Primitive Archer
Main Discussion Area => Arrows => Topic started by: DC on April 18, 2019, 09:45:26 am
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In my quest for light arrows I'm playing with tip weight. If I reduce the tip weight by 25gr I can take 5# spine out of the arrow. Same dynamic spine and the arrow still flies nice and makes the arrow maybe 30gr lighter. Then I can do it again. Another 30gr etc. Obviously there is going to be a point where this goes bad. Is it when the FOC moves too far back?
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25gr lighter tip weight will increase spine value by 5#. Lighter tip make spine stiffer.
Spined arrows shafts are sold as if they were a 28" finished arrow with a 125gr tip. ie. shafts with an indicated 50 to 55# spine weight are to be used as a 50 to 55# spined, 28" arrow with 125gr point. Any changes to tip weight or arrow length will change the effective spine value.
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Seems like I've heard you say that before Pat....
;D ;)
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That's what I said. If I take 25gr off the tip it makes the arrow 5# stiffer so I can reduce the spine by 5#. Yes he has said it before and I think he misunderstood me then too.
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Yes, I guess I misread what you wrote.
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Sorry Pat sometimes I don't write very clearly.
So "Obviously there is going to be a point where this goes bad. Is it when the FOC moves too far back?"
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I've not dealt much with FOC so I doubt I could give you a good answer. I guess if you are bare shaft testing the arrow would loose stability the farther back the FOC is. Fletching would change that though due to drag.
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the turkish flight arrows actually have a negative FOC.
usually though negative foc is purported to cause arrows to somersault once the velocity bleeds off.
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There must be a saw off point with the FOC where accuracy starts to suffer and increasing the fletching size to compensate just bleeds off speed. I have to do some reading on your website.