Archery Calculators-Calculate Arrow Speed, Kinectic Energy,Front of Center % I found this calculator and I know stats like these are pretty notoriously iffy at best. Without a Chrono, how accurately can an arrow's speed be predicted? I am going to order some new arrows and am not completely satisfied with my pass thru success. I know lots of variables but it seems to be an issue that began last season. As far as my tune, I shoot pretty much any 125 bhs or field points to the same spot and there seems to be zero wobble. I don't paper tune... I vaneless bh tune to 15 yards. I have never had arrows not hit the dirt before... this year after 5 deer... I have had two clean passes... the rest have been stopped by my Quick Spins... Yes arrows are being lost/snapped. My set-up 2004 Hoyt Protec 3000XT limbs Cam1/2 70 pounds +- (I am maxed out.) IBO was 305 when new New strings, cables, bushings and bearings last year 30 inch Beman ICS Hunters 10.3 gpi 33 grain Quick Fletch. Quick Spins Standard nock and insert 125 Grain Muzzy Broadhead I am going with 430 as my total arrow weight. This chart says I should be somewhere around 276 fps... I don't think it is anywhere near that fast. Any experts tfox maybe?
Using the calculator, It shows my arrow @ 273 f.p.s. Over my chrono I am shooting 268. I would think it is close enough for practical applications.
assuming your at 30" draw length that 276 number figures about right. Believe it or not calculators like backcountry are fairly accurate if your using correct data. I have two chronographs, a blue shooting chronograph and prochrony, both consistently read within 2% of each other. ..and the calculator. Now thats assuming the bow is making its Ibo speed. I keep a 350 grain arrow to measure every bow against its avertised IBO , surprisingly despite that it is popular to flame on bow companies for overstating IBO rating I have found most are pretty dam close. So whats this all mean? Not much in relation to your question or problem...ie a higher percentage of pass thoughs. Lets take things step by step and first negate some variables and see what we can improve on to get the performance your looking for. Lets assume your bow is tuned to the hilt, your getting plenty of speed with 430 grain arrow, and plenty of KE and more importantly momentum. Pretend we are fixed at 430 grains for the sake of the discussion. So lets see what we can change arrow wise that will get you where you need to be. Start at the broadhead if your not already using a COC head switch to one with no more then 1 1/8 diameter , take your pick there are a bunch out there( for example VPA , or Solids).That will get you a little more penetration from the start. Next move onto the shaft, if your not already shooting a small/micro diameter shaft switch to it. (GT kinetic, easton Injections, FMJ, acc, black eagle rampages ). The smaller shaft out penetrate a larger providing all other variable are equal. Move back to your fletching, if your shooting a high profile fletching you might want to switch to a lower profile that hangs up less, for example 3 " aee elites. Lastly lets look at arrow weight , or rather the location of the weight. Lets try to put as much of that 430 grains in the front as we can. Remember we cant change the weight so want to repostion the weight we do have. Use a shorter arrow with lighter spine, and hence less gpi ... by making it shorter we will make it stiffer and allow us to up the weight of the in the front (FOC) . We can use either a heavier broadhead, or insert( brass or weights) or a combination of the two. Now a combination of all of the above should help get you where you want to be. Sent from my GT-P3113 using Tapatalk
Trial covered it. Sounds like if you would have been using feathers that you would have had passthroughs with the current setup. Sent from my SAMSUNG-SGH-I317 using Tapatalk
Thanks guys... I did have some math errors. I am probably more like 270-280 grains. I started using the Quik Spins last year and made only two shots which passed through but barely. I do think they are hanging up. The QSs are high profile and very rigid with a tab on the back side and I do hit shoulder blade some... usually the soft part. The Bemans are medium diameter but I have never had a problem with them not blowing through before, nor with the Muzzys. I did use feathers before but tried some of these and love the way they shoot... but good grief lost/broken arrows and lost BHs are getting expensive. I was thinking about upping my arrow weight but when I ran the numbers, I was worried about losing too much KE if I fell below the point of diminishing returns. Which is why I wanted to know how accurate the calculation is. So refiguring my arrow weight, I am right at 475 grains, 263 FPS and 72.97 KE. I couldn't wrap my mind around any way 70 pounds wasn't enough KE. Will probably just switch back to either regular vanes or feathers. Thanks again...
One last question... Easton XX78 2317... I used to shoot 2219s with 4 inch feathers with fingers and loved almost everything about them. 2317s are the correct spine and pretty close to the weight I am looking for but... I am seeing 11.4 gpi seems to be just about the perfect weight/KE balance. What are the advantages of the FMJs and HIT inserts? I have those inserts on some old arrows and do not care for them. I tried some expandables and found the deployed blades were splitting the end of my arrows. The FMJs are also bit pricey. What say ye?
If the blade rest against the shaft or are held in place by the arrow screwing on the broadhead you need to use the broadhead adapter rings so that doesn't happen Sent from my iPad using Tapatalk HD
The rings work very well, or you can use a short aluminium footing that will make a FMJ or any arrow with HIT insert about indestructible.
Where can you get the footing. and do they weigh enough to add to FOC Sent from my iPad using Tapatalk HD
This thread shows it better then I can explain it....I made a bunch for FMJ, and also GT Kinetics. I love the micro diameter arrows but I never a fan of half outsets or HITs...though honestly like my buddy says ..The HITS only fail when you hit what you shouldn't... Keep scrolling to the bottom of the first page to see the rest of the photos..... How to make your axis fmj's indestructable!!!
By the look of the picture that footing is about 2 inches. Based on the GPI of the 2219's they weigh about 28 grain correct? How much would that effect FOC Sent from my iPad using Tapatalk HD
It would increase FOC, providing you have enough spine to handle the added weight your OK... The benefits are your not only adding FOC / weight(KE & momentum) but you are correcting the weakest point in the HIT system. Accomplishing both without the alignment issues and possible failure of an outsert. Your get the strength of the collar/footing with the precision of the HIT...
Would they cause increase drag and difficulty removing arrows from a target? Sent from my iPad using Tapatalk HD
Yes to some extent however not to any degree that caused me concern. Furthermore the tapering of the footing helps with that. And in a broad-head target your not even going to notice it...only a bag.
Thanks. Sorry for all my questions. Last one, will these work on an axis arrow? Sent from my iPad using Tapatalk HD
Size and spine? But it should for example....FMJ .340 you would use a bar5 ring same as the .340 axis. You can find footing sizes for most any popular arrow online right now. Let me know if you need help.
