The Case of the Missing Scarf

November 12, 2012

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Today, I had a day off work. This was excellent news because:

1) I needed a day off work.

2) The airplane needed me to have a day off work to get some stuff done.

Really, there are only a few things left on the right wing before I can call it complete and catch the left wing up. The lower outboard skin, inspection covers, pushrods, and wingtip. I’ll probably wait until both wings are complete to do the pushrods and wingtips.

That leaves the skin and the inspection covers.

Here’s the lower outboard skin, just kind of hanging on the wing (makes for good storage).

Also, You can see I kept my extra pieces of blue tape here while I finished the inboard skin.

After pulling the skin off, I realized that I already prepped the skin through deburring and scuffing the inboard side. Nice!

Already scuffed. (If you look at the date of the linked post, it was February….of 2011. Ouch.)

I guess you also get a closeup.

Anyway, I got the C-Frame out again and dimpled all the holes.

I did not dimple the wingtip attach holes. Haven’t even thought about those yet.

After dimpling, I cleaned the skin, took it outside, and got it primed between rain showers.

Back in on the workbench, it’s drying.

I still like doing the blue vinyl stripe trick.

While the skin dries, I went ahead and deburred and dimpled the rear spar. I was so lazy when I did the inboard wing, I only deburred and dimpled the holes required to get that skin in place.


Then, I did the same deburr/dimple trick on the remaining spars.

You can see my conduit and wire-pulling string, also.

I guess this is another angle.

Okay, primer is dry. Let’s pull off the blue vinyl before getting the skin in place.

One bay.

All the bays. Man, those clean lines look good.

Oh, almost forgot to mention. Anytime you have a lap joint with two skins, don’t forget to use the edge roller to put a little kink in the edge. It helps lay the edge down when the two skins are pulled together.

My edge roller.

Here’s a good shot of how the skins lay on top of each other after rolling a bit of the edge.

Nice seam there.

After that, I didn’t think there was anything else before getting started. (I’ll come back to this.)

Getting the skin clecoed on.

After getting the first bay riveted, I realized I had forgotten to bevel the two skin edges like I had on the upper skins.

So, here’s my plan: leave it alone. The  amount it sticks up is minimal, and the bottom of the wing is less critical than the top (so says physics). I’ll either remember on the left wing, or do it the same so they are symmetrical. I’m going to go talk to our super-smart aero guys to see if there is any real concern.

After the first bay…

Then, with much straining, pulling, pushing, stretching, etc. I managed to get the second bay done, too.

To help you see what I’ve completed, I pulled the blue vinyl off where I’d finished.

It looks soo good.

Counting rivets, that two at the top is a “carry-the-two.”

So. 3.5 hours, 107 rivets. Not bad.

Taylor, get your butt over here so we can do some more.

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I Hate Drilling Stiffeners

August 15, 2011

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I’m still trying to nail down a good time for continued wing skin riveting, so in the mean time, more ailerons.

But first, a little taste of how I like to walk the dogs. Or rather, how they walk me.

In the same vein as last night, I’m not really a big fan of drilling stiffeners. Maybe it’s because I’ve done it on the rudder and both elevators, but it’s just kind of boring.

You can tell it’s boring by my lame pictures tonight.

After drilling some stiffeners, a boring picture.

Halfway through the 32 total stiffeners, one of my #40 drill bits broke. Boring picture.

I labelled each stiffener with the aileron (right or left), side (upper or lower), and then 1 through 8 from inboard to outboard.

After about 45 minutes of that, I decided a nice small (15 minute) task would be to knock out the edge finishing.

Did anything assist me in that decision? Yes.

A pretty bad cut on my knuckle from dragging it across a skin edge. Ouch. (So far, this project has cost some blood and sweat. I’m sure the tears are on there way…)

All the edges edge-finished, and some nice round corners.

Here are both aileron skins and the four piles of stiffeners, all matchdrilled.

I may be done with drilling stiffeners. Who knows.

1.0 Hours. I bet tomorrow’s post is called “I Hate Deburring and Dimpling Stiffeners.”

(Actually I don’t hate deburring and dimpling stiffeners. I can do it inside, where the A/C is nice and chilly.)

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Dimpled Right Upper Wing Skins

July 31, 2011

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Holy crap I got a lot done today. If you remember from yesterday, I forgot to attach a wire for the float fuel sender. Instead of ordering an appropriate sized wire, I used some of the only aircraft grade wire I had laying around, which was some 16 AWG. I know that is way too big (we’re just measuring a resistance), but it’ll work so I can install these tanks for the last time today.

Some people run two wires, but I checked the resistance through the tank, and I’m getting a nice solid reading from the tank itself, so here’s my one wire to the center conductor.

First official aircraft wiring. Done.

After reinstalling the tank, I held the wire to the negative lead and held the positive lead against a few different points on the tank.

All read between 38Ω and 240Ω or so, so I’m good.

Sweet. I don't have to unseal the tank to attach another wire to the sender body.

I’m flying through these skins right now. Pretty soon, I’ll have nothing left to do other than install the upper wing skins.

On tap for today is some dimpling and priming.

Here’s the inboard skin, ready for dimpling.

...on the nice vacuumed workbench.

Oh yeah, don’t forget your scarf joint. (A nice transition from the inboard skin to the outboard skin by the tank so there isn’t a big step.)

Looks good from this angle.

I also filed down the inboard side of the outer skin (the one I’m holding below).

Okay, this looks like it will work.

For some reason, you can see a little of the edge on the left side of the picture, but I didn’t notice this with my naked eye.

I’m very happy with it. It is a great transition from tank to skin.

I'm very happy with this.

After the scarf joint, I spent about 2.5 hours dimpling.

I've been using the male die on top with great success.

More dimpling.

After a little prep, I shot these with self-etching primer.

I sprayed them outside, then moved it back inside to dry.

For the outboard skin, I actually hung it inside-out on the wing.

More priming glory.

The wingwalk reinforcement skin.

And finally, the exterior side of the inboard skin where it will underlap the outboard skin.

3.0 hours of dimpling fun. All I have to do now is deburr and dimple the skeleton. Then, skin riveting!

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Finished Drilling Right Top Skins, Started Deburring

July 25, 2011

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So, while today is probably kind of boring for you…it’s exciting for me.

Why is it exciting for me? you ask…

Because I’m starting on the wing skins, and that means that coming up is some wing skin riveting, and that means that pretty soon, I’m going to have WINGS in my garage.

(Oh, also, I tricked the girlfriend into putting in some manual labor on the airplane. Ha. I’m so sneaky.)

First thing’s first. I ordered two new camera batteries. The one in the camera taking the picture says “12/09.” (Thanks, sister! Still one of the most used Christmas presents of all time! The one that replaced was the original from my Aunt Jan way back in 2002. Whoa.)

Now I'll never be out of camera go-juice.

Okay, let’s get on with it. A few days ago, I was clecoing on the top skins and realized that I hadn’t finished matchdrilling them. I think I only got half of them done. (I’ll go check my entries from then…)

So, back to 50% clecoed, and out came the air drill.

Okay, let's get to drilling.

After a loud 30 minutes of match drilling (“making loud noises”), I brought the wingwalk doubler and inboard top skin into the kitchen for some deburring and scuffing.

In the middle of deburring and scuffing the right wingwalk doubler.

After mucho mucho more cramping fingers minutes, I had some deburred and scuffed inboard wing skins.

Interior side...

...and exterior side.

Next up for these will be to dimple, then prime, then rivet to the wing (after prepping the corresponding ribs).

Before that, though, let’s get the outboard top skin done.

1.0 hour.

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Right Float Sender, Riveted Leading Edge to Spar

July 23, 2011

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Guess what? I worked on the airplane today, so the observant of you should realize that I am NOT on my way to OSH. Boo.

No use worrying about the spilled milk, though. More time for me to work on the airplane.

I need to leak test the right tank, but first, I have to finish sealing it up completely. Last post, I got everything sealed except for the float sender. Here’s the plans shot showing the sender, but it’s showing it mounted to the access plate. Mine will be the same dimensions, but entering from the rear of the tank in the second bay.

A couple 90° bends, and I'll be cooking with gas.

That was easy.

To install in the sender, you line up the plastic piece with the slot in the metal housing, and slide the float wire in.

Can't get any easier than that.

Now, let’s clean up and get this thing sealed in there.

Five #8 screws after swishing in some MEK.

After cleaning up a whole bunch, I put the rubber gasket in place with some sealant (couldn’t decide if I needed some or not), then put the float in, then more sealant around the edges, and some sealant for the screws.

Looks good to me.

I retested the sender and noticed 240 Ohms to 80 Ohms (I think I saw something lower before). That’s okay, my EFIS (Electronic Flight Information System) will calibrate the range of fuel levels based on resistance later.

Okay, that was about a half hour, and there are plenty of hours left in the day, so let’s move on. I think the next thing on the docket is to get the leading edge on the spar permanently. I have the leading edge landing light installed, and the tiendown bracket is good to go.

A changing of the plans picture…to the wing rivets and skins page.

Always fun to change plans.

After a few long minutes of getting the spar holes countersunk, I rubbed the scotchbrite pad over the length of the flange, cleaned up with MEK, then taped off to get some primer on there.

Ready for primer.

Sorry the light kind of precludes the primer from showing.

Okay, before I just start riveting the leading edge to the spar, I want to make sure everything lines up again. So, I want to put the tank on the spar, and the opposite skin from where I’m working.

Before I can get the tank on, I need to grab some nutplate for the inboard tank z-brackets.

Looks like AD3-4 and K1000-3 nutplates.

Here they are.

Done. I couldn't countersink very well along the spar bars, so I went a little light and used oops rivets on the very top and bottom (right and left here) holes.

Then I grabbed the outboard lower skin, and got it clecoed on.

Here's just the leading edge clecoed.

Then, I grabbed the tank and put screws in every 5th hole.

And a screw in every hole along the tank/leading edge joint. Everything lines up great and looks awesome.

I told you it looks awesome.

With the leading edge 50% clecoed, I decided it was finally time to show the FAA I’m really building this airplane. Sorry this awesome picture of a pre-squeezed rivet blocked the shot.

My visor says "Foxy's" on it. Anyone? Oh, and that rivet size looks appropriate, let's get to squeezing.

After 65 rivet squeezings, I had the upper leading edge skin riveted to the spar.

The leading edge looks so cool with no clecos in it.

After 65 more rivet squeezings, I had the lower leading edge skin riveted to the spar.

Oh man, I'm so excited.

GOOD DAY IN THE SHOP, high fives all around.

So….0.5 hours toward the tank. 2.5 hours toward the wings.

6 rivets for the spar nutplates, and 65 rivets each on the top and bottom of the leading edge. That makes 136.


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Started Banging Rivets on the Right Leading Edge

April 22, 2011

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Well, even though my last post said I was getting back into the mood of airplane building, it’s been almost a MONTH since I spent time on the project.


Anyway, I had a day off today, and I managed to spend a couple hours in the airplane factory.

Let’s see if I remember how to take and post picture.

After a little garage cleanup, I got the right leading edge out and got back to deburring all of the holes. I think deburring took about 30 minutes.

My hand hurt after deburring all of these. I need to deburr more often.

Once done, I took the cradles off the skin and opened her up to do some scuffing.

I haven't totally finished the leading edge light installation, but I can do that after the ribs are installed.

Then, I broke out the c-frame and started dimpling. This actually takes awhile, because you have to be careful not to punch any extra holes in the skin.

Even though I can reach these dimples with my squeezer, I think you get better, crisper dimples from the c-frame.

Here's me doing the forward-most hole in the top of the leading edge skin.




Well, after 242 hours, and thousands of dimpled holes, I finally joined the club.

To tell you the truth, it’s really not that noticeable, except for the fact that it is on the top of the wing (AND YOU’LL ALL NOTICE IT)!

Anyway, I used some flat sets and pounded it flat, then filed it down a little, and dimpled the primary hole.

Here's the extra dimple pounded flat.

And the orginal hole dimpled. still needs a little filing here.

I could throw a fit and order a new leading edge from Van’s, or I could just build on, and cover this with filler and paint.

(I don’t think I can polish the wings anymore.)

Well, in the interest of building on, I decided to do a little riveting today. I had a couple ribs prepped (my legend: R2 and R3), so I got them prepped, primed, and clecoed in place. (Making sure to cleco one rib on either side of those so the leading edge was perfectly straight.

Here are the ribs clecoed in place.

Of course, I use my normal tape-over-each-rivet-head trick to minimize scratches, dings, and marring.

I shot and bucked every other one (no mistakes) and then replaced the clecoes with rivets, moved the tape over, and finished the row.

(Needless to say, I started with the bottom of the leading edge, so any mistakes due to out-of-practice riveting wouldn’t be so obvious.)

Gratuitous shop head shot on the lower surface of the first rib.

Gratuitous shop head shot on the lower surface of the second rib.

Wash. Rinse. Repeat. (Crap, I meant flip, cleco, rivet, repeat.)

Gratuitous shop head shot on the upper surface of the first rib.

Gratuitous shop head shot on the upper surface of the second rib.

Umm, did we not have enough shop head shots today?


Here’s the “club” rivet. I think I’m going to leave it like this, and just watch it for cracks, but someone will probably tell me I need to drill this out and replace it with some other solution. We’ll see.

(big. depressed. sigh.)

Seriously, I need to control myself with this camera.

Oh, and I was having trouble counting rivets today, which was weird.

So I just started writing them down. Can you guys check my math?

3 hours, 58 rivets, 1 figure-8. Boo.

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Right Tank Work

February 26, 2011

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Oh man, I had a great day today.

I’ve been kind of slowly approaching the tanks on my project. I don’t have a lot of apprehension about tank sealant, but I want to close out a few things in other places before I venture too much further.

Nevertheless, I made some big parts (at one point I had a whole wing!), but of course, by the end of the night everything was disassembled. Having the tank assembled allowed me to do most of the prep work I needed to do.

At this point, if I want to, I could go back and finish the leading edge lights on the right leading edge and start actually putting the leading edge together permanently.

Of course, I could always go back and catch the left wing up to the right. But that would be BORING. (I’ll probably keep myself entertained with the leading edge and then go back to the left wing before setting up for tank sealing.

On to the pictures!

First thing, I bolted all of my right z-brackets to the main spar.

The girlfriend was napping, so instead of riveting the inboard nutplates to the spar, I just used some spar An365 nuts.

My best tool today was the 3/8″ power drive socket that came from a gift my girlfriend’s dad gave me.

I can’t imagine having done these by hand. 2 minutes versus 20 minutes, maybe?

I don't have a picture of the whole set, but it is a really nice Dewalt driver set.

Okay, with the z-brakets bolted to the spar, it’s now time to get the baffle in place with the tank skin.

Here's the baffle.

Then, I had an epiphany. A lot of people cleco the skin to the baffle, but then don’t really have a good way to clamp the tank assembly in place to accurately drill the inboard and outboard z-brackets. Some people try to clamp it really well, others will pad the tank assembly and try to use tie-down straps around the whole wing.

I read (and re-read) the instructions, and came across a step that simply says

Drill the spar attachment screw holes and the W-423 screw holes to final size using a #19 drill.

Well, I couldn’t find a reason not to do that now, so I grabbed my recently ordered #19 bits and got to work.

Here it is.

Then, I decided that I should just go ahead and dimple the holes. Can’t find a reason not to.

(Although now that I’m re-reading the manual, I see a statement in there that says to dimple the tank skins using a c-frame and a hammer. Oh well, I think the dimples look good.)

Here's s a dimple for a #8 screw.

And with a AN509-8R8 screw.

After that little test, I went ahead and finished the rest of the spar attach holes.

These should let me really solidify the tank in it's final position for all drilling. No messing around with tie-downs for me!

I cheated a little and didn’t assemble the middle ribs. I figured the two end ribs would be sufficient.

Things are looking big now. This is the top side.

And the bottom side.

Here’s a closeup of the #8 screws helping me align the tank.

This worked great.

There were a few places where things didn’t line up perfectly, but this difference (tank on the left, leading edge skin on the right) is less than 1/64″. I’ve way zoomed in on this next picture. I would call this basically perfect. Some careful edge finishing on the leading edge will line up these seams nicely.

I can’t even figure out how I would improve this if I wanted to, which I don’t.

Lining up pretty good. For reference, that is a 1/8" hole, and I think that step is about 1/10 of the hole. Multiplication tells me it's about 1/80." There's no way any of you will ever notice this on my plane.

Near the leading edge, the gap looks amazing. Remember, this is my macro setting on the camera. Those are all 1/8″ holes.

Great (lack of) gappage.

At the leading edge, I couldn’t figure out why I had a little step here. Again, this is really small, and I’m totally happy with it.

This small step is hardly noticeable.

So other builders will drill the inboard and outboard z-brackets (which requires removing the leading edge) then you have to remove the skin to get to the other z-bracket holes, then you have to re-install both the leading edge and the tank skin to drill the tank-to-leading-edge #19 holes.

Why not do them now? Everything is rock solid and perfectly aligned.

I first matchdrilled the #40 hole into the flange behind the prepunched holes, then I enlarged the hole to #21, then finally #19.

After that was all done, I moved on to the inboard z-bracket. Like everyone else, here’s a picture of me drilling the z-bracket holes.

I had to use the flash here because this side of the tank was in a little big of a shadow. (I bent the bit a little while drilling to make sure the hole was straight.

After drilling and adding a cleco (9 times), I had the inboard side done.


Then, I apparently took another picture of the whole wing because I was so excited.

It's so big (TWSS).

Then, I struggled for about 10 minutes trying to really gently pull the leading edge off without disrupting the tank alignment.

Turns out, the joint plate and leading edge inboard rib fit so well, the friction kept me from sliding it out.

I had to remove the inboard rib (and joint plate) from the leading edge to get it to come off.

Of course, Jack and Ginger are playing in the background.

Then, the same drilling drill (ha) on the outboard side of the tank.

One done.

Nine done.

Alright, let’s get the rest of these z-brackets drilled.

After removing the skin, I saw (bracket) metal underneath all of the baffle prepunched holes. That means I didn't reverse any of the brackets.

With my drill stop attached to my #40 bit, I drilled the 25 remaining holes.

It's nice to be at this point, I've been reading about this whole process on everyone else's build sites forever.

After pulling the ribs and baffle back off, I saw holes in all of my z-brackets.

Holes were right where they were supposed to be.

Don’t believe me? Here’s an example.

Notice how the holes are slightly off-center? This was exactly what I was expecting. See the “checkoway method” explanation on my previous post (about 1/3 the way down).

It feels good to see these holes exactly where I thought they would be.

Then, I deburred the holes I just drilled in the right z-brackets.

Z-bracket holes deburred.

That was about 3 hours worth of work. Great day, and the tank alignment was great.

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