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Re: [SCA-Archery] Fletching by the numbers

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  • Edward deWitt
    Carolus, You said the bare shaft will rotate clockwise.  Is this just from a right hand bow or will a left hand one do the same?  If they both rotate the
    Message 1 of 9 , Mar 4, 2010
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      Carolus, You said the bare shaft will rotate clockwise.  Is this just from a right hand bow or will a left hand one do the same?  If they both rotate the same way, could this be like toilets spinning the same way above the equator and opposite , below?

      --- On Thu, 3/4/10, Carolus <eulenhorst@...> wrote:

      From: Carolus <eulenhorst@...>
      Subject: Re: [SCA-Archery] Fletching by the numbers
      To: SCA-Archery@yahoogroups.com
      Date: Thursday, March 4, 2010, 4:03 PM

       

      Yes, an arrow without fletching will develop a clockwise rotation on its
      own due to torque. Once fletching is added, however, this force is
      overcome by the rotational or stabilizing effects from the fletching.
      When tuning a bow a bare shaft should be used. Search the web for "bare
      shaft tuning" for instructions. Using wooden shafts this can be really
      tough and do not expect to get results as perfect as described. Prepare
      your arrows as normal with balance and spine properly configured. Then
      build another arrow identical with the exception that there is no
      fletching. Use this arrow to tune the bow.
      Carolus

      G P wrote:
      > I had always believed that rotation was due to the angles of the
      > feathers, too, but I seem to recall coming across something recently
      > (I wish I could remember what!) that said that the arrow will rotate
      > all on its own, even without feathers; feathers are only there to
      > stabilize wobble (like the tail-end of a weather vane--catch the wind
      > in order to always be at the back). Is this true?
      >
      > Geirr
      >
      >


    • Carolus
      it is a factor of torque and is not related to the handedness of the bow. To remember torque effects use the right hand rule. Curl the fingers of your right
      Message 2 of 9 , Mar 4, 2010
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        it is a factor of torque and is not related to the handedness of the
        bow. To remember torque effects use the right hand rule. Curl the
        fingers of your right hand and extend your thumb. The thumb points the
        direction of travel and the fingers the rotation. This applies to the
        lateral forces generated by rotational torque as well. If you were to
        remove the lug nuts from a tire and move the car forward, the left side
        wheels will want to pull away from the car but the right side wheels
        will be held in place. Remember the rotational effect imparted to an
        object moving in a straight line is very slight and is easily overcome.
        It really doesn't give any stabilization to an arrow but it is
        detectable. One of the best places to see this effect is in the old
        films of the Apollo moon shot launches. The black and white paint was
        so the rotation of the Saturn V could be tracked. That rotation was not
        induced by intent but by rotational torque induced by the movement of
        the rocket itself.
        Carolus

        Edward deWitt wrote:
        >
        >
        > Carolus, You said the bare shaft will rotate clockwise. Is this just
        > from a right hand bow or will a left hand one do the same? If they
        > both rotate the same way, could this be like toilets spinning the same
        > way above the equator and opposite , below?
        >
        > --- On *Thu, 3/4/10, Carolus /<eulenhorst@...>/* wrote:
        >
        >
        > From: Carolus <eulenhorst@...>
        > Subject: Re: [SCA-Archery] Fletching by the numbers
        > To: SCA-Archery@yahoogroups.com
        > Date: Thursday, March 4, 2010, 4:03 PM
        >
        >
        >
        > Yes, an arrow without fletching will develop a clockwise rotation
        > on its
        > own due to torque. Once fletching is added, however, this force is
        > overcome by the rotational or stabilizing effects from the fletching.
        > When tuning a bow a bare shaft should be used. Search the web for
        > "bare
        > shaft tuning" for instructions. Using wooden shafts this can be
        > really
        > tough and do not expect to get results as perfect as described.
        > Prepare
        > your arrows as normal with balance and spine properly configured.
        > Then
        > build another arrow identical with the exception that there is no
        > fletching. Use this arrow to tune the bow.
        > Carolus
        >
        > G P wrote:
        > > I had always believed that rotation was due to the angles of the
        > > feathers, too, but I seem to recall coming across something recently
        > > (I wish I could remember what!) that said that the arrow will rotate
        > > all on its own, even without feathers; feathers are only there to
        > > stabilize wobble (like the tail-end of a weather vane--catch the
        > wind
        > > in order to always be at the back). Is this true?
        > >
        > > Geirr
        > >
        > >
        >
        >
        >
        >
        >
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        >
        >
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        >
      • Geirr pík
        (Small side note: That s not actually true. http://www.snopes.com/science/coriolis.asp) Geirr
        Message 3 of 9 , Mar 4, 2010
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          (Small side note: That's not actually true.
          http://www.snopes.com/science/coriolis.asp)

          Geirr


          On Thu, Mar 4, 2010 at 7:31 PM, Edward deWitt <sagebowman@...> wrote:
          >
          > Carolus, You said the bare shaft will rotate clockwise.  Is this just from a right hand bow or will a left hand one do the same?  If they both rotate the same way, could this be like toilets spinning the same way above the equator and opposite , below?
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