ORIGINAL: foodstick
if you are cutting a constant chord wing stack up your wood as thick as you can for your saw. A bandsaw works best. Lay your pattern on top. Run some long pins down thru the top, and also up from the bottom so the wood stays stacked precisely. Cut it outside the line on the saw leaving the line on the top part. now set them on your belt/wheel sander and gently take them down to the line, ..Unpin and you are set.
I have used foodstick's method and it works really well for same shaped ribs. Two cautions when you get to the disc/belt sander shaping operation: 1) make sure the pins that hold the ribs together have the heads pushed flush with the two outer(top and bottom) pieces of balsa. If not, the balsa may not always be flat against with the guide/table of the sander, 2)make sure that your guide or table is exactly perpendicular to the sanding disc/belt. If not, you will be making a really nice set of tapered ribs.