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[ksurf] Re: 4 LINE WIPIKA

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  • Bruno Legaignoux
    ... The power of 4 line Wipika can be released up to 80% when it is on the edge of the window. The Wipika can t collapse because of its curved shape and
    Message 1 of 3 , Nov 1, 1998
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      srosso@... wrote:

      > Bruno, With a wipika and 4 lines, how much of the total power can i let off
      > if i want ? I have heard estimates that for some 4 line soft foils they are
      > desgined to release up to 30% of the power - This does not seem like much.
      > A sail on a boat can be 100% luffed (depowered) theoretically. What is your
      > estimate ?

      Dave Culp wrote :

      > Don't know about Wipikas (Bruno?), but most 4-liners
      > cannot stand to have their angles of attack reduced (luffed)
      > sufficiently for depowering--the kite collapses first.

      The power of 4 line Wipika can be released up to 80% when it is on the edge of
      the window.
      The Wipika can't collapse because of its curved shape and "rigid" leading edge.
      It is why we can give it a very low angle of attack.
      But, a bit like a sailing boat when she goes downwind, "opening" the sail
      doesn't reduce the power as long as the wing is in the middle of the window.
      That means that sometimes you can be overpowered (and dragged) but only for a
      few seconds, unless you fly a 8.5m in 10 knots wind and the wind suddendly
      reaches 40 knots.

      As everybody knows ;-) the power of a wing/sail increases at square the
      wind speed. If the power of a kite, static on the edge of the window, is 30kg
      at 10knots wind, it will be.... 270kg (and not 90kg) at 30 knots wind !
      Theoretically.
      With a 2 line kite, you'll be dragged on the beach with 15 knots wind because
      the power will be 68kg (and not 45kg).
      With a 4 line kite, at 30 knots the power can be reduced at 270kg x 20 % = 54kg
      without collapse risk. Cool !
      Theoretically it is possible to fly a 8.5m with still more wind but practically
      any pilot error can make him flied/dragged.
      And if the wind is off-shore, passing on trees, buildings or hills, the 4 lines
      will not be so efficient.
      So be careful even with a 4 line Wipika.

      If someone tells you that a Wipika is less efficient than a parakite, just ask
      him if he tried a 4 line Wipika !

      > Also, I need a suggestion for my quick release system - I am using a line
      > connected 3 meters up on one of my lines... This line I am presently
      > connecting to my harness cross bar . Any suggestions ? Maybe to the wrist
      > velcro system ?

      Yes, it is better to the wrist.
      Bruno


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    • srosso@bunge.com.br
      Bruno, What strength lines do I need on the front and back for a 4 line wipika ?? for 2 lines I understand that it is 200kg strentgh. stefano ... Subscribe,
      Message 2 of 3 , Nov 3, 1998
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        Bruno,

        What strength lines do I need on the front and back for a 4 line wipika ??

        for 2 lines I understand that it is 200kg strentgh.

        stefano


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      • Bruno Legaignoux
        ... Definately 200kg for the front lines. It is possible to use 135kg for the back lines but for safety reasons I prefer 200kg lines (less tangles, less
        Message 3 of 3 , Nov 4, 1998
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          srosso@... wrote:

          > Bruno,
          >
          > What strength lines do I need on the front and back for a 4 line wipika ??
          >
          > for 2 lines I understand that it is 200kg strentgh.

          Definately 200kg for the front lines. It is possible to use 135kg for the back
          lines but for safety reasons I prefer 200kg lines (less tangles, less
          cutting...)

          Bruno



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