OK Iam placing the backer pieces in the ailerons, flaps and elevators!
Doing this:
1. Removing one end of the surfaces to allow insertion of backer
2. Fab a backer out of hard balsa.. mark the centerline on the backer
3. Using a #13 acid brush on a long stick.. Iplaced epoxy inside the surface wher it goes
4. Butter up the outside of the backer
5. Slide it in, reglue the end removed in #1 above
6. Dremel out the slot for the horn, then attach the horn..seems like a lot of extra work for an "ARF"!!!