3 Replies Latest reply on Jan 18, 2013 12:37 AM by Rick McWilliams

# How do you sketch an aerofoil?

Has anyone built an equation driven sketch for a NACA 0018 section or simliar? When I enter the equation in the equation box it all looks good but produces a straight line.

This is the equation I want to use where t =0.18 for the percentage chord.

• ###### Re: How do you sketch an aerofoil?

Change t from .018 to 18.  I think the percentage chord is number percentage.  I used a differant variant of the wing equation that I will post.

• ###### Re: How do you sketch an aerofoil?

This variation allows you to input the length an thickness of the wing:

t/0.2*(.2969*(x/(L))^.5-.1260*(x/(L))-.3516*(x/(L))^2+.2843*(x/(L))^3-.1015*(x/(L))^4)*2

8/0.2*(.2969*(x/(96))^.5-.1260*(x/(96))-.3516*(x/(96))^2+.2843*(x/(96))^3-.1015*(x/(96))^4)*2

where x1=0 and x2=96

this made a wing 96" long x 16" wide

• ###### Re: How do you sketch an aerofoil?

The 4 and 5 digit series NACA airfoils have nice formulas for the shape. You might prefer the low drag laminar flow shapes of the 6 series. Beware of wiggly curves that curve through points will generate. A careful manual redraw with only 3 to 5 knots per side can make a very good fit. It is best to have an upper and lower surface curve. Use curvature combs to obtain smooth curvature shape. There should be 0 or 1 inflection point per surface.