Monthly Archives: January 2015

Starting the wings!

I finally got started on the wings today.  Section 13.

Most of the previous sections started with something mundane like cutting apart and deburring a couple of parts.  Not Section 13!  No, it has you cut some raw j-channel, bolt it to your (expensive!) spars, and then drill away!  The instructions are pretty clear, but I must have read through them a dozen times trying to make sense of it.  It is easier with the spar and j-channel in front of you.  I measured several times to get the right length.  Be sure to cut the large stiffeners from the 8′ sections and the small stiffeners from the 6′ sections.  A couple builders cut the small ones from the 8′ ones and had to order new angle.  Not expensive, but time consuming.  So, the upshot is that you cut two long pieces (for each spar) and two short pieces.  The total length is a bit more than the length of the spar (not an issue, these parts don’t really go here, you are just using your spar as a very expensive hole spacer).  The overlap is in the middle.  I used clamp cleco’s to hold the angle in place.  You need to ensure that the j-channel stands 1/16″ proud of the spar edge.  A real pain.

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The illustration doesn’t depict the overlap very well and I didn’t find another builder log with good pictures.  It looks like this:

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On the bottom edge, the overlap occurs where you aren’t supposed to drill anyway.  On the top, I did the large piece, unclamped it, and then did the small piece.  It seemed easier and more consistent than trying to manage the nested parts.

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Here’s the top edge of the left spar.  You can see the gap where the nut plates go and you don’t drill.  Be careful to note that the DO NOT DRILL section includes one hole BEYOND the nut plate.  I would drill a couple holes and add a cleco.  Drill a couple more and add another one.  It was monotinous!  And the compressor was running a lot because the drill uses a lot of air (much more than the rivet gun) (and because I have a small leak in the connection).

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In the end, you get 4 parts.  These have to be labeled carefully because top and bottom look very similar.  And there will be a left and right version of each (when I finish the next spar).  This is the left W 00009A upper stiffener.

 

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You pull the stiffeners off and set them aside (used in a later section) and then drill the remaining #40 holes.  That went really fast and didn’t use nearly as much air as the match drilling

Next week:  The same thing with the right spar!

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At the tail end…

I finally got started on the top-most skin on the rear fuselage.  This looked really hard to do solo.  So I talked my son into helping (it only cost a trip to the hockey skate shop and a lunch at the local Chinese restaurant).  I thought about just bucking the rivets with the fuselage on it’s side, but with two people I worried that it would be hard to co-ordinate.  I know one other builder (working with a helper) did it with a back riveter, so we tried that.  I padded the ground, and we lifted the fuselage down.  I padded the inside with moving blankets so I wouldn’t bend or crush anything.

 

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I was on the inside with the back rivet gun.  My son was on the outside with the back rivet bucking bar.

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It only took a couple hours and we were done!  I’m skipping sections 11 & 12 for now.  I think it will make the eventual move to the hangar (and Chicago!) easier.  So for now, it is the biggest item on the trophy wall.

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Next up!  The main spar and the wings 🙂

 

Unusual attitudes…

I’m getting very close to the end of the tail cone build… I started it just one month ago, but I’ve put a lot of hours into it!

The last steps are to mount the top sides and top skin.  This gets hard because the fuselage is so big at this point and it’s getting hard to reach everything.

I got a bit of build time in on New Year’s day… a great way to start the year!  The shop was a little cold though!

 

I had enough time in the afternoon to deburr, dimple, and prime/paint the side skins.

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The piece is very big and some of the reaches are hard to get to with the curve and the j-channel.  I used my reduced diameter dimple die and worked carefully around the channel.  It was awkward, but I was able to do all of it without a helper.  With the pieces dimpled, it was time to prime and paint.

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I came back in on Saturday for a full build day.  I had some fix up work to do before embarking on the skin riveting.  I opted for flush screws for the rear cover plates.  I didn’t read ahead in the instructions carefully at the time and neglected to see that I needed some different nut plates and screws to do this.  I ordered some from Van’s (their nut plates are cheaper than the other suppliers) right before Christmas.  They got here on the Friday after New Year’s.  I also needed some new pop-rivets for the rudder guides (I put the rudder cables in backwards… an easy fix at this point!).  So I went about installing those pieces.  I was able to get all 16 nut plates with my longeron yoke.

I finished the edges on the cover plates and marked them (on the inside and the blue plastic).  They are not symmetrical!  There is a left and a right and a top and a bottom.  Be very careful if you decide to do the flush option as you get one chance to dimple correctly!

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With the catchup work done, it was time to attach the top side skins.  These skins are almost 8 feet long and really very awkward.  However, once I got one cleco in, the rest of the holes just lined right up.  I really like these kits!

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I contemplated how to do the riveting here.  I know that one builder (with a helper) back riveted the whole thing.  I didn’t think I could convince my normal helpers (wife/son/daughter) to come out in the cold, so that was out.  I thought about moving the assembly to the ground and to then reach in, but that didn’t seem workable (and I didn’t think I could safely lower the tail cone to the ground by myself).  I ended up tipping the fuselage on it’s side.  This gave me plenty of access to all the rivets.   This puts the fuselage in a unusual attitude (a knife edge turn perhaps!).

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I was able to reach and buck all the rivets with ease.  I had pre-marked the spots that got 3-4 and 3-4.5 rivets so I would remember to switch sizes.  It went so well  on the left skin, that I spun the fuselage around and started the right skin!

My trusty bag of AN426 3-3.5 rivets that seemed impossibly full when I started finally gave up the ghost and ripped.  I transferred the remaining rivets to a small bin.  The wing uses mostly 3-3 rivets.  It’s like saying goodbye to an old friend!

I almost got all those in, but it was getting late and it was snowing.

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So I just did a quick back rivet job on the top skin and called it a night.  The job was a bit too quick as it turned out.  The j-stiffener didn’t seem right when I riveted it in place.  It didn’t fit well and didn’t turn out flush.

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So I snapped another FAA-selfie and called it a night…

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The j-stiffener still bothered me and I figured I would work it out the next day… …and I did.  I sat bolt upright in bed at about 7am and realized that I had forgotten to dimple the stiffener.  That explained everything.   It also meant that I had 20 some odd rivets to drill out.  All but one came out nicely.  I stayed very centered on most of the heads and they snapped right off.  You can see the neatly centered holes and the rivet stems with a nice clean edge.

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One rivet didn’t come out so well.  And I cut my finger tip trying to swipe away some aluminum shavings (I forgot to make our family’s daily invocation – “We don’t have any time for a trip to the emergency room!”)

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Not a big deal.  I clecoed it all back together (after dimpling this time!) and reamed the hole out to 1/8″.  Then I put in an “oops” rivet.  The head is gold instead of silver, but that will be hidden by paint.  Almost indistinguishable, even on the inside.

With the top (re-) done, I clecoed it in place.   I also built a big (8′ x 3′) shelf to hold the tail cone when it’s done.  It fits nicely above the crate holding the wing parts.  I’m very close to getting a new trophy on the wall!

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The first revision of the instructions left out a step to rivet the top skin stiffener to the forward bulkhead.  It is in the revisions (and in the gotcha’s list).  Even if forgotten, it is easy to fix later. I was able to reach inside and squeeze 3 4-4 rivets in the holes to finish it off.

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While I was in there, I reattached the static line to the static port.  It had previously pulled out of the hole and I reapplied the recommended gasket compound.  However, it pulled out again.  Sigh.  I’ll try JB-Weld and see if that holds better.

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I think I need a helper to rivet the top-most skin on.  The reaches are very long otherwise.  I might be able to make it, but it will be so much easier with some help.  So I went home and cooked a nice dinner for the family (teriyaki pork medallions, pickled vegetables, quinoa, and red wine poached pears.  Very tasty!).