Flap details.

Instead of using the supplied horn pockets I always use brass or alunimum tubing and epoxy to accomplish the same thing. The suplied hinge pockets will do the job if you lay it up this way. Both ways will account for any twist in the horn and produce perfectly flat control surfaces, elevators and flaps. The close up shot shows the tube installed after drilling a slot along the flap end to the pocket and another drilled hole from the slot to the hinge opening in the flap. I cut a piece of tubing long enough to butt against the inside end of the pocket end but not too long to stick out of the top and interfeer with the horn wire. This also keeps the epoxy out of both ends of the tube. I use a straight edge at the leading edge with shims to allow room for the horn upright and shims under the flaps to allow room for the bottom of the horn upright. A shim is needed under the horn ends to center them. In this case the flaps are 1/4" and the tube is 1/8" so that makes a 1/16" shim under the tubes to center them in the pocket. I used celophane tape to keep the shims in place under the pockets and mainly to keep the epoxy from running out. A few light weights on the flaps will keep them aligned until the epoxy cures. Make sure the weights are placed over the shims. Taper the flaps/elevators if you want, I don't.