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Re: [ksurf] Re: LE diameter size

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  • 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 1 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.
      >
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