Category Archives: Vertical Stabilizer

Due to various distractions, assembly of the Vertical Stabilizer has taken a number of days, whenever I could catch an hour here and there.

I decided a while back to include a conduit up to the top nose rib, as many have done before, and a fabricated a doubler plate to support the conduit end connection, with a couple of flush riveted plate nuts to provide possible support for any future fitting that I don’t know about yet, such as an antenna. I also added a plate nut to the rear spar, to provide a grounding point for a braid to the rudder, again because it is easy to do before assembly.

The riveting went OK. I drilled out and replaced a few, which turned out to be easy enough. There are a few rivets on one side of the lower front spar flange that I’m not happy with. I decided to leave the lower rib cleco’d for now so it can be removed, and wait for a TC to come over and review that area.

Once the blue stuff is removed and the exterior skins cleaned up, it is quite hard to take a reasonable picture of the outside because the Alclad is like a mirror, and reflections make the surface look horrible. In actuality, the surfaces are very clean.

Dimpled the VS skin, and underlying structures. Countersunk the VS rear spar where called for. Vertical Stabilizer parts are now all ready for priming.

Dimpling the VS skin

Countersinking VS rear spar

I decided to conveniently forget about all the farm jobs today and put in some work on the vertical stab.

I de-burred all the ribs, assembled the ribs and spars, and match drilled. Based on numerous Internet posts about nose rib skin bulge, I thought I would check the fit of the nose ribs into the VS skin as a separate operation. I started with the lowest (widest) nose rib, and sure enough, it was simply not possible to cleco the two inner most holes without causing a bulge in the skin. The general advice seemed to be that material needs to be removed from the front of the nose rib in order to allow it to fit. Some individuals have reported taking as much as 3/8 inch off the front of the ribs, but I didn’t want to jump in that deep. So I sawed around 1/8 inch off the front, cleaned it all up, and tried the fit again. This made zero difference, which makes sense since taking this material off made no difference to the shape and distance between the forward most rivet holes. Further research on the forums brought the solution to light – flute the nose of the rib. I thought about this for quite a while since it seemed like a one-way street, and decided it was either bulges, remove a lot of material from the front, or fluting, so I went ahead with the flutes and this completely solved the problem – no bulges.

For the middle and upper ribs, I didn’t remove any material, I fluted them. There’s only really room for a single flute on the narrow top rib. I assembled the VS this way and it all went together well, with no bulges. I match drilled all the #40 holes, moved every cleco over one position, and match drilled the rest. For the nose ribs, I put a cleco in every hole, and removed them one at a time, match drilled, and replaced.

VS skin cleco’d ready for match drilling

Continued on today, match drilling #30 the entire VS rear spar assembly, including the rudder hinge brackets. With a clecko in every second hole, there was plenty of support there to rest the entire assembly on the cleckos.

Match drill #30 VS rear spar assembly.

With the assembly still together I did the countersink for the #30 holes on the VS-1008 rear spar doubler.

Countersink VS-1008 rear spar doubler

Today I match drilled the VS-1003 spar and VS-1014 spar flanges, in accordance with step #2. Tossed up whether to use the hand drill or the drill press, but the plans specifically state to keep the drill as square as possible, so I opted for the drill press. I made up a platform for the spar, using a recovered side panel from the empennage crate.

Setup for VS-1003/VS-1014 match drilling

Setup for VS-1003/VS-1014 match drilling

Definitely overkill, but I figure I would use the platform many more times for items that are best done with the drill press.

The setup worked just fine.

I also de-burred the VS-1008 rear spar doubler today

The first hole drilled in the project

Match drilling VS-1003 to VS-1014 flanges.

Still waiting for some tooling to arrive, and to finish various workshop items. I’ve been in no hurry to officially “start”, but for want of something else to do, today turned out to be the random date that I did the first work on actual parts of the aircraft. The place where everyone starts – cutting the VS-1014 flanges. So, I marked them out, used my awesome bandsaw to do the rough cuts, and took these down to dimension with a Vixen file. I also de-burred the flanges, as well as the VS-1003 rear spar that they fit into.

Filing the diagonal cuts on the VS-1014 flanges

That’s it. Section 6 step 1 completed without incident.