Tank attach angles

Well, we had quite a day out here. We decided to run down to the beach with dogs and make a half-day or so out of it. Unfortunately, things got interesting on the way home – the car overheated. Seems I have a bit of a cooling system leak somewhere. I managed to make it home without any more overheating, but at the cost of driving with the heater running full blast. In the Houston summer heat. Actually, it wasn’t that bad on the highway, except for my feet getting thoroughly cooked. I now know that this car’s heater is tremendously effective.

Anyway, by the time we got home, I was tired again and I took a nap. Then it was finally out to the garage, where I got to work on the T-405 tank attach angles. I’m glad I decided not to try to do these last night; they weren’t terribly difficult, but there was a lot of time-consuming “how should I do this…” along the way. If I’d put some time pressure on myself to finish it last night, I might well have messed something up.

First, the chunk of angle gets cut to the rough length of the attach piece:

IMG 2057

One side gets a symmetrical round profile, while the other is shaped to fit inside the nose of the inboard tank rib. I used one of the reinforcement plates as a pattern for this. Here’s the cut line I made on the first angle:

IMG 2058

Roughly cut to size in the bandsaw. I did a fair amount of vixen file work to fine-tune the shape, but I can’t remember if this photo is before or after I did that:

IMG 2059

Then it’s over to the bench grinder to remove all those nasty tooling marks and make all the corners nice and smooth:

IMG 2060

The second angle went a lot quicker, mainly because I could just use the first one as a pattern instead of having to carefully lay out cut lines. Here’s the pair:

IMG 2061

These will eventually get drilled to the tank ribs, but that will wait until I can get the right wing caught up with the left. Weather tomorrow looks good, so provided my local Napa has a good stock of 7220 primer, I can finally get those right wing ribs primed and then work on riveting that skeleton together.

I also took some time tonight and read through the instructions for the capacitive fuel sender kit. I can see that these tanks are going to take some time; there are lots of little details that have to be attended to. Fuel senders, access holes, vent lines, caps, drains…fun times!

Posted in Fuel Tanks, Wings | Hours Logged: 2.5

Tank stiffeners

So I had a good little mini-vacation this past weekend. I even got in a little flying while I was in Raleigh, doing an Arrow checkout up there. I’d hoped to be able to take my niece up for a flight, but unfortunately the weather on Monday and Tuesday wasn’t agreeable. While I was gone, my shipment from Van’s came in, in a nice wooden crate, which Josie got to manhandle into the house by herself (sorry babe). Wednesday night, I moved the crate into the garage, opened it, put everything away, and then tore the crate down. Hooray, more scrap wood! Then I took the rest of that night and last night off.

Tonight I decided to make all the tank stiffeners. These will be attached to the bottom skin between the ribs to provide, well, stiffness. After all, each of these tanks will hold 21 gallons of fuel, which weighs 126 pounds! The stiffeners come prepunched, but they’re also attached together into long strips that have to be cut to size using notches for reference. I finally learned my lesson here after making stiffeners for the tail: I removed the blue film before I cut the stiffeners to size. Much easier to remove the film from four long pieces than from 48 short pieces.

After a lot of work with the snips and a sore right hand, I had a pile of scrap pieces and a larger pile of very rough-edged stiffeners:

IMG 2052

IMG 2051

Then it was time to spin up the bench grinder to clean up the edges. I gave that grinder a workout tonight – I probably ran it for about 40 minutes straight. When I was done, I had a bunch of nice smooth stiffeners:

IMG 2053

I was about 90 minutes into the evening at this point, but I didn’t quite feel like quitting, so I decided to look at fabricating the T-405 inboard tank attach angles. These get fabricated from raw angle and attach to the nose of the inboard rib on each tank. There’s also a reinforcement plate that goes on the inside nose of the inboard and outboard ribs on each tank. Since the attach angles are made to fit the contour of the nose rib, it seemed like a good idea to clean up the reinforcement plates first to use as a guide/pattern. So I broke them out, removed the film, and fired up the bench grinder yet again to take the corners and tooling marks off. Very nice:

IMG 2056

From here, I found the piece of raw angle that the T-405s are fabricated from. I briefly considered getting started on them, but it was getting late by this point, and I was a little worried about cutting corners if I decided to try and make them tonight. So I went inside instead; I’ll probably do the attach angles tomorrow. Actually, now that I look at the weather, tomorrow looks clear. If I can restock on primer tomorrow morning, I should take advantage of the good weather and get the right wing ribs primed. Maybe I can get the right wing skeleton riveted this weekend too. Right now the right main spar is living on the workbench because I don’t have a good place to store it. It’d be nice to have that whole workbench back…

Posted in Fuel Tanks, Wings | Hours Logged: 2

Right wing rib deburring

Just did a short stint in the garage tonight. My main goal right now is to get the right wing ribs to a point where I can prime them the next chance I have. So tonight I pulled the right skeleton apart, deburred everything, and undertook the tedious task of peeling off the little stickers that identify the parts. But now when I have a good weekend day, all I have to do is take them out back, clean them, and prime away.

I guess from here I’ll work on some of the small items for the tanks; some of those I can work on before the right tank is together, like the nose rib reinforcements and so forth (actually, the stiffeners would be a good target item here too). I also got a ship notification from Van’s today, so either late this week or early next week I should have my replacement skins and other stuff.

Also, a side note: I’ve been kind of dreading the upcoming messy task of sealing the tanks. A couple nights ago, a ran across a discussion on VAF about working with sealant. Rick, who apparently has worked on some big military projects, has some sealing techniques that are different from the Van’s instructions, but sound much less painful and messy. I’m glad I found that discussion, because I intend to use those techniques, and hopefully I won’t end up hating ProSeal as much as most people.

Posted in Wings | Hours Logged: 1

Fitting left tank, right wing skeleton drilling

So when we left off yesterday, I’d victoriously dropped the fuel tank onto the spar, only to find that the joint plate was too wide. As such, the first order of business today was to fix that. First off, I measured the gap with the tank slid as far outboard as possible; this way I could tell what the minimum amount of material to remove would be. Turned out to be a hair over 1/8”. After removing the tank and measuring the exposed joint plate, it turned out that I needed to remove enough material to leave 11/16” of an inch showing. Which is – surprise! – exactly what the instructions said in the first place. Though, in my defense, the wording was something like “there should be 11/16” instead of “make sure there is exactly 11/6”.

Whatever. So I went ahead and marked a cut line all the way around the plate:

IMG 2032

I’d spent a bit of time mulling over the best way to make this cut, and I eventually settled on just using the snips. The downside of the snips is that they leave a rough surface that needs a fair amount of cleanup, but about the only other method I could think of was to use a Dremel cutoff wheel, which is just annoying and imprecise. So I pulled the plate off and went to town with the snips.

it was a long and tedious process; the plate, after all, is something like four feet long, and with it being curved, that just adds to the fun. By the time I finished the cut, my hand felt on the verge of cramping. Now I had a nasty rough edge, so I broke out the vixen file and went to work. This, too, proved to be difficult, as there wasn’t much of a good way to clamp the curved plate, so I ended up just holding it in one had while I filed. If this sounds iffy, good call. In the course of the filing, I learned that a vixen file will remove skin just as effectively as it will remove aluminum.

Finally, I had the thing cleaned up, and I finished it off in the bench grinder for a nice edge. All told the cutting, filing, and general cleanup took me almost an hour.

So I put the plate back in place, put the tank back on, and all was well. Now the tank sits nice and tight against the leading edge:

IMG 2034

With that done, it was time to drill the tank attach brackets. With the tank slid over in place, I put a couple of ratchet straps around the wing to hold the tank nice and snug:

IMG 2033

The inboard bracket is drilled first, because, well, it’s the only one visible. These holes are kind of nerve-racking to drill, what with the spar right under them. I used a drill stop for all these holes, and I checked the thing about every five holes to make sure it wasn’t coming loose. Soon, the inboard bracket was drilled:

IMG 2036

Next, the leading edge assembly comes off to reveal the outboard bracket, which can then be drilled:

IMG 2037

And finally, the clecos between the tank skin and the baffle and outboard ribs are removed, allowing the interior brackets to be drilled in place:

IMG 2038

Since I don’t really have anywhere to store the leading edge and tank assemblies, I just put them back on the spar for now. Then, I decided it was high time I got to working on the right wing, so I clecoed the right skeleton together and got it all match drilled. About this time, dinner showed up, so I decided to call it a night.

I’ll be out of town next weekend, so I guess the next opportunity to get the right ribs primed will be two weeks away. I suppose I’ll get them deburred this week so they’ll be ready to go when I get some good priming weather. In the meantime, I can work on some of the common tank pieces – there are a number of things to fab up, like stiffeners, mount plates, fuel lines, level sensors…yeah, no shortage of things to do.

Posted in Fuel Tanks, Wings | Hours Logged: 5

Left tank attach brackets, tank fitting

Technically, I did a little work last night, but not enough to merit writing an entry. All I did was go out and finish stapling the carpet onto my C-frame table thingy, which took maybe half an hour. I also placed a nice-size order with Van’s on Friday: replacements for my damaged skins, replacement tank brackets (plus a few extra for good measure), tank sealant, and a few other sundries.

Today, I set out to redeem my bracket mangling from out last outing. First up was to drill the inboard bracket (for the third time). This time I got the center hole where it was supposed to be, squared the bracket to the spar, and drilled the other two holes. Nothing to it when you actually use a good sharp drill bit:

IMG 2023

Next up I drilled the center bolt hole in the other six brackets for this wing. To help to this in a consistent fashion, I only measured the first bracket before drilling, and then I set up a little arrangement on the drill press table so I could quickly drill the other five brackets:

IMG 2025

I’m leaving this in place for when I get the replacement brackets next week; at that time, I’ll go ahead and drill the six outboard brackets for the right wing as well. Might as well go ahead and get them done, even if that skeleton isn’t together yet.

From there, I went down the spar, bolting each bracket in place and drilling it using the spar holes as a guide. The work went fairly quickly, although it left a large amount of metal shavings in my previously spotless wings:

IMG 2026

Oh well, that’s what the shop vac is for. Next, the outboard brackets get drilled for nutplates. There are nice little jigs out there for drilling nutplate mounting holes, and I hear they’re nice, but honestly, I didn’t find it to be too tedious at all to just use the nutplates as my patterns. I picked out three nutplates to be sacrificial, since I’d be bolting/unbolting them many times. This let me set up each bracket and drill all its holes in quick succession:

IMG 2027

Next I gave all the brackets a good deburring, both the holes and edges (the edges were pretty rough). Then I countersunk the opposite face for the flush rivets, since this side will sit against the spar. Finally, it was out to the back yard for a good cleaning and priming. I masked off the bracket face that will attach to the tank baffle; this will get a coat of sealant, so the primer would be counterproductive to getting a good seal there.

Here are all the primed brackets in place, ready to be bolted on for tank fitting:

IMG 2029

Now it was time to cleco the tank assembly together. This was a real chore; the leading edge is tough to get together, but the tank skin and ribs are made of thicker material, and it takes a fair amount of force to get some of this stuff into alignment. Oh, and I ran out of silver clecos while doing this, and had to kind of ration the things to get everything together. Guess it’s time to order some more.

But finally, it was all together and it was time to set it on the spar and see how everything fit. And it’s hard not to cackle when you see this sitting in your garage:

IMG 2030

Except there was one problem. Back when I was doing the leading edge joint plate, I found that I had more plate sticking out than expected, and I was worried about it interfering with the tank rib, so I moved it outboard a bit before drilling. The good news is that my concerns were well-founded. The bad news is that I still have an interference problem. This is as far outboard as the tank will go before the rib makes contact with the joint plate:

IMG 2031

So I’m going to have to trim that joint plate now, which will be a bit of a pain. Since the plate is bent, I can’t just run it through the band saw. I guess I’ll probably have to remove it, draw a guide line, and trim the thing with my snips.

I’m kind of glad I’ve held off on the right wing skeleton. On the one hand, if I was doing these tasks on both wings simultaneously, I could probably go a little faster by combining tasks. But on the other hand, I’d be making mistakes like this twice. Now, when I do the right wing joint plate, I’ll know better than to fudge the specs.

Posted in Fuel Tanks, Wings | Hours Logged: 7

Tank attach angles, C-frame fixture

First order of business today was simple: drilling the skin hole for the tiedown attach to full size. I actually skipped a step a while back that’s relevant here; the plans tell you to draw a couple of lines on the bottom skin that intersect at the center of the tiedown attach bracket. Then, when you set the leading edge in place, you’re supposed to use those lines to determine if the prepunched hole in the leading edge is located correctly. Well, I forgot about those lines until I’d already pulled the bottom skins off. Whoops.
But it’s actually pretty easy to check the location of that hoe otherwise. First off, there’s a gap between the skin and the attach, so you can see in there a bit; it appeared that things were aligned OK. To double-check this even more, I found an Allen wrench that fit in the skin hole, inserted it, and angled it until it hit the edge if the hole in the attach bracket. In this way, I could look at the angle and pretty effectively determine if things were OK, and they were. Si I busted out the Unibit and drilled the hole up to 3/8”. I don’t have the tiedown eyes, but I screwed in a carriage bolt to check the fit, and it looks great:
IMG 2018
Then it was on to the tanks. Now, somehow I got the idea in my mind that tonight I’d be setting the temporarily assembled tank on the spar and looking at a whole wing-shaped object. That was…a bit optimistic. There’s a good bit of work that has to be done on the tank attach angles first. I dove in headfirst with the inboard angle. This one is different from all the others in that the bolts go in from the forward side and screw into nutplates riveted to the spar, wheres the other angles have nutplates riveted to them, and the bolts go in from the back side. I started with the inboard one because this is where I riveted those nutplates ahead of schedule, and I wanted to go ahead and find out if that was a mistake.
First, I laid out the spot for the center bolt (of three) and drilled it to full size on the drill press. Then I bolted the angle in place and squared it against the spar bars. Since I’d be using the nutplates as a guide, I’d have to drill the other two holes undersize at first and then enlarge them in the drill press. The first problem was picking the right bit. #30 was kind of small, and didn’t fit the nutplate very well; not good for precision. #19 was too big. So I busted out my cheap drill bit set (MISTAKE) and went with a 5/32” bit. I wrapped it in a layer of blue tape to hopefully avoid messing up the nutplate with the bit.
Somehow it never occurred to me that I’d be drilling these holes from between the wing walk ribs, a rather narrow space. I had to hold the drill really awkwardly, but I got it in place and drilled the first hole. Then I removed the angle from the spar, drilled that hole to full size, and bolted the angle back on with those two holes. Repeat for hole #3, and…immediately I could see that the holes weren’t straight. The angle had apparently moved while I was drilling hole #2, probably because that crappy drill bit was taking forever and I put some extra pressure on it.
Drilling through the nutplates wasn’t the direct cause of this, but it was clear to me that my from-the-hip solution wasn’t helping matters any, so I went ahead and drilled out all three nutplates. I grabbed a fresh attach angle, intending to try the inboard one again, but this time I misdrilled the first hole, such that I couldn’t even get a socket on the bolt to put it in place. ARGH
I was pretty disgusted with myself, so I abandoned the tank stuff for the evening and decided to work on something else: building a table for the C-frame. I got away without this while doing the tail, but it was kind of a pain. I feel this will be a necessity for dimpling the big wing skins. I picked up and cut the lumber over the weekend, and it’s just been sitting around waiting to be assembled.
Here’s the assembled frame. I built it such that the C-frame can be placed in any one of three spots, for extra flexibility:
IMG 2019
I started adding the carpet on top, but it was getting late and I was getting tired, so I quit after just putting one of the three panels on:
IMG 2020
I guess tomorrow I’ll try the tank attach angles again, or I might just take the evening off and try to think through this problem a little better. I’ve got to place an order with Van’s soon anyway; I think I’ll just go ahead and order a bunch of extra attach angles. I doubt they’re expensive at all.

Posted in Fuel Tanks, Wings | Hours Logged: 3

Left leading edge joint plate

My goal for tonight was to get the inner leading edge rib and the joint plate drilled. This position is where the leading edge and the tank will meet; the W-423 joint plate is what hold the two together. This joint plate will be riveted in assembly with the inner leading edge rib, and the exposed edge will have nutplates mounted, which the outer edge of the tank skin will attach to. The fun part is that neither that inner rib nor the joint plate are predrilled. The even more fun part is that the rib flanges face outboard, so they’re not exposed with the leading edge together.

So what has to happen is this: the rib is slid into place inside the leading edge skin, aligned, and the rear flange is drilled in assembly with the main spar and clecoed into place. Then the joint plate is weaseled into pale between the rib and skin, everything is aligned carefully, and the holes are drilled. The tough part is that with the rib flanges out of sight, there’s no real way to get direct feedback about whether the alignment is good.

To start with, I wanted to prebend the joint plate to make it easier to slip into place. The easy way to do this seemed to be to just bend it around the rib itself. First I did a rough check to compare the joint plate length to the length of the rib flange. Turns out there’s a little extra:

IMG 2008

Because I’m a little OCD, I had a strong desire to have the same amount of material overlapping the rib flange on both sides. So I measured that overlap above, cut it in half, and made an alignment mark. Next, I drew a layout line 1/2” from the edge of the joint plate. This line will align with the skin holes to help me set the depth correctly. Then I went to town clamping the plate to the rib:

IMG 2009

IMG 2010

This didn’t really have a huge effect on the plate; only the area at the leading edge of the rib really had any plastic deformation. Still, better than nothing. Next up, time to slip that rib in place and drill the main spar holes. Those holes sit really close to the main ribs aft of the spar, so space is kind of limited. How to deal with this? With an absurdly long drill bit, of course:

IMG 2012

I triple-checked alignment between the skin and the rib, added a clamp just as insurance to keep everything in place, and did my drilling. Nothing to it:

IMG 2013

Okay, now to slip the joint plate into place. This is where it gets fun. I painstakingly got the plate aligned, then ensured the rib was in place too, tapping to and fro with a mallet. The fun part is that moving the rib tends to move the plate and vice versa, so there’s a bit of tail-chasing that goes on here. Finally I had things straight, and I went around measuring another time just to be sure. But there was an anomaly – according to the instructions, there should be 11/16” of joint plate exposed for the tank to mount to. I had more like a full inch. It seemed like a small amount, but if it interfered with the tank rib, that would be A Big Problem.

To check the fit, I grabbed the inboard tank rib and a Z-bracket, clamped them together, and held them roughly in the spot where they’d live. It was hard to be certain, but I felt that there might well be some interference. So I decided to move the joint plate outboard a bit; instead of having my layout line in the skin holes, I shifted it until it just disappeared. This still left me with some excess joint plate, but only by a couple sixteenths. Once again, I measured, re-measured, measured again, etc. Finally, there was nothing to do but to start drilling.

I wasn’t too worried about accidentally hitting the spar, but I used a drill stop just for good measure. I started with the aft most holed on the top side, drilled, clecoed, re-measured everything, drilled a couple more holes. clecoed, re-measured, and so on all the way to the rib tip. Then I went around to the bottom side and repeated the whole thing. I was pretty obsessive about re-measuring to make sure nothing had shifted.

Finally, all the holes were drilled, and it was time to remove the clecos, pull the rib and joint plate out, and see if I’d violated edge distances anywhere:

IMG 2014

Oh boy…nervous…don’t want to have ruined parts…oh boy……..Whew! Everything looks great. If anything, the holes are a little close to the rib face; they’re definitely nowhere near too close to the edges:

IMG 2016

That’s it for tonight. Tomorrow, I’ll be moving on to the left tank. I’m continuing to put off right wing work because of another thing I want to settle. Back when I was riveting the left skeleton, I went ahead and riveted three nutplates that will mount the most inboard tank attach bracket. Well, I realized there’s a reason to leave those nutplates off; the tank attach brackets are not predrilled, and have to be drilled using the spar as a guide. I’m confident I can do this effectively with the nutplates in place – all it should entail is drilling the brackets to #30 in assembly, then enlarging the holes for the AN3 bolts. But I want to test that procedure before riveting the left wing skeleton, so I can make an informed decision on whether to rivet the same three nutplates ahead of time there too. If I have problems on the left, I can leave the nutplates off and not waste time.

At the rate I’m going, I’ll probably end up finishing all the basic tank fitting on the left wing before moving on to the right. Meanwhile, I’ve got an order list going for Van’s. Come to think of it, I’ll have to make that order before I can really get going on the right wing, since I need to replace the two skins that got ruined in the move. I guess I should go ahead and order the Proseal for the tanks too. I’ve been holding off on that since the stuff has a shelf life of just a few months. Better to wait until I’m  close to doing the tanks, which I think I am now. I figure I might be ready to start sealing those SOBs in the next few weeks.

Posted in Wings | Hours Logged: 1.5

Match drilled bottom left skins, started on leading edge

After taking the dogs for a walk in the arboretum this morning, it was out to the garage in the afternoon to do lots more match drilling. I didn’t realize it at the time, but I was suffering from my first building-related repetitive motion injury. I woke up this morning with an odd ache in my right wrist, like I’d slept on it funny or something, but that didn’t seem right. I forgot about it quickly and moved on with my day…until, just before match drilling, I decided to add a couple clecos to help alignment in some spots. As soon as I squeezed the pliers and tried to twist a cleco into a slightly-undersized hole, that ache made perfect sense.

Anyway, I went to town on the bottom skins and got them all match drilled, and then removed the bottom skins and put them back in their storage stand. The top skins stay clecoed on for the duration, but the bottoms come off to allow access inside the wing. This was a straightforward procedure, so I don’t have any photos of it, but I would like to point out an unsung MVP of this whole process:

IMG 2004

I got this little rolling work stool from Harbor Freight, and it’s worth its weight in gold for working on the wings. Much better to sit and roll along instead of hunching over or something. I actually have two of these stools…

The next item is the leading edge, so I put the skin in the nice little cradle I have and started clecoing. This is kind of a challenge, as the skin is mostly bent to shape, but not quite, and it ends up taking some force to pull everything in alignment before inserting clecos. Better yet, the leading edge is large enough that you can’t really put a cleco in the front outside and still reach inside to wiggle a rib around. It wasn’t a horribly frustrating endeavor at all, but a bit tedious.

Then I set the whole assembly on the spar and clecoed it in place. I also began to realize that riveting the spar connections for this thing is going to be interesting. I can barely even reach inside the leading edge assembly to touch the rivet holes, and someone is going to have to hold a bucking bar in there. Whee!

Here’s the wing with the leading edge clecoed in place:

IMG 2006

The next thing to do will be to work on the inboard rib for the leading edge. This rib, for whatever reason, isn’t predrilled. There’s also a joint plate that goes between the rib and the skin; the outboard edge of the tank will attach to this plate. The plate has to be fabricated, set in place, and the whole assembly drilled, while maintaining alignment and edge distances. I gather from other build logs that this has been a difficult task for several people. So I’m going to do some reading and research before I jump into this task.

It was about time for me to come in, have dinner, and give my parents a call anyway, so I quit for the evening.

Posted in Wings | Hours Logged: 4

Match drilled top left wing skins

Very productive day today. I picked up where I left off last night with the wing walk doubler. The basic procedure here is to lay the doubler in place under the skin, and then use the skin as a drill guide to drill all the holes to the ribs. I put a piece of my scrap MDF on the bench top to drill into, and used a drill stop to ensure I didn’t drill right through that MDF. The nice thing about clecos is that you can merrily cleco aluminum into the wood underneath it. In this case, I lined up the doubler and initially clamped it in place with cleco clamps. Then I drilled a couple of initial holes and used those to cleco the whole works to the MDF. That gave me alignment so I could remove the clamps and finish drilling the rest of the holes.

I totally meant to get a picture of the finished doubler, but I forgot and all I have is this photo of the skin clecoed down over the doubler:

IMG 1966

From here, it was time to cleco all the top and bottom skins in place and match drill them. But first I wanted to see if I could rearrange the camp holding the inboard main spar to the wing stand. I did some tinkering around here, but never did come up with a good idea. I tried just clamping one side of the spar, but that kind of torqued the whole assembly and in general wasn’t going to be conducive to building a straight wing. I was getting a bit frustrated, just about resigned to having a clamp in the way for the foreseeable future, when suddenly an absurdly simple solution came to me. You see, the bolts that hold the horizontal pieces to the stands go all the way through the upright. All I had to do was switch the horizontals to the outboard side of the upright.

All that worrying and frustration, and I ended up solving it just by undoing and replacing four bolts. *sigh* Now I had plenty of room on the inboard end:

IMG 1967

Better yet, this made it far easier to get the wing set up securely. Ever since I found out I made the bases too short, I’d always been looking at the stands with an attitude of “well, I can work around this.” That is, I knew it wasn’t right but I figured I could make do. Now, however, the setup is really and truly right. I can clamp the inboard end down securely, and instead of tweaking things manually to remove twist, I can use the adjustable horizontals and make a truly repeatable setup. Basically, this made me very happy, even if it did mean having to go through the whole routine of leveling the setup, checking for twist, taking the sag out of the spar, etc.

Finally, time to start clecoing the skins on. This isn’t an especially complex procedure – there are four skins, two top and two bottom, plus the wing walk doubler. The main deal is there are a lot – and I’ll repeat, a lot of holes. Even clecoing only every fourth hole or so, I used about 75% of my silver clecos, three coffee cans worth. (I think the coffee can is the official unit of measurement for clecos. You can count them, but that’s way too much work.)

I asked Josie to come out and grab some photos of me actually working on the wing, which is what you get to see now.

IMG 1970

I had a helper come out for a bit too. Astute observers will note that I’m scratching his nose with one hand to distract him so I can place the cleco with the other:

IMG 1986

And then I was done with the top skin, and there were two dogs, and there had to be a photo op:

IMG 1990

OK, on to the bottom skin. But first, here’s a photo from the bottom. The shiny stuff on the left is the wing walk doubler. See, I told you I made it!

IMG 1996

OK, now to really put on the bottom skins. Let’s start with the inboard one. Oh wait, something’s wrong here. Argh, the bottom inboard horizontal arm interferes with the skin! And here I thought I was done modifying these stands… (The skin is supposed to align with the rib visible to the left.)

IMG 1999

After mulling over this for a bit, I decided to just replace that big piece of angle with a smaller piece from some scrap I had lying around. These pieces are just held in with self-tapping bolts, and they don’t go all the way through the upright. Oh, and they’re long enough to account for those 2×4 blocks. Rather than go run to Home Depot for shorter bolts, I made a little wooden spacer so I could reuse the bolt I had. Excuse me? Ghetto? The term is “redneck engineering,” thank you very much.

IMG 2000

Anyway, where was I? Oh yes, clecoing skins. Back to that. Another half-hour or so, and the bottom skins were in place:

IMG 2002

OK, time to bust out the drill and reamer and get to match drilling. I started with the top skins. The fun thing here is just how much things scale up from the tail kit. After feeling in danger of a hand cramp from the cleco pliers, I moved on to my right index finger getting tired from squeezing the drill trigger over and over and over and over again. And my arms were tired from holding the thing up. I can’t imagine trying to do this with, say, a heavy cordless drill (though the air hose presented annoyances of its own).

Eventually, the top was done, and it was getting on to about time for dinner. At first I was going to break for food and then match drill the bottom skins, but we decided to watch a movie instead, so that was the end of airplane work for Saturday. Tomorrow I can finish the match drilling, then move on to the leading edge and tank stuff. But at some point I should get to match drilling the right wing; that way I can take advantage of the next good weather weekend and get that thing primed and then riveted together.

 

Posted in Wings | Hours Logged: 5

Wing walk doubler, misc stufff

Short day in the garage today. I had originally planned to go fly a bit today to stay current, but I fell victim to the notorious fuel-injected Lycoming hot start affliction. I couldn’t get the Arrow started to save my life, and after about five tries, it didn’t even want to turn over. I took mercy on the starter and gave up at that point. I then learned that they’ve been having hard start issues with the plane anyway, and it was going to get new mags installed that very afternoon. So I gave them an extra couple hours to work on that and saved myself a couple hundred bucks. On the way home, I stopped at Home Depot and bought some C-clamps and plumb bobs so I could finalize the left wing on its stand.

Back at home, after goofing off for a bit, I got to work. The first order of business was to finalize the clamping arrangement for the inboard main spar. I had just put some of my quick clamps on for a temporary fix, but now the C-clamps I bought would do the job. But first I needed something to pad between the clamps and the spar reinforcement bars; I don’t want to mar up those beautiful pieces of work. Some scrap wood from the H-stab moving fixture worked great, but only after I drilled some shallow holes to fit over the big shop heads on the spar.

Once I got to clamping, though, I realized things were going to be tight. The bases I made for the wing stands are barely long enough to fit the wings, a problem that annoys me greatly. You see, when I first sketched out those bases, I figured that the lengthwise pieces should be 120” long. This was especially convenient, since I could just buy 10’ 2x6s and not have to cut them. But then I reviewed my plans before I got to building, and somehow I convinced myself that 120” might be too long for the spars, and so I cut each piece down a couple inches. So basically, I second-guessed myself for no good reason and actually created more work out of it. *sigh*

Anyway, thanks to that little bit of stupidity, things are pretty tight on the inboard stand. The clamp kind of has to sit in this position, which is going to put it in the way when I’m skinning and so forth:

IMG 1962

However, after reviewing the plans, I see that the fuel tanks sit a bit further outboard than the skins, so I think I may be able to flip this clamp and get some better working room. But I discovered that towards the end of the night, so I’ll wait until tomorrow to test that theory.

Next task was to put the plumb bobs on strings and hang one from the main spar on each end of the wing. Then I could measure the distance from the string to the rear spar and ensure that I had the same measurement at both ends, and in turn ensure I wouldn’t build any twist into the wing. I was actually a bit surprised by this, as I found about a 3/16” difference with the skeleton hanging naturally. So I did some adjustment of things before clamping the skeleton down fully, and now it’s nice and square.

IMG 1960

Now, what to do from here? My original plan was to start working on the right wing skeleton; I could go ahead and cleco/match-drill the ribs, then deburr and try and get everything primed this weekend. But the weather has been spotty lately, with frequent afternoon storms and showers, and since I prime outside, that’s a bit of a problem. I decided instead to move forward with the left wing. The general path from here on out is to fit and match-drill the wing skins, fit the leading edges, and then move on to the joyous world of fuel tanks and Proseal.

First though, a wing walk doubler must be made. This goes under the main wing skin on the inboard part of the wing; this is where people will walk while getting in and out of the aircraft, so some extra structural strength is needed here. This is also one of those parts of the project where Van’s does not give you a nice prefab, prepunched piece; you get to cut these to size out of a larger sheet. And since the finished product is relatively large (9 3/8” x 26”), it’s too big for me to cut stuff on the bandsaw. Time to break out the snips

This led to an amusing farce during which I was looking at my three pairs of snips, trying to remember/figure out which was which: straight? left? right? ARGH. Well, straight was easy to figure out, and I’m making a straight cut, so I’ll just use those. It wasn’t so bad once I just got to work. After rough cutting with the snips, I attacked the edges with the vixen file to smooth them and shape to the final size, and then all the edges got cleaned up on the scotch brite wheel. The next step is to clamp this in place on the inboard wing skin and use the skin as a drill guide, but it was getting late by this point , so I knocked off for the night. As such, all I have right now is a rectangular piece of sheet. Holes will be forthcoming:

IMG 1963

Side note: the little strip of aluminum I cut off with the snips curled up into an amusingly consistent spiral. It actually looks kind of cool. I should save these and sell them as modern art sculptures or something.

IMG 1964

Posted in Wings | Hours Logged: 3