Carlson Skunk Works

Well, the past couple of weeks has seen the assembly of the wing rear spar frames and the webs for the rear spars. Therefore, progress continues to be made.

The webs for the rear spars were scarfed last week and the assembled spar frames were sanded. This was a bit of a project since my wife has banned any further sanding in my basement work room. Therefore, I had to bring the spars up to the garage for sanding, then clean them off and bring them back to the basement.

Here are some pictures of the wing rear spars during construction:

This is the long view showing everything ready to be glued. I built two of the spar frames like this and will apply the webs to opposite sides so that I end up with right and left spars.

This shows the filler block for the jury strut attachment.

This is the root end of the assembly. I put a stop block at this end to provide a good reference point for other measurements.

Here is the center of the spar where the strut will attach. I cut the filler block a bit long and ended up having to fit the compression strut fillers at rib position 8.

Of course, the tip end of the spar. I ended up using a piece of left over 9mmX18mm material from the front struts to make the end of the spar. Once the glue had cured I sanded it down so that it is now level with the rest of the spar.

Once both of the rear spar frames had been glued and the glue allowed to cure, I cleaned off all of the wood blocks from the spar table. I then took the web material and laid it out for gluing. I left the parchment paper and one layer of wax paper on the table. I ran one web down the left side of the table and the other down the right side of the table.

Before I scarfed the web pieces I marked them so that I would know which pieces went together and in what orientation. That way I made sure the grain was running in the right direction.

I went over to Menard’s and picked up a bunch of clamps. Then I started at the root end and clamped the first piece of plywood to the table, scarf side up to accommodate applying glue. I worked on both webs at the same time, so the joints lined up as I went along.

Then I fitted the next piece of plywood so that the scarf joint was nice and level and smooth. At this point I clamped the second piece of plywood to the table. Next I lifted the end of the second piece of plywood and applied the glue to the joint. When I had glued the first joint of both webs, I laid a piece of wax paper across them, put a short board across the table and clamped the board over the joints. This should apply an even pressure across both scarf joints.

Then I moved on the next joint and continued working my way toward the tip end of the webs. As I moved down the web I moved any extra clamps along with me. I tended to use lots of small clamps to keep the web pieces from moving while I glued the joints. I ended up with four scarf joints in each web.

Unfortunately, I forgot to take any pictures of the process. I will try to get a picture of the fully clamped webs for the next post.