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Thread: Straight fletch with less straight arrows

  1. #13
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    I thought fishtailing and porpoising were visible to the naked eye ,and show that the tail of the arrow is waving about side to side or up and down. Flexing of the shaft is too fast to be seen without slo mo video.
    So a very high nocking point could lead to an arrow coming out tail high and the fletchings try to correct that and create the up/down waving of the shaft which we would try to remove by moving the nocking point down.
    Similarly a centre shot that is way off would generate a slow waving side to side as fletching try to correct the initial wave to one side. Being visible to the archer they would probably try to get rid of it by adjusting centre shot or even draw weight or change arrow spine.
    The flexing is going to happen no matter what.





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  3. #14
    In the Gold AndyW's Avatar
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    Hi, Re. the initial question. Your numbers are a factor of 10 out. A 0.01 arrow would be way better than a 0.06 arrow as that would vary by little compared to about 2mm difference over the length of the shaft.
    When you consider the actual numbers of 0.001 and 0.006 can anyone tell the difference even at the two extremes - doubtful, human error is a much bigger variable. If you want a comfort blanket which cost 4 times the price for effectively the same product then go with the 0.001s but at the most they are an eighth of a mm straighter at 30 odd inches total length.
    If you do the trigonometry this equates to roughly a 1.5 cm difference in where the arrow will impact at 90m.
    I think it pretty much doesn't matter to most of us.
    Personally, I shoot 0.003s ( LOL ) and I use a hard offset because my finger release is a bit dodgy but if I were shooting 90m they would be small and straight fletch for speed.
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  4. #15
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    Thanks I don't think I got it wrong in that 001 is straighter than 006. My point is that if the arrow is fetched straight with a 006 arrow would that make it fly straighter than an offset fetched 001 arrow. I think that it probably wouldn't make a big difference but it was the principle of the effect that am interested in. As the arrow flies and twists around the front and back nodes either porpoising for compound or fishtailing for recurve does the oscillation at the point increase or decrease with the different fletching. Obviously the correct spine (or not) would have an effect here also

  5. #16
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    More drag will keep the front end on a more even track. So offset should, in theory work better.
    "Time is an illusion. Lunchtime doubly so." Douglas Adams

  6. #17
    It's an X AIUK subscriber. Rik's Avatar
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    Quote Originally Posted by Michael Burrows View Post
    Thanks I don't think I got it wrong in that 001 is straighter than 006. My point is that if the arrow is fetched straight with a 006 arrow would that make it fly straighter than an offset fetched 001 arrow. I think that it probably wouldn't make a big difference but it was the principle of the effect that am interested in. As the arrow flies and twists around the front and back nodes either porpoising for compound or fishtailing for recurve does the oscillation at the point increase or decrease with the different fletching. Obviously the correct spine (or not) would have an effect here also
    I think you're getting confused with FOC here. The more forward you have the centre of mass, the smaller the circles the point describes... That's separate from oscillation which isn't generally big enough to notice...

    <edit> fletching drag (mostly to do with size, but also angle) feeds into the speed of reaction of the shaft to it being out of line and damping of the fishtailing etc, so it gets less over time.

    spinning the shaft helps even out progressive errors (say if the shaft is tending to curve away from a straight line of flight, due to setup or conditions). Faster spin would give a tighter spiral, but it's a trade-off; tbe energy for that spin has to come from somewhere...
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  7. #18
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    Porpoising and fishtailing don't work around the front and back nodes.
    Think of a tubular bell hanging from its frame. We can move the bottom to one side and let go and the tube acts like a pendulum swinging side to side, but it makes no noise. That swinging is fishtailing and we see it. If we strike the tube gently we hear a note and see very little movement of the tube; that is the oscillation of the tube and it's what arrows do that we can't see. That happens around the front and back nodes.
    Fishtailing can be reduced with big fletchings, and it can be reduced even more with well matched arrows and well set up bow. The oscillating can't be stopped in the same way, that happens because the shaft buckles under the sudden load from the string.

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