sail aerodynamics

Discussion in 'Hydrodynamics and Aerodynamics' started by Guest, Mar 21, 2002.

  1. Mikko Brummer
    Joined: May 2006
    Posts: 513
    Likes: 50, Points: 28, Legacy Rep: 258
    Location: Finland

    Mikko Brummer Senior Member

    Maybe +- 0.5 degrees for twist, +-0.5% for camber, +- 0.5 degrees for the leech exit angle. Twist is the most important.

    Yes, for 25 years or so, both flying shapes & the data to CFD. See here for an example from the early 90's.. We still use cameras (video) to pick up the sail shape.

    How would you use a microphone?
     
  2. Skyak
    Joined: Jul 2012
    Posts: 1,194
    Likes: 25, Points: 38, Legacy Rep: 152
    Location: United States

    Skyak Senior Member


    The microphone picks up turbulence of the boundary layer and clears up outside the boundary layer. A microphone is a dynamic pressure sensor.
     

  3. Mats Lind
    Joined: Feb 2020
    Posts: 1
    Likes: 0, Points: 1
    Location: Stockholm

    Mats Lind New Member

    Thanks Mikko,

    To me the flap seems to have been an outright success, it tested superior at all angles and scored a win on the track. This even as it does not seem from the picture that you tried to keep its height-to-cord constant over the height of the sail by tapering it off towards the masthead just like the sail itself. I guess this is behind most of the underperformance versus your 2-D test. And I guess also that you had to keep its height down due to concern over class rules. What I gather from literature, the flap-height optimally occupies most of the boundary layer but it should not reach the free-stream. Hence you should not expect a small flap to be efficient in slow winds as you then are dealing with thick boundary layers, but if you were able to sport a larger flap it might get a good addition to much needed lift in that case.

    Doesn't your wind tunnel and race track experience point to good use for flaps, especially for cruising when not constrained by rules?
     
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