The point where the arrow leaves the string?

PLEASE HELP TO FUND ARCHERY INTERCHANGE

geoffretired

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Hi Andrew. Thanks for the encouragement. I cannot see how the answer would benefit my shooting or anyone else's for that matter; but I want to know for reasons that are nothing to do with an archer's performance. I just want to know the truth!
Why have some people gone to considerable trouble to use high speed videos to produce slo mo videos of arrows in flight? Why not find out what position the arrow is in at the point of separation, using the same voideos?
What I find interesting is how many responses to my post actually told me things about the arrow whilst on the string, that had nothing to do with my question. Is the arrow straight or nearly straight?? Is it at maximum bend, as I suspect, or nearly at maximum bend??
having nodes in line does not answer my question. If arrows have nodes in line the arrow can be bent or straight... but which of the two exists at the point of separation?
 

Whitehart

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Curiosity has got the better of me, I too would like to know the answer now :) somebody I know must have the answer.
 

geoffretired

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It was Joe Tapley who first mentioned this on here,some years ago.
At the time I had guessed that separation would take place when the shaft was straight; not when flexed towards one extreme or the other.
He pointed out that a flexing shaft is moving faster (side to side) when midway across from one extreme to the other i.e. when straight.
With the nock end trpped on the string, the front end would sway across to whichever side it was moving towards and if release happened at that stage the the sway would continue. The flexing would also continue but the sway on a bare shaft would not be corrected, it would sway or swing further to one side... just as we see it does when shooting bareshafts at longer and longer distances. The bareshafts don't just shoot off to one side on a straight path. they swing further off line at inceasing distances.
 

jerryRTD

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You are making a false assumption when you say that the nock is trapped by the string. the nock moves in conjunction with the with the string as the string moves around the fingers causing the first flex and with that flex the nodes
. At the point of separation the arrow becomes a freely suspended oscillating mass with two nodes . It is these two nodes that detemin the path of the arrow not the assumption that the arrow will go in the direction the point is pointed in.
 

geoffretired

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Jerry, yes the string and the nock move together while the arrow is being pushed by the string. BUT the string does not simply travel on its own path. The arrow is fixed to the string and flexing at a rate dictated by the shaft, At the same time, the string is trying to get on with its own flexing flight path. The two are effecting each other, changing the movements that each would make if they were separate. It is this restriction on the nock end of the arrow that disturbs the flexing of the shaft. It doesn't stop it flexin;, but it restricts the back but not the front. So the nodes you talk about can show when the arrow is free from the string. But before separation the front end of the arrow is less restriced than the rear and a waving at the front is generated.
 

Whitehart

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I thought the question was is there an optimum position of the string when the nock leaves the string, or does it not matter
 

Gavin Eisler

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This is a bit "how many angels on a pinhead?", the last thing I do when tuning my recurve is the brace height tune, go through the brace height range adjusting from min to max three string twists at a time , note which setting gives the tightest groups. i dont need to know at what point in the strings oscillation the arrow decouples or where the nodes are, I just want the tightest groups.
I also struggled with the concept of arrow point swinging more than the nock as the arrow moves through the power stroke, really? Surely the extra mass at the front of the arrow would move less than the nock.
 

geoffretired

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I guess the position of the string at separation has an effect on the way the arrow travels. It will be to one side or the other of its oscillation, or on centre. If on centre it will be travelling quickly across towards its extreme. Flicking the tail as it separates.
Gavin, I think the string pushing an arrow forwards from the back end means it is very unlikely to travel along a straight path. Ignore the flex for a moment and imagine how the string could push the arrow straight ahead. With the string following an oscillating path the front end of the arrow will be sent to one side as the force will not be down through the long axis of the shaft. The flxing will have an effect on that but cannot reduce the effect to zero.
Try launching a bare shaft arrow by throwing it with your finger on the end of the nock.
 

Timid Toad

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Ironman
There must be some effect as tortional stiffness of limbs reduces horizontal flutter. This in turn contributes to needing a lighter spine than might be suggested by charts. Unless your loose is pants.
 

Gavin Eisler

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The string does not vibrate in one plane, like a guitar string it has nodes, one of the benefits of bow asymetry is that the arrow does not leave the centre of the string, so many factors come into play, deviation from release, string harmonics and so on, messing around with string / brace height and tring mass/ materials, play around till you hit the null point .
 

jerryRTD

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Jerry, yes the string and the nBut before separation the front end of the arrow is less restriced than the rear and a waving at the front is generated.
In fact the front end of the arrow is restricted by the button. because the first flex of the arrow pushes the arrow into the button as can be seen on the hi speed video.
 
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geoffretired

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Gavin. yes the string vibrates. The effect on the shaft is to move the nock end side to side. The flexing shaft wants to vibrate side to side ,too so there is a bit of restriction from each to the other.
Jerry, yes the button retricts the front side to sid emovement of the shaft... but only for a short travel and then the shaft is free from all button contact. The front moves because of flexing and becuase of the fact that the shaft isn't dead in line with the travel path of the string.
 

Stretch

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There must be some effect as tortional stiffness of limbs reduces horizontal flutter. This in turn contributes to needing a lighter spine than might be suggested by charts. Unless your loose is pants.
Agree with this and there is also the second factor that the curve profile delivers the power back to the arrow in a different delivery profile. So the stored energy is not delivered all at the same part of the cycle. That affects how the arrow bends.

Also worth noting that this can also make it more difficult to get good clearance - especially if you have a ropey knuckle-dragger loose like me.

Stretch
 

jerryRTD

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Gavin. yes The front moves because of flexing and becuase of the fact that the shaft isn't dead in line with the travel path of the string.
Correct as soon as the string is release
Gavin. yes the string vibrates. The effect on the shaft is to move the nock end side to side. The flexing shaft wants to vibrate side to side ,too so there is a bit of restriction from each to the other.
Jerry, yes the button retricts the front side to sid emovement of the shaft... but only for a short travel and then the shaft is free from all button contact. The front moves because of flexing and becuase of the fact that the shaft isn't dead in line with the travel path of the string.
It only needs a short while for the nodes to form .
 

geoffretired

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Jerry, that may be correct, but my question is about the arrow and whether or not it is straight at that point of separation. I feel that it is fully flexed.
 

Timid Toad

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My instinct would say that it is not, but to what extent depends on a lot of things.
The loose sets up a series of movements that we know will damp out as the arrow travels.
However, some bows send their arrows on their way at very different points in their flexing cycles (BH, power stroke, TS etc), which leads me to think that there is no reason that flex should not continue before reversing after separation.
The bow imparts energy to the arrow that needs to dissipate. The arrow has various means to handle that, one of which is flex. There is no reason for it to stop flexing just because it has left the string.
 

geoffretired

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Hi TT I was not saying that the arrow stops flexing at or after separation.
The flexing continues from the start of the finger release and is still going on when the arrow hits the target.That has been seen in videos
What I am saying is that the side to side movement of the front of the arrow, stops at the point where the flex is maximum and about to change direction and flex back the opposite way. I think that separation from the string takes place at maximum flex. When the side to side movement has stopped.( or is very slight.
 

geoffretired

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Thanks again.
I couldn't make out what stage in the flex, the arrow was in.( flexed or about straight)
On my pc I cannot pause the video at any point in order to see a single frame.
 
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