That solution is facinating, now that i finally think i understand it.

You wrote earlier about having problems about aligning curves to the surface... I guess you chose to make the curves and then tried to position them (curve and cv's) to the isoprams on the wing, so that they would eventually match...

but... if i get you right (?) then you wouldnt have to make those curves by hand....

Here's how i picture in making ONE section/profile;

1) just pick a isopram on the wing and make a curve out of it...

2)then do the same for with the bottom surface...

3) if the two curves are not right untop each other, in top orthogonical-view, then pick one of the curves and use the "snap-by-point-over-axis-move" to move the curve a little to the side, so that the two curves are right untop each other.

4) With these two seperate curves i guess you now need the front curve, and then attacth these three curves into one, for the birail-action later on.

5) just use the side view (orthagonical, as usual) to make the approximated front-curve... then move this curve in top view, "snap-by-point-over-axis-move"... and fit this front-curve so that it connects the two other curves for the attacthment action (under "curves" of course).

I dont know much about the birail, im still a newbie .