Flap deburring, pushrod fixup

After giving myself a day to think about it, I decided to go ahead with the idea of filling the remaining rod ends with epoxy. The main thing that had kept me from doing this last night was worrying about the rivet holes. I didn’t want to totally fill the rod ends and then have to drill those holes again; to me, that was just asking for a misdrill and who knows what kind of ugliness.

So the plan I came up with was to basically cast the rivet holes in place, as it were. First, I set aside six of the AD4-12 rivets. These are the rivets called out for the pushrod ends, but they’re too long and so I’m not going to use them anyway. I coated each rivet with a thin layer of car wax to act as a release agent. After all, I don’t want to permanently install the rivets at this stage! Next, I mixed up a batch of epoxy, stuffed each rod end with epoxy, and then inserted the waxed rivets into each hole. Finally, I cleaned up the squeezed-out epoxy as best I could.

The end result:

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Once that epoxy hardens, it should provide some extra support for the rivet shaft and hopefully prevent the shaft from buckling during riveting and contributing to the clinching problems I had.

With those sitting aside to cure, I got out the flap components and went to work preparing them. I knocked down the edges of the inboard reinforcements with a vixen file, then finished polishing the edges on the bench grinder. Then I sat down with the ribs and spars and took care of deburring all the holes.

I suppose I should shoot an email or phone call to Van’s to see if my fuse kit shipped yet, and if they can get me the tracking info. I’m kind of surprised that they don’t notify you of the shipment without being asked; I figure most people probably prefer to have more than a couple days advance notice of the delivery date so they can arrange to be home, or on my case, to go pick up the kit.

I also gave Grove a call last Friday and it sounds like my gear legs should ship out in the next couple of weeks. I’m about to be up to my ears in airplane parts…

Posted in Flaps, Wings | Hours Logged: 2.5

Right aileron, pushrod fiasco

Did all the riveting on the right aileron today. It sure goes a lot faster the second time around… I did have a heart-stopping moment while riveting the top spar-skin rivets though. As before, I had the aileron standing up on end, and I was almost done, just three rivets left to go. I turned to grab another rivet, and when I turned back, there was my aileron, toppling ungracefully over. Unmindful of my cries of dismay, it rebounded off my work stool and plunked to the concrete. Fortunately, it was undamaged. I figure that between the stool breaking its fall a bit and it landing on the nose skin – which was reinforced by the counterweight – I got off lucky.

There are a lot of blind rivets in the ailerons, which means a lot of rivet stems left over after everything is done:

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Once I had the aileron done, I mounted on the wing as with the left one. Next I went to work putting the appropriate washers and spacer in place at the hinge points. The outboard hinges are easy, requiring only washers, but the wider inboard brackets require a spacer to be fabricated from aluminum tubing. This isn’t a complex process, but it is painstaking, carefully shortening the cut piece of tubing to the proper length for a snug fit.

Here’s the inboard bracket and the washer and spacers and such in place:

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Both ailerons in place on the wings:

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Next I decided to work on the aileron pushrods. I started with the shorter rods, which connect the bell cranks to the ailerons themselves. These pushrods are made from steel tubing, with rod ends riveted into the ends. I spent a fair amount of time carefully cutting the provided tubing to length and then laying out the rivet hole locations – no prepunched holes here! After drilling everything, it was time to rivet.

Riveting these pushrods seems to be a frequent source of consternation for builders. The rivets are very prone to folding over when driven, making for ugly shop heads. I chose to use shorter rivets than the plans call for, and I figured it couldn’t be that bad…wrong. The first rivet I tried with the squeezer clinched in nasty fashion:

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The problem was immediately obvious: I’d tried this with the squeezer held in the vise and me holding the rod in my hand. I imagine the rod rotated a bit when squeezing. That wasn’t too smart of a way to do this.

I decided that there was no way to hold the squeezer and the rod steady for this procedure, so I decided to try the rivet gun instead. I clamped the pushrod in the vise with the rivet as close to the jaws as possible. This worked great on the first two rivets, and for a moment I thought I’d cracked the code.

Nope…the next two clinched despite me being really careful with the bucking bar. So I drilled those out and then decided to call it a night. I was getting into the mindset where I really wanted to solve a problem, at the expense of really thinking through the options. That’s the kind of mindset where I tend to make problems worse.

So I’m not really sure how I’ll handle this. I’ve seen where guys have set the rivets using a C-frame, but I don’t see how that will make the rivets any less likely to clinch. The plans mention the option of welding the rod ends, which I guess I could do, though it seems kind of ghetto to do that after drilling the rivet holes. Another couple of builders have addressed the issue of the rivets bending inside the hollow rod end by filling the rod ends with something like JB Weld to hold the rivets better. I thought about doing that, but it’ll be a little messy since I already drilled the rivet holes.

So who knows…we’ll see.

 

 

Posted in Ailerons, Wings | Hours Logged: 6.5

Finished left aileron

And once again, not the most productive day. I had held out some slim hope of priming flap components today, but that was obviously not workable, given how much prep I still have to do on that stuff. So rather than try to do that, I went back to the left aileron. I’d been under the impression before that it’d be really simple to finish this thing up, and that was kind of true, but as usual there were some small things that slowed the process down.

With the top skin/spar joint riveted, the next step is to install the end ribs. There’s a specific riveting order in the instructions for this part of the assembly which I neither remember exactly nor care enough to go look at the instructions to relate. Once you start working on rivets on the bottom, though, it’s important to secure the aileron to a flat surface to keep it straight. The instructions call for weighing the aileron down, but I didn’t have anything good for this purpose. Since the aileron naturally sat nice and flat on the surface, I just took a short piece of scrap wood and lightly clamped the trailing edge down to the surface. Then I just kept checking that the aileron was sitting flat during the following steps.

Aileron secured on the flat surface:

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Before long, a lot of rivets had been squeezed and pulled and I had a finished aileron:

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Next, I installed the hinge brackets, torqued the fasteners, and added torque seal:

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This part of the process took way longer than I expected. As seems to be common, access to the bolt heads was limited, especially on the forward side. At one point I tried turning an old deep socket into a thin wall socket with the bench grinder, but it didn’t work out too well. I eventually ended up holding the bolt heads with an adjustable wrench,

Now, where to store this thing? I guess I’ll just temporarily attach it to the wing. I just put the bolts through the brackets and lightly installed a lock nut; I haven’t bothered with the various washer stickups and spacers that will be in place for the real assembly, though I’ll need those before I can get to fitting the flaps down the road.

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At this point I broke for dinner, and after that it had cooled off rapidly in the garage, so I called it a night. Tomorrow I should be able to finish the right aileron and get to some flap work.

Posted in Ailerons, Wings | Hours Logged: 3

Left aileron riveting

Well, that was a lot of fun. Assembling the ailerons starts off deceptively easily: you attach the nose ribs to the counterweight with blind rivets. Then the nose skin goes on, followed by the trailing edge skin, and this is where the fun begins. The top of the trailing edge skin is attached to the nose skin and spar with solid rivets, but even with the bottom of the skin not clecoed to the spar, access to the inside is pretty tight. I must have spent half an hour just trying to figure out how to position the aileron so I could get the riveting done. In the end, my solution came from reading Jamie Painter’s build log, not my own ingenuity. You just put the aileron on end and now you can (relatively) naturally access both sides:

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Even so, bucking has to be done by feel. But I got the hang of it pretty quickly, until I got to a rivet that was close enough to a stiffener that I couldn’t use the tungsten bucking bar. It took three tries to rivet that thing, and I ended up having to draft Josie to hold a flashlight and hold the skin while I worked. Removing the first two bad rivets marred the skin around the rivet head too, but hey, that’s what paint’s for…anyway, getting that one stupid rivet took probably half an hour total. But finally, I had all those top rivets done:

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I’d kind of hoped to get this thing finished tonight, but oh well. It wasn’t for lack of trying, that’s for sure. The good news is that things should be easy from here on out; the rest of the rivets on the aileron are either accessible with a squeezer or are blind rivets. I imagine I’ll have this thing wrapped up pretty quickly tomorrow, and hopefully riveting the left aileron will go faster now that I’ve worked out the technique for the most part.

Posted in Ailerons, Wings | Hours Logged: 2.5

Right flap prep

Not a lot to report tonight. Mostly it was a replay of last night – match drilling the right flap top skin, then fitting and drilling the reinforcements for the inboard end. As I expected, it went quite a bit faster the second time around. Once I’d finished getting the right flap to the same point as the left, I needed to prep each inboard flap end for the pushrod attach point. This just involves drilling a previous hole out to 1/4” and then drilling for a nutplate that will mount inside the inboard rib.

With that done, I tore both flaps back down to bare parts, peeled off all the blue vinyl, marked each part, and now everything is ready for a good long deburring session:

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Now to decide whether to keep trucking on the flaps, or go back and start riveting the ailerons together. I’m leaning towards the latter right now, but we’ll see how I feel tomorrow, I suppose…

Posted in Flaps, Wings | Hours Logged: 1.5

Left flap prep

Started out tonight by match drilling the left flap skin, which I’d clecoed in place before knocking off last night. To be really careful about avoiding putting a twist into the structure, I put 2×4 blocks under the flap so it was resting on those instead of the clecos while I match drilled. Per the instructions, I match-drilled the top holes before flipping the flap over and doing the joint between the top and bottom skins.

The next order of business was to take care of the reinforcements in the inboard end; these provide the mount point for the flap actuator. There are two parts; the first is a flat plate that rivets to the end rib, and the second is fabricated from aluminum angle. Here’s the flat plate clecoed in place and drilled to the end rib:

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But there’s more fun to be had here. The inboard rib isn’t perpendicular to the spar, so that reinforcement has to be bent so the portion forward of the spar mates correctly with the angle bracket. And that plate is pretty beefy, so it takes a good bit of force. At first I just tried clamping the plate in the vise between two pieces of scrap poplar, but it was hard to get everything aligned properly. So I ended up using the bracket as a guide to drill holes in the poplar blocks, then I ground the heads off two rivets and used them as pins to hold the entire assembly together:

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After committing repeated acts of violence on that plate, the bend was finally correct and I was able to cleco it back in place, clamp the rough-cut angle bracket on, and drill the rest of the rivet holes. Here’s the final reinforcement assembly in place:

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Now I just get to repeat all this with the right flap tomorrow…but it should go a lot faster since I figured out a lot of stuff tonight.

Posted in Flaps, Wings | Hours Logged: 2

A little priming, a lot of flap work

So my first order of business for the day was to run to the nearest Napa and buy up their entire stock of 7220 self-etch primer. I should be set on that stuff for a while now, I think. Back at home, it was fairly rainy today, so I ended up priming just inside the garage door again. First up, I shot 7220 primer on the aileron spars. Next, I mixed up a small batch of EkoPoxy for the counterweights. Since I knew that I’d have a ton of extra epoxy primer mixed up, I decided to use the surplus to prime the insides of the counterweights as well as both pairs of aileron pushrod. The instructions recommend pouring the primer into the pushrods to do this; I decided to just spray it into one end with the spray gun until it ran out the other. It worked, but there’s a whole lot of waste in this technique:

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The bigger issue was that instead of using the surplus primer for this, I used all of the batch just on coating the insides. And I hadn’t sprayed the outside of the counterweight; that was going to be my last step. Fortunately, it’s acceptable to apply this primer with a brush, so my ghetto solution was to dip a paintbrush in all that extra primer that had run out of the tubes, and then I brushed that onto the counterweight tubes. The finish will look cruddy, but that’s OK, it won’t be on display.

Next, I went to work riveting the aileron skeletons, though I didn’t get very far. Step 1 was to rivet the hinge reinforcement plates onto the spar. Most of the rivet holes remain unfilled, since they rivet in assembly with the ribs:

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The next step in the instructions is to rivet the counterweights to the nose ribs. The counterweights that still had wet primer on/in them. So that was the end of aileron work for today. Time to move on to the flaps. First step was to match drill the ribs to the spars, then the bottom skin gets clecoed on, the holes in the reap spar are drilled to the internal ribs, and finally the bottom skin is match drilled.

Next up is drilling the piano hinge half that the flap will rotate on. The provided hinge pieces are much longer than needed; the plans say the hinges should be 56”, but the spars are a little longer, so I cut the hinges to be the same length as the spar. I realized about halfway through the drilling, when checking the plans, that the hinge doesn’t actually go the full length of the spar, hence why it should be a little shorter. I just went ahead and drilled the entire length of the hinge; I’ll trim it to the proper length when the time comes.

Anyway, drilling the hinges was fairly repetitive: After clamping the hinge in place, I just went down the spar, drilling, reclamping, and clecing as I went:

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All done!

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Finally, I clamped the top skin into place on the right flap:

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The next step is to match drill this skin, but I stopped short of doing that. We’re going out to catch a movie, so I needed to get showered and ready to go. I guess I’ll keep going on the flaps for the time being, since my workbench is now covered with all the stuff I’ve been using for the flaps.

In other news, I called Van’s last week to check on the status of my fuselage kit. The only big piece I’m waiting on is the roll bar, which is off getting powder coated now. Sounds like the kit will be crated and shipped this coming week!

Posted in Flaps, Wings | Hours Logged: 6

Priming, tinkering with flaps

Didn’t get a lot done today. The main thing I wanted to get done was priming, but no sooner had I finished cleaning all the aileron parts when it started to drizzle. So I brought all the parts inside the garage and waited for them to dry even longer than I’d originally expected. I was able to set up my table and shoot primer on the small parts just inside the garage door though:

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But that’s all the priming I got done. I’m on my last can of 7220, and I think I’m going to keep using the 7220 for internal parts that don’t need to necessarily look good or have a tough finish. The rattle can is much easier than mixing up batches of epoxy all the time. So I suppose I’ll make a Napa run tomorrow morning and then try and get the spars primed. I do still want to use the EkoPoxy to do the counterweight pipes, and while I’m mixing up a batch, I figure I’ll prime the insides of the aileron pushrods as well. I cleaned those today too, and considered trying to prime them, but I thought it was better to let them dry overnight to ensure there’d not any remaining water inside them.

In the meantime, I started tinkering with the flaps a bit. The instructions say these are the easiest control surface to build, but I’m skeptical. The construction is actually kind of interesting. First off, in lieu of using stiffeners like the ailerons, the flaps have ribs throughout; I presume this is because they’re subjected to greater aerodynamic loads. Even more interestingly, the skins come in two pieces, but not joined at the trailing edge. The bottom flap skin terminates in a sort of quasi-spar that rivets to the trailing end of the internal ribs. The top skin, in turn, wraps around the trailing edge and includes the aft 20% or so of the bottom skin.

Kind of hard to explain, but here’s the bottom skin with an internal rib in place, showing the design:

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I didn’t really mess with the flaps much though. Some shims have to be constructed before doing any real match drilling, and I didn’t really feel like getting involved with all that today. Kind of feels like I have too many separate things going on right now; I’d rather finish the ailerons before I go nuts messing with flaps. Or maybe tomorrow I’ll feel more like playing with the flaps, we’ll see.

Posted in Ailerons, Wings | Hours Logged: 2.5

DImpling

So yeah, it’s been a few nights since I did anything. The main reason is that it’s been rather cold here, and I don’t have a heater for the garage, nor do I intend to get one. While it’d be useful on nights like these, given the Houston weather it’d spent about 98% of the year just taking up space in the garage.

Tonight I got to work dimpling all the aileron parts. First up were the spars, which were mostly easy. However, the bottom holes which are drilled out to #30 for blind rivets need to be dimpled too, and the larger dimple die set has a larger base, and the flange is pretty short. Which is to say, I fired up the bench grinder and conducted another tool modification.

Much better:

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From there I did all the ribs and the trailing edge skins. Before dimpling the leading edge skins, though, I wanted to roll the skin edges a bit. I noticed when I clecoed the ailerons together that the top of the nose skin in particular seemed to want to pillow a bit. I want these skins to fit nice and tight, so I got out the until-now-unused edge forming tool and went to work. I’ve heard lots of guys say that they find this tool hard to use, but I thought it was pretty straightforward.

The slight bend line is barely visible in this photo, just on the outboard edge of the rivet holes:

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After dimpling the easy holes on the nose skins came the fun part. The rivet holes attaching the nose skin to the counterweight pipe needs to be dimpled for a flush rivet. Problem is, a regular dimple die can’t be used here due to the curvature of the skin. I already knew the accepted approach to this though – just cleco the counterweight pipe in place and use its countersunk holes as female dimple dies. The challenge was figuring out how to support the assembly against me hammering on the male dimple die.

After much experimentation, I came up with this Rube Goldberg assembly of scrap 2x4s and 2x6s:

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Worked great though!

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And that, I believe, is it for aileron part prep. It looks like the weather will be OK Saturday, so I should be able to get all this stuff primed and then get to work assembling everything. Maybe the remainder of this week I’ll tinker with the flaps some.

Posted in Ailerons, Wings | Hours Logged: 2

Deburring

Another day with not so much airplane stuff. I had another “little thing” to work on that I thought would take basically no time, so of course it actually took about three hours. The weather was good, but I pretty quickly abandoned the idea of being able to prime today – there’s a ton of prep work to be done before I get to that point. Case in point, I spent 2.5 hours today just deburring parts. I still have to do a bunch of dimpling and countersinking, but at least all the holes and edges are deburred.

I didn’t take any photos today, there’s not much to see really.

Posted in Ailerons, Wings | Hours Logged: 2.5