Building the Xmas tree

Today was the day when I hoped to have something that looked like an actual piece of airplane to work on. Having spent a fortnight preparing all of the parts that would make up the Vertical Stabilizer, I thought that a full day in the shop (this being first time that I had a full day to devote to it) would be enough to get it all assembled. At a minimum, I wanted to get what I call the 'Xmas tree' built up. It's the framework that supports the skin of the vertical stab:

The first step was to radius the narrow ends of the VS-1204, VS-1205, and VS-1206 ribs. "As shown in figure 1," was the promise. As it appears is often going to be the case, the drawing doesn't convey nearly as much information to a novice builder as Van's seems to think it does. I know what it means to radius something, that being somewhat academic if you know what the word 'radius' means, but I wasn't sure how much material they wanted removed, or why it needed to be removed in the first place, for that matter. Once I took a look at the narrow end of the VS-1204 rib, though, I could see what needed to be done and why.

The "why" is that the process of folding the front of the aluminum rib over to form flanges on the sides causes the bent over metal to extend past the most forward part of the rib. It's hard to describe; a before and after picture might help:

The one one the left has not been touched. See how the side flanges extend past the front of the rib? That will cause problems when installing the rib flush against another part. In the case of a skin being formed around the rib, that problem would be an unsightly bump in the skin.

The one on the right has been 'radiused' (def - verb: to abuse with a grinding wheel) to remove the extra metal that would have caused the problem, The plans suggest that a fine file is a great way to remove the unneeded metal, and I'm sure it is. But a ScotchBrite wheel is even better:

The VS-1204 and VS-1206 were a piece of cake, but I ran into some confusion with the VS-1205. You see, it had a tab on the front, where as the VS-1204 and VS-1206 didn't. What's more, the drawing of the VS-1205 in the plans didn't show a tab either. After an unwarranted period of wondering how the plans could be so wrong, it struck me that maybe it wasn't the plans there are at fault at all! Could it be possible that I was looking at a part other than the VS-1205? Easy enough to find out: just go pull the blue vinyl that had been covering it out of the trash can and double check the identifying tag. Ah, mystery solved. I was attempting to work on the HS-1205. Makes all the difference!

With that mystery solved and all three of the ribs ground down to fit, it was time to 'flute' them. Surprisingly, this doesn't involve holding them up to your mouth and blowing across them to play Jethro Tull music. No, fluting means making little indentations in the flanges of the ribs to straighten them out. The bending of the flanges around a curved rib causes it to bow. Fluting the flanges takes up some of the excess metal to remove the bow. Again, it's easier to show than to explain.

This rib has not been fluted and you can see how the end of it bows up:

To flute it, you use fluting pliers (aptly named, eh?) to put small creases in the flanges. Here is the business end of the fluting pliers:

All it takes is a very light squeeze in the flanged part of the rib between each of the rivet holes. It's something that is very easy to over-do, but if you start small and just increase the flutes a little bit at a time, it's pretty easy to quickly flatten a rib:

I did one of them, and as I was patting myself on the back for a job well done, I realized that something was amiss with that rib: it hadn't been deburred. Why, you ask, would I have not deburred it? Well, I reply sheepishly, because no one told me to. You see, Van's figures you know that it needs to be done by this time and they figure that you don't want or need to be nagged about it. We're all adults here, right? I did two things: I sat down and deburred the rib, and I made a note for myself in the plans to remind myself in the future that I should deburr everything first:

It takes awhile to deburr those things! Maybe that's why Van's is so quiet on the subject - why be the bearer of bad news? You have to deburr all of the rivet holes, then the flange edges, and finally the edge around the lightening holes in the middle of the rib. As you can see in my note, I quickly realized that doing the deburring before fluting is a lot easier:

 

This drawing in the plans is interesting for another reason. This is the first drawing that I had to work on to see it in the correct perspective. When I first looked at it, I thought it showed the vertical rib from the front and the ribs attaching to it going diagonally to the rear of the picture. That made the flanges look all wrong, though, so I kept staring at it until I realized the it shows the vertical rib from the rear and the ribs attaching to it angling towards the front of the picture. Again, perspective it makes all the difference!

I was just finishing up the deburring when Co-pilot Rick arrived to provide some much needed QA inspecting and to provide an extra pair of hands in the building of the Xmas tree. It's hard to hold all of the pieces in place and rivet at the same time; it's been one of my biggest challenges. With him holding stuff in place while I riveted, it didn't take long to get the ribs attached to the front and rear spars:

Oh yeah, the box helped too.

 

Here it is all put together:

The time just flew by, and before I knew it, it was quitting time. With the skeleton built, the next step is to install the skin. That's a non-trivial job since there will be a lot of prep work required, but once it's done I will have an actual aerodynamic airplane part done.

Here's a preview:

It was a chilly, blustery, cloudy day today and would have been wholly unsuited to flying. In other words, it was the perfect day to have something fun and interesting to do in the basement. I'm loving every minute of this!

Saturday morning in the Schmetterling Design Bureau

I'm a morning person, but only as a result of being averse to a 35 mile drive in rush hour (such as it is in Columbus, OH) traffic. I've been getting up at 5:30am for so long that I don't even need or use an alarm clock. That's great, but only for five days a week. It's not so great on the weekends, especially since the rest of the household wants to sleep in, and they want it to be quiet as they do.

That gives me a lot of time on weekend mornings to find something quiet to do. For part of the year, I can watch Formula 1 racing on TV. For the rest of the year, it's a lot trickier to keep myself entertained. Today I sat down at the computer and played around with paint colors and designs again. I know it's way too early to give any serious consideration to it, but it's relaxing and fun.

I'm still leaning towards a retro scheme based on the air racing planes of the early 1930's. Today, the famous Roscoe Turner and his Gilmore-sponsored Wedell Williams Racer were the inspiration:

I didn't get the front of the stripe right (waking up early is one thing, being attentive to detail that early in the day is quite another):

Maybe I'll fix it tomorrow morning, but probably not.

Help! I don't understand the lingo!

The EAA provides very useful video tutorials on their web site. For your convenience, I have created a Video Glossary over on the right side bar.  For eBook readers, here's a link:

http://www.eaavideo.org/channel.aspx?ch=ch_hints

Installing nut plates

No, nut plates aren't those little trays you set out for guests to snack on when they come over on Superbowl Sunday. Nut plates are used to provide a replacement for a nut & bolt arrangement where the back of the piece being attached won't be accessible. Consider the parts that I've been working on for a week now. If you remember, I'm working on the back part of the tail fin to which the rudder will eventually be attached:

Once the skin is riveted to the frame of the tail fin, it will be impossible to get at a nut in there while the rudder hinge is bolted on. So instead of using a nut, we use a nut plate. The nut plate is permanently riveted in place, in this case by using small solid rivets. The smaller #3 rivets are much easier to squeeze than the larger #4 rivets that were used to build the rudder hinge assemblies, but to offset that they have the added complexity of being flush rivets. That means they sit flush against the surface that they are being riveted to. If you remember, they are able to do that because we used the countersink tool to clear away some material around the hole. Note that they aren't quite so easy that I didn't end up having to drill one out. It slipped up in the hole as I was squeezing it and didn't end up flush at all. Quite the opposite.

Here's what the flush rivets look like from the outside (when you do it right):

On the other side, deep under the skin, they look like this:

See how that works? Pretty cool, eh?

Here's how it will look when the rudder hinge thingy gets bolted on:

That will be years from now. I think it's one of the last things you do.

That's it for tonight. The next step involves rounding radii on some of the ribs that give the tail fin its aerodynamic shape, and once that's done they need to be fluted. I'll describe fluting when we get to it, but the point is that I'm going to wait until Saturday when the Certified Fluting Expert that I keep on retainer can make a shop visit.

Thou Shalt Commit Rivetry

I started out the night with some countersinking on the big old getting-tired-of-seeing-it vertical stab spar. Countersinking is done to provide space around a hole for a rivet head to fit down into so it will be flush against the skin. Imagine it as a very tiny toilet bowl. Or, just see if you can pick it out in this picture:

Four of the holes are countersunk. The big ugly black thing to the left of the metal is the countersink tool. It goes in the drill just like a drill bit. The bit is inside the black cylinder and comes out when downward pressure is applied. The amount of bit that comes out is set by adjusting the cylinder by twisting it in or out on the threads. You set it for any given job by testing it on a piece of scrap metal until a rivet sits flush against the metal when placed into the hole. With the precise adjustment made, the bit then works differently on every single hole you try to countersink.

Well, at least it does when I do it.

The countersinking of those holes was the last task before riveting that part (and its mirror image part) onto the spar. That was done with blind rivets. Blind rivets are nice because they don't require access to the other side of the metal as is the case with the solid rivets I squeezed in last night. That's not important with the spar I'm working on, but it will be very important later on when doing things like riveting skins onto wing ribs.

It's really pretty easy. The rivet has what is essentially a nail running through it. If you pull really hard on the nail, it will compress the rivet. If you pull hard enough, the nail will break loose and the rivet will remain in place.

Here's a before and after view of a blind rivet:

You can also see where I did some test holes to set the depth of the countersink tool.

It didn't take long at all to pull the eight rivets that would permanently attach those two parts to the spar:

This is the side that will be visible, so the "manufactured" rivet head is on this side:

This side will be inside the tail, out of sight forever. So this is the side where the "shop" head of the rivet goes:

All in all, a good night in the shop. Nothing broken, in other words.

Eight rivets down, 12,492 to go.

More firsts

More "firsts" tonight.

Last night, I received a welcome influx of high quality aircraft building tools from Co-pilot Rick so tonight I was able to really dive in and clear out some of the backlog of work. Sounds odd to "be behind schedule" already, but I've had parts waiting for deburring for lack of good tools.  Before moving on to anything new, tonight's first task was to work through the backlog. The ScothBrite wheel, some small files (which I already had but for some reason never thought to use), and a neat edge deburrer got everything cleaned up and ready to go in just about an hour.

I had primed the rudder hinges last night so they were ready to be riveted together, but I wanted to squeeze a few practice rivets first. I see on other bulder's logs that they just grab a piece of the scrap metal that came with their kit to test and/or practice with, but I can't figure out where they're getting it. It must be the lower number RVs that include that. With the -12 kit, the only spare metal I have so far is shavings from drilling and deburring, and I vacuum those up every night. I made a quick run to the hangar to grab some leftovers I kept from metal projects I did while I was taking a few A&P classes and brought those back to the shop to play with.

I'd been warned that squeezing #4 (1/8" diameter) rivets was tough, but the first practice rivet went fine. As did all but one of the ten that I needed to do to finish up the rudder hinges. The fifth one I did started to bend as I was squeezing it.



So, my fifth squeezed rivet was rapidly followed by my first drilled out rivet. Ain't that grand? Fortunately the drilling out of the bent rivet went easily and well. I'm sure there will be plenty more. Here are the completed rudder hinges:



With step one finally completed, I moved on to finishing up step two, which is match drilling all of those holes in the big spar that forms the tail end of the vertical fin and supports the rudder. Many, many holes to be drilled. It was here that I realized that I still don't fully understand the strange dialect spoken by Van's manual writers. One step said to match drill the #40 holes near the bottom of the part. The drawing helpfully showed that area, along with a tag that said "MATCH DRILL #40 - THREE PLACES."

All well and good, that, except for one thing: there are six #40 holes there. But... the holes could be considered to be in three pairs of two, if one were desperate to understand just exactly what one was being told to do. It's interpretive, see?

And that would have been just fine. I would have drilled the six holes and spent a night sleeping the deep, restful sleep of a man with a clear conscience. Except for one thing: the next step was to "MATCH DRILL 3/16" HOLES - FOUR PLACES." There were four holes. Arranged in two pairs of two. For consistency, one would expect that to be described as "TWO PLACES."

I drilled all four without compunction, but now I'm wondering about those doggone #40 holes!

It was nice to be making good progress again, but there were some moments that threatened to ruin my mood. None of them were all that big in and of themselves, but a series of minor annoyances can have a profound impact on your reaction if you were to (hypothetically, of course) do something as dense as dropping your drill on the floor and breaking your #30 bit. Just saying that could be the case, mind you. It's not like I could ever be that clumsy, right?

From the mail bag:

Brent said...

Looks like your squeezer is the main squeeze. That thing is crazy good. AD4 rivets are tough with a Tatco or avery squeezer, but the cam in the main squeeze makes it easy.

I actually prefer my main squeeze over the pneumatic squeezer.

DaveG said...

Brent -

Exactly right - it's the Cleaveland Tools Main Squeeze. At $400 for the squeezer and dies, I doubt if I would have bought it myself given the relatively low number of solid rivets in the -12, but I was able to borrow it from Co-pilot Rick. Good tools and good buddies willing to loan them out make it all sooooo much easier!

Good news and bad news about presumptive paint scheme #1

The good news? It was apparently a pretty good idea.

The bad news? It's such a good idea that's it's been done:

Does the fact that it's been done mean that I won't? No, probably not. I'd change the big 9 to a 12, though, and see if I could get double six dice to match the 12.

But still... people will always say "Hey, you copied Tom Sampson's paint job." The RV community is very small, you know. People talk. Pictures are gathered.

I still like the 20's air race motif, though, so I go to thinking about just finding something slightly different. Google proved reticent about offering me up a good selection of pictures to chose from, though. The only one I could find in any quantity and in color was a few small pictures of the Texaco #13:

Not much to go on, is it? But I did learn that the airplane is hanging in a museum in Chicago, and I'm looking for another excuse to got, after all. I could go get some pictures of my own. But Google is bottomless - I kept looking.

I found this:

The box in back is a model of a Texaco air racer. That thought got me to thinking...

thinking...

thinking...

Hey! Don't I already have one of those??

Well, yes. Yes I do!

The colors remain red and white, some decals would have to be made, and I think it would have to be "Texaco #12," but this will work for now as presumptive paint scheme #2.

When it's a good idea to disappear

It's the night of Co-pilot Egg's Homecoming Dance. The boys will be here soon for pizza and noise, but Egg and her BFF are currently flitting about making last minute preparations to their faces, hair, and dresses. It's a really good time for Dad to blend into the background.

As such, I played around with making a very rough draft of the paint scheme idea from a couple of days ago:

There on the tail where that nice script font says "Gee Bee?" You have to imagine that it says "Arr Vee," and that there is a "Twelve" underneath it in a block font. You also have to imagine that someone with more drawing skills than I have made that picture.

But even with my less than rudimentary drawing abilities, it's pretty cool, eh?

Evangelism

On any topic where there is a meaningful amount of room for opinions, you will eventually run into evangelism. For example, most people agree that 2 + 2 = 4, and anyone having a different belief is simply ignored. There simply isn't a lot of wiggle room in whether you believe that simple equation to be true or not. Subjects of any importance whatsoever are seldom (rarely?) as binary as the true or false proposition of mathematics, though. On any more complex subject, the strength of personal opinions will fall roughly into one of these categories: uncertain and don't care, uncertain and open to suggestion, certain but willing to tolerate other opinions, and so certain that no other opinion can or will be entertained. That final stage is what I define as evangelism.

There are three demographics that are well known for the high degree of evangelism in their ranks: the religious folk, the political junkies, and pilots. Get any group of pilots together (and by 'group' I mean two or more) and get them talking about flying (which is easy since that's all they will want to talk about anyway) and you will soon see that at least one of them is evangelical on at least one topic. Some of the more common are high wing vs. low wing, straight-in pattern entry vs. 45 degree entry on downwind, whether or not pilots that check in with a new controller by saying "with you" should be thrown into a pit filled with 1000's of rabidly hungry Chihuahuas, nose wheel vs. taildragger, and Lycoming vs. Continental engines. When it comes to people building airplanes, one of those evangelical topics is the question of whether or not to use primer.

There are two questions, really. The first is how much (if any) to prime the interior parts of the airplane and if so, what primer to use. On the prime-every-surface side are people that live in a corrosive environment, typically those on the coastal regions where there's a lot of salt in the air. The why-bother crowd are folks that live in dry, arid regions. Me? Well, I live on the coast of a corn field. It's not dry, but it's not salty either. That puts me in the group that generally think it's enough to prime parts that have had their alclad coating removed. We've already seen a part like that here at Schmetterling:



The inside part of those assemblies have had the alclad layer sanded off on the sides to smooth them out. I'll want to prime it.

Having decided that, the second question came up: prime them with what? Naturally, there are a dozen answers to that. Two-part epoxy and hours of preparation is at one extreme of difficulty, a spray can of self-etching primer from Napa Auto Parts after a quick wipe-off with some soapy water is at the other. The Napa spray can being on the easy side, in case you didn't figure that out on your own.

Here's what I decided on:



Anything else is overkill. Most of the 40+ year old Cessnas and Pipers you see at any midwest airport are not heavily primed and they're still going strong. In forty years, I'll be 88. Even with an LSA, I doubt that I'm still going to be flying or in the least bit concerned about the state of this airplane.

In addition to buying a can of primer, I also made a trip to Harbor Freight to pick up another mover's blanket. I'm going to be working on a part with all of the blue protective vinyl removed and I don't want to set it on an unprotected surface, especially one with so many protruding screw heads that could put a deep scratch into the vulnerable aluminum. Cost of the blanket? $4.99. Final tally at the Harbor Freight cash register? $42.

Cashier: "Did you find everything you were looking for?"

Me: "Yes, plus another $37 worth, thank you very much."

That happens every single time I go there.

After my morning errands, I picked up Wingman Ted, who is mid-way through building an RV-10 and his Co-pilot Wayne at the airport. Wayne is also going to be building an RV-10. They were looking for somewhere to fly and decided to come visit the Schmetterling Aviation shop. After a nice visit and lunch at BW3 (where I got to see the only good part of the O$U - Purdue game), I dropped them back at Bolton and headed back to the shop.

Today's job was to start drilling the holes in the spar cap I worked on yesterday. And again, there was a little head scratching. Basically what it came down to is whether the instructions that said MATCH-DRILL #30 THESE HOLES meant just the holes I have circled in red or if it included the blue holes too:



It's as if I'm learning the nuances of a new dialect. I understand the words, but their true meaning sometimes still eludes me. In this case, it was a simple matter to look ahead in the plans a few pages and definitively determine that I was to drill both red and blue.

The directions say that you should drill and cleco every fourth hole. That went well enough after the first hole. What happened on the first hole? Well, the bit drilled through the metal and then kept on going, right through the new blanket. The bit pulled a bunch of blanket material back up through the hole. Oops! After that I started putting a small plank under the part as I drilled it so the bit would have someplace less irritating to come to rest. The every-fourth-hole method results in a nice zig-zag pattern:



The next step is do the same on the other side. I can't do that as I am out of clecos. I could shuffle around the handful that I have, but the shop floor will be closed tonight anyway for spouse date night. It'll wait until tomorrow, unless the weather is nice for flying. My RV-6 misses me.

I read ahead a little bit and found that once the other side is drilled, it all gets taken apart for deburring and general clean-up. After that the directions say to "Match-drill the rear spar flange holes."

To which I said, "Huh? Wouldn't I have just done that?" After an embarrassingly long time thinking about it, I realized that no, no I hadn't. I had drilled the web holes. It's another example of that new dialect I'm learning. The 'web' is the wide part of the spar, the 'flanges' (there are two, actually) are the thinner, bent over parts. The sides, if you will.

I'm on hold now until Co-pilot Rick brings over some tools. He will be a welcome addition to the shop; my current assistant Hogarth really isn't all that into it:

Friday!

Although it was an abbreviated work week after taking Monday and Tuesday off, it felt like a full week. The first day back after even just a couple of days off is stressful as pent up demand for my services hits full force as soon as co-workers start coming in, but even after burning all of Wednesday getting caught up I was able to get some good work accomplished. I'm in the middle of at least a half dozen long- and short-term projects, but with only two full working days left in the week I concentrated on small stuff.

Even with only two days to spend I got two new customer-facing reports done, and the technology I'm using for these (Microsoft C# and Crystal Reports to programmatically generate PDF files, if you must know) is somewhat brittle so any progress at all is gratifying. These particular reports turned out very well, if I do say so myself, and I'm particularly proud of the one I did today. The one I did yesterday was mostly to spec, although a clever two-line approach for each data row that I came up with answered a thorny issue having to do with horizontal page space. The one I did today was my own idea, and although it used the same data as the other report, it presented it in an entirely new way that garnered a few of the "oohs" and "ahs" that IT folks just live for.

Somewhere during the half hour commute home I went through my daily transition from SME (subject matter expert) to VI (village idiot). In this case, the transition to "airplane builder" was especially jarring. You see, I'm very much still in head scratching mode. I look at the plans and instructions with the same level of comprehension my dog Hogarth demonstrates when he sees me perform what to him are the minor miracles of turning darkness to light and summoning forth water on demand.

So, here's where we're working:



The red ellipse is around the rear spar of the vertical stabilizer. You might also call it the tail fin. The blue ellipse is around the part that I worked on tonight, the VS-1212A Lower Spar Cap. The VS-1212A and VS-1212B come in one big part called the VS-1212. The VS-1212 has to be separated into the A and B components. That's pretty easy; I just cut them apart with tin snips and filed the leftover tabs off. The part that had me perplexed was this:



"Remove Area Shown Hatched" is pretty easy to understand, but what I didn't know was where to draw the line, so to speak. There were no markings on the part to show where to stop removing metal:



Once metal is removed, it's darn hard to put back on, so I wanted to think about it awhile! After staring at it for awhile, I decided that I could just use a straight edge to continue the slanted edge all the way down to the end of the part like so:



Then I just traced a line with a Sharpie marker:



Once that was done, it was just a matter of clamping it to the table and filing it down to the line:



There are a still lot of rough edges to be deburred, but I clamped it into place on the spar just to see if it looked reasonably right:



I'll either deburr it tonight or wait until tomorrow morning. Once it's deburred, it has to be drilled to match the holes pre-drilled by Van's into the spar. That should be pretty straight forward. I hope to have it done before noon when I will sit down to watch THE Ohio $tate Buckeye$ play the Purdue Boilermakers.

Is it too early to be thinking about the paint?

Well, of course it is!

Does that mean I won't?

Well, of course not!

I wonder if something like this would work:



I was only able to work for about an hour tonight, but not for lack of time; It was a tool availability issue.  I think I'm ready for a final brush-up and riveting of the rudder hinge supports, but I don't have a rivet squeezer quite yet. Sometime this weekend, I hope.

For tonight, though, I had to file away the "tabs" left from hacksawing the parts apart:





The filing didn't take long, but using sandpaper to smooth the edges of the parts did. Once that was done, the bearings had to be pressed into the sandwich and the assemblies clecoed back together:



I'm starting to remember why I like working with aluminum so much. It's so soft and easily worked that it almost feels like a very viscous liquid.

Into the abyss

I just couldn't put it off any longer: I had to make the first step. Sure, it was only one small step for man, and an even smaller step for mankind, but it sure felt important!

It really couldn't have been easier: find the VS-1210 and final drill #12 the eight 3/32" holes. Sounds easy, right?

Well, not so fast. Should I put it in the drill press and ensure a straight hole? I could do that, but I'd have to clamp the part down and if I got it aligned just a bit off center I'd end up elongating the hole. So, maybe I should just drill it with my nifty new hand drill. The bit would more or less correct itself if my alignment was off, but what if I had the drill at an angle? What would that do?? I finally decided that the hand drill was the way to go - the piece is so thin that any angular error would be tiny. Seriously, I stewed about that for an entire day! Sort of. I was at work and struggling to get caught up after a two day absence, so that took most of my available brain cycles. I stewed during the rare respites when someone wasn't after me to do something. I swear, some days I don't dare emerge from my office; they're out there waiting like lions hoping a hapless gazelle will walk by on the way to the watering hole.



Once the decision regarding drilling method was out of the way, I had to convince myself that the drill bit inhabiting the #12 spot in the box was, in fact, the #12 bit. Things may have gotten moved around over the years, after all. Ah, my aging eyes simply aren't up to the task without a significant amount of aid:



The actual drilling, while significant in that it was the first time tool had touched metal, was a bit (heh, "bit" - get it?) anti-climatic:



With the holes successfully drilled, we find that the VS-1210 is actually four parts and that they need to be sawed apart. No real tool selection decision to be made here: hacksaw!



Here they are, alongside a couple of other parts that arrived as one, but are now two:



These all get assembled together with a pair of bearings (yet to be found, but I'm betting they're in one of the brown paper parts bags) to form the hinge point for the rudder. But first they need to be fit together into assemblies and the holes need to be final drilled to a #30 size. Putting them together temporarily brought another momentous event: the first cleco:



One down, 100,000 to go!

Here they are, clecoed together, drilled, and ready to be taken apart again for deburring:



That's it for today. Now I need to decide whether or not to buy another bench vise and clean up these kinds of parts with a file, or spring for the $55 or so to buy a ScotchBrite wheel for my bench grinder.