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After you glue the firewall to the engine box sides,
reinforce it with 1/2” triangle stock on the inside of the
firewall-above and below mid-plate. Drill out the center
hole so that the carburetor passes easily through the
firewall. If you want it to be super strong, bolt 2 small
pieces of aluminum angle to the front (see diagram).
Hinging
Like I said, the rest is very easy.
Hinging is a very simple matter. We recommend that you hinge all the control sur-
faces in two steps allowing the glue to dry between steps.
Before you start gluing anything, test fit each control surface. Aileron to wing, ele-
vator to stabilizer, rudder to fin/fuse, with the hinges in place. Make sure the
hinges go in the holes smoothly and that there is ample room for the hinge
“knuckle” so there is no large gap between surfaces. The hinge lines are beveled.
The point of the bevel should be at the center of the hinge pin, this assures that the
hinges are aligned and centered on the hinge line.
Once you are certain that they all go together smoothly, take one surface and re-
move the hinges. If you have a needle oiler, place 1 or 2 drops of oil into the hinge
and work it back and forth. It’s also a good idea to put some lite oil (like WD40)
on a rag, and to wipe the edges of the hinging surfaces with this rag. The oily resi-
due will keep spilled glue from sticking to the ultracote covering. Then wipe off
any excess oil from the surface. Glue the hinges into the holes securely using the
glue you prefer. I have had good success with Pro-bond polyurethane (not the pro-
bond yellow furniture glue) because when drying it foams up slightly and fills the
gaps between the hinge and the mounting hole. Pacer Hinge glue works great for
the same reason.
