Chapter 6: Fuselage Assembly
In my first departure from the plans, I decided to jig the fuselage upside down. What better way to keep the upper longerons nice and level than to put them against a flat, level surface? Logistically, jigging upside down is easier and I was able to guarantee level longerons without futzing with the jigging set-up. It was very simple and very reassuring to walk around with a square and spot-check things to ensure all bulkheads, centerlines, and perpendiculars were where they needed to be. It seems like it takes extra work to do this, but I guarantee it was faster, simpler, and more accurate than jigging upright. I wouldn't dare change the structural design. I just chose a different jigging procedure.
Sorry again. I didn't buy a new camera until after the fuselage assembly was
completed. Please reference other
Step 1 – Fuselage Assembly
(Again, I’m using my own jigging process.)
I removed my work table from its stand and placed it on the floor. (Remember that my work table is two solid core doors screwed to 8-inch roof rafters 10 feet long.) I moved one of the doors by 5 inches to make a convenient hole for the instrument panel to protrude through. I used my Smart-Level (a must-have tool) and used shims to level the table.
I drew a centerline along the length of the table, making sure it was square with the ends. I placed the fake firewall (upside-down) onto the end of the tabletop, made sure it was level and square, then anchored it in place with screws. Measuring from the firewall, I marked off the FS positions for F22, the IP, and the bottom and top edges of the seatback. I used a square to draw the perpendicular reference marks. I placed two small wood blocks just behind the 60-inch line to locate and hold the top edge of the seatback in place during assembly.
I trial fit everything first. I made sure the bulkhead centerlines lined up exactly with the centerline on the work table. (They did!) Once satisfied, I put two screws through the very front of the upper longerons. With the reference screws for the fake firewall and F22 positions, I could take everything apart at will and guarantee repeatability of the set-up.
Instead of using ropes, boards, and bungies, I used drywall screws to hold the sides and bulkheads together during fuselage assembly. I floxed the bulkheads in place and waited for cure. This all worked neat for me, but I would only recommend using the dry-wall screws if all your bulkheads fit perfectly to your fuselage sides. As it turns out, there were absolutely no gaps between the bulkheads and the sides during trial fit, so I didn't have to overly squeeze the fuselage sides anywhere to take out any gaps. Even F22 fit right on the money. I don't credit the good fit to workmanship as much as I credit it to just staying on the lines as per the drawings.
After cure, I followed the same process to install the landing gear bulkheads. These bulkheads are easy to locate by using those gage blocks. Still, I used my square and the FS position marks on the work table to ensure they cured in the correct positions.
You might want to think seriously about moving the F28 to be 6.25 inches behind F22. (See Zeitlin FAQ 12.1 and 12.2.) You'll find out later in Chapter 12 that you may not have enough room between F22 and F28 to fit the canard. My canard trailing edge hit the fuselage sides and I ended up cutting out and moving my F28 to the 6.25-inch position.
Step 2 – Center Keel and Seatback Brace
There was nothing difficult with building the seatback support and keel/heat duct. I tried to lay up all 7 UND layers for the seatbelt attachment points on to plastic first, then transferring them over the seatbelt attachment tube. It didn't work. Too much glass, too many bends. So I separated them into 2 layers max and reapplied.
Don’t bend that fuel valve bracket yet! All bends must be perpendicular to the grain in the metal, or the bracket will crack. I made mine successfully but decided not to use it. I chose to mount my fuel valve in the center console, just aft of the throttle quadrant.
Step 3 – Installing the Fuselage Bottom
If I were building the plane again, I’d cut out the forward edge of the landing brake to be full width across. Although the plans hinge length is strong enough, extending the hinge full length makes the brake easier to fabricate in Chapter 9.
Here’s a view of the bottom showing the Clark foam spacers micro'd in place and the lattice structure I used to hold the bottom curvature during glassing. Check closely and you'll see the drywall screws used to secure the big honker piece of clark foam (under the landing brake) to the PVC foam.
I almost forgot to add the 3rd layer of BID for the rear passenger floor area, but caught it just in time. According to Nat, orientation is not critical, so to avoid a seam, I merely rolled out the BID cloth from left to right across the aft section of the floor.
I did not have the stamina to attempt the 2-BID taping all in one session. So I floxed the bottom in place, crawled underneath to scrape away the excess flox, then collapsed. I finished the 2-BID tapes the next morning.
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