Foil section at low Reynolds numbers.

Discussion in 'Sailboats' started by whaletail38, Sep 18, 2008.

  1. whaletail38
    Joined: Jan 2005
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    whaletail38 New Member

    Can anyone suggest good foil sections to investigate at very low reynolds numbers, approximately 50,000 please?
     
  2. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Try to look for a research work by Dieter and Althaus, the title is "Profilpolaren für den Modellflug". It is a very nice work on different low-Re profiles, used for aeromodels. It is in german, but the language of graphs is universal. ;)
     
  3. markdrela
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    markdrela Senior Member

    Not enough information. You need to specify a desired Cl range and any structural thickness constraints.
     
  4. whaletail38
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    whaletail38 New Member

    The desired cl range is 0.2 to 0.4 and the tickness to cord can go down to as little as 6%. Leeway angles up to 5 degrees.
     
  5. markdrela
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    markdrela Senior Member

    Since you mention leeway, I assume you mean cl = +/-0.2 to +/-0.4 (i.e. a symmetric section). What you want is a thin RC glider tail airfoil. The HT08 or HT12 or HT13 should work well. http://www.charlesriverrc.org/articles/drela-airfoilshop/markdrela-ag-ht-airfoils.htm
    These have 100% laminar flow in your cl range, and hence are completely immune to low-Re effects, since laminar separation resistance is independent of Re. So if this is for an RC sailboat, they will work OK no matter how low the wind speed.
    These show how to hand-sand them accurately in wood, without templates:
    http://www.charlesriverrc.org/articles/allegrolite2m/tail_sand.pdf
    http://www.charlesriverrc.org/articles/allegrolite2m/tail_shaping.pdf
     
  6. whaletail38
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    whaletail38 New Member

    Thankyou very much. I'll check these sections out.
     

  7. lazeyjack

    lazeyjack Guest

    thanks
    Stu
     
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