The firewall (F2) is made up from either 2 or 3 parts, depending on whether you want a top hatch.
Decide whether you want a hatch for battery access. If you want a hatch, just laminate 1/8 birch ply F2 and F2B, and save F2T (balsa) for later. If you don’t want a hatch, add F2T to the firewall assembly, or don’t if you don’t want to. It’s not critical.
I like to laminate with Titebond, but you could use epoxy if desired. Put the parts together with the etched center lines facing out, so you can use them to line up your engine mount.
F3 and F3B:
Laminated with Titebond:
The kit includes a lite ply landing gear drilling jig. Clamp the jig to the landing gear.
Find a way to support the landing gear. I like a little piece of 2×4.
Use a 1/8″ drill bit to mark the hole locations on the landing gear. It’s not necessary to drill all the way through yet. Just a dimple is enough.
Remove the clamps and the jig to make it easier to hold the landing gear firmly, and drill the 1/8″ holes all the way through the landing gear. We’re starting with 1/8″ to reduce drill wandering. The bigger the bit you start with, the greater the inaccuracy will be.
After the fuselage is built, the landing gear will be used as a template to drill holes in the airplane for mounting, and the holes will be drilled larger. Don’t be tempted to drill them larger yet, though.
Now it’s time for the fuselage sides. Each fuselage side is made of two 45″ long pieces. The bottom piece is obvious. The top is a long narrow strip with a stabilizer cut-out at one end. Use your favorite method to edge-glue the top and bottom portions of the fuselage sides to make full size sides.
Also edge glue the front doublers from top and bottom portions. Note that each doubler has a template etched into it to help with placement of the servo rails later.
Go over the fuselage sides and doublers with a sanding block on both sides to get rid of stepped joints or glue globs.
To attach the doublers and the other extra pieces to the fuselage sides I think medium CA is a good choice.
Stick the aft doubler strips onto the fuselage sides. Align the outside edges as accurately as you can.
The tail post doubler goes between the top and bottom strips. Press it backwards as you glue it so it’s tight against the top and bottom strips, even if that makes it hang out the end of the fuselage.
Flip the fuselage side over and trim the doubler off as necessary.
The aft doubler strips act as a jig for proper placement of the front main fuselage doubler. Make sure you place the doubler with the etched servo rail template facing the inside of the plane. Slide the aft end of the doubler between the top and bottom doubler strips and check for proper alignment. The doubler should not protrude past the front of the fuselage side, and the edges should be aligned with the fuselage side outline all the way around. If it is misaligned somewhere, figure out how to line it up. Slight misalignments can usually be fixed by trimming where the main doubler contacts the aft top and bottom doubler strips. When you’re satisfied with the fit, apply glue and carefully stick it down.
After the main doubler is attached you can attach the 3/8 balsa triangle stock firewall reinforcement. The front edge of this piece is aligned with the inside of the notch at the front of the doubler.
The inside edge of the fuselage side needs to be tapered slightly at the tail post. To be geometrically correct, each side should have a taper starting 9/16″ from the tail post, and the thickness of the fuselage side and doubler at the tail post should be 3/16″ thick.
You can set the fuselage side at the edge of the table to sand it, or block it up with a couple of 2×4 scraps. The tail post should be 3/8″ thick when assembled to match the thickness of the rudder. Try not to overdo the angle. (It looks pretty overdone in the following photo.)
Attach the little vertical strips in the aft fuselage. These strips are supplied in the kit. Attach the servo rail to each side. The rail is made of 1/4 x 1/4 x 12 basswood, and the location is etched into the fuselage doubler. (The rail is present in the photo, but it’s hard to see because the wood is all the same color.)
Drill holes in F2 for blind nuts to match whatever engine and mount you will be using, and add holes for fuel lines and throttle cable.
The bottom edge of the firewall needs to be sanded to a slant to match the bottom of the fuselage. Set the firewall into place on the fuselage side and make a mark to show how much material needs to be removed.
Here’s what it looks like after sanding.
If the blind nuts for your engine mount interfere with the triangle stock, relieve the triangle stock to allow a proper fit.
Now the fuselage is ready to be built, which will be covered in the next section.