Before moving on to sheeting the fuse exterior, I'll cover a few additional reinforcement steps that should be taken now. First let's go ahead and add the supplied balsa tri-stock along the inside of the fuselage where the top, bottom and side wall edges meet. Run this stock as far back into the tail as your sheeting goes, which should be about 6 inches or so past the back end of the cockpit area.
Now you can pull out the plywood F-2 firewall plug to insert into the front end of the fuse tunnel. Test fit and and sand as needed for a snug fit, then go ahead and glue it in with some 30-45 minute epoxy.
Once that epoxy has set up, you can go ahead and add the tri-stock on the backside of F-2 around its perimeter, where it meets the top, bottom and sidewall sheeting. Later, we will eventually coat the entire backside of F-2 and the surrounding interior sheeting with epoxy to fuel proof it (from F-2 back to about the wing saddle area).
Button up the tail
You will find a slit in the tail section running from the back of the stab slot to the very end of the fuselage tail. This is where Jack runs the foam cutting wire into the end of the fuse to cut out the stab slot. Once you are sure your stab is going to fit into here properly, go ahead and glue this slit closed.
With the slit gued and dried, you can now begin really fitting your horizontal stab to its slot. The slot is a little more than one half inch longer than the depth of the actual stab (from LE to TE). This would permit an area for elevator joiners if you decided to go that way, and also gives you some flexibility in positioning your stab to your preference.
I wanted mine towards the forward end of the slot to match the A-7 plans as close as possible. So, I glued balsa into the slot both in the front and back ends of it, with most of the balsa going into the rear end of the slot. I shaped the balsa to match the LE and TE of the stab, then test fit and adjusted as needed until the stab had a nice snug and square fit. When satisfied, go ahead and remove the stab from the fuse.
Optional centerline stripping
This next series of steps is a totally optional modification. I've seen a number of builders using this mod in one form or another, and thought it was a great idea. The premise is based on the fact that your fuselage will soon be sheeted from to large pieces of sheeting, one on the left half and the other on the right. These pieces of sheeting will meet along the fuselage centerline at both the top and bottom of the fuse. While these next steps are not required, they can make the sheeting process a little easier, and can potentially give you a stronger seam joint between the two pieces of sheeting.
The animation at right illustrates what we will be doing. Essentially you cut a groove in the fuselage along the centerline in which you will embed a strip of balsa, then sand and shape to match the fuse contour. The two edges of your sheeting will mate here on top of the balsa strips down the length of the fuse.
Use whatever you like for stripping, I cut one of the 3/16" x 1" balsa capstrips in half to get two pieces at 3/16" x 1/2" for mine. Some guys only do the high stress area running along the fuse topside from the cockpit to the tail fin. You can also do this area on the bottom of the fuse, or, like me, do the top and bottom from nose to tail.
Remember, this process is totally optional and not required. I decided to give it a shot as it made sense to me. Using the light balsa strips won't add hardly any weight, and shouldn't affect the balance much at all. Next, we finally move on to actually sheeting the fuse exterior.
Oh yes, one more step before proceeding to the sheeting of the fuselage exterior. You'll need to get some scrap 3/16" balsa sheeting and add it to the vertical surfaces of the wing saddle area where the wing trailing and leading edges will mate in. Sand this flush to the fuse exterior surface and you can then sheet out over top of it.
