Wow…between things becoming crazy at work, and getting some kind of stomach bug, it really has been 2.5 weeks since I touched this project.  Even today, I slept in pretty late in an attempt to recover from a long and stressful week at work, and then spent some time fixing up a side project of mine.  I did resolve to do something out in the garage today though…so I went out and got to work on the right leading edge ribs.

Deburring these things is tedious.  I’d already taken care of all the big edges previously with the bench grinder and die grinder, but all the little nooks and crannies need attention.  The leading edge/tank ribs in particular have lots of these, especially on the nose of the rib.  Oh, and the instructions say to pay special attention to this area to make fitting the skins easier.

I ended up figuring out a pretty decent method, using a couple of mini files and one normal one.  I’d use a mini flat file to hit up the small straight areas, then use a rat tail file to work the corners and such.  That still left the nose area a little rougher than I liked, so I ended up using a normal file to really work the nose area down and get it smooth.

I’m probably going overboard with this stuff, but better to do it right the first time.  Plus I just feel better about my work this way.

Wow, that actually went pretty fast.  After all that rib-straightening drudgery, it’s nice to be able to go out in the garage and really feel a sense of accomplishment in a fairly short period of time.  It helped that I basically had all my tools set up and ready to roll after my test piece from last night; I had one countersink cage set up with a #40 bit, adjusted for the flush rivets, and the other set up with a #30 bit, adjusted for the screws.  That let me basically just rock & roll through tonight’s work without a lot of the time-consuming trial-and-error setup stuff.  Very nice.

Anyway, last night I got about half of the rivet countersinks done on the bottom spar flange before knocking off for the evening.  Tonight, I went out and finished that flange, then flipped the spar around and did the rivet holes on the other side.  As I mentioned/planned last night, I then riveted a single nutplate in place and did a single test countersink for the screw, then put my tank skin substitute piece in place.  Perfect fit!

I got into assembly-line mode from there.  Basically, my procedure went like this:

• Insert a cleco into one rivet hole for each nutplate
• Lay a nutplate on top of the spar flange by each hole
• Use the previously inserted cleco to cleco each nutplate in place, aligning the other hole
• Drop a rivet into the second hole for each nutplate
• Go back down the line, pressing the rivet down while unclamping and reclamping each cleco.  This was my way of ensuring that the nutplate was well-placed.
• Squeeze the previously placed rivets
• Remove the clecos and replace with rivets
• Squeeze the other rivets
• Lay the spar down (for better stability) and countersink the screw holes

In this way, I riveted all 60 nutplates and did all the screw countersinking in under an hour.  Very nice.

Once I get the tank attach nutplates on the other spar, I’ll need to go back and prime all those countersinks, since the bare aluminum is now exposed.  That should work out nicely; I can easily get the other spar done this week, and have Saturday to prime the flanges.

In other news, I talked to Daniel Schoning this weekend, and it just so happens that he’s wrapping up his wings and will be done with his wing stands any day now, which he’s offered to give to me.  The only issue is that he had his stands bolted to his garage floor; between not owning this house and wanting to be able to move the wings around to keep the garage functional, that’s not going to work for me.  But he suggested just mounting them on a rolling cart of some kind.  I think it’s a good plan, and it’ll save me some fabrication.  His only condition was that I donate them to another RV builder when I was done.  I can handle that.

Started out today by doing some rib deburring.  Josie got about halfway through the main right wing ribs last weekend – just touching up the little nooks and crannies – and we’d left the stack sitting on the workbench.  I was planning on getting rolling on spar countersinking, which would require the bench, so I decided to just sit down and finish that stack up so I could get them back on the shelf for storage.  Man, if I thought the tedious repetitive stuff was done when I got the last rib straightened, I was wrong. (for the record, I thought no such thing, and I only mention it here for the purposes of rhetoric)  Just sitting there with a couple of needle files, filing, checking, filing, checking, filing… whew.

That done, I brought over the first wing spar and clamped it down on the bench.  Like other parts, the holes for the nutplates are undersize, so I started by reaming the rivet holes out to #40.  That was easy, but then I wasn’t sure about what size the screw holes needed to be.  I got out a #27 bit and drilled a test hole in some scrap, but found that wasn’t big enough.  On the other hand, the #21 bit looked too big.  I sure didn’t want to go hacking up this beautiful spar.  Then it occurred to me that I might not even need to drill those holes to final size anyway.  The procedure specified in the instructions is to rivet the nutplates in place, then use a #30 countersink for the screw hole; that bit will center nicely inside the threads of the nutplate.  Using this method, in turn, means that it’s not necessary to get the hole to final size for the countersink bit to center, since I’m not actually using a #8 screw countersink.

Of course, the screw still has to go through there, but it’s possible that by the time the countersink is deep enough to accept the tank skin, it’ll be deep enough that the hole is large enough anyway.  It was time to put together a test rig.  First problem: there’s no raw material in this kit that’s the same thickness as the main spar channel. But it turned out that the piece of angle aluminum I bought for aligning the trim tab was the perfect thickness…nice!  So I sawed off a section and proceeded to rivet a nutplate in place.  Then I got a piece of scrap sheet the same thickness as the tank skin and drilled and dimpled it for a #8 screw.  This is necessary to get the countersink right, since it accepts the dimpled tank skin, not the actual screw.  With a bit of trial-and-error, I had the countersink right, and wouldn’t you know…it was deep enough that the hole was bigger than the screw.  So after about an hour or so of work, I’d convinced myself that I didn’t actually need to find the right drill size for the #8 screw.

Here’s my little test setup.  Still need to get the countersink a little deeper; the skin piece isn’t sitting flush…

(I did, however, note that the screw holes in the tank skin are undersize…so I’m going to have to figure this out/get the right bit before too much longer…)

Finally, I went to work with the #40 countersink, working on the nutplate rivet holes.  I got through about half of those on the bottom of the spar before dinner arrived in the form of pizza delivery, which seemed like a good time to stop for the evening.  Tomorrow I should be able to get into a good rhythm, knock out the rest of the rivet countersinks, and then start riveting nutplates on.  Even though I went through those complex testing machinations, I think I’ll start by riveting a single nutplate and then countersinking, just to make sure that there’s not a hole size issue in the real thing.  Worst case, I have to drill out a single nutplate…no big deal.

Some of tonight’s countersunk rivet holes:

At this rate, it won’t be long before I’m riveting the skeletons together and hanging them on the yet-to-be-constructed wing stand!

Yep, sat down right after getting home from work and took care of the last ten before heading out for dinner.  I’m glad to have that behind me, though there’s stil the drudgery of deburring these things…oh well, a little bit at a time.

Luckily, I should only have to make up one more title like that.  I got through all the left leading edge ribs and four of the main ribs tonight.  That just leaves ten main ribs to straighten, and the mains actually go pretty quickly as compared to the leading edge/tank ribs.  It was a little brisk out on the garage, so I worked inside at the coffee table with Shawshank Redemption playing in the background.  I even recruited Josie to snap one of those “prove you really did build this thing” photos.

That’s it for the work summary, though I feel compelled to share a brief humorous tale regarding making assumptions.  I’m pretty sure I’ve mentioned here a few times the backordered parts from my wing kit, in particular the large number of tank attach nutplates, which represent a significant amount of work to be done on the main spars.  When I called Van’s back in April to check on my backordered parts, the impression I got was that they had my missing tank ribs and the nutplates for the stall warning kit, but not the tank attach nutplates; they went ahead and shipped what they had.

When that box arrived, I found the two tank ribs and a paper bundle.  I admired the ribs, and just stuck the bundle on a workbench somewhere.  Since I’m not planning on even using the stall warning kit (I want a real AoA system instead), I didn’t even give that bundle the time of day.  Since that time, I’ve lamented on several cccasions how I wished I could be taking care of those tank attach nutplates, blah blah blah…

Well, today I got a package from Van’s.  Finally, my prodigal nutplates!  I opened the package and found…ten nutplates.  I was expecting the 210 tank attach nutplates. I was quite confused.  A look at the inventory sheet revealed that these were, in fact, the stall warning nutplates.  Wait, then what’s in that bundle that’s been collecting dust for four weeks?

You probably guessed it.  It contained those 210 tank attach nutplates.  The stupid things have been gathering dust in the garage while I complained about not having them yet.

*sigh*

Finally, a good productive weekend day in the garage.  Things started out kind of rocky…when I started working on that first tank rib, I found myself right back in I-really-don’t-want-to-do-this-tedious-work land.  But eventually I just put my head down and kept at it, and before long I was rolling through ribs at a pretty good clip.  It seems there’s a pretty strong mental thing going on here.  It kind of reminds me of when I actually used to run.  The first five minutes or so, all I could think about was how much I didn’t like running, how I wanted to stop, blah blah blah.  In those five minutes, decided to stop was an easy decision to make. (fortunately, on a lot of those runs there was an, um, very encouraging Marine Gunnery Sergeant on my tail)  But once I got past that point, it was pretty easy going.  I got past the discomfort and just cruised.

Anyway, I guess the ribs are kind of like that.  I just have to plow through the initial unpleasantness, and once that’s done it’s almost a cakewalk.

All told, I got through the tank ribs for both the right and left wings today.  That just leaves me with the left wing leading edge and main ribs.  I expect to get those knocked out tomorrow.  Josie also came out and worked on deburring the ribs I already straightened.  I hit all the easy rib edges a while back with the bench grinder and die grinder, but there are still lots of nooks and crannied on these things that need attention.  This is more tedious stuff, but Josie says she actually finds the deburring to be kind of relaxing.  I’m more than willing to let her take care of that stuff.

My minor reward for being productive today was clecoing the right tank ribs to the tank baffle, giving a little preview of what the inner tank structure will look like.

Had a nice turnaround from my last evening in the garage.  Maybe I was just in a more productive state of mind or something.  Maybe it had something to do with hanging out with the Falcon RV Squadron guys over the weekend, which afforded me the opportunity to try out the front seat of an RV-8…which in turn afforded me the opportunity to look out over the nose and imagine nothing but clear blue sky out there.

Anyway, I digress.  Last time I did on tank rib and three main wing ribs in about an hour and a half.  This time I finished the rest of the right wing ribs – eleven in all – in less time.  I celebrated this milestone by performing another one of those completely-unnecessary-yet-totally-giggle-inducing temporary assemblies.  I got out the appropriate inboard skins and clecoed together the inboard wing section. (minus the spars, of course)

Stack of finished ribs:

Wing section assembly:

In addition to my motivational problems last time out, I think that there’s some technique making a difference here.  Fluting has an effect on the squareness of the rib flanges and vice-versa.  It seems that fluting tends to make the flanges bend outward a bit, which then has to be corrected, which in turn undoes a bit of the fluting, and so forth and so on.  I think previously I was maybe fluting too much, which caused the flanges to need extra tweaking, which caused the flutes to need tweaking…this time, I tried to start off fluting less than I thought I needed and creeping up on a good level of straightness, and I found that the flanges seemed to need less work to straighten up.

(or maybe I’m less of a perfectionist this time out, I dunno)

Ugh.  I don’t do well with tedious work.  Which is unfortunate, because this rib prep stuff really fits the bill.  I guess that knowledge is part of the reason I haven’t been out in the garage much lately, although I have been out of town the last two weekends, so that’s a kind-of excuse.

Anyway, today I actually managed to get myself out in the garage after work.  The tank ribs for the right wing seemed like the next logical attack point.  Hoo boy, are these things all kinds of wonky.  Definitely worse than the leading edge ribs…I’m guessing that since (I think) they’re thicker material than the leading edge ribs, they’re more susceptible to warping.  I worked on one of the things and got it mostly straight, but man, I just did not want to keep doing this stuff.  I went back in the house for a bit.

When I came back out, I decided that maybe what I should do is try something a little less challenging.  So I put the tank ribs aside and went with the main ribs.  I figured that since they’re less curved than the tank ribs, they’d be easier, and I could boost my sense of achievement.  Well, I guess they really are simpler, but on the other hand they’re bigger.  It seems a lot easier to put a twist in these things if you’re not careful while fluting.

Oh well.  I got three of them done.  Yep, 90 minutes in the shop, and a grand total of four ribs straightened.  Seems like it’s going to be a real grind getting these things done.  I’m probably like 15% done with these ribs so far.

Well, the CPR class after work didn’t happen today.  The class was sponsored by my office, but we’re in the news business, and the stuff up in Boston caused some technical problems with us.  Since most of the people who’d signed up for the class were busy handling that mess, the class was pushed to tomorrow night.  I’ll be honest…I didn’t really want to go work on the ribs tonight.  I think it still seemed like a big tedious task, and it was easier to just procrastinate.

But I didn’t do that.  I went out and got to work anyway, starting with the right wing leading edge ribs.  The process is pretty straightforward: bend the flanges to a nice right angle with the rib face, and flute the ribs to take the bow out of them.  I decided to take extra photos tonight to help document this process.

This is a shiny, new, untouched rib.  Notice how the center of the rib isn’t even touching the table due to the bow caused by the forming process.  This isn’t going to work; the rib needs to be straight.

Some work with the fluting pliers pulls the rib back in line:

The flanges are also frequently not square:

But a little work the hand seamers brings them back into line:

Of course, it gets a little more complex than that in the curved portions of the leading edge ribs.  See, fluting the flanges also tends to bend them relative to the face, and bending them tends to change the fluting job.  In practice, I found that the best procedure for the leading edge ribs was to flute first, then go back and bend the flanges square, then go back and fine-tune the fluting before making one final check of the flanges.

Josie came out and got some photos of me slaving over the ribs.  Bending flanges:

And checking squareness:

So yeah, 90 minutes and I managed to prep exactly six ribs.  The good news is that the leading edge and tank ribs should be the tougher part of this job; their curved profile means lots more distortion.  The main ribs should be comparatively easy.

After that tedious work, I decided it was time for one of those temporary assembly tasks that serves no purpose except to give me hope.  In this case, I clecoed those newly prepped ribs to the leading edge skin.

That’s it for tonight; maybe I can get to work on the right tank ribs later this week…

I’m a little disappointed in myself for not being very productive this weekend.  I did finally start getting my feet wet with prepping the wing ribs, but that seems like kind of a daunting task.

I started out today by riveting the remaining rear spar.  This kind of work I can roll on all day long…it’s straightforward and the results are obvious.  I did, however, manage to mangle my very first rivet, so I had to drill that little bugger out and replace it.  But I got the rest of the rivets shot, and that left me with the decision of where to go next.  I’ve really been putting off this whole rib prep thing, but as of that moment, there wasn’t anything else to do.

So I pulled out all the ribs and set them out on the workbench:

Step A was to deburr the edges.  For the long edges, I fired up the bench grinder and went to town for what seemed like an eternity.  Actually, it really wasn’t that bad, but it was definitely getting tedious already.  Next, I went after the lightening holes with a small scotchbrite wheel in my die grinder.  Side note: Extended use of the die grinder pretty much equals extended running of the air compressor.  It doesn’t take long with that thing to trip the pump, and apparently the pump can just barely outpace the die grinder’s air usage.

Okay…now what?  I still needed to work on the edges in all the little cutouts, like at the corners of the ribs and the tip of the nose ribs.  Problem is, most of those holes are too small for my files to get into effectively.  I think it’s time to invest in some needle files for getting into these tight spaces.  Okay…if not that…I guess I’ll start looking at straightening the flanges.

The intent of this operation is to ensure that all the rib flanges are at right angles to the rib face.  This will help ensure that the wing skins sit nice and flat.  This, along with fluting the ribs to remove any bowing induced by the forming process, seems to be regarded as one of the more dull and time-consuming tasks of the build, and I can see why.  I set one rib out, grabbed a small piece of aluminum angle to use as a square reference, checked the rib…hmm, this seems pretty good actually. I tweaked the flange a bit with the hand seamers to make it even better, but suddenly I felt like I wasn’t sure if I was doing this right.  The angle piece I was using didn’t really sit flush against the rib, and I was skeptical if its usefulness as a reference.  I just felt like I needed to do some reading on this subject before diving in.

I feel like this is probably some combination of generic do-it-right jitters with my procrastinatory nature.  Faced with a tedious task, I found an excuse to stop, go in, and do some research.  And then I found other things to occupy my time, such that I didn’t go back out in the garage again.

On the one hand, this is particularly annoying to me since my free time is limited in the near future.  I’m doing CPR classes after work three days this week, and the next two weekend are booked up with other activities.  On the other hand, maybe it’s better for me to attack this rib prep in small doses, instead of trying to bang out a ton of them over the course of a Saturday or some such.  At any rate, I’m just going to have to push through…at the end of the tunnel, I’ll have an assembly that looks like a wing skeleton.

Which reminds me, I’m going to have to build my wing racks at some point here too…