Matchdrilled Right Tank Z-brackets

February 20, 2011

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Well, it’s been a little while since I was out in the garage banging away on the airplane.

I have a few things piling up on my list of things to do. Among others, I could have finished up the landing light install, moved on to the left wing rib preparation, etc., but I kind of felt like continuing on with the right wing.

Van’s says that you should do both of the (insert noun here) if you want to save time.

Well, I have time, and don’t need to rush through this.

That means, on to the fuel tanks. The first step is to start removing metal on the Z brackets that hold the tank to the front of the main spar.

Let’s see, here they are.

Labelled appropriately. I wonder why Van's underlined the label in blue...

Oh, I almost forgot! The ceremonial plans change!

(Triumphant music...)

Okay, so there is lot’s of talk about the Checkoway method and what that is, but no one really does a good job of explaining it. I’ll give it a shot, and try to give credit where credit is due.

Basically, Van’s wants you to:

  1. Install the z-brackets (after some steps to get both sides of them drilled)
  2. Cleco on the baffle (“back wall” of the tanks) to the z-brackets.
  3. Cleco the skin to the baffle, then adjust fit as necessary by elongating holes in the baffle.
  4. Remove the skin and cleco in the ribs.
  5. Cleco the skin back on.
  6. Remove the whole thing for matchdrilling off the wing.

The Checkoway method (from what I can tell, because I never actually made it to his site before he took it down…):

  1. Drill only the aft side of the z-brackets, then bolt them in place.
  2. Attach a clecoed tank into position
  3. Drill the inboard baffle-to-z-bracket holes (doing this now, instead of before, ensures the tank is perfectly aligned.)
  4. Remove the leading edge to drill the outboard baffle-to-z-bracket holes
  5. Remove skin and ribs, leaving baffle in place.
  6. Now finish baffle-to-z-bracket holes.

The Checkoway method basically has you wait until you ensure propoer tank alignment before starting to drill holes in the front flanges of the z-brackets. If you do it Vans’ way, you might misdrill a z-bracket, and it will throw off the whole tank alignment.

Anyway, many sites have kind of hinted at this stuff, but Ethan really spelled it out nicely, and I have to give him some credit.

Of course, I’m out in the garage, so iPhone saves the day.

Ooh, remind me to charge up tonight, looks like I'm a little low on electrons.

Okay, as part of this whole Checkoway method, one of the suggestions is to move the “centerline” (future drilling reference) of the z-bracket flanges  to favor the type of fastener you’ll use later.

On the inboard-most bracket, you primarily use a socket to tighten or loosen bolts from the wing root. Hence, you should move the centerline (and resulting holes) AWAY from the web for better socket access.

On the other 6 brackets, the spar attachment is from the rear spar, so there are no access issues, but the front flange needs a blind rivet, so if you move the holes CLOSER to the web (allowing for enough room for the nutplate), then the whole thing slides over and there is more room for your blind rivet puller during final tank construction steps.

(I spent an hour in the garage tonight, and most of that time was just trying to wrap my head around this idea.)

Once I had it all sorted out, I laid (layed? Emily, which one is it?) the z-brackets out and started marking them with really obvious arrows.

Right wing inboard one gets moved AWAY from the web, second one is moved CLOSER to the web.

After some really precise (HA!) line drawing. I finally used my center punch to mark a good starting point for my #12 drill. (#12, because that’s the holes size for AN3 bolts.)

Punched.

Inboard bracket drilled.

Second one drilled.

After drilling the second one (actually, I checked before drilling, but didn’t snap a picture till after), I held a nutplate over the hole to make sure I didn’t get too close.

Looks good.

Then, I needed to bolt these in position to drill the other 2 (of 3) holes. I spent a few minutes removing the lower inboard right wing skin and laid (Emily!!) the brackets in position.

I love working on the airplane. Therapy for the soul.

Okay, I have my centerline and a hole. Let’s bolt them up. (I added tape and a washer for spar-protection.)

Centerline through both holes...

Everything was going fine until I got to the inboard bracket. This doubler prevented me from getting it snugged up.

Bummer.

So, I just moved it to the top side, knowing I’ll have to backdrill from underneath. No biggie.

See, worked great. (You can see I used sacrificial nutplates, instead of regular nuts...easier to tighten since once you get it started you don't have to hold the nut.)

Back to the outboard brackets…

I’d drill the top hole, stick an AN3 bolt in, then drill the bottom hole.

Wuhoo! I love making aluminum shavings.

After all 7 were matchdrilled. I headed inside.

Good progress today.

1 hour. It was basically 45 minutes of staring at the plans, the instructions, and other builders’ sites, then 15 minutes of marking and drilling.

With the start of the tanks, I need to start thinking about ordering some Black Death (Proseal (tank sealant). I used this stuff on the rudder, and it really wasn’t that bad. I’m just calling it Black Death to be funny…or at least conformist.)

I can’t decide if I’m going to order the quart, or a whole bunch of the smaller tubes, which are easier to work with, but more expensive.

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Devinyled Two More Wing Skins

October 6, 2010

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Well, I manage to put in another “inside” night tonight on the airplane.

I’m not sure why I took this picture. I think I was waiting for the soldering iron to heat up.

Some of the airplane parts in the corner. I need to get back to drilling out the rudder skins one of these days.

Anyway, I finished up the right lower outboard wing skin, and then moved on to one of the upper outboard wing skins (they are identical, so it isn’t a left or right).

Here's the right lower outboard wing skin before devinyling.

And after.

I totally forgot to take any pictures of the upper outboard wing skin I got done.

One hour tonight (30 minutes per skin). One more short session, and all my skins should be devinlyed.

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Rolled Right Elevator Leading Edge

July 31, 2010

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How exciting! I get to roll the right elevator leading edge today!

Okay, if you couldn’t sense the sarcasm there, I’ll lay it out for you. I hate rolling leading edges.

This first section actually turned out nice after the roll. It was pretty easy to squeeze these together and rivet.

See? EasY!

Then, I took a picture of how I tape, which I have since ammended.

Now, I put tape along the entire edge, overlapping once piece with another.

Of course, since things started going badly, I forgot to take more pictures, but rest assured, I have some unintentional puckering between rivets on one of my rolled sections. The crappy thing is that once you roll and remove the pipe and tape, it is really hard to go back and re-roll.

Anyway, I moved on to installing the rod-end bearings.

Here is my rod-end bearing tool.

You can see how the rod-end just fits right in there. (The purpose of the tool is to help turn the rod-end in the nutplate without putting any pressure on the actual round bearing in the center.)

Tightening.

They want you to install the elevator rod-ends to 13/16″.

That's 13/16".

Right on the money.

After getting those in, I set the elevators aside and moved back to the trim tab. Here, I’m using wood backing (so the pilot of the countersink cutter has a good guide) and countersinking the holes on the top of the spar only (you can’t dimple the top, because the hinge sits just underneath the spar flange).

I'mi using a scrap piece of wood flooring here.

Then, it was time to dimple the skin. I only got the tab to a place where I can cleco it back together. I still have to fabricate some trim tab riblets.

Dimpled tab skin.

Then, I dragged the horizontal stabilizer out of the storage room and installed the elevators. Once I realized I had to drill out the hinge brackets to #12, the bolts went right in.

It looks like an airplane. And it's huge.

I’ll take more pictures of it for you sometime, but for now, I’m just going to leave this assembly on the workbench for a few days and admire it.

3 hours today.  22 more rivets.

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Prepped and Primed Left Elevator Skin

July 11, 2010

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Well, after an exiting morning with the South Carolina Breakfast Club, I was fraught with motivation. (I don’t know if I am using “fraught” correctly…)

Next thing on my long laundry list of things to do on the left elevator is to prep the skin for riveting to the skeleton. First thing, I got out the soldering iron and pulled off some more of the blue vinyl. While I was at it, I pulled off the blue painter’s tape I had been using to protect the back-riveted stiffener rivet lines.

All that shiny aluminum really makes me happy.

Then, on to deburring. I deburred both exterior sides of the skins, and then moved on to deburring the interior of the skins. I follow very closely with my maroon scotchbrite pad to help me remember where I have deburred (you can easily tell the difference between a deburred hole and one that has yet to be deburred…I am more using the scotchbrite pad as an excuse to give my fingers a rest…it is hard spinning that drill bit over and over and over).

The background holes are #40 (3/32") and the foreground holes are #30 (1/8"). I drilled these holes to #30 now because I don't want to wait until after the skin bending (at which point I won't be able to deburr them). Also, having the holes to final size will help with the annoying pop rivets that go in them.

Next up, dimpling the skin-to-skeleton holes. I scuff the interior of the skins before dimpling, because it is easier to scuff without dimples getting in the way.

I use my masking tape trick on the male dimple die, and I get ZERO circles around the dimples. So nice.

All holes dimpled.

Time to move on to edge-finishing. This little 90° corner is a tough one, but I think this ended up nice.

Edge-finishing.

After edge-finishing, I cleaned up, wiped everything down with MEK, and primed. Fast forward 30 minutes later, and now I get to pull the vinyl out of the skins (I’m trying to remind myself constantly to not forget the RTV in the trailing edge of the elevator bend before riveting.)

I probably add some time to the project by masking all of this stuff off and priming just the contacting surfaces, but I think it looks great (no one will ever see it) and I think I'm saving weight. Maybe not, but I sleep better because I do this.

It looks so good. I love this part of a subassembly, I'm getting close to riveting!

Last, but not least for the day was to prep and prime the two outboard ribs. These fit back to back and support the counterbalance and counterbalance skin.

On the priming table after getting a light coat of self-etching primer.

3.5 hours today on the project, but I’m only logging 3.0 here. See here for the other 30 minutes.

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Started working on the Elevator Tab

June 20, 2010

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After some more days of not doing anything, I managed to make it out to the Pilots N Paws fly-in today. It was good motivation for working on the airplane.

Anyway, I’ve drilled the left elevator skin to the skeleton, and the next step is really to take everything apart, deburr, dimple, countersink, prep, prime and assemble…

BUT…

I have some things that need to be done first. Mostly, the directions want you to bend the elevator tab “ears.” Well, I don’t think I want to go the bent route. Here’s what I am worried about. I don’t think anyone would really notice, but I don’t love the way this looks.

Bent trim tab ears. I think I'm going to cut mine off and make little ribs.

I think with some work, I could make them look like this, but given how finished these surfaces are, I don’t know if they started as bent ears or riblets.

WHOA! This is awesome. This guy really finished this joint up nicely. Everybody be jealous.

Finally, I found a really nice riblets version. I like this, and this is what I am going to be aiming for (although I am going to try to use solid rivets.

Great finish on the cut-instead-of-bend tab ears. I'm going to strive to make mine like this.

Anyway, I also think cutting the ears off (not bent down in the way) will allow me to use solid rivets in the blind-rivet locations on the top and bottom of the elevator (outboard trim spar rivets). We’ll see.

First step is to get the skeleton re-clecoed in the skin.

The trim spar and the inboard rib.

Van’s wants you to countersink either piece for flush rivets (not for any real flush reason…I think they need to be #40 size holes, and they don’t give you any universal head AN470AD3 rivets). Anyway, per standard practice, I dimpled both.

Dimpled instead of countersunk.

After clecoing together the skin, I am ready to start the headscratching with the tab. Let’s find the tab spar.

There it is.

Let’s go ahead and cut off these tabs. After careful measuring and marking, I’m ready to put blade to metal.

Inboard side. I'm nervous about chopping these off.

Outboard. (see how I lined up the line parallel to the flat portion near the top and to the left of the relief hole near the bottom? This doesn't work. Read on to find out why.

After a quick snip (not too close to my final line) I removed the vinyl from the interior of the skin in preparation for using a file and scotchbrite pad to clean everything up.

Devinling before finishing those cuts.

After working carefully with a file and edge finisher…

Looks good.

Before I really finalize things, I’d like to get my tab placement set up. First, I tried using this extra piece of rudder stiffener.

It worked okay, but I later switched to something a little longer.

After some moving around and fiddling, I re-read the directions, which tell you to bend the elevator ears down along a bend line that is perpendicular to the hinge line. Well, that means that the cut lines should be perpendicular, too. Of course, like I mentioned before, my original outboard line wasn’t perpendicular. All that file work for nothing.

I drew new lines (one on top of the other, ignoring the needed clearance).

Drawing new, perpendicular lines.

Then, I made a “pretty close” cut with the snips. I’ll need to really clean this up, as well as move the line to the left for clearance purposes (I’ll wait until the hinges are drilled to really see what I need. (The instructions call for 3/32″, but that is for the blind rivet head clearance that I won’t have to worry about.)

Pretty close, but still needs trimming and finishing.

Next, I moved back to the tab. Here’s my new line.

I'm bummed because the upper part of the tab, factory provided, is not perpendicular to the hinge line. That means there will be a slight angle there. Bummer.

After getting those refinished, I got the tab mocked up. I kind of worked backward. I want to use the inboard edge and the trailing edge to get placement, then verify I have adequate clearance on the outboard edge and between the tab and elevator for the hinge (there are some hinge dimensions on the plans). I think I’ll have plenty of room.

This looks good, but I'll have to keep trimming that outboard edge.

Here's a closeup. You can see the edge near the top of the tab is angled a little left. This is how it comes from the factory. The marker line and aft portion of the tab are both perfectly perpendicular to the hinge line (line through the center of the rivet holes).

Later this week, I’ll work on getting this perfect, then tackling the riblets that need to be constructed before doing any more work with finishing the skin.

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Drilled E-701 (Left Elevator Skin) to Skeleton

June 17, 2010

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Wow, it’s been a week since I’ve worked on the airplane.

I have an excuse, though. I’ve been installing wood floors. Here’s the living room, almost done.

Anyway, if you remember from the last post, I had the left elevator skin clecoed to the skeleton. I went ahead and match-drilled the skin to the skeleton. Instead of using my cordless drill (because it’s quieter), I broke out the air drill and went to town. I love the way that thing sounds.

Forgot to charge the camera battery, so it charged while I drilled.

After matchdrilling both sides, this picture is me in the middle of removing all of the clecos.

Then, because I felt like I would be short-changing you if I didn’t have two pictures for you, here’s another one.

After disassembly.

Here’s the catch, though. I have a lot of thinking and pondering to do about some things.

First of all, I am planning on cutting off the elevator tab (and elevator) bent ears and just making a rib out of them. Jason Beaver did it pretty successfully here and here, so I’m basically going to copy him.

The question is whether to prep and rivet the left elevator now, the cut off the “ears” after riveting, then try to fabricate a rib, matchdrill, dimple, prep again, etc., or should I re-cleco everything together and do all of that fabrication now.

Many people use blind rivets for the extra tab fabrication, but I think I am going to try to use solid rivets. I have had some success in the past with solid rivets in tight spaces using a special bucking bar (namely, the end of a BFS (“big-freakin-screwdriver”). The question will be about dimpling.

Also, I can probably cut the ears off, but leave a little extra material. I need to make sure I line up the cuts on the elevator and tab to minimize the gab between the two, and I don’t want to cut to much off of either side. Maybe I’ll mock them up, cut one side to where I think it should be, and make sure the other side can be cut more precisely to match the first cut.

Also, many people use blind rivets for the four trim spar rivets on both sides (per the plans), but I think I can assemble in an order that allows me to use solid rivets, especially since I’m going to cut the elevator bent tab ears off; I should be able to reach in there with a bucking bar.

See how much thinking I have to do?

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Drilled E-714, Clecoed Left Elevator Skin

June 10, 2010

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Hey Look! Andrew’s not dead! Yeah, I’ve been working on some house projects. Back to the left elevator tonight, though.

I managed to catch myself up with where I was and push on today. I need to get that counterweight drilled.

Here you can see the counterweight, counterbalance skin, and the two end ribs around which the other parts reside.

After placing the weight in position, you cleco on the skin (difficultly) and get ready to match-drill. Of course, I met the same challenges I did on the right elevator…namely, I broke a drill bit (#40 size). After getting a pilot hole drilled, I took everything apart and separately enlarged them all to #21. Air tool oil was used with great success after the pilot hole was drilled.

Ready to start drilling.

I didn’t take any pictures, though, because I was getting frustrated. (At first, I was dipping the drill bit into the oil, which meant I had to take the lid off. Then, after stepping away a few minutes later, I placed the screw lid (with the flip-up spout) back on the oil bottle and immediately flipped it over to aim oil into the pilot hole. Guess what! I forgot to tighten down the lid. There goes the lid, and about a 1/2 cup of oil…all over the counterweight, table, and floor.)

Now do you see why I forgot to keep taking pictures?

Anyway, after that debacle (which of course gets counted in the build time…it’s time spent building, right?)

Anyway, here is that same assembly (sans weight) before clecoing on the skin.

In preparation for clecoing on the skin, I needed to handle E-606PP, which is the trim tab hinge spar. Since I was looking ahead earlier and dimpled the hard-to-reach holes (you can see in the skin below), I need to do something with the spar to accept those dimples. If you read ahead in the directions, the spar is countersunk on the top flange (because the hinge is riveted beneath the spar flange, it can’t be dimpled), and dimpled on the bottom flange.

June 10 Update: After countersinking these four holes, I later did some more research and realized that the countersinks called for (due to the hinge) don’t really apply here, because the hinge stops short of these four holes. I could have (and wished I’d ) dimpled. Boo.

Here are the two parts that need to fit together nicely.

Finally, I got the skeleton and skin clecoed together.

Wuhoo. It looks like an airplane.

A solid hour. Maybe more this weekend.

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