I need help, been building many years wings on a jig but this one has me stumped
center section built no problems. Wing tips are 18 in long double taper thickness
from 2 in to 1 in.  What is the best way to build this section of the wing without building
a warp into it. Cant use jig that is the problem.

    thanks Albert Kraus
                MAAC 4381-L

For something that short and small, I would simply shim up the spars. As Ty mentioned, the LE and TE will remain on the same plane.

Draw a center line on the root rib and the tip rib. Then shim the spar so the tip rib is level with the root and that will work. I also cut a piece of balsa to sit under the TE of the ribs. They are very weak (usually) until you get the TE and some sheeting installed. The TE shim will be a constant height.

Hope this helps,

Ron