Left Spar Arrived from Vans

September 21, 2010

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I was home at lunch today randomly (so I could pick up more propane for tonight’s planned grilling session), when I passed a FedEx Express van.

Hmm. That’s weird. Last Thursday, I got an email from Jessica at Van’s saying they had shipped my left spar back to me via FedEx Express, and it was supposed to arrive tomorrow.

Using some critical thinking skills (and the realization that I had NOT been diligently tracking my package over the weekend), I figured the FedEx Van was in the neighborhood for me. I flipped around and followed the driver back to the house. (It’s amazing how incrementally excited I got after each turn back toward the house.)

Anyway, the spar arrived, and it was, in fact, a new, undamaged spar.

Came in its own cute little crate.

No damage!

I didn’t post a lot about my left spar before, because I wanted to see how it would end up before posting to the world, but here’s a quick summary. My left spar, as received in the wing kit, had a pretty small dent in the lower inboard flange. While it was probably airworthy, I was concerned that I didn’t know how much margin on top of limit load I had lost (if any). Also, would there be any residual stress in the area of the deformation, and what long-term stress cracks should I anticipate based on this dent? Do I have to disclose this damage if I ever sell the airplane?

(Background: The airplane is designed for +9/-6 Gs, and the limits placed on the airplane are +6/-3 Gs. The idea is that a spar with damage might really only be good for 8.8 Gs now, or maybe 8.5 Gs (or, admittedly, 8.999 Gs…it was a really small dent).

(Philosophical question: If you could quantify the new margin, and a spar was good to a known 8.5g instead of 9g, and you were still limited operationally to 6g, would you accept it? I still don’t know the answer to this. I think an 8.5g spar would meet the design intent of the airplane (but Andrew! what about 8.4g?!), but what if I accidentally over-g the airplane, something breaks, and I am falling helplessly to the ground. With a “perfect” spar, at least I know it was all my fault. With a dented spar, I’d be cursing Van’s the whole way down.)

(Dear Mom. There is no way I’ll ever over-g the airplane. Stop worrying. It was just for discussion purposes.)

If we could quantify what I’ve lost if I continue to build with the damaged spar, I may be okay to proceed with enough residual margin, but I have a hard time putting a spar in my airplane knowing it isn’t perfect structurally and not being able to quantify what I’ve lost. For the record, I’m an engineer… this has nothing to do with the small scratches and scotchbriting everyone has on their spars. I’m talking about material deformation.

Anyway, Gus and I talked (about loads…bending, drag, torsional, etc., but I’ll leave that out of here for now), and they really don’t have the capability to do an analysis on a spar flange like that, so he agreed to send me a replacement spar if I could send the other one back. (They can do an ultimate load test on a completed wing, just for future trivia.) Luckily, since this was shipping damage, ABF has picked up the shipping tab. (ABF customer service was less than optimal).

I feel a little guilty about standing ground about the damaged spar, but I think some of that has to do with work (if a spar had come into work like that, we would have either immediately rejected the part and sent it back, or performed enough engineering analysis to deem it acceptable as-is or with a repair). I want to be able to take my airplane to +6/-3 Gs and not always question whether my margin is the same as everyone else’s.

(I’ll leave out the more philosophical discussion about whether the margins on top of the posted limits are equal given the widely-ranging construction practices and skills that appear to be out there in the build community. I have to assume the airplane is designed to fly with plenty of margin after being built by a below-average builder, but can still pass Tech Counselor and DAR/FAA inspections.)

Ultimately, Van’s did a great job managing my concerns and communicating quickly and effectively about the whole problem. I really do appreciate their commitment to customer service, and their willingness to listen to my engineering concerns about the defect.

Thank you, Van’s.

Now.

Back to building!

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Posted by Andrew

Prepped Right Wing Main Ribs, Clecoed Skeleton

September 18, 2010

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I’ve been at a little bit of dilemmna the last few days trying to figure out what direction to take with the project.

I still have the left rear spar to work on (until the left main spar shows up from Van’s…shipped yesterday…should be here Wednesday), or, I could move ahead with some rib prep on the right wing.

For the sake of  seeing something cool at the end of the day, I think I’ll move ahead with the right wing, and hopefully I’ll be able to get it onto a wing stand (yet to be designed) by the time I can get the left spar caught up to this point.

With rib prep, I’ve decided not to follow the suggestion to do all the ribs at once. I’m going to do them a few at a time to save my sanity.

First thing, let’s find some ribs.

I've pointed out to you before that I am at a little bit of a disadvantage building the right wing first, from the plans that only show the left wing.

Notice here that of the three different kinds of main wing ribs, there are both left and right versions in each of the wings. From what I can tell, the flanges face left or right based on what will be easiest/accessible to rivet.

So here are some main ribs (I count 11 in the picture, there are really 14 main ribs in each wing).

My goal today was to get the ribs clecoed to the spars, so I’m only going to finish what I have to (out of efficiency, not laziness). This means I’m going to edge finish most of each rib, then move on to fluting and flange straightening.

The edge finishing (except the little crevices) only took about 30 minutes on the sanity-saving scotchbrite wheel.

The fluting and flange straightening took 2 more hours, though. Ugh.

I took all 14 right main ribs inside and watched the UNC-GT and the Vandy-Ole Miss games.

Here's a rib, halfway fluted.

After fluting (holes are straight), but before finishing up the flange-straightening (to 90° from the web).

After a little while, my hands were hurting from all the fluting, so I took a picture of what I have done so far.

Looks like 5 done, 9 to go.

My "to go" pile. {sigh}

And after another couple of hours, I had the main ribs edge-finished, fluted, and flange-straightened enough to cleco them to the spars.

I really didn’t think I’d get this far tonight. (I have to keep in mind there is still a lot more prep on the ribs before I can actually prime them and get them riveted to the spars.

Pretty. (Pretty big!)

And of course, here is the obligatory “down the lightening” holes shot.

Every other builder on the plant has taken this picture.

But that’s not all! I have variations on a theme.

It's Ginger!!!

And Jack!!! (I promise he is there, just hard to see.)

After sending the dogs back inside for their Saturday afternoon nap, I just stared at this thing for awhile.

It just looks so cool!

3.0 hours today.

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Posted by Andrew

Finished Right Rear Spar

September 14, 2010

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So on the scale from “no help at all” to “girlfriend built the plane all by herself,” we made a few steps last night.

After dinner (thanks Mi Pueblo!), I convinced the lady friend to come outside and help me finish up the last few rivets on the right rear spar.

I talked her through going to the plans, looking at the rivet callout legend, and then putting the rivet in the appropriate holes, making sure to avoid the “rivet later” holes.

We were planning on having her actually squeeze the rivets, but the AN470AD4-6s (and -8s) were too much. She ended up holding the spar steady for me and helping with rivet layout. (See, I told you it was a small step toward “girlfriend built the plane all by herself.”)

I’m working towards being able to call from a business trip across the country and tell her to do something offhand like, “Hey honey. Can you hang the engine for me tonight while I’m away? Great. Thanks. Bye!”

Here's the plans shot for the reinforcement fork.

Of course, we were too busy being in love (with each other and the airplane) to take very many pictures, so you just get the end result. The main squeeze did a great job reaching all of these rivets (mostly due to the 4″ no-hole yoke).

Final rivets in the fork-only area. 38 rivets here.

Closeup of the fork and doubler plate together.

Final rivets in the doubler plate. 7 more rivets here.

Finished product.

0.5 hours (thanks, girlfriend), and 45 perfect rivets.

For those of you paying attention to the totals, that brings me to 175 hours (after 261 days) and 2409 rivets (of an estimated 20,000). Still a long way to go.

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Posted by Andrew

Primed and Started Riveting Right Rear Spar

September 12, 2010

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Well, after a $15 stop at Napa ($10 for primer, $5 for sensor-safe RTV), I got back to work on the rear spar.

I spent a lot of time just kind of staring at everything today. The instructions are careful to point out that at the inboard part of the spar (where the reinforcement fork is), you can’t reach the spar flange holes with dimple dies for later dimpling, so you should do it now.

With that in mind, I wanted to make sure I got everywhere that may need dimpling later, so I also dimpled above the two (middle and outboard) doublers. You can see in this picture (the middle doubler) where I decided it would be a good idea to dimple (drill, deburr, then dimple, of course) the flange holes. I did this for both the spar and the doubler plates, which also have flanges on them.

The middle spar area, shown after drilling, deburring, and dimpling the flange area.

Same thing here. Also, I dimpled the 4 outboard holes (instead of countersinking), per previously approved builders who have talked to Van's.

I got back to thinking about the tank dimple dies, and whether they were really helping with skin-to-structure attachments. The idea is the the tank dies (which are deeper to account for pro-seal while riveting the tanks), when used on the skeleton, allow the regular dimple in the skin to sit better once riveted.

I got out some scrap, dimpled the “skin” with regular dies, and dimpled the “skeleton” with one tank and one regular die.

You can see on the left, those are the regular dies. The ones on the right is a regular die sitting in a deeper tank dimple. The tank dimples didn’t help anything sit better, because they were both fine.

A little blurry, but the "skin" sat equally well for both set of dimples.

The tank (deeper) dimple is on the right. You can see I'm not having any "seating" issues on the left.

Anyway, I think I am going to go back to using the regular dies on everything. Enough about that, though, let’s prime!

The rear spar components, getting primed after some more edge finishing, washing, drying, and positioning in my wood floors boxes.

Also, I went back and masked off the spar where I had countersunk.

Some of the nutplate attach rivets are not as flush as I would like them to be. I may get a rivet shaver and shave some of these down and reprime. We'll see how the tank skin sits on them.

Back on the rear spar, I posted a couple pictures of my edge finishing procedure. First, use the Permagrit block to smooth out the tooling marks. This picture is the resulting burrs that need to be deburred.

The permagrit is great, but it does leave some pretty decent sharp edges.

Then I used my “v” deburring tool to knock off the 45°.

After this, I usually use a scotchbrite pad to smooth everything out.

After blowing the aluminum dust off with shop air and a good wipe-down with MEK, I took the spar outside so I could paint the grass with my overspray.

I think this is the second side. Only one bug landed on my spar. I left him there for now. (He may be my first passenger.)

After a few hours, I returned out to the garage (workshop/mancave) to do some riveting.

First step: Ignore Van’s suggestions to tape off all of the holes that don’t get riveted now. (I know the warning bells must be going off right now, but it all worked out fine. Just have to read the plans carefully.

I left clecos in all of the “do not rivet now” holes. 6 regular AN470AD4-4 rivets on the left, and some AN426AD4-4 (I think) rivets in the dimples on the right.

SEP 14 UPDATE: WHOA! Those 4 on the right can’t be set now, because the W-712 outboard rib will get riveted to these holes, too. Glad I didn’t get to happy with the rivet squeezer.

These 10 can be riveted now. (Sep 14, 2010 Update: Nope. Just the 6 on the left can be set now.)

Same exercise here. Only 5 rivets can be set now.

I didn't really mark anything here, because I didn't really start on riveting the fork on yet. Next post, I'll be very careful about what to rivet.

Then, I actually started riveting. I love my new Cleveland Main Squeeze. Squeezing these An470AD4- rivets is so easy now.

Here are the 5 shop heads from the middle of the rear spar.

The same 5 from the manufactured side.

Oh, and I did 6 more at the W-707F doubler plate, but forgot to take pictures. 11 total. Also, I was mixing this and house projects over the course of a few hours, so I’m going to estimate it was about 2.0 hours today.

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Posted by Andrew

Right Rear Spar Doubler and Reinforcement Fork

September 8, 2010

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The next step on the rear spars is to trip the W-707D and W-707G Rear Spar Doubler and Reinforcement Fork to size.

These parts are shared between the RV-7 and RV-8 (and maybe more, I’m not sure), and must be trimmed if you are building the -7.

This is a tricky trim job, though, because many people have future troubles with drilling the rear spar to the fuselage and maintaining the required edge distance for the hole in THESE PIECES.

It would be best not to overtrim, and leave even less margin than what is already there.

The plans and construction manual both point to Dwg 38, which is of course not included as a full-scale sheet in the wing kit, so I got out my preview plans and started staring.

Even though I’m only working on the right side for now (will bring the left wing up to the right side’s progress when I get the replacement spar from vans), I’m going to do both sides of this now while I’m all mind-prepped to do it.

A snapshot of the applicable portion of Dwg 38. Looks like I should start measuring and marking. (No cutting yet, though!)

Keep in mind here that you measure from the edge you are about to start cutting away, so once you start cutting there is no double-checking your measurements.

Of course, I'm being dumb by doing the right side first (left is shown in the drawing above.)

Here are both lines drawn, measured, double-checked etc. It's still all making sense, so that is a good thing.

The bottom cut off. (For you OCD types, I realize I should have made the other cut first, which would have been a little less cutting overall, but oh well).

I decided to cleco the two smaller pieces together first, then transfer the lines to the bigger forks, and do those separately.

Ready to transfer the lines.

Of course, I didn’t get any in-progress shots of the fork cutting, but it went well. I then clecoed the left and right assemblies together and grabbed this shot after a few passes on the scotchbrite wheel.

At the end of this project, I am going to go back and count how many toes ended up in all the pictures. Here's...{counting}...6 more.

After some time on the scotchbrite wheel, I have two ready-to-cleco parts.

Nice and scuffed.

Then, I clecoed the doubler plate and reinforcement fork to the right rear spar and started matchdrilling.

Matchdrilling.

I had a hard time deciding if I should enlarge some of the rib attachment holes in the fork and doubler plate to final size, and I decided I would. I couldn’t find anyone who said it would be a bad idea, and now I’ll get to deburr and prime all of the rear spar components.

I did leave the majority of the rear spar “future” holes alone, though. I guess per the directions (indirectly, just in step order), I’ll drill those after priming the rear spar.

Here's a picture from the backside (actually, front side) of the spar.

Of course, I was careful to mark and enlarge to #40 the flange holes that need to be dimpled now (the reinforcement fork prevents the female side of the dimple die from getting behind these holes).

I didn't actually dimple, though. I need to leave something for tomorrow.

After taking everything apart and deburring holes, I have a few pieces ready for priming, and a rear spar with some remaining deburring before priming.

I scuffed the rear spar where I had already drilled and deburred to help remind myself what I have left to deburr.

Today’s hour was a good one; a few things ready to prime, and just one deburring and priming session away from being able to rivet the rear spar assembly together.

I need to go buy some more Napa 7220 Self-Etching Primer.

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Posted by Andrew

More Right Tiedown Work, Started Right Rear Spar

September 5, 2010

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Whoa, it’s been awhile since I actually got any work done on the airplane. I’m going to blame my exploding lawnmower (long story), business trips, and the wood floors project.

Anyway, I managed to find a good bi-metal hole saw from the aviation department at Lowe’s, so I chucked that thing up in the drill press and started in on the spacer lightening holes.

Under all that mess is a spacer with a freshly cut hole in it.

I am not really a fan of cutting those things this way, but I don’t have a fly cutter (apparently the one from Harbor Freight sucks), so this was the best I could do.

They actually turned out really nicely.

Two spacers, that go against the spar web.

Like many other builders, I taped them down before putting the tiedown bracket in place, flipping the spar over, and matchdrilling the remaining 7 holes.

After everything has been matchdrilled, I pulled it apart. Looking good so far.

Then, I skipped a couple pictures, but basically You bolt the tiedown bracket, spacers, and nutplates in place and use the nutplates to backdrill the attach holes (small ones on either side of the bigger holes). They all turned out great, except for the upper left set, which for some reason are a little crooked. It doesn’t matter what the nutplate ear orientation is, I was just annoyed they didn’t turn out perfectly aligned.

Somehow that upper left one's alignment got away from me.

Then, you have to countersink the nutplate attach holes (this side of the spacers must sit flush against the spar web).

These rivets aren't set (I still have to prime all these pieces), but I just put them in there to see how my countersinks were. (The lower left one is a little deep, but this is thick spacer, so it shouldn't be a big deal.)

I don’t have any primer, so I decided to move forward (“aft”?…ha…airplane coordinate system joke) to the rear spar. After getting out the W-707A rear spar channel (make sure to grab the correct one, there’s a left and a right) and the W-707E and W-707F doubler plates, I took the blue plastic off of everything and started getting things clamped in place.

The W-707F is laterally aligned with the outboard edge of the rear spar channel.

The W-707E gets laterally aligned by measuring; the outboard edge of the doubler plate should be 50 3/4" from the outboard edge of the rear spar channel. Easy enough.

Then, I fired up the air drill for some matchdrilling.

{air drill noises} Whose finger prints are those?

{more air drill noises} Also, I traced out the aileron pushrod hole onto the doubler plate.

After some though about how to do this, I decided to forego the step drill (Unibit) trick (I don’t have a Unibit…how’s that for a trick!) and just drill some holes and then get the dremel out.

It turns out that all the little fancy metal saw and milling tools aren’t really as easy to use as the 1/2″ sanding drum . Save yourself some time and just get the sanding drum out. Very easy to control.

Looks pretty good to me. (This crazy little torture device that looks like a saw got away from me and cause that scratch. I'll have to buff that out.)

After clecoing back to the spar turns out the thickness of my line made my initial pass a little small. (Better small than big.)

More sanding, anyone?

Much better (still needs some edge finishing).

I totally forgot. Even though I don’t have primer to finish up the tiedown bracket, I can still tap the tiedown hole.

Here's the 3/16" x 16 tap.

After having a hell of a time getting started, they turned out really nicely.

1 full turn in, 1/2 turn out. Wash. Rinse. Repeat.

I managed to get both brackets done, even though I really haven’t started on the left wing yet.

I'll need to deburr the edge, but this should work just fine.

I ended up going to 1 1/4″, even though the directions tell you to only go 1″. Some other builders had to go deeper once they actually got their eye bolts, I figured it would be easier to do now than to wait until the brackets are in the wings.

2 productive hours today.

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Posted by Andrew

Started on Right Wing Tie-down Bracket

August 26, 2010

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Wuhoo, the new squeezer showed up!

After a few minutes of messing around with it, I grabbed the two K1000-4 nutplates and studied the plans carefully on which side of the spar they go. A quick hint (other than just reading the plans) is that the nutplates go on the side that couldn’t possibly need to be flush (in between the spar cap bars).

Anyway, here, I’ve countersunk for AN426AD3-6 rivets.

The two larger holes are examples of where Van's (or Phlogiston) buffed out some spar scratches with some scotchbrite.

Oh yeah, I also flipped the spar over and deburred (you can hardly see the deburring) the backside of the holes I drilled to #40.

The little silver rings are where I deburred. Because these will be totally covered by the nutplate and the shop head, I'm going to refrain from spot priming them.

I used the new squeezer to set my only 4 rivets today.

Don't these look pretty? (There are small rings around the rivet heads. That is from the cleco I used to hold the nutplate on while riveting the other side.) It seems weird the cleco made that little mark.

Moving on to the tie-down bracket. First thing, I need to fabricate the W-726 spacers from this 1.25″ wide angle stock. I’m supposed to cut 4 of them, 2 for each wing/tie-down).

Why is this one on the ground? Is it because the light is good for the camera? NO. It's because it is @&*!@ hot after cutting. Ask me how I know.

Here are the other three.

Each of these spacers should have a 1″ hole cut in the center for lightening (not lightning). Since all of my hole saws are in sizes other than 1″, I decided to grab the W-731 tie-down bracket and get to work on that.

Okay, the manual says to cut the tie-down bar to length from the AEX stock.

Okay (…searching plans…), looks like 7  15/32″. Of course, I measured 7  7/32″ marked, and almost cut before my gut told me something was wrong.

The bar is actually 7 16/32" ( or 7.5"), so I'm not going to cut them 1/32" when I'm sure the edge finishing on the scotchbrite wheel will be more than enough. (Also, it doesn't appear the extra 1/32" will interfere with the top or bottom skin at all.

I keep walking by this sticker and laughing. I thought I would share.

Translation: "If something doesn't fit right, you've royally screwed something up."

Okay, back to the tie-down. After marking and drilling the one (of four) holes for the spar in the bracket to 3/16″, I stuck an AN3-7A bolt in there and just eyeballed the alignment.

(You are supposed to drill just one, then fit the bolt through the whole assembly. Then, you flip the entire assembly over and matchdrill the tie-down bracket from the back.)

I was a little concerned that there was some overhang on the right side of the bracket. (I measured and drilled very, very carefully).

Looks like there is some overhang on the plans, too. Sweet.

Anyway, I stopped there because I can’t really matchdrill everything until I get the spacers placed behind the tie-down bracket, and I can’t really do that until I have the lightening holes drilled (the spacers will be riveted to the tie-down brackets in four places, which in turn hold some nutplates on).

Here are my spacers for the right tie-down bracket.

1 hour, 4 rivets.

Now, I need to find a good hole saw or fly cutter.

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Posted by Andrew

Finished Countersinking Right Spar Flanges

August 24, 2010

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Well, tonight wasn’t a long night in the shop, but it was a good night.

First of all, there was a package sitting on my doorstep when I got home from work. After the excitement for my new Cleveland Main Squeeze died down as I realized the package wasn’t from Cleveland Tools, it quickly came back when I realized it was the missing W-712-R ribs that I had been shorted (what a cruel world!) in my wing kit.

Who knew I could get so excited about wing ribs.

Drumroll please!

{Triumphant music}

Okay, Andrew. Time to settle down.

Let’s finish up this right spar flange countersinking.

From the first issue of the 2005 RVator (thanks to Brad Oliver, for the link) and to A VAF Post (again, thanks Brad), I was able to make this cute little HTML table for you.

From the first 2005 issue of the RVator (page 10):

We countersink until the top of the screw is level with the surface, then go 2 clicks deeper on the microstop. The actual outside diameter of the countersink measures .365″ to .375″.

Countersink Widths for Numbered Screws
Screw Size Width [in]
#6 <0.3125
#8 0.365-0.375

So, I broke out my trusty digital calipers, zeroed them out, and dialed in .370″ (right in the middle of 0.365″ and 0.375″).

Just for kicks, I thought I would show you how much bigger that is than a #8 screw. The larger size allows the dimpled skin to nest nicely in the countersink.

WHOSE TOES ARE THOSE!?

SOMEBODY’S TOES KEEP GETTING IN MY PICTURES!

Anyway, I proceeded with countersinking the tank skin attach holes only (the access plate attach holes are smaller.) I am following the directions here exactly, using a #30 piloted countersink (which nestles nicely in the #8 nutplate) as my guide.

I stopped and verified the countersink depth every few holes. Looking good!

About halfway done with the bottom flange.

Here’s a countersink for your viewing pleasure.

The rivet on the right doesn't look flush, but it is. I promise.

Finally, I finished with the bottom flange. (Notice the three sets of four countersinks on the right side of the picture. Those are for the access plates. They use a #40 piloted countersink and are countersunk to a width of 0.312″ (which is less than 0.3125″)).

Ta da!

Oh yeah, now I have to do the other side.

With a noticeable lack of in-process pictures, I finished the top flange also.

Ta da! (Déjà vu?)

1.0 Countersinking-filled hour tonight.

And, I’ve finished the first three paragraphs of the wing section of the manual. Score!

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Posted by Andrew

Right Spar Countersinking and Nutplates

August 22, 2010

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Well, today was the first official wing construction day. While Van’s is trying to figure out what to do with my damaged left spar, I figured I should get started on the right spar.

First thing…yup…a plans change picture!

The plans for the wing are a little different. There are about 4 separate sheets of different views for the wing. You guys get to see just the general layout one.

Wuhoo! A wing!

Now, let’s get to work. First thing, I very carefully put my beautiful right spar on the edge of the workbench and clamped the flange down very lightly. The spar will tip over onto the table (away from the camera) if the clamps let go, so I’m not too worried about clamping them down too much.

Every builder that has a website makes a comment here about how the construction manual really holds your hand and steps you through the process on the empennage, but then kind of just makes general statements for the wing. For example, the only real construction step on the first page of the wing section says:

“To begin wing construction, rivet the tank skin attach platenuts to the spar as show in DWG 16A, Detail A. Machine countersink the platenut attach holes in the W-706A spar flange.”

Wait. What? That is like 1000 steps, condensed into one statement. It ended up taking me 3.5 hours to do that one step (I admit, I also delved a little into a step a few steps down):

“Attach the K1000-06 platenuts for the W-822 access plate to the W-706A flange. See DWG 12.”

Fine. I see how it’s going to be.

Let’s get started.

Where is my countersink?

A lot of builders start out thinking they should make a nutplate jig and countersink the screw holes before riveting the nutplates (sorry Van, I call them nutplates) on so they can use the jig as a guide for the c/s pilot to avoid chatter. Van’s suggests using the installed nutplates as the pilot guide. After those builders spend some time making those jigs, they eventually abandon the idea and fall back to the Van’s method. I’m going to do something I don’t normally do and FOLLOW THE INSTRUCTIONS. Sometimes, I try to get cute with extra ideas and fancy engineering solutions, when really I should just do things by the book.

So I grabbed my countersink with a #40 c/s bit, tested in some scrap, and positioned the countersink cage over one of the nutplate  attach holes.

The c/s pilot didn’t fit. What?!

You mean I am going to have to drill all of these holes out to #40 first? Ugh!

After drilling every one of the attach holes out to #40, I finally got the countersink and cage loaded back into my cordless drill (slower and more trigger feathering ability than the air-drill) and got to it. Here are my first 10 countersinks.

The blue tape is to prevent metal shavings from getting lodged in between the spar cap bars and the spar web.

Anyway, I continued down the row, being very careful to slow myself down and not to fall into too much of a routine. I could feel this was going to be one of those areas where I would be going through the motions and mess something up. (I did make a mistake while drilling out all the holes to #40. I accidentally drilled out a skin attach hole, too. No biggie, but a perfect example of moving too quickly in a habitual way.)

I stopped about every 6 countersinks and retested my countersink depth using a AN426AD3-4 rivet. They are all perfect. Here is the end of the row, looking back toward the “diagonal” wing-walk attach holes.

Pretty, pretty.

Then, I flipped the spar over and did the bottom flange. Also, there are some access panel nutplate that get attached now, too. I went ahead and countersunk for those attach rivets, also.)

Bottom flange, sobriety-maintaining Sprite-zero, and the girlfriend's cordless drill I'm borrowing (pronounced "you can have it back when you pry it from my cold, dead hands"). Thanks girlfriend!

Phew, that was a lot of countersinking. (I think I counted 144 total countersinks for just the nutplate attach holes. There’s another 72 for the screw holes (in the middle of each set of three holes) I’ll have to do later.)

Next, I grabbed some K1100-08 nutplates, some silver 3/32″ clecos, and some AN426AD3-4 rivets and started getting ready. My plan is to cleco the nutplate to the spar, insert one rivet, then after riveting that one, take the cleco out and rivet the other side.

Cleco in one side, unset rivet in the other.

Down the line, everything ready to rivet.

Redundant picture.

Ahh, this slower, more thoughtful approach is paying off. Can you see the error that I almost made?

Which one of these is not like the other?

Here's an example nutplate before I take the cleco out and put the other rivet in.

I can’t remember why I took this picture. I think I just took out all the clecos, and I thought it looked cool.

Ready to set the second half of the rivets.

No pictures of the second rivets, but here’s one of the other (now top) flange.

You can see all of the nutplates on the lower flange.

Anyway, I set all the nutplate attach rivets on the upper flange, and then called it a day. So I got to cross off the two statements in the construction manual I highlighted above, and next up is to use the installed nutplates as c/s pilot guides for countersinking the screw holes.

Oh, and then I get to repeat on the other spar.

3.5 hours of countersinking and riveting today. 144 rivets, 1 drilled out (the rivet split in two!). Good times.

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Posted by Andrew

Bought Cleveland Main Squeeze

August 21, 2010

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Recently, I’ve been kind of unhappy with my economy squeezer that I bought from the Yard. (I think Avery sells the same squeezer).

The squeezer is great for the majority of tasks on the empennage, but it only has one yoke, and I really need a no-hole yoke for some of the tighter-access areas at the end of ribs and such.

So, to buy a no-hole yoke, it looks like I’m going to have to buy a new hand squeezer (insert long back and forth about pneumatic squeezers here. I’m okay with hand-squeezing for the whole airplane, but I want one that can exchange yokes with a pneumatic squeezer if I decide to get one in the future).
So, for no small chunk of change (thanks, savings!) I got Cleveland’s Main Squeeze model 22 and the 4″ Thin-Nose Pneu. Yoke. I won’t be able to use this yoke for dimpling (still have the economy squeezer for that), but this will be great for squeezing rivets.

Aug 27, 2010 Update:

My new squeezer showed up. The actual squeezer is unbelievably light, and the yoke is unbelievably heavy. Even before installing the yoke, I can tell this is a much higher quality tool than my “economy” squeezer.

Here are the two separate purchases from Cleveland.

Ready for ACTION!

This should give you an idea of the difference in quality between the two.

In addition to being easier to squeeze, I am most impressed with the yoke. While I was squeezing rivets with the smaller 3″ yoke, sometimes the yoke would “give” a little. I can only describe this as the “c” part of the yoke opening ever so slightly. This had the result of pulling the top of the yoke back just a little, sometimes shifting the shop head a little to one side, or in some cases, sliding the flush set along the manufactured head side during squeezing. Most of the rivets turned out okay, but I no longer have this problem with the new yoke.

Here’s a picture of SRS (shifting rivet syndrome).

Big difference in quality (pronounced "price reflects this") and operation.

Bravo, Cleveland.

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Posted by Andrew

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