Starting the vertical stabilizer: match drilling skins and spars, deburring ribs

I was in a bad mood after my mistake on the HS spars, but I got a lot happier when I found out that my DRDT-2 had finally arrived. It was super easy to set up and I can already tell that it will be much appreciated when it comes to extensive dimpling for the spars and the larger skins.

Side note: this thing is HEAVY. That's probably for the best though – I don't want it moving on me halfway through a dimple.

Since I can't do much more with the horizontal stabilizer until my replacement front spars arrive, I decided to move on to the next major assembly – the vertical stabilizer. If there's anything I've learned from all of my research, it's that keeping up the momentum is important when tackling long projects like an airplane kit. By working on a consistent schedule rather than on a whim, the project will be completed at a much more reasonable pace.

Compared to the HS, the VS is much more straightforward to work on. The VS spar doubler is already shaped to its final form (but will still need to be deburred later on) and the lightening holes that were optional on earlier kits were already cut out for me.  It had a pretty significant bend from the factory which I had to straighten out by bending the opposite way over my knee, but that wasn't too difficult. The VS doubler and the rudder hinge brackets get clecoed to the VS spar and one of the lower hinge brackets has its holes match drilled to their final size. Simple, fun stuff.

Once that's done the next step is to "prepare the ribs", and that doesn't mean rubbing them with a good seasoning. Since the skin will be sitting tight against the ribs, all of the flanges of the ribs need to be deburred thoroughly to prevent any creases or cracks when the skin gets riveted on.

I found that the best method to do this was 1) a few passes with a file to remove large burrs, 2) a few more passes with the deburring handle flat on the edge and at an angle on either side for a more consistent edge, and 3) a couple of light passes with a red Scotchbrite pad for a smooth finish. The long, straight edges were easy to finish this way, but the smaller flanges were a bit more complicated. I could get a few burrs with the file, but a lot of the spaces were too small to fit the file into. I actually managed to use the Scotchbrite wheel on the bench grinder and some careful maneuvering of the rib to get most of the small flanges. Since the deburring handle has a swiveling reamer, I was able to use it and the red Scotchbrite pad in the tiniest spaces.

After deburring all of the ribs, the time finally came to put together the VS skeleton and then put on the skin. The ribs didn't quite line up with the holes in the skin at first, and I discovered that this was because the flanges on the ribs that connect to the front spar weren't bent quite enough to match the angle the front spar is at. A couple of quick adjustment to the flanges with the hand seamer and everything lined up almost perfectly.

At this point the skin could be completely clecoed on. Let me tell you, it felt really nice having the tail of my airplane standing on my workbench.

While the skin was on I match drilled all of the holes that connect the skin to the ribs and spars. This is where things start to get tedious. Cleco every other hole, ream, then move every cleco over one hole and ream the rest. Then, flip over the part and do the other side.

Starting the horizontal stabilizer: filing spar doublers, rear spar match drilling, front spar mistake

My tool kit arrived from Cleaveland, or most of it anyway. The DRDT-2 is still on backorder, but I won't need it until I start large-scale dimpling (i.e. the skins) so I'll be finally be able to start building my airplane!

Well, almost. Cleaveland bundled in a free practice kit in the form of a small aluminum phone/tablet holder that requires drilling, deburring, dimpling, and riveting to be assembled, not unlike the airplane kit that's sitting beside me. The aluminum pieces were covered in the same blue wrapping as the Van's parts, and just enough rivets were included to put it together. It was a fun little project that resulted in a functional phone stand that I'll actually be able to use to prop up my phone while I'm working.

Having had some practice with my new tools and with nothing else to stand in my way, it was time to finally take the first step. The journey begins with two parts – the HS-609PP rear spar doublers. These are just a couple pieces of aluminum that need to be prepared to be mounted to the rear spars.

The first task to be completed is "breaking" the edges of each piece by rounding them with a file. The corner on each edge is just enough that the doublers won't sit flat inside the spar channels, so about a 1/32" radius of material needs to be shaved off each corner so they'll sit flush with rear spar. I started by using the file to remove material and the Scotchbrite wheel to remove the file marks, but I quickly realized after multiple passes on a single edge that I just wasn't removing enough material. I fixed this by using the full length of the file (basic tool technique, I know) and pressing a bit harder to remove more material in the initial pass, then using the Scotchbrite wheel to clean up the edges and remove small amounts of material as needed to make the doublers sit flat. After a while, everything fit into place nicely.

The next step was to round the tips of each doubler to a 1/4" radius. I did this by measuring the radius and making the outline with a sharpie, then grinding away the material using the Scotchbrite wheel. This gave me very clean, polished ends on each doubler. Man, this Scotchbrite stuff is amazing!

The end result vs. the stock part.

Marked.

Almost there. I rounded both parts a tiny bit more before calling them done.

I then took a red Scotchbrite pad and sanded the doublers to a "400-grit sandpaper" finish as specified by the plans. This removed the gunk from the stick-on part labels from Van's and also removed the stamped ink labels identifying the stock, leaving a very nice brushed aluminum finish. A quick pass with the Scotchbrite wheel on the edges to remove any tool marks and scratches and the doublers were finally done and looking great.  Have I mentioned how much I love these Scotchbrite things?

Stock part on the left, sanded part on the right. The amount of light reflected really shows the amount of polish that the Scotchbrite pad left on the sanded part.

I clecoed the two doublers to the two rear spar pieces and admired my work. It's nice to have an airplane-sized part on my workbench.

Using the reamer I final drilled each hole in the assembly to #30, then I clecoed on the elevator hinge brackets so I could final drill those too. You may notice that the clecos changed from silver to copper; the silver clecos wouldn't stay in place after the holes were enlarged, so I went to the next size up. I made sure to label and number each piece to make sure they get put together the same way after I inevitably have to disassemble them for deburring and priming.

I ended up using the drill bit to match drill these brackets. With the top holes clecoed, the bottom holes were 98% aligned but were off juuuust enough that the reamer couldn't handle it.

The pieces for the center hinge bearing mount needed to be clamped together and clecoed onto the spar to be match drilled. I had to remove a bunch of clecos just to get at one of the holes I needed to drill, so I drilled two of the six holes I needed to drill, clecoed them, then drilled the rest of the holes with the piece off of the spar. The results were good, but the brackets weren't completely level with each other since the HS-411APP and HS-411BPP weren't exactly mirrored parts. This is a pretty common and minor issue from what I've read and the parts still sit on the spar just fine, so I won't worry about it too much.

I'll need to prime the VA-146 bearing, but that can wait until I have some primer to do it with. I set the rear spar assembly aside and began work on the front spar. First, the HS-00001 doublers needed to be separated. A quick run of the band saw followed by some grinding with the Scotchbrite wheel yielded two clean pieces.

I took out the front spars and started working on what would be the first major mistake I made in this project. To start, I clecoed the HS-710 and HS-714 reinforcement angles to the HS-702 front spars to join them. The plans then call for the HS-702 pieces to be trimmed to match the drawing so that they have a 6 degree bend and relief notches to prevent cracking along the bend. 

My screw-up? I jumped straight to the notch-making and completely skipped the first step. That is, I skipped the very first step that says I was supposed to trim the spar flanges to 5 3/16" from the end before marking the bend line and cutting out the notches. I didn't realize it until after finishing the notches and making the 6 degree bends. The plans say to match drill the HS-00001 doublers with the spar, but the measurements in the plans weren't matching up with my measurements of the parts. I scratched my head, remeasured the parts, and searched the forums for answers, but it wasn't until I looked back at the plans that I noticed the ghost cut-out of the flange that I should have cut by now.

Apparently I briefly forgot that Step 1 is supposed to be done before Step 2. 

The notches I made weren't bad and the bends were just about perfect, but they were in the wrong spot. One order of replacement parts from Van's later and the total price of my mistake ended being 2 hours and $70. I was pretty upset at first, so I decided against trying to build while angry and called it a night.

Cutting these notches was good practice at least...

While frustrating, this experience taught me to read the instructions and the diagrams more closely before cutting any metal, which is a good lesson to learn on the first step rather than when I'm almost done with the part. Plus, now I have some scrap aluminum to practice on.

The nice thing about these kits is that there's always something else I can be working on, so I'll start work on the vertical stabilizer while I'm waiting on my new HS spars to be shipped.

VS skin damage, workbench retractable gear

I'm not sure whether I missed it during the inventory or if I did it myself when I was moving around parts, but I discovered a bend in the lower right corner of my VS skin. It's the widest skin and it sits pretty much right next to the side of its box, and the damaged corner had been punched right into the cardboard. An amazing discovery when you just got the kit a couple weeks ago and haven't even't received your tools yet...

Thankfully, it wasn't very much damage – it only went through the very first prepunched hole on the corner and the skin was only bent by about 8 degrees or so. That said, it was disappointing to already have a damaged part this early on.

If the damaged area had been any larger, or if it would have costed less than $85 plus shipping to replace it, then I probably would have just ordered a new skin. I've heard that "straighten it and build on" is the advice Van's usually gives in these situations, so I decided to avoid the expense and attempt to fix the damage myself.

I went to work with a cloth, a small block of wood, and a mallet. I covered the skin with the cloth to prevent any surface damage and then used the wood block and the mallet to gently tap the skin back into its original shape. The results aren't perfect, but the skin is straight again.

There's still a slight deformation on the corner, but it's very minor and probably won't be an issue structurally. It's bent inward toward where the VS spar will be, so I don't have any concerns about the aft edge of the skin flaring outward. Cosmetically it's a little annoying, but it looks as though most of the damage will be covered by the tail fairing and paint.

It honestly looks a lot worse in these pictures than it does in person. I double checked with the folks over at the Van's Air Force forums and they agreed that it probably isn't worth scrapping the whole skin for this tiny corner. Perhaps the perfectionist in me will replace the skin later on and use this one for sheet metal practice, but I'll keep it for now.

You can still see where the bend is when the light catches it, but it won't be nearly as noticeable once the tail fairing is in place and everything is painted

I'm still waiting patiently on my Cleaveland tool kit to arrive (the DRDT-2 and a couple other items are on backorder), so my next project to keep me busy in the meantime was to finish adding "retractable gear" to my workbenches to make moving them around the shop a little easier. I modeled mine after the retractable casters seen in this video from EAA.

I already had four 5-inch casters lying around, so about $10 worth of cabinet hinges, eye screws, and paracord and half an hour of cutting more 2x4s resulted in some nice retractable wheels.

Mine differ from the EAA's in that I decided to have the additional 2x4s run all the way up the legs to the tabletop (for looks more than anything), but they function identically. Lift the bench and kick the boards into place to use the casters, then lift the bench and pull the paracord to remove the boards and allow the casters to retract when finished. This should make moving the benches a lot easier and a lot less noisy on the concrete floor.

GEAR.....................DOWN

GEAR............................UP

...And at this point there's not much more I can do until my tools arrive. All I can really do is continue to wait and try to keep myself occupied some other way. Probably by browsing the VAF forums and daydreaming about my plane, but what else is new?

Empennage inventory

The Journey Begins

My timing with finishing the workbenches couldn't have been much better since the empennage kit arrived the very next day! I was fortunate enough to have a gap in my schedule that allowed me to be home to sign for the packages. The FedEx guy saw the "High Dollar Aircraft Parts" on the boxes and assumed that it was a drone. I didn't have a chance to correct him before he drove off.

The two boxes were relatively small, but I could tell from the weight of each that they were densely packed with what will eventually be the tail of my airplane. To say I was excited was an understatement – I was downright giddy!

I'm not sure I've ever been more excited for a couple of cardboard boxes

Like choosing which present to open first on Christmas morning, I chose to start with the smaller box so I could save the excitement of the big box for later. The very first thing that jumped out at me was the paperwork, which suggests that you should read it in its entirety before proceeding any further. Like a good boy, I did as I was told and read the important stuff before obtaining the four-page inventory sheet.

Unpacking the smaller box revealed a surprising number of aluminum parts. It's been said before, but the people that pack these boxes are masters of their craft. I don't think a single square inch of space inside the box wasn't filled with something. 

Unwrapping each part from its paper wrapping was like opening another gift – each one a surprise. Among the items in this box were all of the fiberglass rudder, elevator, and stabilizer tips, spar doublers, and the electric trim servo and mounting pieces. Also included were all of the counterweights for the elevators and the rudder, which probably accounted for a lot of the package's heft. Spreading everything out, I started to worry that I might not be able to fit all of the parts on the benches.

The hardware bag alone takes up nearly half of the whole inventory sheet. There are a lot of different rivets, nutplates, bolts, nuts, screws, washers, et cetera that all needed to be accounted for. Thankfully a note on the bag says that the rivets didn't need to be counted individually, I just had to make sure that each bag was there. Inventorying was an exciting process for me, but even I don't have the patience to count each of the hundreds of rivets in that little bag. Everything else in the bag was accounted for, so I won't need to worry about missing any hardware at a crucial moment later on.

This bag may be small, but it's as important as it is heavy

Once the smaller box was empty (and after I thoroughly checked it for any parts I missed, as per the instructions) I turned my attention to the larger box. Lifting the lid unveiled a tightly-packed group of all the skins, which were duct-taped to each other and to the box itself to prevent any movement during shipping. The skins themselves were thankfully undamaged during shipping – they were the pieces I was worried about the most.

Removing the duct tape also removed some of the blue vinyl from the skins, which caught me off guard. I know that these skins are durable and shouldn't get damaged that easily, but I still would have preferred that the film remained attached until I started working with the skins. Eh, not a big deal.

Cutting the last piece of duct tape caused the box and the skins to suddenly shoot upward, startling me. I quickly realized that the skins were actually quite springy, and removing the last of the tape caused all of that compressed elastic potential to be released at once, right in my face. I laughed at myself, then moved on.

*sproing!*

Besides the skins the larger box contained longer items such as the spars and spar reinforcements, all tightly wrapped in a cellophane and brown paper package. Again, the amount of stuff they fit into a compact space is amazing.

When I finally got through the whole list I was pleased to find that, not only was nothing missing, nothing was damaged. I dreaded potentially finding a part that would be unusable and having to wait while Van's shipped a replacement, but I'm happy to report that that won't be the case for the empennage kit.

In the end I managed to fit everything but the skins onto the tables. I might need a bit more storage space for the next kits...

The whole inventory took a lot less time than I expected it to – just a single afternoon. Of course the empennage kit is the smallest kit, so the wing and fuselage inventories will probably take quite a bit more time. I really don't mind though. The inventory is often touted to be the most boring part of each kit, but it was an exciting process to count, bit by bit, every airplane part that I'd soon be working with. What's better is that, after poring over the preview plans ad nauseam, I was already familiar with most of the parts I was unwrapping. That was just another shot of confidence for me as I embark on this journey – I may not have ever done this before, but at least I'm not totally lost.

As much as I want to start building right away, I don't have any of my tools. Cleaveland called yesterday to let me know that a couple of the items were on backorder but the kit should ship by the end of this week or next week. The journey will officially begin soon enough. Onward!

EAA workbenches

Over the past couple of days, I put together some workbenches that I'll be using throughout the build. I was a bit unsure of how well this would go since I had never really done any real woodworking by myself before, but this turned out to be a fun two-day project that has me excited for the build to come.

I used plans that were published in EAA Sport Aviation magazine available here. As a novice woodworker, the shopping list and cut list was much appreciated and the diagrams were clear and easy to follow. The only real issue I have with the plans is that, since the article was published in 2010, the estimated costs are quite a bit lower than the actual costs. Even the cheap 2x4s alone are each $1.50 more than they were 8 years ago, so unless you already have enough 2x4s, screws, and MDF/plywood lying around, you can expect to spend at least $100 to complete the two workbenches.

The first half of the build was simply cutting all of the 2x4s to size, which took longer than I expected it to. All 45+ cuts took all morning, so I ended up starting assembly of the parts after lunch.

Per the plans, I built the upper frames on the garage floor to keep the tabletop as true as possible. I thought I had done a good job of selecting 2x4s with minimal warping, but there ended up being a slight twist in each frame once everything was glued and screwed. It really wasn't a big deal to me since the MDF I'd be attaching to it would be fairly level and I wasn't going for absolute precision here.

After spending all morning on the ground cutting wood, the pillow was necessary to avoid destroying my knees.

Attaching the legs was fun now that the shape of the benches was beginning to emerge. I tried my best to make everything as square as possible. After all the legs were attached I flipped over each bench and made adjustments to individual legs to eliminate any large wobbles.

Doublers attached. The tables are starting to look a little more hefty now.

The lower frames went together as easily as the top frames and fit securely onto the legs.

The final 8.5" doublers were where I expected to have a little trouble and I wasn't wrong. Only one of the eight pieces ended up being level with the main 33" leg while the rest were just slightly too tall. Cutting off the excess lengths with the miter saw was easy and the results were pretty much perfect for each leg.

Flipping over the benches for the last time, I realized that a couple of the legs were taller than the top frame where the MDF would be attached and would create a significant gap between the frame and the tabletop if left unchecked. A quick sweep with the belt sander was all it took to level things out.

Time for the tabletop and lower shelf. The 1/2" plywood at Lowe's was pretty crappy and riddled with some deep knots that looked as though they could scratch aluminum pretty easily, so I ended up buying some 1/2" MDF instead to use for the lower shelf.  The MDF was only $6 more for the whole 49"x8' sheet and was actually cheaper than the premium plywood, so it wasn't that much more expensive and I got better-looking tables out of it.

Preparing the MDF to attach to the frame with scews gave me my first countersinking experience. I made sure each screw head ended up slightly lower than the surface to ensure that there would be no contact between the screws and the aluminum parts. Finally, I sanded around each screw to make sure the surface was smooth with no material protruding up from around each hole. I'm pretty happy with the results.

Aaaand, done. Looking good!

There's still a tiny bit of wobble on each bench depending on where I place them in the garage, but sticking some wood chips left over from cutting the 2x4s under the legs solved that. I'm really not that concerned about wobble since the benches will be moving around a lot and the floor in each location is going to be slightly different.

Overall, I had a lot of fun putting these together. Again, this was the first project I've done by myself that involved me actually fabricating and building something rather than just assembling it, so I'm more than happy with the end products. Building was also more therapeutic than I expected. Once you get into the groove, it's easy to lose yourself in your work and tune out everything external. I can totally see why someone with a lot of their mind would escape everyday life by coming out to the shop.

The best thing about building these benches before the arrival of the empennage kit is confirming to myself that, not only am I willing to undertake this project, but that I'll also have fun with the process of building it. True, building an airplane is going to be way more complicated than building a couple of simple workbenches. That said, spending a few hours on a fun solo project like this has made me feel a lot more confident about starting the plane.

The empennage kit arrives tomorrow. Time to get to work.