Monthly Archives: February 2014

Now I know why it takes so long to build an airplane… (VStab continued)

I spent President’s Day in the shop this week and made a lot of progress fitting the vertical stabilizer skin to the skeleton.  It went together fairly easily despite a warning in the instructions that you might have to play with the rib/spar alignment to get it to come together.  The nose ribs were the hardest to get right.  The radiusing helped a bit and then just a tiny straightening of the rib flanges finished the job.

The matched hole job is astounding.  Everything fit together very nicely.  As I added each cleco, everything pulled together.  I found that giving each one a tiny wiggle as I worked through the line, ensured that I had a tight and aligned fit against the ribs.  The nose ribs’ front hole is not prepunched, so you have to drill it through yourself.  I had to use a couple cleco side clamps to pull the rib flange close to the skin to get an accurate hole.  After a bit of finagling, I got the whole thing clamped together.

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You can also see the score lines where I used a soldering iron (rounded off tip!) to melt through the plastic along the rivet lines.  This leaves most of the protective coat in place to keep from marring the skin.  I’m going to paint, not polish so a few scratches won’t be a problem, but better to keep it as shiny as possible.

The next step was pretty easy.  I just had to match drill all the holes on both sides.  This meant removing a cleco, drilling the hole, and replacing the cleco.  Lucky for me, I’m a little bit ambidextrous, so I was able to pull the cleco with my left hand whilst running the air drill with my right.  It went pretty fast.  I had a drill stop on the bit to make sure I didn’t push the hole through the other side!

The new air compressor worked well, but it was so cold in the garage (15-20 F) that I had to use a heat gun to preheat the compressor block to make sure the oil wasn’t too viscous.  With 11 gallons of air @125PSI, it was able to do most of the holes (drill was running at 40 PSI).  I had to recycle the compressor once to top it off at the very end.

Then the instructions ask you to do the most depressing thing.  Take it all apart!

You need to remove the burrs and chips that inevitably get made as you drill.  I also need to smooth the edges (to remove areas where cracks can start), prime, and dimple for the flush rivet heads.

I didn’t get a full day in on the next Saturday.  I went flying instead (a bit gusty, but good to get up again — the weather has been awful for flying), had a nice lunch with the wife (important to keep her happy), and helped a friend pack and move.  Despite all that, I did manage to get a couple hours in the shop.

The first point of order was to unclamp and prep the skin.  I started pulling clecos out and pulling of the plastic.  I had to deburr the holes.  I’ve ordered an adaptor so I can run a deburring bit in an electric screwdriver, but it didn’t arrive yet, so I’m hand deburring for now. You move the tool from hole to hole, slide the guide pin in and give it a gentle turn.  The interwebs are full of stories of people pulling too much metal off.  You just need to pull the slightest amount to remove the rough edge.  Here’s a picture of me tipping the tool into one of the 100+ holes (both sides!) that need deburring in the skin.

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I’m priming, so the entire inside coating has to come off.  Some of the ink from the coating comes off on the skin, but when I prep it for priming, it will come right off.  I’ve done this one as a selfie since the common wisdom indicates that the build log should show that I built it myself rather than contracting out the fun.

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The skin is awkwardly large, so it is hard to final polish the edges.  I tried using the scotchbrite wheel on the bench grinder, but it was too difficult.  I was sure to mangle the skin.  In the end, I used my smooth file (and the bastard file for a couple of rough spots) and a piece of scotchbrite pad to polish it out.  In the end, the edge has a bit of a “wavy” feel, but at least it is continuous and differentiable rather than piecewise smooth (math joke).

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I was tempted to prime the skin, but I ran out of time.  I always make my mistakes in the last 10 minutes of a session, so I opted to wait.  I did, at least, get a chance to check out my paint warming system.  The primer does not go on well when it and the metal are below freezing.  I bought a cheap hot water bottle and heated some water in the microwave to make a little hohlraum (physics joke) for warming the rattle can and my rivets.  I suspect at least part of my squeezing problem lay in trying to drive them at 10 degrees F.

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Next up: Priming and dimpling the skin.  Deburring, smoothing, and priming the ribs/spars.  Countersinking the spars.  Then riveting it all together!

 

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Working on the vertical stabilizer

After my drill out problem with the vstab’s forward spar, I backed up and redid the two messed up parts.  Van’s support said that I would be OK with a relief rivet drilled and countersunk next to the original hole (with a caveat of carefully checking for cracks on each condition inspection).  For $30, it was easy enough to order replacement parts and try it again.

So the forward spar was easy enough to assemble, but the rear spar has a lot more going on.  It has a beefy doubler plate running about 2/3 of the way up the spar.  It also has 3 sets of hinges to install.  I got everything lined up and cleco’d together and then did the match drilling.  This was pretty easy, but with my good air compressor offline (I just returned it and will get a 20 gallon replacement model), I was using my 2 gallon oil-free compressor.  Oil free is nice because it is low maintenance and cheap, but it makes up with it by being incredibly loud.  I was wearing my ear protection the whole time, but it was still noisy.  Probably angering the neighbors!  I’ll have my new compressor online soon.

 

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The hinges are in identical pairs.  The arrows will help me remember (literally) which way is up!  Here, the hinges get match drilled through the hinge, the doubler, and the spar.  Not much metal removed, mostly just enamel that leaked into the hinge when it was painted.  I’ll give the hinge a quick spray of primer to cover the bare metal inside when I get around to priming.

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The plans ask (rather quietly) to radius the flanges on the nose ribs.  This is to avoid faceting where the skin stretches over a sharp bend in the flange and kinks.  I used my bastard file and a fine file to taper down and radius out the edges.

 

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The basic skeleton is fit together with cleco’s.  A careful observer will note that the tip rib is upside down! (I fixed it after the picture was taken).    The next steps are to final drill the rib attachment holes and to test fit (and drill) the skin.  This is a little tricky because there are several holes that will not get rivets at this step (to handle fiberglass fairings that go on later).

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After the test fit, there is still *lots* to do.  I will need to take everything apart.  Finish the deburring and dimple all the holes for the flush rivets.  And I need to prime all the interior parts (and the inside of the skin).  Then the fun begins!

 

The first rivet

I finally got into the workshop to build in earnest…  But before I could dig in, I had a few nagging tasks left over to finish.  Here’s my dimpling station.  It’s at a convenient standing height and I can do large sheets with it.  I kept the 45 degree angle so I can do the bent sheets like the vertical stabilizer more easily.  The carpet should keep the skins in good shape.

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With the side show out of the way (I still have to fix one of the overhead lights, but I’ll wait for a warmer day (20F today) when I can open the garage door and not freeze to do that), it was time to actually think about building!

The first step was to dig out all the parts for the vertical stabilizer.  I pulled some of the parts out during inventory, but had trouble locating some of the other parts.  The VS-0401 was hiding in a bag labeled “miscellaneous parts.”  That one I found quickly enough because I read about someone else’s travails in finding the part.  I had more trouble with the hinges, parts VS-410PP, VS-411PP, and VS-412PP.  I combed through the 10 pages of inventory sheets, but couldn’t find them.  They were in bag 1901 labeled “empennage hinges”.  Duh!2014-02-08 10.42.05

The instructions start innocently enough.  Cleco on a doubler plate, do some match drilling.  The next step though, is to trim the VS-702 front spar.  I bought a Ryobi band saw at Home Depot last week in preparation for the aluminum cutting.  The experienced builders at the workshop last month said that a bandsaw made it all so much easier.  So, I had to take a break and set that up.  I used one the “Hints for Homebuilders” tips to cut through the spar with a wood backing piece (the wood cleans the blade of aluminum chips after making the cut).  It worked like a charm.

I deburred and  smoothed the spar and plate.  The last step on the first page is to rivet the plate on.  Time for my first rivet!  I had to prime the mating surfaces before doing that, so I sprayed on some green self etching primer.  It was a rough go with the cold.  I’ll have to bring a warming box of some sort in the future.  I set up the squeezer, and voila!  The first rivet went in.

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It was nearing the end of the day, but I wanted to push on and get the rest of the plate riveted.  Five of the six flush rivets went in fine.  I bungled the last one.  Alas, when I drilled it out, I made a figure-8 hole.

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Not sure what the best course of action is.  I’ll post on VansAirForce and ask Vans directly.  It’s either no big deal, or I’ll have to make and replace the double plate.

 

 

Empennage inventory

The first kit arrived three weeks ago, but I hadn’t a chance to actually dig into the contents in any way.  The first weekend, I was at the EAA workhop, then last weekend I was out working on my IFR rating.  I really wanted to have a block of time (that also wasn’t bitter cold) to work through and find all the myriad pieces in the crate and get them organized.

So, yesterday, I got that chance.  I finally moved most of the aircraft tools out the factory.  I also finished up a tool cart and most of the DRDT-2 dimpling station.  It was funny, I still hadn’t touched any of the parts in the crate sitting in the middle of the garage as I worked around it.  It was almost as if I knew once I touched a part, I would be committed to the action of building.

Finally, after a quick lunch with the wife, I dove in.  The biggest part of the problem is where to put everything as you take it out.  Most of the small parts were headed to a cabinet that the bike shop left behind in the garage, but the skins and spars are huge!  There was also the reams and reams of paper to deal with.  I read horror stories of small parts buried in scraps of paper that get discarded, so I carefully unrolled and checked each of the many sheets of packing paper.  I didn’t find a single part, but I guess it pays to be careful.2014-02-01 14.37.06

I think this is because Van’s now packs parts into what it calls “sub-kits.”  These are bunches of semi-related parts that are artfully fit together into a compact  bundle.  They are wrapped in plastic sheet and tucked into a corner of the crate.

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It would have been nice to keep them snugly wrapped, but I needed to verify the inventory within 30 days and I wanted to check for part damage and I worried about moisture getting trapped inside the plastic wrapping.

So I carefully opened each bundle and worked through the parts.  Since the inventory sheet was also organized by sub-kits, it made it a lot easier to find all the parts to check them off.  This was extremely helpful since scanning 5 pages of similar sounding names for E904-1-R is a real pain.

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It took about four hours to get through the entire inventory. I was hoping to use the crate as a storage shelf, but in the end, I pushed it up against the wall and left it on the ground to hold all the skins and spars.  I pulled out the spars and doubler for the vertical stabilizer (the first part of the build) so I could get started on them during the next session.  You can seem them on the table in the left of the picture below.

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There’s still some garbage to sweep up and the dead light (above the ladder) to replace and the dimpling station to complete and a couple tools to set up, but I’m really close to actually starting.

Still a lot of work to do before I actually squeeze that first rivet, but it’s about to get very real!