To seal the gap between the aileron is very easy. Just use the covering that is going to be put on the plane. Cut a strip about 2 inches wide and then fold down the middle. Put the aileron at full up or down depending which side of the wing that you are working, and using a trim iron cold first put it in place and move the iron back and forth a couple of times to mold the covering. Then heat the trim iron and push the covering into the gap sealing it to each side. Then just seal the balance of the materal over the wing and aileron. Now you are ready to put the covering on the wing. I use the same color as I am covering the wing with. Then you can end the covering on the back edge of the wing into the gap but not across it. I usually use monacote but it will work with other coverings as well.