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This is a new concept to me that I'm trying to understand. The idea is that arrows with the balance point being forward of center (heavier towards the arrowhead) makes arrows fly better and penetrate deeper.
From what I've been able to gather... this is because:
1. When the balance point is closer to the arrowhead, the fletchings have more torque to straighten out the arrow faster as it leaves the bow. This means you can have less fletching and less drag.
2. When the arrow hits the target, a more forward weighted arrow will flex less upon impact and have less chance of deflection. Basically the arrow penetrates straighter and deeper because the weight is more towards the front of the arrow.
Does anyone else (Preston) have any other insights into why forward weighted arrows are better? My biggest question is HOW to tune an arrow to a bow? Goals are to make the arrow fly straight and penetrate deep.. but what are some of the options for tuning? Less fletching, heavier arrowhead, etc?
The majority of the research for the concept I believe comes from the Ashby reports. You can google them and find a lot of info on it.
This site has a lot of videos that I haven't had a chance to watch yet but they look informative.
Tuning your arrows depends first on what type of arrow shaft you'll be using? Homemade wood, professionally made wood, or carbon/aluminum? If you're using professionally made woods shafts, carbon, or aluminum it easy to tune them. You get a couple of arrows for each spine group starting at your bow's poundage and moving up to about 25 pounds. For example, if you have a 55 pound bow, then get 2 arrows spined at 50-55, 55-60, 60-65, 65-70, & 70-75. Make sure your points are the same you intend to use, because changing your point weight can affect arrow flight. Then with your test kit of arrows, stand about 25 yards away from a VERY LARGE target (like a bunch of hay bales or pile of dirt), and shoot your arrows. If you're right handed, then arrows that are too lightly in spined will fly to the left, and arrows that are too heavily spined will fly to the right (opposite for left handed shooters). The correctly spined arrows will fly straight without any fletching. Oh yeah almost forgot the most important part- Shoot the test arrows BARE SHAFTED, i.e., no feathers.
In order of importance: 1) properly spined arrows, which fly straight is the first step in adequate penetration. 2nd, heavy arrows penetrate best, Ed Ashby recommends a minimum of 650 grains arrow weight for animals elk size and bigger. 3rd, high/extreme FoC. BUT just as important is the style of broadhead you shoot. Read Ed Ashby's "The Natal Study" for information on the effectiveness of different broadhead types.
To get more FoC you can taper your shafts so that the nock end is narrower, you can use heavy broadheads, and for carbons, you can use heavy inserts/adapters.
Cool! That is a great tip to shoot the arrows without fletching. Find the ones that fly super good without fletching then slap some feathers on there and they'll be money. Thanks for the tips... I'm inspired.
Those videos have some great info and they really lay the groundwork for the "perfect arrow". There's a neat section on some native papa new guinea arrows and how they have been using FoC before there was modern contact with them.
My wood arrows tuned in really nice, but they don't have the FoC I was hoping for. As Dr. Ed Ashby says, all of these factors will benefit you, but you can pick and choose to build your arrows. So for now I'm happy with the woods, even with the low FoC, because they fly so nice, and they are heavy, and the broadhead is up to Ashby standards.
But I'm working on some ExtremeFOC carbon arrows. Having a tough time tuning them...
Awesome. What is the trouble with tuning your carbon arrows? Are they too bendy now with the heavy forward weight?
Not sure, some of the more experienced folks think my arrows are too stiff, so have to try some lighter spines. Although, one guy said maybe the wooden bow just doesn't want to shoot carbons...!
Figured it out with some help from the pros. Tested a 500 spine arrow and it flew straight on with no tail wag. Those other arrows were spined too heavy and were bouncing off my handle which made them oscillate back and forth. Just kind of surprised me that I would have to go down in spine weight. Always more to learn!
This arrow comes out to 29% EFOC. Just 1% shy of Ultimate-FOC (>30%). Total weight of the bare-shaft is 588 grains, so 62 grains short of the 'magic' number, 650 grains. I'm going to foot the arrow to protect the insert from splitting the shaft on impact and if that doesn't bring it over 650, then maybe heavier heads or internal weights...
Hey folks, so here's the finished arrow. I was able to get it over 650 grains (according to the Ashby studies, once you're arrow is over 650 grains it will penetrate through heavy bones 100% of the time, given that you have the other broadhead and arrow characteristics he calls for, so 650 grains is the weight to shoot for, and not just for big animals but also for deer incase you hit a humerus or scapula). The shaft is 288, insert 100, point 250, and a "special" brass footing at +/- 95 grains for a total bareshaft weight of close to 680 grains, plus a little glue and feathers and its more like 690 grains. I took a 11/32 brass piping and cut it into 3" segments to foot the shaft. Not only did this add the necessary weight but it also helps protect on impact from the insert busting out the sides of the shaft. I used a 4 feather fletch, 2 inches long. Still at 29% EFOC with 445 grains up front.
These are the first arrows I've made/shot with a really high FOC, and it is AMAZING! These things shoot straight, flat, and quiet. It sucks to have to use carbon out of a selfbow, but I am extremely impressed with this arrow setup. And with all the experiments, these properties should guarantee deep penetration. I sure hope I get some opportunities to try this season!
Too cool Preston. I'm very inspired. I'd love to hold one of those arrows and see how the weights compare to what I'm used to. I've been scraping like crazy trying to finish an osage bow because I want to start experimenting with arrows! Trying to figure out how to apply these principals to primitive arrows. I know cane arrows with antler foreshafts were common. Going to have to knap some long, pointy, fat arrowheads to get the weight up there. Will keep you posted with how it goes.
In those videos you put the link up for, the natives he showed had hardwood points, which were really heavy. Good luck I'd like to see what you can come up with.