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Re: [ksurf] LE diameter size

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  • Loco 4 Olas
    sounds like the opposite to me. ... From: To: Sent: Friday, June 03, 2005 4:23 AM Subject: Re: [ksurf] LE
    Message 1 of 6 , Jun 2, 2005
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      sounds like the opposite to me.

      ----- Original Message -----
      From: <CCKiteboarder@...>
      To: <kitesurf@yahoogroups.com>
      Sent: Friday, June 03, 2005 4:23 AM
      Subject: Re: [ksurf] LE diameter size


      > Are you saying that you don't believe the claims that are being made for
      > the advantages of a
      > smaller LE Tube?
      >
      > Steve
      > Carson City, NV, USA
      >
      >
      >
      > 06/02/05 4:41:02 AM, Hung Vu <hungvu2000@...> wrote:
      >
      >>I played around with some airfoil analysis and by reducing the leading
      >>edge diameter from 10% to 5% of chord, the maximum L/D ratio of the
      >>airfoil increases from 115 to 126 (induced drag is not included) and the
      >>maximum Lift Coefficient increases from 1.57 to 1.79.
      >>
      >>So it's around 10% to 15% increase in airfoil performance for both
      >>maximum L/D and Lift by reducing the LE diameter in half.
      >>
      >>I also increased the LE diameter to 15% and the result was not very
      >>desirable so you definitely don't want to go there.
      >>
      >>P.S., These numbers should be taken as an approximate.
      >>
      >>P.P.S, The airfoil moment (tendency to flip over the nose) is slightly
      >>more stable with smaller LE diameter
      >>
      >>P.P.P.S., Most modern LE diameter on market is around 9 or 10% of chord.
      >>
      >>Hung.
      >>
      >>
      >>[Non-text portions of this message have been removed]
      >>
      >>
      >>
      >>If you are new to kitesurfing, please visit
      >>http://www.KitesurfingSchool.org/faqs.htm for the answers
      >>to the most frequently asked questions.
      >>
      >>=== to unsubscribe, please send an email to
      >>kitesurf-unsubscribe@yahoogroups.com ===
      >>Yahoo! Groups Links
      >>
      >>
      >>
      >>
      >>
      >>
      >>
      >
      >
      >
      >
      >
      > If you are new to kitesurfing, please visit
      > http://www.KitesurfingSchool.org/faqs.htm for the answers
      > to the most frequently asked questions.
      >
      > === to unsubscribe, please send an email to
      > kitesurf-unsubscribe@yahoogroups.com ===
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
      >
      >
    • ex_cpe
      ... ..........I thought about this but didn t have/take the time to put the tape to two new, 05 Kites: Windwing Rapture 15M and Naish Torch 14M. I like both
      Message 2 of 6 , Jun 21, 2005
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        --- In kitesurf@yahoogroups.com, Hung Vu <hungvu2000@r...> wrote:
        > I played around with some airfoil analysis and by reducing the leading
        > edge diameter from 10% to 5% of chord, the maximum L/D ratio of the
        > airfoil increases from 115 to 126 (induced drag is not included) and the
        > maximum Lift Coefficient increases from 1.57 to 1.79.
        >
        > So it's around 10% to 15% increase in airfoil performance for both
        > maximum L/D and Lift by reducing the LE diameter in half.
        >
        > I also increased the LE diameter to 15% and the result was not very
        > desirable so you definitely don't want to go there.
        >
        > P.S., These numbers should be taken as an approximate.
        >
        > P.P.S, The airfoil moment (tendency to flip over the nose) is slightly
        > more stable with smaller LE diameter
        >
        > P.P.P.S., Most modern LE diameter on market is around 9 or 10% of chord.
        >
        > Hung.
        >


        ..........I thought about this but didn't have/take the time to put the tape to two new, 05
        Kites: Windwing Rapture 15M and Naish Torch 14M. I like both kites - for different
        reasons, but they seem to come from different schools of thought. The Naish School of
        Evolution and Hansen's Vision Lab.

        The Rapture looks a lot like the new announcements from Cabby and Takoon except
        without: fussy cordage, baggage of royalties and a 'borrowed' design. I prefer people who
        stick their necks out and try something new - even if it's Best with their new Hellfish.

        Numbers: The Torch has a diameter of 10"/25.5cm and the Rapture has a diameter of
        13"/33cm....but to my surprise: both have a cord (L.E. to T.E. on the C/L) of 80"/203cm.
        My ADD has kicked in, so I'll leave you to the calculations...and don't flog me if I'm off a
        couple of cm's.

        So Hung: wazzit mean?

        Jim
      • ex_cpe
        ... who ... 203cm. ... ..........ERROR! Forget I said diameter - the circumference of the Torch is roughly 20 / 51cm and the Rapture is 26 /66cm.
        Message 3 of 6 , Jun 22, 2005
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          --- In kitesurf@yahoogroups.com, "ex_cpe" <wetstuff@i...> wrote:
          > --- In kitesurf@yahoogroups.com, Hung Vu <hungvu2000@r...> wrote:
          > > I played around with some airfoil analysis and by reducing the leading
          > > edge diameter from 10% to 5% of chord, the maximum L/D ratio of the
          > > airfoil increases from 115 to 126 (induced drag is not included) and the
          > > maximum Lift Coefficient increases from 1.57 to 1.79.
          > >
          > > So it's around 10% to 15% increase in airfoil performance for both
          > > maximum L/D and Lift by reducing the LE diameter in half.
          > >
          > > I also increased the LE diameter to 15% and the result was not very
          > > desirable so you definitely don't want to go there.
          > >
          > > P.S., These numbers should be taken as an approximate.
          > >
          > > P.P.S, The airfoil moment (tendency to flip over the nose) is slightly
          > > more stable with smaller LE diameter
          > >
          > > P.P.P.S., Most modern LE diameter on market is around 9 or 10% of chord.
          > >
          > > Hung.
          > >
          >
          >
          > ..........I thought about this but didn't have/take the time to put the tape to two new, 05
          > Kites: Windwing Rapture 15M and Naish Torch 14M. I like both kites - for different
          > reasons, but they seem to come from different schools of thought. The Naish School of
          > Evolution and Hansen's Vision Lab.
          >
          > The Rapture looks a lot like the new announcements from Cabby and Takoon except
          > without: fussy cordage, baggage of royalties and a 'borrowed' design. I prefer people
          who
          > stick their necks out and try something new - even if it's Best with their new Hellfish.
          >
          > Numbers: The Torch has a diameter of 10"/25.5cm and the Rapture has a diameter of
          > 13"/33cm....but to my surprise: both have a cord (L.E. to T.E. on the C/L) of 80"/
          203cm.
          > My ADD has kicked in, so I'll leave you to the calculations...and don't flog me if I'm off a
          > couple of cm's.
          >
          > So Hung: wazzit mean?
          >
          > Jim



          ..........ERROR! Forget I said 'diameter' - the circumference of the Torch is roughly 20"/
          51cm and the Rapture is 26"/66cm. Dummm-sh_t.. My hands think better than my
          head.

          Jim
        • Hung Vu
          Jim, The newly corrected numbers would bring the Torch and Rapture LE size closer to the industry norm of around 9 to 10% of chord. P.S., My Patriot 9.8 LE
          Message 4 of 6 , Jul 3, 2005
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            Jim,

            The newly corrected numbers would bring the Torch and Rapture LE size
            closer to the industry norm of around 9 to 10% of chord.

            P.S., My Patriot 9.8 LE size is around 8.5% of chord.

            Hung.

            ex_cpe wrote:

            >--- In kitesurf@yahoogroups.com, "ex_cpe" <wetstuff@i...> wrote:
            >
            >
            >>--- In kitesurf@yahoogroups.com, Hung Vu <hungvu2000@r...> wrote:
            >>
            >>
            >>>I played around with some airfoil analysis and by reducing the leading
            >>>edge diameter from 10% to 5% of chord, the maximum L/D ratio of the
            >>>airfoil increases from 115 to 126 (induced drag is not included) and the
            >>>maximum Lift Coefficient increases from 1.57 to 1.79.
            >>>
            >>>So it's around 10% to 15% increase in airfoil performance for both
            >>>maximum L/D and Lift by reducing the LE diameter in half.
            >>>
            >>>I also increased the LE diameter to 15% and the result was not very
            >>>desirable so you definitely don't want to go there.
            >>>
            >>>P.S., These numbers should be taken as an approximate.
            >>>
            >>>P.P.S, The airfoil moment (tendency to flip over the nose) is slightly
            >>>more stable with smaller LE diameter
            >>>
            >>>P.P.P.S., Most modern LE diameter on market is around 9 or 10% of chord.
            >>>
            >>>Hung.
            >>>
            >>>
            >>>
            >>..........I thought about this but didn't have/take the time to put the tape to two new, 05
            >>Kites: Windwing Rapture 15M and Naish Torch 14M. I like both kites - for different
            >>reasons, but they seem to come from different schools of thought. The Naish School of
            >>Evolution and Hansen's Vision Lab.
            >>
            >>The Rapture looks a lot like the new announcements from Cabby and Takoon except
            >>without: fussy cordage, baggage of royalties and a 'borrowed' design. I prefer people
            >>
            >>
            >who
            >
            >
            >>stick their necks out and try something new - even if it's Best with their new Hellfish.
            >>
            >>Numbers: The Torch has a diameter of 10"/25.5cm and the Rapture has a diameter of
            >>13"/33cm....but to my surprise: both have a cord (L.E. to T.E. on the C/L) of 80"/
            >>
            >>
            >203cm.
            >
            >
            >>My ADD has kicked in, so I'll leave you to the calculations...and don't flog me if I'm off a
            >>couple of cm's.
            >>
            >>So Hung: wazzit mean?
            >>
            >>Jim
            >>
            >>
            >
            >
            >
            >..........ERROR! Forget I said 'diameter' - the circumference of the Torch is roughly 20"/
            >51cm and the Rapture is 26"/66cm. Dummm-sh_t.. My hands think better than my
            >head.
            >
            >Jim
            >
            >
            >
            >
            >If you are new to kitesurfing, please visit
            >http://www.KitesurfingSchool.org/faqs.htm for the answers
            >to the most frequently asked questions.
            >
            >=== to unsubscribe, please send an email to kitesurf-unsubscribe@yahoogroups.com ===
            >Yahoo! Groups Links
            >
            >
            >
            >
            >
            >
            >
            >
            >


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