Vertical Stabilizer

With my Dad in town, it was great to get his expert advice and handiwork with the firbreglass fairings. Being a boat builder back in New Zealand, my Dad has a lifetime of skill and experience working with all kinds of things including fiberglass. He’s a master at the stuff, so he went to work on the rudder and vertical stabilizer fairings.

The VS fairing needs an insert of glass on the aft edge and Dad made quick work of getting it made up and glassed in. the only real challenge was getting the fairing square. The piece is molded in two half’s then glued together, but there seems to be some slight misalignment of the halves casing it to be slightly lopsided. Dad got it pretty straight, so it looks awesome.

I rigged up a better solution for my air hoses today, then final drilled the few holes that need it in the rudder. Most of the rudder parts are pre-punched to final size, and just need a little deburring. Then I debuted the skins, getting ready for dimpling, then assembly.

Here is what I ended up with for air hoses:

It’s much better with the hose coming down from the ceiling than to be dragging it around on the floor. The coiled hoses are very light weight, and are only rated to 120 PSI, which is well above anything I’ll be using them for.

I made up a little template to assist with the trailing edge drilling. The holes need to be drilled perpendicular to the chord line of the trailing edge wedge, which turns out to be 6 degrees forward of square with the skin. I found that the drill naturally hits that angle because the trailing edge wedge is already drilled to that angle, and the skins are so thin, it’s easy to get it pretty close. On a couple of holes the drill caught the upper (left) skin, and ended up enlarging the hole slightly. Once dimpled, will see if I need to do anything about it.

I final drilled all the holes in the top ribs, and matched drilled one on the front, but didn’t get a picture.

Then it was onto deburring, which is very carefully done given how thin the skins are. I made up a practice piece to see how excessive debuting affects the hole, after dimpling. It’s amazing how a few spins with the deburring tool remove enough material to really expand the hole diameter once dimpled. I got all of the left skin done, and partly through the left one, but I’m so tired I need to go to bed now. Will tackle some more tomorrow.

Today I riveted the vertical stabilizer skin to the forward spar and ribs, clecoed on the rear spar, and started riveting the skin to the rear spar. It was getting late and I was tired, so I decided to stop before I started making mistakes.

First, each family member signed one of the inside skins, leaving a few secret messages.

Then I started with some more experimenting with my adjustable squeezer set, and with some practice parts to get my rivet bucking skills somewhat current. I set up a cradle of cardboard and clean rags to keep the VS on it’s edge, which seemed like the best approach for bucking rivets.

Overall, I was happy with the way everything turned out. I had to drill out two rivets, both times the bucking bar slipped off the rivet. I was able to remove both without enlarging the hole, so replaced with the same sized rivet. The second rivet was annoying, as I somehow put a minor dent in the rib and skin when the bar slipped. I’m not sure how it happened, but the result is a slight bump in the skin near the rivet. The main thing is that the rivet set well the second time. You can see how the light is slightly distorted around the middle rivet in the picture below.

I was able to squeeze rivets along the edges of the skins, even the most forward holes on the top rib.

I can see why the plans recommend setting the manufactured heads aft on the rear spar. There is very little room to get at the skins rivets along the rear spar. I did the easy rivets with the squeezer, but I didn’t want to tackle those with less clearance tonight. I’ll try to finish up the remaining rivets on this piece tomorrow.

Tonight I received my adjustable set for the pneumatic squeezer, along with some scrap aluminum. I spent an hour drilling, counter-sinking and riveting some practice pieces, and documenting the settings needed for each length rivet. Then I re-squeezed all of the rivets on the VS spars and ribs, and they all came out great. The hardest three rivets are where the root ribs meet the front spar. There isn’t much room, and the ribs aren’t square to the spar. I had to switch to my rivet gun with a double offset piece to finally get those done.

With the rivets done, I can finally complete the Vertical Stabilizer. I clecoed the frame to one side of the skin in preparation for riveting. But it’s a bit late in the evening now to start riveting. I’ll try to knock it out tomorrow.

With the primer coat looking ok, I proceeded to start riveting parts together. First up was the doubler plate on the front spar, then the rear spar doubler and hinge attach brackets. For the front spar plate I used the pneumatic squeezer. For the rear spar, the pneumatic squeezer wasn’t viable. The -6 and -7 rivets were too long for the pneumatic squeezer with the yokes I have, and the squeezer couldn’t develop enough power to squeeze the rivets. I need a yoke with a wider throat to allow me to use it with those longer rivets. So I used the hand squeezer to do all the rear spar rivets. It came out looking good.