More Rudder Stiffeners

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After a very busy end of the work week, I managed to squeeze a couple hours of airplane time in the shop today. I started by mocking up the R-902 front spar, and drawing a black line on the left rudder skin (this is the forward bottom edge of the left skin). I’m going to draw out all of the mating surfaces on these skins, since they will have to be primed at different times (more on this later).

Forward bottom corner of the left skin. You can see the front end of the only full size stiffener.

Next, I dove into match-drilling the stiffeners and skin. Here are the first size holes drilled. I don’t want any waviness in the rudder, so I am clecoing every hole as I drill. (You can see that like everyone else, I am drilling straight into the MDF that’s on top of my workbench. This works well, and is basically per the plans.

First six holes of the stiffener to skin match-drilling process.

After I finished the first (lower) stiffener, the next one needed to be cut down to size. I made another mark on that stiffener, this time in line with the front spar line I drew earlier. Now, when I trim the stiffeners on the aft side of that line, there will be no interference with the front spar.

Getting ready to trim the second stiffener.

Then, I got in the groove, so the next picture was after a few of the stiffeners. I used my cordless for this. Not as noisy.

Lower 4 stiffeners done on the left skin.

All done with the left side. Oh yeah, it was 60° today, so I worked with the garage door open. So nice…

There's something really rewarding about getting to this point. OH MY GOD!, WHAT IS THAT MARK BETWEEN THE FIRST TWO STIFFENERS!?

A closer look…


I turns out I dropped my cleco pliers from about 8 inches right after I completed the first stiffener. Instead of immediately pulling up the stiffener to inspect the exterior skin, I guessed that it was going to be salvageable and pressed on.

To put it into context, it is just above the first "L" in "ALCLAD."

It’s not that bad, but it would be very noticeable If I polish. (Even if I paint, it is still a pretty big mark.

From the other (exterior) side. Bummer.

Anyway, I’ve heard people talking about using the back of a spoon to gently massage stuff like this out. I spent about 15 minutes gently massaging, and I ended up with this. It looks worse than the original picture, but it is pretty flush now, and I think with a little more work may even go away.

After massaging. It's good, but not great.

Anyway, after that fiasco, I laid out the right skin, marked the front spar and trailing edge wedge on the skin, and started match-drilling stiffeners. I was in such a groove that I forgot to take a picture when I had all of the stiffeners drilled and clecoed. (I didn’t forget to take a moment to admire it, I just forgot to share it with you.)

After removing most of the clecos post match-drilling.

Also, while all the stiffeners were in place, I drew lines on each side of the stiffeners so I would have a guide for devinyling.

I call it match-drawing.

After pondering my next few steps (debur, dimple, scuff, clean, prime, backrivet the stiffeners on), I decided I need to get the vinyl off for deburring.

Here's the wooden stick I use as a guide for the soldering iron.

I don’t think I’ve shown you guys my round-tipped soldering iron yet. Here you go.

Soldering iron, heating up.

After running the soldering iron down the pre-drawn lines, I get to devinyl. I say “get to” because I like this part.

Whose fingers are those?

All done with the stiffener devinyling. You can see I didn’t do all of the outlined parts, because I want to prep and prime those later. (Have to assemble the skeleton, cleco on the skin, and match drill before you can debur, dimple, prep, etc. the rest of the stuff. Also, I need to find out if people are priming the trailing edge area before using Pro-seal. I have a feeling people are just scuffing, but I’ll ask the forums to make sure.

Ready to deburr, dimple, scuff, and prime.

Next up, devinyling the left skin.

2.0 hours today. Gotta go get cleaned up for festivities tonight.

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