counterbalance skin | Andrew's RV-7 Build Log

Left Elevator Skin Riveting

July 23, 2010

I wasn’t very good with the pictures today, but I did get a significant amount of work done today. I basically did a lot of skin riveting, and all went well, with a few exceptions.

First up, try to use solid rivets on the outboard part of the trim spar where they instructions say you can use blind rivets.

"Blind rivets? We don't need no stinking blind rivets."

The top row (actually the bottom of the elevator) turned out well.

These aren't the prettiest or most perfect shop heads, but they are within spec, and will do the job.

Then, I flipped the elevator over and did the top (which was harder, but actually turned out better than the bottom). I forgot to take pictures though.

I moved on to the counterbalance skin and set have the rivets, then removed the clecos and set the other half.

Here's every other one set.

Wait a minute! I’m going to need that trim tab hinge (forward half) primed so I can rivet it on the elevator.

Up on the priming table for some self-etching primer.

Moving on to the rest of the skin, here are half of the rivets set in the leading edge and inboard edge.

Halfway done with one side.

Then I removed the clecoes and finished up the first side (except for the trim tab area).

After the hinge dried, I clecoed that in place and got to it.

Clecoed in place...

Half the rivets set, clecoes removed...

All done, with the tab half of the hinge installed to make sure I don't have any binding.

Then, I flipped that bad boy over and finished the other side.

IT LOOKS LIKE AN AIRPLANE PART!

Wow, big day today. 172 rivets, four of them drilled out. (Notice how I just glossed over the riveting of my trim riblet? That’s because it was about an hour of my two hours outside. What a pain in my aft.)

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Leave a Comment » | Empennage | Tagged: Blind Rivets, counterbalance skin, Elevator, Priming, shop heads, skin riveting, solid rivets, trim tab hinge | Permalink
Posted by Andrew

Preparation for Left Elevator Skin Riveting

July 21, 2010

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Now that my #10 dies are here, I can proceed with the counterbalance skin and preparation for riveting.

This is how #10 dimples are supposed to look.

No cracks!

After beveling the exterior of the counterbalance skin, drilling the two fairing attach holes (that will be doubled up with the elevator skin) to #28 and dimpling to #6, I threw the counterbalance skin and the little trim riblet up on the priming table, opened the garage door, got the respirator out, and shot these two with primer.

Primed.

After that was done, I clecoed the counterbalance skin in place and riveted the two rivets on each side that can’t be reached after the skeleton is inserted.

There's a nice lap joint there that could have used some edge-rolling, except I FORGOT TO EDGE-ROLL, EVEN THOUGH I JUST BOUGHT AN EDGE-ROLLING TOOL!

The two rivets in question on the top.

Nice shop heads.

And two more on the bottom.

Then, before inserting the skeleton, you loosely place the counterweight in position and partly insert the two screws.

Okay...

Then, I riveted the little riblet I made to the trim spar.

Skeleton, ready to be inserted into the skin.

Closer look.

Of course, I then realized that I needed that area open so I could attempt to buck the four rivets outboard of that point. Drilled out that rivet.

At least I remembered to put some RTV along the back edge of the stiffeners.

After that, I got the skin clecoed on.

It's looking like something that slight resembles an airplane!

Another angle.

I’m kicking myself for not edge-rolling that one lap joint. I only remembered that I didn’t when I woke up in the middle of the night. My two options are to leave it, or drill out 4 rivets and edge roll. Maybe I’ll rivet the rest of the joint (two more rivets), then decide whether it is bad enough if the edge picks up at all. I don’t think it will, but I’ll start there so if I have to take it apart, it will only be a few rivets.

1 hour. 4 rivets, one drilled out.

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Leave a Comment » | Empennage | Tagged: #10 dies, #6, clecoed, counterbalance skin, edge-rolling, riblet, Riveting, RTV, skeleton | Permalink
Posted by Andrew

Riveted E-703 and E-704 to E-702

July 18, 2010

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Even though I haven’t been feeling all that well in the last few days, I did sneak out in the garage for 30 minutes. I was mostly motivated by the arrival of my replacement E-713. Here she is, in all her beauty. (Let’s not mess this one up, too, Andrew.)

Ah, a non-mangled part for a change.

After admiring E-713 for awhile, I moved on to riveting E-704 and E-703 together. Here are 8 lovely shop heads.

Looks good on this side.

And then I riveted my extra credit one leg nutplate in the tooling hole for further control surface balancing. Because I’ll want to balance the control surfaces pretty well while they are polished, if I ever decide to paint, I’ll have to add weight back in. This will be the best way to do this.

Thinking even further ahead, if I put a screw in here, I'll make it short enough that it falls out before binding. Or, I'll safety wire it. I'll have to think more about that.

And the other side. This was fun to rivet because I had to do both rivets at once.

That was it for today. 14 rivets, one of them had to be drilled out and replaced. Now, I’m just waiting for my latest Avery order so I can finish up the replaced counterbalance skin.

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Leave a Comment » | Empennage | Tagged: Avery, control surface balancing, counterbalance skin, drilled out, E-713, Nutplate, polished, Riveting, shop head | Permalink
Posted by Andrew

Left Elevator Counterbalance Skin

July 13, 2010

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A short half hour tonight. First thing was to grab the primed end ribs and get them clecoed to the left elevator spar. No problems there.

Looks good. Ready to rivet (but not tonight).

Next, I need to get the counterbalance skin taken care of (must be riveted to the skin before the skin can be riveted to the skeleton).

You can see I clecoed it in place and drew a line where the two overlap; I'll use this as my primer line.

Then, I realized I’m going to have a hard time deburring, dimpling, and scuffing with the blue vinyl on. [sigh] Off with the vinyl, re-cleco, redraw my line, then back off to deburr, dimple, and scuff.

After dimpling with tank dies where the skin sits under another dimple, and regular #40 dies where it doesn't.

While I had the #6 dimple die out (I’m attaching all fairings with screws for now), I moved over to the elevator skin and dimpled there, too.

Make sure you drill all holes that need to be dimpled with the #6 dies to #28 drill. This is slightly larger than the #30 you are used to.

Again (for the search engines), the correct drill bit size for a #6 screw and #6 dimple die is #28. Ask me what happens when you dimple a hole that isn’t drilled to the right size. (Hint: the same thing that happens when you overdimple using something other than a dimple die because you are too cheap to buy a #10 die…see below…)

Okay, back to the counterbalance skin.

These are dimpled to #8 (I don't have a #10 dimple die). last time, I used a punch set (with a little rounded lip on it) to enlarge the dimples to the equivalent of #10 dimple die.

Let’s countersink the counterweight as a female dimple die.

Looks good.

Uh oh. I went a little far with my makeshift die. I stared at this for approximately 0.0000001 seconds before realizing I had to scrap the part.

See the ginormous cracks? Yeah. Not good.

A closeup of the other one. Oops.

So, the reordered part count is up to 2.

I’m not worried, I have some other stuff I can be doing while I wait for a replacement counterbalance skin (E-713, $8.85) from Van’s. Also, I immediately put in my order with Avery for a #10 dimple die (along with some clecos, an edge roller tool, and some more drill bits).

USE THE RIGHT TOOL FOR THE JOB, ANDREW!

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Leave a Comment » | Empennage | Tagged: #28, #6 dimple die, blue vinyl, clecoed, counterbalance skin, Deburring, Dimpling, end ribs, left elevator spar, primed, scuffing, skeleton | Permalink
Posted by Andrew

Trim Tab Fitting

July 1, 2010

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Okay. Today was a pretty productive day. I had taken everything apart, then realized I still had some more fitting to do on the tab, so I put it all back together again. Before that, though, I thought and thought about what to do about the two holes on the right side of the picture. These are for the fiberglass tips, and they are supposed to be matchdrilled later, after the counterbalance skin is installed as a lap joint underneath. How can I deburr parts that are riveted together if I drill through both? Maybe it’s not a big deal, but I decided to drill them to #30 now (for #6 screws).

Two holes the right before drilling...

...and after.

Then, I was thinking ahead about the safety wire trick you have to do with the hinge pin. Why not drill that now, so I can deburr before priming?

I drilled this just larger than 0.060, which is one of the biggest safety wire sizes.

Next, time to deburr and dimple the left elevator spar.

Me dimpling.

And after everything was dimpled, a nice picture down the spar of my blurry recycling bin, golf clubs, and motorcycle jack. (No motorcycle anymore, but the jack comes in handy to lift the corner of a car when a tire needs to be taken off for one reason or another.)

Spar! (I'm tired, so we are down to one word captions for the day.)

Another shot of the same.

Dimple! (Wouldn't it be annoying if I everything I wrote ended in an exclamation mark?!)

After edge finishing the two hinge reinforcement plates, I shot them with primer.

Primed!

Then, my attention turned back to the tab. I’ve clecoed the elevator half of the tab hinge back in, and on the right you can see my drilled riblet!

Drilled riblet! (Okay, I've had enough of the exclamation points.....!)

Here’s a better picture. I basically drew a line perpendicular to the hinge line up from one of the holes along the trim spar, then spaced them at 1.5 and 3 inches. That spaced everything evenly, and gave me plenty of edge distance all around.

Don't look at my edges, they aren't finished yet, but you get the idea.

Then, I stuck the tab on and inserted the hinge.

As some would say, "Easy Peasy."

Other direction, just for kicks (not as much deflection due to cleco interference, but again, you get the idea).

Because I bought a longer section of hinge to replace my bad first attempt, my hinge pin was long enough to actually fit (Van’s says they will send you the real one (because it needs to be longer than 18″) in the finish kit.

I got to bending.

After more bending, I ended up with something like this.

Ooh, isn't that pretty! The safety wire hole I drilled earlier is in the middle there, and will allow me to safety wire this hinge pin to the spar so it won't COME OUT IN FLIGHT!

Then, I figured out how to do video. They speak for themselves, but keep in mind that while my gap is intentionally small, I still need to edge finish, which will open them up.

Another video, this time a little closer. You can see I am pushing and pulling left and right to make sure there is no interference even with the small amount of play in the hinge. I think I am okay, but this will probably open up a little after edge-finishing.

Two hours of late-night-hinge-pin-bending bliss.

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Leave a Comment » | Empennage | Tagged: #30, clecoed, counterbalance skin, Deburr, dimple, edge finishing, fiberglass tips, hinge reinforcement plates, left elevator spar, matchdrilled, riveted, safety-wire, tab | Permalink
Posted by Andrew

Final Prep for Right Elevator

May 20, 2010

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Well, after deciding not to work out tonight (in favor of wine), I made it out to the garage pretty late for some final prep work before riveting the right elevator.

Tonight's build partner, 2004 Manyana (play on words) Crianza. A delicious tempranillo from Spain.

On with the building, you say? Fine.

One of the last real fabrication items I have left on the right elevator was enlarging the counterbalance skin dimples. To make a long story short, I don’t have #10 dimple dies, so I dimpled with #8, and then planned on using the AN507 screw head and a nut tightened down to enlarge the dimple enough for the screw to sit flush.

This did not work.

Okay, instead of waiting for a week for a $40 dimple die to arrive, let’s be creative.

Plan: matchdrill two holes in a block of wood, countersink the holes, then use a flush set to enlarge the dimples.

Here's my block of wood, later to be countersunk.

Well, I don’t really have any good pictures of my attempt, because that didn’t work either, and I was getting frustrated.

Finally, I told the girlfriend to come out and listen to me explain the problem. (I knew this would help me come up with a solution.)

Without even flinching. “Why don’t you use a bigger screw to make your dimple?”

my face = <deer in the headlights>

Of course! (Except I didn’t have a bigger countersunk crew, but it set me down the right path.)

This should work. (It's my punch set that came with my rivet gun.)

Setup recreated (I had a piece of tape on the skin to prevent marring.)

The hole on the left has been "enlarged." This worked great!

Okay, let’s move on. Next up, I needed to locally bevel the edges where the spar and tip rib are underneath the counterbalance rib (so the top skin doesn’t show the transition bulges. So I marked those, and also started thinking about how to attach these empennage tips. See the two undimpled holes to the right? Those are two (well, 4, two on top and two on bottom) tip attach points that will eventually be drilled, deburred, and dimpled. Might as well do it now so I don’t have to worry about deburring between riveted sheets.

Lining things up to wrap my head around this interface.

I flipped the pieces over and drilled them to #30.

The top two holes have been drilled and deburred, ready for dimpling.

After dimpling…this #6 screw fits pretty well. (Editorial note: I’m pretty locked in to attaching the elevator tips with screws. I know there is really no reason to take the tips off, but right now, I don’t want to commit to blind rivets.)

That #6 screw looks like it will fit pretty well.

Once the other side was done, I primed the interior (and taped off exterior) side of the counterbalance skin.

Priming. You can see the two #6 dimples at the top of the left side of the skin. (I'll do the rest later...the rest are all accessible in the future.)

While that dries…let’s devinyl!