letting me know.

Thanks Wife and Kids are always first to me! Thanks for the kind words!

Thank you!

Are you suggesting that at certain weight the energy transfer is maximized? I shoot crossbow. My Center point Wrath 430 ha maximum energy around 670gr. But there is a wide window where the energy if flat. I will use the point where 97.5% of maximum energy is achieved, to have faster speed and flatter trajectory. This differs from what shown in this video, to have the same efficiency regardless of weight.

Thank you!

Thank you!

Thank you!

Glad I can help! Haha, trad is an art more than it is science one day I’ll dive back into trad. Take care, Lucas

@@Lucas_Palmer_bownerd_engineer I wish it was more science but I'm glad it's not. Peace brother.

Thank you very much! My pleasure.

Great suggestion! Thanks for the idea!

It would be great to get a good slow motion camera! So much could be studied. Glad you enjoyed the video and thanks for the support. Lucas

free version is now available on iOS search Archery Ballistics. Pro version should be soon. Take Care, Lucas

I plan on doing much more testing on this to come. Your results are interesting to me usually in my experience the heavier arrow just slightly out penetrates a lighter arrow in foam targets, very minimal difference. My issue with many archery targets, as a comparison, is friction is the primary reactive force that is stopping the arrow. Which for animals the forces more closely resemble drag and cavity formation. Cavity formation being the force necessary to break bonds of the medium.

I agree completely about trad bow. Yes sharpening/ sharpness is absolutely something I will be talking about a lot when I do broadhead testing. 👍

​@@Lucas_Palmer_bownerd_engineerI'd be curious to do a deep dive into the grind angle on the broadhead. Some older resources say 25 to 30° is ideal, but I've got great results going to just under 20 degrees and sharpening to 2000 grit. Of course when you are achieving sharpness by reducing the grind angle, there is some trade-offs in the durability.

⁠@@ThirdLawPaira lot of those question and answers are going to depend on the steel the broadhead uses. I want to explore the oxidation and corrosion rate of various broadheads as it relates to edge retention and durability.

@@Lucas_Palmer_bownerd_engineerSure, but most broadheads use a cheap forging steel like 1095. Even the so-called "premium steel" broadheads use a mid-grade tool steel like A2. So you could make a reasonable analysis based on common metals in popular broadheads.

@@ThirdLawPair very true! Finally someone that understands that these steels are not “premium”!! Do you have a preferred knife steel? I like the 420hc for cheaper knifes, my favorite hunting knife is made with s30v. I’d like to get my hands on a magnacut, s35v, and some others as well to play with.

My apologies I somehow missed your comment. The stiffness/spine of crossbow arrows is even more important and the whole system is very sensitive. You want a crossbow bolt to recovery very quickly so very stiff, very straight and strong nocks. I have not personally used a crossbow but from a force/engineering analysis I would start there. The arrow mass is going to important as well because crossbows achieve a very high velocity. I hope this helps. Take care, Lucas

No doubt you have lots of experience and make these recommendations based on that. Many other very experienced archers disagree with some of your comments, especially the penetration argument. Personally, I have had bad luck with cone shaped and pyramid (i.e, Muzzy) broad heads but I am an experiment of one. I respect your opinion and experience and I would love to hear more about your tests. I have had better luck with COC like Magnus Stinger, two blade broad heads. Although they are not particularly stout... 10-15 years ago, I lost a herd bull with a quartering away shot with a Muzzy; due to no exit wound. (again, I concede that this is an uncontrolled experiment of "one" and that there is no assurance that a heavier set up with a stout COC Broadhead would have yielded better results). On most elk hunts since "losing" that herd bull, I'm loaded with an Abowyer Brown Bear BH which is a very thick, conventional 210 grain (with aluminum adapter) Broadhead and TAW of 625 grains. Sadly, whenever I'm "loaded" with that set-up I haven't had a shot at an elk. Whenever I was loaded with lighter set ups, I sometimes had opportunities and never got a pass through at ranges from 23 yds to appx. 40 yards (I'm going back 30 years here on some of those unfortunate events, with somewhat ancient equipment on the first one, but relatively equivalent equipment on the last two "no exit wound" hits). Given my unfortunate experience, the #1 thing I want is a high probability of a pass through in order to get a decent blood trail and more tissue damage, #2 is likelihood of at least a double lung hit if things go awry and I hit the on-side scapula. If I can achieve those two things, and I've practiced enough to achieve excellent "field accuracy" and taken shots with reasonable probability of success i.e., quartering away or broadside at an acceptable range - usually that means =< 40 yards) then I've stacked the odds greatly in my favor. I simply haven't had good luck with lighter arrows (430-450 grains) and/or cone shaped or "trocar" points that just don't seem to penetrate well based on my personal experience. I agree that if you have structural failure on a COC you will have problems and IMO, most commercially available mass-market COC BH's have weak aluminum ferrules and adapters and the blade thickness is too thin. So, they are somewhat more likely to bend at the point, or fail at the ferrule / insert junction than a more robust design. They are probably constructed that way to achieve commercial mass market success at a price that most hunters are willing to pay. Frankly, I think Iron Will's Broadhead blades are a bit too thin but they are much thicker than most mass market COC BH's and they probably do present a decent balance necessary to achieve commercial success and field success. Plus, they have steel or titanium ferrules and are available at weights that have mass market appeal (albeit at a luxury price). They should not bend at the ferrule and they have better tip strength than most COC BH's. FWIW, Bill V at Iron Will is an experienced Mechanical Engineer who has worked in that field for something like 20 years. Bill did what I would call a "Non-Dynamic" test where a device tested the pounds of pressure necessary to get various outcomes - 1) penetrating skin, 2) muscle, 3) scapula, etc. The difference was dramatic between a "stout" COC Broadhead (I don't count a Stinger as "stout") and the various other head types. Again, this is a "non-dynamic test". I can imagine that a high speed impact test could yield somewhat different results from the Iron Will static test. The best tests would be on living tissue at typical impact speeds. With difficulty, you can find the test results information on Iron Will's website. I put limited value (but greater than zero) on all those RU-vid tests where someone shoots at an old isolated bone like a deer or elk scapula, especially if the bone is not covered in skin, meat and is not "fresh". Most of those tests available online are clickable entertainment designed to generate clicks and profits for the channel and not much more. One of the advantages of Ashby's tests on dead animals is that he conducted them quickly after the animals death. IIRC, he found that his results deviated somewhat if the animal had been dead for a while. Of course, it can be argued that given his usage of a low velocity long bow with very heavy arrows, and given his objective of assuring a mortal wound upon hitting "heavy bone" on a Cape buffalo (not heavy bone on an elk) .... given those objectives and equipment his results are probably not totally applicable to high KE bows of today especially for usage on elk or smaller game like deer.

First question are you shooting compound or traditional. You can shoot a heavier gpi shaft to increase weight it does not have to be just point weight. However, to dial in spine you can change arrow length, longer to weaken shorter to stiffen, which will alter the dynamic spine of the shaft. Based on spine charts from Black eagle, Victory, Easton it looks like you could shoot up to 250 grains of point and insert weight with 400 spine, personally I would still go with a 350/340 spine shoot a 28in shaft and you should be good for a compound. As long as your bow is tuned. A trad bow will take a little more playing to get good arrow flight. For reference my wife shoots 47 lbs at 25 in draw and is shooting a 400 spine arrow that has a TAW of 505. It leaves the bow at 205FPS. That arrow has an ethics steel insert with collar 135 grains on the front and a 100 grain point. so 235 grains up front. Technically she is "overspined" but has perfect arrow flight. That same bow will shoot will also shoot a 360ish grain standard axis 500 spine build out of the same bow with the same tune both shoot clean bullets through paper. I only mention this to say that it can absolutely be done. However, with everything these are only recommendations for a well rounded arrow. None of it is "necessary" to kill. If you are happy with your setup roll with it and go hunting. Take care, Lucas

@@Lucas_Palmer_bownerd_engineer Thanks for your help. As far as spine weak or stiff I was using archers advantage software. I should have said my draw length is 28 its just I shoot a 27.5" Mathews because they seem to draw long, I was trying to emphasize I don't shoot a lot of speed and so 400 spine fit well for me. I could try a higher GPI shaft but I use easton axis arrow and really like them and do not want to switch. You are right about trying a longer arrow length. I will plug it into Archers Advantage and see if I could bump up to 340..

If you want to add weight I’d suggest add it in a way that generates a more durable arrow or more effective. 25% foc is a great achievement make sure your arrow is flying perfect. 20 grains could be a stiffer arrow, a stronger broadhead, a more durable nock (nocks are critical to accuracy and good flight), a better insert, a wrap if you so desire which may be beneficial for blood tracking.

@@Lucas_Palmer_bownerd_engineer I agree. Among the carbon shafts that has been rated for spine the strongest I could find is 150, with GPI ranging from 8.1 to 11.9. I am leaning toward 8.1gpi as the saved weight could go to the insert. Some pros argue the longer arrows will be more accurate. From your theory I infer the otherwise. Is this correct? Instead of FOC, I think the "steering factor" is more relevant. I define Steering factor as (0.5+FOC)/(0.5-FOC), which describes approximately the vane leverage over the tip. Even a better definition would use the vane location instead as the correction force is mostly from there.

@@statgenie6575 interesting theory about longer arrows being more accurate. In my opinion accuracy completely depends on what bow, what shooter, what arrow, what situation. The questions become was the longer arrow more accurate or was it reacting off of the bow in a more correct manner leading to a better arrow flight producing a better group if so. A shorter arrow with the same dynamic spine would presumably perform similar. However then you need to consider the ratios between fletch and cg and point and cg. I have yet to test any 150 spine arrows I am using a 250 spine right now. Thanks for the comments!

@@Lucas_Palmer_bownerd_engineer arrow weight distribution has relatively small impact on the FOC or steering factor. FOC approximately equal to 0.5 x (F - B)/W, F is front weight including BH + Insert, B is back weight including vanes and nock, W is total weight. If anything, longer arrows will buckle more than shorter arrows if they have the same spine index. So in theory shorter arrows should be better, at least not worse. But the community in general believes the longer arrows are more accurate. Maybe longer arrows launched more accurately? I do not see how that is possible.