what is it about carbon foam?

geoffretired

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I am glad this thread is continuing.The more we discuss ; the more truths come to light. The more misunderstanding, too! And I mean MY misunderstandings.
I think we mentioned limb stability some time ago and it is back again. There has been a lot of chats about torsional rigidity/stiffness recently and recurve shapes and sizes. If I understood some of what was said, a recurve limb under stress can become unstable in the sense the recurve part would like to bend the other way. It's the sort of thing you sometimes notice when you string the bows,yes?
Stretch has reminded me about his aim being steadier with one set of limbs despite the holding weight being the same. Perhaps that is down to the limbs being steadier when under load. Kid Curry mentions arrow spine tolerance, and differences in two different limbs. That could be the effect of different torsional stiffnesses??? Or am I getting confused again?
Perhaps "forgiveness" is a good word after all, but it could also be misunderstood. I know Stretch has mentioned this before, forgiveness does not mean it applies to everyone using the same equipment. Perhaps the term "A forgiving bow/set up" has been misused at times by archers who think a particular set up will be universally forgiving; so it will work for them, too.
When I shot recurve in the 80's I had X7's. I also bought some Bemans to give them a try. They were awful! My groups were all over the place. What was interesting though, was the way I felt when shooting them. Not the way I felt about the awful groups, but the feeling when making the shots. The arrows were lighter than X7 and I felt that the arrows were getting out of the bow so fast that my follow through was happening long after they had gone. I felt as if I was getting left behind. I went back to X7 and the groups returned after an end or two. I felt I was shooting properly again. Later I went back to the Bemans and put some earth screen tubing down the insides of them. It was a close fit so it should stay in place well. I compared the weights and they were now the same as the X7. As soon as I shot them, I felt "normal" again, they were leaving the bow when I was ready if that makes sense. The groups returned too.
Perhaps I should have left them as they were and tried to get used to how they made me feel. Perhaps they would have felt normal eventually.
 


Rik

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I have two bow setups. Only difference is SF Fibre limbs and Xtour limbs. My SF limbs will take a wider range of arrow spines before they start to contact the riser than my Xtour. My SF limbs are more 'forgiving' on poor arrow selection.
But which scores better...? And which gets the higher ten count...? I mean it's one thing to make kit selection simpler, but if that doesn't also aid results, then it's kind of not useful. On the other hand, if the looser matching kit gets better results, that's entirely positive (at this point, at least).
 


geoffretired

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I think KidCurry's example is a good one. It shows what he means regarding forgiveness. In a way, it also removes the archer from the equation; he isn't saying he shoots better scores with one setup, it's about the bow and arrow and how they behave with one another.
Perhaps one set of limbs is faster and causes contact with the weaker arrows?
I wonder if different archers would get similar results? If one set of limbs is faster, we might expect that they would.
 


Whitehart

Active member
Most ILF & Compound bows today are just a machine that is capable of repeating the same actions exactly the same each shot. Humans are not machines and not capable of repeating the same actions exactly the same from shot to shot.
Machines are told what to do and do just that, humans are told what to do and try and do it, sometimes question why, even think that they are doing what they are told, when their actions are totally different.
Unfortunately we operate the bow, so we transfer all our inconsistencies to each shot to the bow and the bow responds and puts the arrow where we are actually aiming (form aligns the front and back sight) not where we think we are aiming.
Training is the process to find a system to help us to execute the same shot after shot or as close as possible.

The better we execute the shot the better the result and the more forgiving/easy the shot feels.
 


geoffretired

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Hi Andrew, yes I agree with all of that. The better we shoot; the better the results will be.
Some people seem to think that some gear and some setups give them better results, than other gear and other setups. I can see why they think that way. I feel there are several ways in which archers can think that way. Sometimes one bow feels nicer to shoot and they feel better shooting it and that leads on to higher scores. Sometimes a change of bow feels different in some way and they don't get on with it and don't keep it, and believe it was not for them. Had they tried the bows in reverse order, they may have got used to the first one and found the next one not to their liking this time. Some bows feel rather leaden and others feel sharp, snappy. That can persuade us to use one rather than the other without giving both a really good testing. There are all sorts of distractions/feelings going on in our heads. I would imagine they are difficult to ignore.
Sometimes it is a change of the set up that suits us better. Stabilisers come to mind here. Sometimes we see or feel the effects of each change and go for the one we prefer. One set up could be better in ways that can be described( front heavy, bottom heavy etc etc) and better in a sense that most coaches/ top archers consider to be mechanically better for the bow.( CoG in a certain place for example).
It seems to me that " forgiveness" has been around in archery for a long time and it has taken on different meanings in different clubs/ individuals by its very nature. It is not clearly defined,( by everyone) difficult to prove, and difficult to check what individuals actually mean by it. It's a nice word, with an attractive idea triggered in our minds and archers do like joining in with the ideas they hear around them. I remember when arrow nodes were all the rage and arrows were suddenly needing an overhang of several inches. That seems to have gone out of fashion.
I think Forgiveness is here to stay.
 


Andy!

Member
Forgiveness is totally here to stay. That's because it actually exists.
There are known and demonstrated physical properties which can be optimised to make a bow and arrow combination resistant to archer's form variation. Granted, they largely apply to compounds, but they exist.
Spinning arrows makes any that aren't perfectly straight, adopt an average straight flight path compared to what they'd do if they were straight fletched.
A long enough site extension on a recurve of sufficient poundage can achieve the same torque compensation.

If you bother to look at how much a flubbed release can do to arrow tune by playing with Jame's Park's recurve arrow simulator, a variation of a mm sideways release at ( I think it was a 42lb draw 28") can cause the software to retune the bow poundage by an extra 1.5 lb's in order to get the nodes to exit the bow parallel to the line of force.

It doesn't take much imagination to realise that if you have a slightly weak tune, and you're having inconsistent releases which give you more sideways motion, that your arrow choice may actually match your bow BETTER on your flubbed releases.
Ever heard people say that a stiff arrow is more forgiving and others say that a weak one is more forgiving?

Have you ever wondered why such contradicting advice exists? When we are talking archers who aren't exactly consistent with releases, and their accuracy isn't brilliant anyway, who can say that their flubbed releases are giving more, or less sideways movement at the release?
Obviously, if your tune is absolutely dead on, you'll be likely to get variations either side of where you're aiming and write that off as accurate, but not precise.
But if you're running a bit stiff and you slipped a minor sideways release that had no much deviation, what may have just happened? Did that single shot just happen to be all tuned perfectly?

I spent hours playing with tiny variations and they all resulted in the software making noticeable poundage increases to compensate.
It told me also that arrow selection requires accurate scales. It's the first thing I ask people who say that "arrow charts don't work for them". This topic came up in one of the very early Easton Target archery podcasts, too.

I think most recurvers have experienced at least one perfect release that triggered all those expressions of wonder. But how was it different to the non perfect ones?

So we've got forgiving by design and forgiving by chance.

I've already covered "forgiving by selective memory of only the good shots"

And you wonder why it's so hard to narrow down and explain. There's definite, random and belief.
 


geoffretired

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Thanks Andy! I can follow that. I think Rik was writing about setting the bow to shoot slightly weak (or stiff) some years ago. It seems to me now that his ideas fit in with what you wrote about.
It doesn't take much imagination to realise that if you have a slightly weak tune, and you're having inconsistent releases which give you more sideways motion, that your arrow choice may actually match your bow BETTER on your flubbed releases.
I am now wondering if the shape and size of the recurve on a pair of limbs, could effect the sideways movement of the string on a bad release. Would torsional stability come into that?
 


KidCurry

Active member
But which scores better...? And which gets the higher ten count...? I mean it's one thing to make kit selection simpler, but if that doesn't also aid results, then it's kind of not useful. On the other hand, if the looser matching kit gets better results, that's entirely positive (at this point, at least).
It's not that simple. The SF limbs will take a wider range of arrow spine variation before hitting the riser. I could say that the Xtours score better, and they do if the spine selection is good, because they are faster they reduce draw length variation errors and can reach 90m point on gold, but if the arrow spine selection is poor the arrows hit the riser. With the same spine variation the SF limbs arrows don't hit the riser so the scores are better, but they won't reach 90m. This is why I would advise new archers to use limbs like the SFs as they are easier to set up well. I would call this 'forgiveness', others may not, I don't really care :)
But on the subject of foam cores these look interesting... 'Akusta Fotron Carbon Foam Recurve Limbs' 100% carbon/epoxy... no fibre glass at all.
 


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Rik

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That's the thing about the term. It seems to imply something about the kit in general, when we seem to be saying that it's actually about the fit of the kit to the individual. "It works better for Y", rather than "it works better".
 


geoffretired

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Forgiveness or tolerant?? I wonder what would happen if we tried to make an archery dictionary of words we use that have different meanings, depending on who you are.
My struggle with things like this is the way there sometimes seems to be no reason for the "forgiveness". I think it is easier to accept when there is an explanation. For example; Andy! explained how a poor release required and increase in draw weight to get the arrows back on line. It seems the poor release slows the arrow. Could that be energy lost to side to side movements? Could limbs that have less torsional stiffness lose more speed in those circumstances?

Good point Rik.
 


malbro

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I am a novice so not the best form but shooting yesterday I used two bows, same arrows, same target, both bows are bare bow no sights shooting from the shelf. With my normal bow a 35lb Diamondback Supreme I can hit the target all the time but grouping is not great. Second bow is an Andy Soars Blackbrook Carbon TDR 40lb draw, and with this bow, and it is the first time I have shot it, I get better groupings. So is it better equipment providing the improvement or is it better matching of the bow to the arrow improving my shots, or is the better bow more forgiving?
 


geoffretired

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I see this as an important question. It must be the sort of question that is asked by many beginner archers. Sometimes it will show when they try equipment at an archery shop, for example.
I can think of several reasons why the second one gave better results.
It could be the second bow is a better piece of equipment; but that is unlikely to show such marked differences, unless the first bow is not very good at all.
It could be a better match to your arrows; that could be tested with bareshafts etc.
It could be that you shot better with the second bow; giving better results. Sometimes shooting an apparently better bow leads us to expect better results,or even try harder to make sure we shoot as well as we can. Like driving a new, expensive car.
It could be that the extra draw weight made your release more snappy, less likely to go off line.
 


KidCurry

Active member
I am a novice so not the best form but shooting yesterday I used two bows, same arrows, same target, both bows are bare bow no sights shooting from the shelf. With my normal bow a 35lb Diamondback Supreme I can hit the target all the time but grouping is not great. Second bow is an Andy Soars Blackbrook Carbon TDR 40lb draw, and with this bow, and it is the first time I have shot it, I get better groupings. So is it better equipment providing the improvement or is it better matching of the bow to the arrow improving my shots, or is the better bow more forgiving?
There is no way to tell from that amount of data. There is a view that when you change to a new bit of kit your scores will go up. I'm not convinced by it but it is quite a popular view.
... ahhh Geoff's comment is more useful :)
 


Andy!

Member
There is a view that when you change to a new bit of kit your scores will go up. I'm not convinced by it but it is quite a popular view.
There's the well known "Three day effect" which is various combinations of "Beginners Mind", Expenditure justification and confirmation bias. I totally believe that the expectation of a change leading to an improvement somehow makes people better.
We see people routinely go to their coach, who tweaks and turns a few things, then gives the bow back. The archer is generally happy with this.

There are a few coaches that take the bow away out of sight, then bring it back, having done nothing... and the archer is generally happy with this.
A certain well known coach from New Zealand demonstrated this to me by pressing a compound, putting a twist on a cable, giving it back to the archer, letting them shoot it a bit and then taking the twist back out after pressing it again.
Archer claimed it held steadier and was easier to shoot.

Improvements to the archers mind are just as valid a performance increase if it raises their points.
 


geoffretired

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Sometimes, new kit or a new set up, brings improvements because the archer shoots better. With the old kit or old set up the poor results can lead to lazy form. The changes can lead archers back to using a less lazy version of their shooting form.
It's a bit like our handwriting gets worse if we just write stuff when the letter formations aren't going to be judged. We then need to send a serious letter( or similar) where we make an extra effort with the writing.
Driving a car regularly on the same route can lead us into bad habits. Changing the car, or the route, can bring back a more alert form of driving.
 


Emmadragon

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I'm not sure if I would count this as forgiveness, but I shot for the first time on Saturday with a new carbon riser and carbon/wood limbs, and it was bliss. Shooting my previous set-up, (glass/wood limbs, metal riser), it was tough to pull 20#. With these, it was insanely easy to pull 23#. I certainly wasn't better as an archer with them, but the whole process was so much easier that I every confidence that once I'm set-up properly (I had to re-set the button, arrow rest and move the string nocking point), I'll be able to concentrate on getting better rather than worrying about my equipment. The new limbs just don't 'stack' in the way that the old ones did. So, are carbon foam limbs 'better'? Still don't know, but I can certainly vouch for carbon/wood limbs. Plus, they are absolutely beautiful.
 


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