The two big pieces above form the bread of the sandwich while the meat is, of course, the wing spars. It is interesting to note that the wing spars to not overlap or meet in the middle as might be supposed. In fact, the spars only extend about 5 or 6 inches into the carry through. Just beyond the big holes on the ends. It is sobering to think that 10 feet of wing is attached by only a few inches of the fuselage spar carry through.
The sides of the spar carry through are riveted to the fore and aft sides.
The side pieces will carry the load vertically to spread it out through the fuselage's side skins. The control column mounts to the spar carry through via these to milled aluminum attachments:
Van allows some of this aluminum to be trimmed back for weight savings. Here is Carol laying out the trim lines.
After a pass through the bandsaw and a little filing we get these two very pretty mounts that are now 50 grams lighter. I'm not sure that I would go through the effort again for a mere 1 3/4 ounces weight savings.
Next there are web stiffener blocks to drill and attach. These blocks discourage the spar web from bending under load.
And then there are nut plates to attach on the spar flanges.
The next step is to assemble the control columns to each other and to the mounts. Van plays a little trick on the unsuspecting builder at this point when the manual says it is possible to remove the columns from the mounts as a unit. Well that is a time saving tip if I've ever heard one, so I plunge on ahead with the column assembly only to find out that it is impossible to remove the columns from the mounts without first removing the aileron pivot bolts. The feed through bar (grey bar below) is the only thing that can remain connected. Anyway, once the columns are assembled and adjusted for parallel, they are disassembled and set aside.
The next step is to fabricate some wood spacers that stand in for the wing spars so that the carry through can be bolted together. The thing about these spacers is that they must be exactly 1.438" thick to mimic the thickness of the spars. No problem, I'll just laminate some scrap 3/4" MDF and trim it down on the table saw. Naturally, after the sawing it was about 1/32 too thin. Suddenly I'm reminded of the old saying, "I cut it three times and it's still too short!" So I laminated some very thin cardboard in between the halves and I was just bit too thick. Crap! This sounds like a job for Captain Belt Sander. Problem solved. And we didn't even have a chance to thank him.
That's about it for the spar carry through.
Ta Da!
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