Loading ...
Sorry, an error occurred while loading the content.

Re: [ksurfschool] Apparent wind effect

Expand Messages
  • Hung Vu
    ... OK. So the apparent wind effect is due to light wind and not big kites. How about the second question? However, in real life, it has not been an issue
    Message 1 of 8 , Oct 21, 2000
    • 0 Attachment
      kiteboard@... wrote:
      > I think it's not so much the size of the kite or board, but rather the
      > efficiency of the gear in light wind, likely due to smoothness of the water
      > surface. In other words, since the water is so smooth (in the lighter winds
      > encountered with larger gear) boardspeed is a higher percentage of windspeed
      > (compared to in stronger winds). That means the apparent wind is also
      > higher, relative to the true wind.

      OK. So the apparent wind effect is due to light wind and not big kites.

      How about the second question?

      "
      However, in real life, it has not been an issue for me in 5-6 knots
      with the XXXL and the FONE 230 board.

      Given the fact that I am lighter, but why should the apparent wind
      effect only applies for heavier person?
      "

      Hung.
    • Eduardo ALDAZ CARROLL
      Hi, I find the discussion very interesting and i just wanted to try to contribute to it In normal boat sailing apparent wind is the total wind that a sail
      Message 2 of 8 , Oct 22, 2000
      • 0 Attachment
        Hi,

        I find the discussion very interesting and i just wanted to try to
        contribute to it

        In normal boat sailing apparent wind is the total wind that a sail sees,
        i.e: the addition of the real or existing wind to the wind effect
        produced by the speed of the boat (similar to driving a convertible in a
        day of zero wind, if you stick your head above the windscreen you feel
        wind in your face proportional to the speed you're going)
        Therefore i would agree that in light winds the apparent wind (the wind
        that actually propels you) is created mostly by the boards own speed and
        the added effect of the movement of the sail,i.e: when moving it in a
        sinusoidal (which unfortunately is not a possibility in normal sailing
        boats).
        However the apparent wind exists always, regardless of the force of the
        wind or the gear your using.
        The goal would be, i think, to find out what combination of board and
        sail will maximize apparent wind given the wind conditions.



        Hung Vu wrote:
        >
        > kiteboard@... wrote:
        > > I think it's not so much the size of the kite or board, but rather the
        > > efficiency of the gear in light wind, likely due to smoothness of the water
        > > surface. In other words, since the water is so smooth (in the lighter winds
        > > encountered with larger gear) boardspeed is a higher percentage of windspeed
        > > (compared to in stronger winds). That means the apparent wind is also
        > > higher, relative to the true wind.
        >
        > OK. So the apparent wind effect is due to light wind and not big kites.
        >
        > How about the second question?
        >
        > "
        > However, in real life, it has not been an issue for me in 5-6 knots
        > with the XXXL and the FONE 230 board.
        >
        > Given the fact that I am lighter, but why should the apparent wind
        > effect only applies for heavier person?
        > "
        >
        > Hung.
        >

        --
        ___________________________________________________________

        Eduardo Aldaz Carroll, tel: +41 22 7679153
        CERN, PS Division fax: +41 22 7678510
        CH-1211 Geneva 23, Switzerland.
        ___________________________________________________________
      • kiteboard@aol.com
        hungvu@netcom.ca (Hung Vu) writes: Keep in mind that skill & a board
        Message 3 of 8 , Oct 22, 2000
        • 0 Attachment
          hungvu@... (Hung Vu) writes:

          << it has not been an issue for me in 5-6 knots
          with the XXXL and the FONE 230 board. >>

          Keep in mind that skill & a board that rails well will keep the nose from
          being pulled off the wind, & allow you to point to control speed. Where you
          ride it may be less gusty when it's light too. Assuming you are fully
          powered up (once up to speed), the only other thing I can think of is that
          the board may be too big, & therefore slowing you down, reducing the apparent
          wind.

          << Given the fact that I am lighter, but why should the apparent wind
          effect only applies for heavier person? >>

          Right now I can't think how rider weight would make a difference (but I may
          come up with somthing later!).

          AND:Eduardo.Aldaz.Carroll@... (Eduardo ALDAZ CARROLL) writes:

          <<However the apparent wind exists always, regardless of the force of the
          wind or the gear your using. >>

          I know it always exists, & did not mean to imply otherwise, just that since
          in lighter wind (flatter water) boat speed is higher (relative to true wind),
          apparent wind is also higher (relative to true wind).

          Mel
        • Hung Vu
          Let s me try to make a summary to make life simpler (or more complex???) for all of us ;-) There is an effect called apparent wind that is more pronounce in
          Message 4 of 8 , Oct 22, 2000
          • 0 Attachment
            Let's me try to make a summary to make life simpler (or more complex???)
            for all of us ;-)

            There is an effect called "apparent wind" that is more pronounce in
            light wind that makes one be overpowered easily at speed. This means a
            smaller wind range for light wind kites (oftenly implies big kites).

            Larger boards extend the lower wind range of the kite such that in light
            wind it is appropriate to use a larger board and a slightly underpowered
            kite (to avoid being overpowered easily at speed). This is my
            experience with the XXXL and the FOne 230 at 5-10 knots.

            Thinner boards (a smaller board is usually thinner) somewhat extend the
            upper wind range of the kite such that in light wind it is appropriate
            to use a thinner board and a right powered kite (overpowered situations
            can be deal with using the knees and rail). This is my experience with
            the XXXL and the Clam Sandwich in 7-11+ knots.

            Apparent wind effect is not "currently" related to rider weight and kite
            size is directly proportional to rider weight. I am 125 lbs. and the
            XXXL project surface is 8.55 m2. Someone 175 lbs or 1.4 my weight would
            need a 12 m2 projected surface kite and a board "his size" (very thin,
            slightly taller than he is and wider than his shoulder width) to repeat
            the same experience that I had with the XXXL and the Clam Sandwich in
            7-11+ knots. Someone 200 lbs. would need a 13.68 m2 projected surface
            kite. Kite type is also VERY important; the kites used should be
            comparable in performance to the open cell XXXL (C-Quad is fine; Stamos
            may be too low performance? I am not so sure about the larger
            Naish/Wipika AR5+ unless they are inflated by helium?)

            P.S. A larger, thinner board would have the widest range (but clumsier
            than a smaller, thinner board) ?

            P.P.S. A thinner board helps to handle gusts such that one don't need to
            use the trim loop much ?

            P.P.P.S. We has gone a loooooong way in light air kitesurfing (the
            largest kitesurfing kite back in 1998 was the Wipika 8.5 m2 .......)

            Hung.


            kiteboard@... wrote:
            >
            > hungvu@... (Hung Vu) writes:
            >
            > << it has not been an issue for me in 5-6 knots
            > with the XXXL and the FONE 230 board. >>
            >
            > Keep in mind that skill & a board that rails well will keep the nose from
            > being pulled off the wind, & allow you to point to control speed. Where you
            > ride it may be less gusty when it's light too. Assuming you are fully
            > powered up (once up to speed), the only other thing I can think of is that
            > the board may be too big, & therefore slowing you down, reducing the apparent
            > wind.
            >
            > << Given the fact that I am lighter, but why should the apparent wind
            > effect only applies for heavier person? >>
            >
            > Right now I can't think how rider weight would make a difference (but I may
            > come up with somthing later!).
            >
            > AND:Eduardo.Aldaz.Carroll@... (Eduardo ALDAZ CARROLL) writes:
            >
            > <<However the apparent wind exists always, regardless of the force of the
            > wind or the gear your using. >>
            >
            > I know it always exists, & did not mean to imply otherwise, just that since
            > in lighter wind (flatter water) boat speed is higher (relative to true wind),
            > apparent wind is also higher (relative to true wind).
            >
            > Mel
            >
          • kiteboard@aol.com
            In a message dated 10/22/00 4:51:57 PM Pacific Daylight Time, hungvu@netcom.ca writes:
            Message 5 of 8 , Oct 22, 2000
            • 0 Attachment
              In a message dated 10/22/00 4:51:57 PM Pacific Daylight Time,
              hungvu@... writes:

              << A thinner board helps to handle gusts such that one don't need to
              use the trim loop much ? >>

              I agree with everything you wrote, including the above, although to be
              perfectly correct I'd change it VERY slightly to say "you don't need to use
              the trim loop AS much". I'd say "If it's not very gusty you don't need to
              use it much".

              Mel
            • mike
              unsubscribe
              Message 6 of 8 , Oct 23, 2000
              • 0 Attachment
                unsubscribe
              Your message has been successfully submitted and would be delivered to recipients shortly.