Month: September 2019

With the priming done, I was able to rivet the spar doublers, spar caps, and the hinge brackets to the forward and rear spars. With my pneumatic squeezer already calibrated (I made a chart with all the various settings), it was a fast and easy set of tasks.

I started by riveting the rear spar doubler. Here it is part way through:

Then I riveted on the hinge brackets:

Then riveted together this part, which contains a bearing:

I clamped it up to keep it square while riveting:

This bolts onto the spar, so I need to get a torque wrench to set these nuts to 28 inch pounds:

Then the forward spar. This has the spar caps, so it’s slightly different. More rivets, and longer rivets. I only got part way through before deciding to take a break for the night:

Following the instructions, I clecoed together a nose and inboard rib and then used it to trace out the shape for the cradle. I had some old particle board shelving, and used that to make the 4 pieces, tracing out the shape onto each one. Then I cut it all out on the bandsaw, cut some aluminum angle for a base, and screwed the angle to the bottom of the cradles, which will allow it to be clamped to the workbench.

Over the weekend my goal is to get all the HS parts primed and ready to start riveting. Depending on timing, I may also get started deburring and dimpling the skins.

I beveled the leading edges of the nose ribs tonight. I also bent two of the nose rib flanges, along with flames fire and aft of two ribs. These rib flange bends are required because the inside edge of the HS skins are angled to follow the shape of the Vertical Stabilizer; at the leading edge the skins are further outboard, and at the aft end they are more inboard. The ribs follow the edge of the skins, so the inboard most ribs are at an angle to the spar, hence the need to angle the flanges.

The front spar doubler sits on the forward side of the front spar, and has a variety of hole patterns. Today I clecoed and final drilled the holes, deburred, and then countersunk twelve holes on the face of the doubler. Then I countersunk the inner most 9 holes on both spar flanges. These will be under the vertical stabilizer and don’t have a skin covering. I messed up on one countersink on the flange, enlarging the hole slightly, probably a couple hundredths of an inch too deep. I’ll look at it again tomorrow, but I may just upsize to a -4 rivet.

Next I’ll be fluting and shaping ribs, and then I’ll prime all of the HS parts, hopefully this weekend.

Tonight I drilled the forward spar caps. These are spar stiffeners that sit inside the spar flange, reinforcing the angle between the spar web and the spar flange. One for the top edge, and one for the bottom. The caps are not pre-punched, and they are slightly bowed, meaning a lot of clamps and Clecos are needed to keep them in position while the holes are match drilled from the spar. Everything looks good, although I anticipate some very minor alignment issues. It’s very hard to keep everything exactly lined up.

Yesterday I drilled, countersink and debuted all of the holes between the Horizontal Stabilizer rear spar and the doubler, and the drilled and deburred the hinge attach brackets.

For all of the final drilling on the doubler, I used a reamer to compare results with the drill bit. There is slightly less burring from the reamer, and it feels like it produces a better result. I tested it first, seen in the picture below.

Today I picked up a few new tools, including a cheap bandsaw to trim some of the thicker pieces that need trimming.

I also clecoed and drilled the flange bearing that makes up the inboard hinge bracket assembly.

Then using the new bandsaw and my vixen file, I trimmed the stringers and spar caps. The bandsaw makes a chattery mess of a cut (I probably need a different blade), but the file cleans it up nicely. A little sanding with scotch brite, and they came out nicely.

Next I’ll be clecoing the spar caps to the front spar, along with the front spar doubler, then doing some more drilling. I’m planing to get all the drilling, deburring and countersinking done, then prime everything (except skin), and then start riveting. This is slightly out of order from the instructions, but the Vans plans have you riveting parts together before priming. I’m sure there’s a really good reason, but it seems counter-intuitive.

Tonight I finished up the deburring on the forward spar, and touched up a few other parts. It’s not really “finished” deburring, since I will need to drill a bunch of holes and debur them, but I completed all the edge deburring for all parts. I then spent some time reading ahead and setting up to start drilling the rear spar tomorrow. The first steps include final drilling the spar doubler, and final drilling the hinge attachments. These hinges are where the elevators will attach, much like how the Rudder attaches to the Vertical Stabilizer.

After several evening sessions this week, I’m almost finished deburring the HS parts. Tonight I finished the rear spar, which leaves just the forward spar before I’m finished. It’s been quite time consuming with substantially more parts than the VS and Rudder. The vixen file made quick work of the edges of the spar, and left a nice smooth edge. Some polishing with scotch brite and the edge came out great.

Hopefully will be done with the deburring by the weekend.

Spent time deburring parts for the Horizontal Stabilizer today. It’s a time consuming process, especially with the ribs which have many corners and crevasses. I’m using a combination of edge deburrers, small round files, small flat files, and maroon colored scotch brite to finish.

The items in the foreground are done, and in the background are next.

I also need to debur both spars, for which I have a new Vixen file, attached to my Dad’s old file handle. This will help on the thicker edges of the spars: