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    #31
    Slow and heavy is the order of the day in my book. I like bows that are fast and quiet off the line and then run heavy arrows (12.5 GPI). Listen to Rat on building FOC.

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      #32
      Funny reading this. I just added some weight to my arrows because I wanted more impact and penetration. I'm shooting a Halon 6 at 27" and 70lbs. All my arrows weight 553-555 grains with 100 grain tips cut at 28". Now that i'm reading this maybe im too heavy. Thats about 16 GPI. Not to steal your thread, but am I way off shooting them this heavy? Shooting Easton Axis 340 spine arrows

      They definitely thump the bag more than the 430ish I was shooting them at before
      Last edited by bcj jones; 03-14-2019, 01:04 PM.

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        #33
        Originally posted by bcj jones View Post
        Funny reading this. I just added some weight to my arrows because I wanted more impact and penetration. I'm shooting a Halon 6 at 27" and 70lbs. All my arrows weight 553-555 grains with 100 grain tips cut at 28". Now that i'm reading this maybe im too heavy. Thats about 16 GPI. Not to steal your thread, but am I way off shooting them this heavy? Shooting Easton Axis 340 spine arrows

        They definitely thump the bag more than the 430ish I was shooting them at before
        You ain't sealing my thread in the least. I will say this, i shoot 540ish grain arrows off my recucve at a whopping 180 fps with stinger broadheads and they go through deer and hogs and don't look like they even slow down. I am probably going to use the same setup for elk, although i might shoot my heavy recurve and 725ish grain arrows at that same 180 fps, but don't really see the need. I just decided that i might like to try the flattest shooting arrow i feel comfortable with, just to do something different. It is all for fun anyway right? Coming off that halon you can probably shoot through 3 deer with that setup

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          #34
          Originally posted by bcj jones View Post
          Funny reading this. I just added some weight to my arrows because I wanted more impact and penetration. I'm shooting a Halon 6 at 27" and 70lbs. All my arrows weight 553-555 grains with 100 grain tips cut at 28". Now that i'm reading this maybe im too heavy. Thats about 16 GPI. Not to steal your thread, but am I way off shooting them this heavy? Shooting Easton Axis 340 spine arrows

          They definitely thump the bag more than the 430ish I was shooting them at before
          Everything in context...
          We are talking about building a fast arrow, safely, on this thread.

          You can't really be too heavy and be unsafe, but you can be too light and be unsafe.

          The OP wanted to know if he was on the right track and wanted opinions about the track he was on; that's all we are doing.

          The merits of his decision aren't really being debated (a few comments, okay), just how to get there safely and how to optimize the light arrow.

          Shoot your heavy arrow with pride, or whatever arrow you want to shoot.

          BTW, my arrows are 17.5 GPI...

          Comment


            #35
            Originally posted by Lightning48 View Post
            LOL, KE is nothing, but just a number and plays no critical role in the arrow. Momentum is the number you want besides the FOC number
            True to some extent. KE is a more speed dependent factor and Momentum is more weight dependent factor. FOC doesn't have as much to do with penetration as most people think. Dr. Ashby is always quoted here, but from what I have read of it and seen with my own eyes, FOC will only increase penetration if it is achieved by adding weight to the front of the arrow. I've seen three identical arrows built with different FOC, and it made no difference in penetration and when they were all the same weight. Momentum is more important there. Extreme FOC increase is also can make arrow flight slightly less predictable. And live tests I've seen about 11 to 15% FOC it's pretty dang good.

            Sent from my LM-V405 using Tapatalk

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              #36
              Originally posted by antiparadigm View Post
              True to some extent. KE is a more speed dependent factor and Momentum is more weight dependent factor. FOC doesn't have as much to do with penetration as most people think. Dr. Ashby is always quoted here, but from what I have read of it and seen with my own eyes, FOC will only increase penetration if it is achieved by adding weight to the front of the arrow. I've seen three identical arrows built with different FOC, and it made no difference in penetration and when they were all the same weight. Momentum is more important there. Extreme FOC increase is also can make arrow flight slightly less predictable. And live tests I've seen about 11 to 15% FOC it's pretty dang good.

              Sent from my LM-V405 using Tapatalk
              can you explain this?

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                #37
                Originally posted by txoutdoorsman24 View Post
                you know I'm not sure what that would calculate to but I get great penetration on every arrow I fling. had a pass through a doe at 60 yards just like a every doe at 20 yards. I like heavier set-ups and keep the FOC in line.



                EDIT...
                Literally just did this on Realtree's website
                Your Setup is Suitable for...
                This rig throws heavy arrows, and with a strong fixed-blade broadhead, it will work on any game animal on the planet.
                Arrow Weight: 508 grains / Arrow Speed: 309 fps
                Kinetic Energy: 107.68 foot-pounds
                Momentum: 0.697 slugs
                not even close. small animals every day. but when you look at capes, most PH tells you above 700 or its a no go. people that hunt elephant hunt with above 1000gr.

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                  #38
                  Originally posted by enewman View Post
                  can you explain this?
                  Excuse my bad engrish typos lol. From what I have seen in real world tests by an engineer, with identical arrows with nothing but an increase in FOC, (same weight, same spine same length) a 20 shot group from the arrows with a higher (~ 30%) FOC was less accurate that a medium FOC but more accurate than a low FOC (~10%). There are diminishing returns. (My unscientific thoughts on the above are) The higher the FOC, or the more off center the weight is, the more the spine comes into play in correcting the "wobble" of the arrow after the shot, or FOC and arrow flexion at the shot are (almost) directly proportional. Obviously there are a lot of variables, but from a very standardized test it proved as such.

                  Sent from my LM-V405 using Tapatalk
                  Last edited by antiparadigm; 03-18-2019, 04:31 AM. Reason: Engrish

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                    #39
                    Originally posted by enewman View Post
                    not even close. small animals every day. but when you look at capes, most PH tells you above 700 or its a no go. people that hunt elephant hunt with above 1000gr.
                    Same engineer did a test on FOC and penetration with the same arrows, and proved in two different tests that FOC did not change penetration unless momentum was increased by adding weight. So if you had two arrows of the exact same variables, (especially weight) and one had higher FOC, they will penetrate the same.

                    I too would agree. For Elephants (although I wouldn't hunt) I would use (a rifle, or) an arrow that feels like a lead pipe. Lol The Realtree thing probably was limited in scope to North American game animals with hooves.

                    Sent from my LM-V405 using Tapatalk
                    Last edited by antiparadigm; 03-18-2019, 04:28 AM.

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                      #40
                      Antiparadigm.

                      I’m going to respond but please don’t take this wrong.

                      One of the biggest problems with people including this engineer. Now I’m going off of what you wrote. If the engineer took an arrow and tested it and it showed that that arrow at 10% out performed a 30% then we need to break it down and see why. The first clue if this is what he did he used the same arrow (static spine) this right here is where he failed. It takes a lot of weight on the tip to get to 30%. So, right here alone this engineer screwed up. He took the arrow beyond the correct dynamic reaction. So his test just went south. His test is no longer valid.

                      As far as foc. Foc is something that most don’t understand. We can’t put it on paper with a formula, so the physics people don’t get it. There was a guy named Hickman. I belive first name was Clarence. Some time in the 40’s I think so give or take 10 years Hahha. He built a shooting machine for his long bow and tested arrows. He built arrow so he could move the foc around. By doing this the arrow never changed taw. Now he was a physicist, I have no idea how or if all things where correct. I would think it was consider what all he did. But he showed that the arrow with higher foc shot further.

                      I will go out and find a paper I have seen. It was written by a physicist about archery. I don’t care if you look st anything in it but the last paragraph. This past paragraph says it all. It was written in 2015 so it’s only 4 years old.

                      Most people that disagree with foc either have built them and didn’t know how to correctly build that arrow so they saw no benifits. That is just ignorance on there side. Or they are people that only regurgitate what they have been told.

                      Eric

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                        #41
                        By the way, this engineer wouldn’t happen to be josh from Jersey is it.

                        Comment


                          #42
                          Originally posted by enewman View Post
                          Antiparadigm.

                          I’m going to respond but please don’t take this wrong.

                          One of the biggest problems with people including this engineer. Now I’m going off of what you wrote. If the engineer took an arrow and tested it and it showed that that arrow at 10% out performed a 30% then we need to break it down and see why. The first clue if this is what he did he used the same arrow (static spine) this right here is where he failed. It takes a lot of weight on the tip to get to 30%. So, right here alone this engineer screwed up. He took the arrow beyond the correct dynamic reaction. So his test just went south. His test is no longer valid.

                          As far as foc. Foc is something that most don’t understand. We can’t put it on paper with a formula, so the physics people don’t get it. There was a guy named Hickman. I belive first name was Clarence. Some time in the 40’s I think so give or take 10 years Hahha. He built a shooting machine for his long bow and tested arrows. He built arrow so he could move the foc around. By doing this the arrow never changed taw. Now he was a physicist, I have no idea how or if all things where correct. I would think it was consider what all he did. But he showed that the arrow with higher foc shot further.

                          I will go out and find a paper I have seen. It was written by a physicist about archery. I don’t care if you look st anything in it but the last paragraph. This past paragraph says it all. It was written in 2015 so it’s only 4 years old.

                          Most people that disagree with foc either have built them and didn’t know how to correctly build that arrow so they saw no benifits. That is just ignorance on there side. Or they are people that only regurgitate what they have been told.

                          Eric
                          I'm totally open to what I said being wrong. I am a perpetual student. I believe we are still on the same page though.

                          I haven't looked it up in almost 6 to 8 years, but I read on several forums and websites about people doing similar tests as described, or speaking just on the theoretics of how it all works. I don't know Josh from Jersey, but he may have been one of those people! Lol

                          I believe the purpose of that part of the test as such is to prove that FOC is not an isolated factor. I see more of a correction in speech, or how we speak about FOC. Obviously by increasing the FOC alone, you change the dynamic spine of the arrow, and on an already built arrow, (Out of the box) you cannot really change the FOC without changing the weight of the arrow, but correct me if I am wrong.

                          As far as FOC and accuracy, the way I understand it, yes, for sure degree of FOC is better, but extreme FOC (past what point I don't know (maybe... think of someone taking current arrow setup with 150gr head and going to 400gr head for more FOC)) can create issues where without proper tuning, flight is less predictable. That's my point. FOC doesn't exist in a vacuum like some people I have seen speak like it is. "Just increase your FOC and it'll be 10x better" or "I'm doing ____ so it will penetrate better because it has 5% more FOC". The momentum or weight change has much more impact on the penetration, rather than FOC, or even KE. It's Semantics maybe...

                          Also, (complete conjecture warning) it seems like wind drift (especially at long range) would be worse on an arrow with more FOC and less mid balance, as the back end could be kicked around a lot easier? Thoughts on that?

                          I'll look up that report, I'm always open to seeing new info, and I never take anything as 100% gospel! It only takes one more report to prove it all wrong or recertify the previously known info! Thanks


                          Sent from my LM-V405 using Tapatalk

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                            #43
                            No one has said that FOC exists in a vacuum, in fact, it shouldn't.

                            Two arrows are identical, 600 gr, one is 20% FOC one is 10% FOC...

                            First, they can't be identical, dynamic reaction will need to be changed on the higher FOC arrow.

                            Second, the higher FOC arrow needs less control surfaces for stable flight.

                            The farther the center of resistance is from the front of the arrow the better the control; that is a known quantity and can't be changed. So, more FOC gives a more stable flight.

                            Wind drift would be less or the same, not more, due to using smaller fletching; and you use smaller fletching because you don't need big control surfaces on higher FOC arrows.

                            Lastly, FOC doesn't increase penetration due to the higher weight, both arrows weigh the same right? The difference is in reducing the lever arm effect, especially when shooting a moving target, and every live animal is moving when we shoot them.

                            All these test done by back yard experimenters, and I say that in high regard, set themselves up for failure by not understanding the basics of what they are trying to prove or disprove. The two arrow can't be identically built because they will react differently, and you can't shoot them into a static target of ballistic gel to see the effect of higher or lower FOC, it will not show it.

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                              #44
                              Originally posted by antiparadigm View Post
                              I'm totally open to what I said being wrong. I am a perpetual student. I believe we are still on the same page though.

                              I haven't looked it up in almost 6 to 8 years, but I read on several forums and websites about people doing similar tests as described, or speaking just on the theoretics of how it all works. I don't know Josh from Jersey, but he may have been one of those people! Lol

                              I believe the purpose of that part of the test as such is to prove that FOC is not an isolated factor. I see more of a correction in speech, or how we speak about FOC. Obviously by increasing the FOC alone, you change the dynamic spine of the arrow, and on an already built arrow, (Out of the box) you cannot really change the FOC without changing the weight of the arrow, but correct me if I am wrong.

                              As far as FOC and accuracy, the way I understand it, yes, for sure degree of FOC is better, but extreme FOC (past what point I don't know (maybe... think of someone taking current arrow setup with 150gr head and going to 400gr head for more FOC)) can create issues where without proper tuning, flight is less predictable. That's my point. FOC doesn't exist in a vacuum like some people I have seen speak like it is. "Just increase your FOC and it'll be 10x better" or "I'm doing ____ so it will penetrate better because it has 5% more FOC". The momentum or weight change has much more impact on the penetration, rather than FOC, or even KE. It's Semantics maybe...

                              Also, (complete conjecture warning) it seems like wind drift (especially at long range) would be worse on an arrow with more FOC and less mid balance, as the back end could be kicked around a lot easier? Thoughts on that?

                              I'll look up that report, I'm always open to seeing new info, and I never take anything as 100% gospel! It only takes one more report to prove it all wrong or recertify the previously known info! Thanks


                              Sent from my LM-V405 using Tapatalk
                              I haven’t found that paper yet, but I will. If you get foc in the mid 30% you can shoot broadheads on a bareshaft. Now it’s not very forgiving but it can be done. I’m building an arrow now to look at this. Major problem is it takes a **** ton of weight to get to mid to high 30% foc. Biggest Robles is we must go up in spine to use this amount of weight. So every time we do this gpi goes up. So it takes even more tip weight. I would venture to say for me to get this amount off foc the arrow will be around 900 to 1000gr. Way more then I hunt with and extreamly more then the average hunter.

                              Now as far as wind. Yes, foc is or can be a problem. If you hunt in high wind you must learn what foc is best. Low foc arrows can be pushed off course. High foc arrows will stay more on course but can be flying at hard angles. It must be built for what we hunt in. This is one of a big problem in the archery world. People just through arrows together with out much thought. We all have done it. But arrows are a penetration system. If we learn how to build them correctly we cut down on wounded or lost animals.

                              I don’t think you are me or others are totally wrong or correct. There are still lots of things out there that we are learning everyday. I started learning and testing dynamic reactions around 2015. I’m still learning. I’ve always said buy .001 arrows. But, I’m testing for an arrow manufacture on straightness. I do not know if they will let me or if they will produce the info when I’m done. But what I will say it’s not that important. Rick mckenny wrote on this years ago and he said no one shoots good enough to see even up to around .010. Out of straightness. I think it’s just marketing.

                              If you have noticed foc is becoming a bigger thing with arrow manufactures. Personally I think they are doing it strictly for marketing. Just another way to make money. I wish there where more testing done. But, I don’t have the time or money for some of the test that need to be done.

                              Eric

                              Comment


                                #45
                                Originally posted by Rat View Post
                                No one has said that FOC exists in a vacuum, in fact, it shouldn't.

                                Two arrows are identical, 600 gr, one is 20% FOC one is 10% FOC...

                                First, they can't be identical, dynamic reaction will need to be changed on the higher FOC arrow.

                                Second, the higher FOC arrow needs less control surfaces for stable flight.

                                The farther the center of resistance is from the front of the arrow the better the control; that is a known quantity and can't be changed. So, more FOC gives a more stable flight.

                                Wind drift would be less or the same, not more, due to using smaller fletching; and you use smaller fletching because you don't need big control surfaces on higher FOC arrows.

                                Lastly, FOC doesn't increase penetration due to the higher weight, both arrows weigh the same right? The difference is in reducing the lever arm effect, especially when shooting a moving target, and every live animal is moving when we shoot them.

                                All these test done by back yard experimenters, and I say that in high regard, set themselves up for failure by not understanding the basics of what they are trying to prove or disprove. The two arrow can't be identically built because they will react differently, and you can't shoot them into a static target of ballistic gel to see the effect of higher or lower FOC, it will not show it.
                                Rat. What if we took some cardboard, make it several inches thick. And then use a blunt tip. Now build some arrows low and high foc. See if there is a difference.

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