Chapter 6, Insert tab "A" into slot "B" ....

Making something that approximates a tub. Three steps, one big chapter time wise.

I made the 10' long assembly rail today, and test fit the sides into the temporary firewall. Found I needed to enlarge the longeron holes slightly, as well as square up the foam/longeron inside corners on both side pieces with a knife, file, and creased piece of sandpaper. It also helped to radius the forward edges of the firewall longeron cutouts. You'll also notice my jig is resting up off the floor, I thought it would help get the 'work' area a bit closer (it did, but my back is still sore), but there was a secondary benefit I hadn't really planned on (read: I got lucky). In the pictures, you can see my bar clamps go under the fuselage. Won't happen if you lay the 2x10 on the floor as per plans. One 2"x10"x10' , two 2x4x92 5/8 wall studs. Cut the 2x4's that go in the front narrower than the width of F-22. Mark centerlines on everything.

Later that night, I mixed up 100g of epoxy for flox, and proceeded to do the glue-up after sanded everything again. Check for level. Swiping the "squish-out" with my finger worked OK, but it smeared a bit further onto the sides than I wished. A bit of sanding will fix, or maybe I should have put down tape on both sides of the joint as a delimiter. No matter. Check for level again.

The side clamps worked out well. Set your bar clamp upright on the floor (They have 'ears' to do so), rest the top clamp slightly behind the seat back. Toss the side boards between, tighten the clamps. It didn't go so bad, considering I'm an Army of one, my two hands worked fine. Also note I needed to add a couple of shim shingles midway along the sides, the boards bowed a bit under clamping.

I glued a couple of 1x1x12" blocks an inch aft if F-28 for clamping. Worked OK mostly, but the right one broke loose. That explains the severe angle of the hand screw. Though it looks odd, it did work to keep the foam straight, and inline with the edge of F-22. The duct tape was added insurance.

Don't forget to check for level again, plumb the IP while you're at it.

The clamps are still on (plans say 24 hours!), and the joints look good. Nothing shifted overnight that I could tell. Killing time, I trimmed F-28 to fit, and marked out 6.25" on the top longeron for its position Mixed up a few grams of epoxy for floxing, and there was enough left over to 2-ply BID tape the aft face only of F-28. Rick Maddy did the same. Good enough for him, good enough for me. Note the piece of MDF spanning the longerons. If the edge is square, F-28 will be plumb. Piece of cake to line up the 6.25" mark too.

Landing gear bulkheads went in earlier, but not before a bit of sanding of the ears and sides. The fuse curves in at the back, the bulkheads were made with square edges. The top edge of the forward lower LG bulkhead needed a bit of trimming (1/16" too tall), and I used the plans 8" x 8" squares of plywood to space it from the aft LG. Before I drilled the 1/4" holes into the aft LG, I double checked measurements with a level, two squares, and several measuring rules. RH side was spot on, LH side was 3/32" wide to the outside. I used a thin washer to space the drill bit away from the 8" x 8" brace. Let's hope I'm right!

Top angled LG was floxed in this AM, flush to the angled LWX longeron. It appears the top edge of this bulkhead will be a fraction short of the spar, but no way I can really tell until the spar cutout is 'fit' to the spar, and the spar installed. This evening I used one long two ply BID tape, wrapping down the forward face, instead of a tape on the angled surface and a short one on the vertical face. Don't know if it makes a difference, it looks neat though.

Added the four ply BID reinforcement tying F-22 to the fuse inside at the same time. I'd though it would slowly slide down the side, but it's not happening. Knock on wood.

Turned the fuse bottom side up earlier, sanded a little, injected epoxy into a bubble or two, made the seat back brace and forward heat duct as time permitted. I opted to make the fuel bracket out of fiberglass as some others have done. A male plug of MDF 1.5" wide, seven ply's of UNI, three of BID. Trim where needed, rivet the nut plates on, install in the seat back brace sides with flox.

As others have found, my IP is a bit short of the bottom. Five minute epoxy two 1/4' strips of 18 lb on, then sand flush with a quick and dirty spline sander (strip of MDF ripped 8" wide, with 'Stickit" sandpaper on the 3/4" edge) that rested on the lower longerons. While I was at it, I also added a slice of foam to the bottom of the seat back and sanded it flush too. It ended up being a tad shy of 1/8", I probably could have filled the gap with flox at the 'install bottom' step, but the spline sander made it seem like a non event.

Per earlier comments, my H-45 foam needed some major edge gluing to make up the foam for the bottom. No comments about the Zebra look please :-) Make the 1" x 2" support frame out of whatever you have that has parallel edges, and is reasonably straight. Pay attention that the cross braces are perpendicular with the centerline, and all should be well. I used small dots of 5-minute epoxy as close to the edge as I could. If lucky, any divots will be sanded out at contour stage.

The plans say one 24x48 sheet of Last-a-Foam is needed for the spacers. I think if you glue up the sanding dust one sheet will be enough, it's real close. Table saw came in handy again for ripping to width and cutting the 30° angle. I started with the spacer for under the IP, and went fore/aft from there.

Cutting the speed brake was a non event. Not pretty in rough form, but it was quick. A block of wood with a 45° bevel as a guide, and a coping saw blade with the 'pin' end cut off. Works best if the saw cuts on the pull stroke. Cut all the straight edges, then get the corners. Wiggle it back and forth a bit, it'll cut its own starter hole.

I opted to do the three step process to build and install the fuse bottom, it remained on my build table for a couple of days till cured hard.Note the custom 'tool' I invented to make the "generous micro radius" in the corners. It's a 4oz poly cup. Variable radius (squeeze the sides), easy clean.

I took one picture of the big lay up, just after the first layer of BID was applied and wet out. One of the boards I used for the frame (the forward most one) cured to the glass, it worked out well when I moved the bottom over to the sides and bulkheads to flox together as the rough tub.

The paint cans I used to weight the bottom down were about half empty, you've seen the nail boxes before, I added four of my longest light-weight bar clamps at the back (red handles), and a couple of wire spools. I added a hand screw to the center stile of F-22 to ever-so-slightly apply a little pressure to keep the bottom of F-22 tight against the fuse bottom. It's just an off-center weight, cantilever if you will.

Taping the inside joints was done with the fuse resting on it's sides. I could even apply a 2-ply tape to the aft bottom joint of the seat back, the plans imply a micro or flox radius of some sort.

I trimmed the permanent firewall to fit the longerons, rough cut for the electrical channel with a series of cuts with a Forstner bit then finished up with a piloted trim bit in the router. The sides of the electrical channel were marred slightly from the router bit pilot, I don't think this will be a problem down the road.

The CGParts rudder brackets arrived, so I laid them out on the firewall and drilled the holes. I used a # 14 drill (.182") to drill the holes so the shanks of the screws are snug in the hole. Ground the flats on the sides per plans, but I notched the plywood to fit the flats rather than filling with flox like everyone else does. I think it'll work better. Stacked three 3/16" hardware store variety washers on each shank, lightly floxed the heads of the screws, then drew them into the pocket with a nut on each screw. I added a dollop of flox into the remaining phillips head recess, then completed the one ply BID on the forward face. After three days, I trimmed the holes, then floxed the firewall into the tub.

Injected epoxy into a couple of bubbles in the tapes, sanded a bit, measured for and line drilled the holes for the aileron torque tubes in the LG bulkheads and seatback, sanded a bit more...

Eye "R" done!