How to Measure Reference Length and Area for a Wing Model.

For standard aerofoil tests the reference area and length used to calculate the non-dimensional coefficients are,
 

  • Area = Wing Planform Area (S)
  • Length = Wing chord length (c)

For a rectangular planform wing the area will be
     S= b * c ,      span x chord.
The aspect ratio of the wing is defined as
    AR = b2/S
and for a rectangular planform this becomes,

AR = b/c ,      span divided by chord.
 
Note: To correctly have 2D flow in the tunnel 10m wide x 8m high section, the wing must span the complete width of the tunnel. This stops air spillage at the tips and stops any 3D flow effects. For 2D flow the span of the wing should be 10m and the Area should thus be 10 x chord.








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