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.
This variation allows you to input the length an thickness of the wing:
where x1=0 and x2=96
this made a wing 96" long x 16" wide
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.