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!).

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