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6551Re: [AWES] Re: Kite-traction speed: speed kiting advance will come from ___

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  • dave santos
    Jun 12, 2012
      Bob,

      Wing Aspect-Ratio does not predict the great merit in "edging" at the interface of mediums of differing densities. By edging a ski or surfboard, the force transfer is basic Newtonian (not Bernoulli lift at all), avoiding liftng-foil problems like flow separation or cavitation, in the case of hydofoils. Throwing a great rooster tail while kitesurfing is thus more akin to knocking around billiard balls, and has a top  efficiency comparable to the Pelton bucket turbine. So it is that edging and foils are currently close contenders in absolute speed sailing, even mixing together as needed by the kite surfer.

      I remember being quite struck with the modest strakes on Dave Culp's KiteShip scale data-platform and demonstrator based on a Coleman plastic canoe (intended to damp roll), "fins" with an aspect ratio of maybe 1/10.  KiteShip had also found that large ships act as low AR hydrofoils of acceptable efficiency when pulled sideways by shipkites.

      These scattered clues suggest to me that edging has a lot more potential yet in performance sailing apps.

      daveS

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