A-symmetrical

Discussion in 'Boat Design' started by san.dam, Mar 12, 2004.

  1. san.dam
    Joined: Feb 2004
    Posts: 14
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    Location: italy

    san.dam Junior Member

    Someone has ideas regarding families of asymmetrical foil sections,having his first third(or fourth) symmetrical? Substantially I mean the leading edge aft zone symmetrical...
    Thanks for
     
  2. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    What are the requirements?
    - purpose
    - chord size
    - speed range
    - minimum & maximum loading per area
    - minimum thickness for structural considerations
    etc.
     
  3. san.dam
    Joined: Feb 2004
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    Location: italy

    san.dam Junior Member

    ... then you want to know all about the project, and curiosity kill the cat...(its for joke..)
    Think at a 0.5m chord lenght,8 to 12% thickness and a range of Rn in field 10^6
    I need a high Cl, but with imposition of symmetrical leading edge zone.
     
  4. tspeer
    Joined: Feb 2002
    Posts: 2,319
    Likes: 305, Points: 83, Legacy Rep: 1673
    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    You'll need to use something like XFOIL to design a custom section. Since you won't talk about the specific requirements, it's not possible to make a more concrete recommendation.

    That general description could be done with a flapped symmetrical section. Sections for keels with flaps are designed these days to have a smooth contour on the suction side with the flap deflected. This leads to a modest crease in the contour on the pressure side or when not deflected, resulting in a small separation bubble. But the drag penalty from it may be acceptable if the increase in max lift with flap deflection allows the area to be reduced.

    See:
    http://www.heymanyachtdesign.com/in3a.html
    http://www.esotec.co.nz/condorkeel/Html/hydro2D_F.html
     
  5. san.dam
    Joined: Feb 2004
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 16
    Location: italy

    san.dam Junior Member

    It would be a variable section foil,really asymmetrical (and not flap deflected) for port and starboard,and neutral in course downwind.
    A drastic reduction of area is expected from this,if we can double the lift coeff.(optimistic)
    Thanks Tom,it seems more and more clearly that the "families" doesnt exist..and need to calculate a custom foil section.
     

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