Initial Wing Fitting

The day for the wing fitting finally arrived!  Dad and I reorganized the garage and maneuvered the fuselage around to the middle to give enough room to put both wings on at the same time.  We strategically placed a few storage bins and blankets underneath each wing and tail to help take some of the weight while we were trying to insert them into the fuselage.

Before we worked on inserting the wing spars to the spar carry through we did our best to level the fuselage.  I was a little nervous about how the wing spar would fit into the fuselage.  There have been a lot of stories online of people who didn't quite get the space correct for the spar carry through area and had to do a lot of unriveting in order to get the spars in.  I was extremely happy to find that the spars slid right in with very little coaxing!  Dad lifted and wiggled the ends of the wings while I guided the spars into position and inserted the temporary bolts.  The rear spar attach gave us a little trouble at first, but we found that we just had to get the fore/aft angle of the wing right to get the rear spar to slide into place.

With the wings in place, the next step was to take a number of measurements to ensure that the positions were equal and within spec.  We measured from the wingtip to the center of the tail - the initial measurement was about 3/16" different from side to side.  A few small taps of the wingtip moved the left wing back enough that the measurements between both sides were almost dead on.  If I remember right, the final difference was less than 1/16".

I don't have a picture of it, but the next job was to check the forward sweep of the wings.  We dropped a plumb bob down from the leading edge at each wingtip and pull a string line between them.  Then we moved each plumb bob to the inside leading edge to see where they landed on the string line.  There was a difference of about 1/4" on the left and a little less than that on the right.  A little tweaking and we got the line to be right on.  With that done, we checked the wingtip to center tail measurement again to be sure it was still good, which it was.

I have to admit, it was pretty cool to finally see the plane with wings!

Surprise surprise, one more measurement!  Following the instructions, we created a block out of a piece of aluminum angle and added some wood and tape to it until we hit the exact size called for.  Then we placed that block on the rear spar line and put a level between it and the front spar.  It needs to be level, and it was right on the money.

With all of the measurements accounted for, it was time to drill the rear spar attach point to lock everything in place.  The edge distance on this part is very tight - to allow for the correct edge distance there is really only one center point that will work.  I used a block of wood as a drill guide to ensure I got the hole perpendicular.

Next up was the front fuel tank attach brackets.  We bent the brackets a couple of degrees (easier said than done) so they would match the angle of the fuselage and still set against the fuel tank bracket.  Similar to the rear spar, these brackets have a pretty small window for edge distance. I drew a little box that gave me the 1/2" edge distance and drilled the bolt hole.

I completely neglected to get pictures of the next couple of tasks, mostly because I was laying on my back under the wings to fit and drill the wing root fairings.  After that, with Perry's help we started fitting the flaps.  We put the flaps on and eyeballed where the pushrod would go through the fuselage to the flap control arm.  I can't say that I loved drilling a big hole in a perfectly good fuselage!  I got the final oblong hole where it seemed correct, even though we didn't set the final length of the pushrods.  I'm waiting on some replacement pushrod bearings before I do that.  I don't love Van's design that doesn't allow for a way to trap the bearing if it were to ever fail.  I ordered some normal pushrod bearings and bolts, and I'll set the flap movement down the road when I final install the wings and control surfaces.

Roll Servo & OAT Wiring

Not much to report today, aside from tidying up some wiring.  I routed the roll servo wiring up to the corrugated tubing and pulled it through.

On the left wing, I finally made use of the hole in the spar flange that is supposed to be used for Van's homemade pitot tube.  Since I went with a pitot tube that looks like it belongs in this century, I had the hole to either fill or use.  Luckily it's the right size for the outside air temperature probe.  I put the probe in place (loosely - it'll have to be pulled away a bit to paint) and pulled the wires through.  I haven't been able to figure out a super clean way to punch through the tubing, so my method of choice is simply a rough cut hole and RTV to hold things in place.  It's kind of odd - the instructions for the OAT wiring say that if you need to make the wire longer or shorter, cut it in the middle and splice more wire in.  The wires come pre-crimped to some tiny molex connectors that connect to the ADAHRS module, so I'm assuming the instructions are there because most people don't have crimpers that tiny to deal with putting new pins on.  The wire is barely long enough to reach the fuselage, so I'll definitely have to extend it.

Autopilot Servos

The Dynon autopilot servos have arrived!  Pitch and roll use the same model of servo, just with a slightly different attach point on the servo arm.

First step for the roll servo was to wire a 9 pin dsub connector onto it.  I must have forgotten how to count when I placed my original wiring order, because I am missing a number of dsub clamshells.  Given that a lot of builders don't even use clamshells and just leave the dsub connectors bare (every ounce counts I suppose), I am not going to stall out waiting to order more.  I have all I need to still be able to connect the dsubs with screws, so the shell is just window dressing.  That being said, since these servos get hidden out of the way, I decided to zip tie the connectors together as well as use the screws.  Belt and suspenders approach.

Installing the roll servo in the right wing wasn't hard, just fiddly.  It was very doable with the wing already closed up, but definitely would have been easier had I done it when everything was still wide open.  I had to do a lot of head scratching on the install - the drawings on the installation instructions don't show how a number of spacers are put in place to offset the pushrod.  Well, they do attempt to show it, but the angle of the exploded view they chose to include in the instructions covers up so many parts that it's impossible to see how it all goes together.  Someone was sleeping on the job when they decided that was the view to use.  After a lot of research, including finding an old version of the installation instructions online that had a useful drawing, I finally got everything sorted out and installed.  My first attempt at safety wire (on the three bolts that hold the servo to the bracket) was super ugly.  The second attempt was passable.  For such a simple task, I still don't have the hang of it.  I suppose learning to do it in a small confined space wasn't exactly setting me up for quick success.

I still need to figure out the wire routing up to the corrugated tubing.  The pushrod will also need to be adjusted once the wings and ailerons are mounted.  I couldn't figure out a good way to adjust the length of the servo pushrod without having the aileron in place to identify the neutral position.

I wired up the pitch servo the same way - my last remaining clamshell and zip ties.  Working on the pitch servo was far easier just because of the open access to the area.  Once again, safety wire was my downfall.  One of these days I'll figure out the trick to it.

Right Wing - Bottom Skin (5)

Finished up the right wing bottom skin!  The main spar rivets on the outboard skin were relatively easy to reach through the access panels and lightening holes.  The inboard spar rivets were another matter.  The inboard ribs (wing walk area) are very close together, and even though I could reach inside the lightening holes at the end of the wing, it was tough to get my hand at an angle to hold the bucking bar.  The wiring conduit across the entire wing added a little complication too.  I had to swap between a couple of different bucking bars to get at the rivets that are trapped between the conduit and the skin in a very small space.  In the end, doing the whole bottom skin solo wasn't nearly as bad as I had anticipated though. I actually think it is probably easier than doing it with someone else.  When bucking blind, the ability to get the feedback in the gun and bucking bar makes a huge difference.  I think only feeling one or the other would end up in a lot of under/over bucked rivets.

I got notice that the canopy side rail shipped today, so after I finished up with the wing I moved the workbenches back and cleaned up the shop.  I'll switch back to working on the canopy while I still have warm weather.  The frame will have to be primed and painted, and the canopy itself needs to be cut.  All of that is far easier with warm weather, so I'm going to attempt to get it done in the next few weeks.  I don't need to get the canopy fiberglass done, just the overall fit and attachment to the frame.  I need to order some Sika adhesive.  I've decided to go the route of gluing the canopy onto the frame vs drilling the plexi and screwing it on.  This was a crazy idea 25 years ago, but in that time it's become a fairly standard approach and gets rid of one more reason for a canopy to crack over time due to 100 holes drilled into it.

Right Wing - Bottom Skin (4)

Another day, a few more wing rivets.  I got the outboard skin done and most of the inboard skin.  I mostly have the spar rivets left to do.

Right Wing - Bottom Skin (3)

Boring pictures that look the same as yesterday, but there's progress, I promise.  I rolled up the inboard wing and started riveting the upper 1/3.

The rivets around the flap brackets are a real pain to set well.  I don't have a rivet set for the gun that is long enough to get the gun out of the way of the bracket, meaning I can't get the set directly over the rivet (and flat).  I ended up using my small mushroom set duct taped to the gun so I didn't have to use the spring.  That gave me a tiny bit more room - not ideal, but just barely good enough.  For the most part it worked okay, but one side of the middle bracket was a bear and ended up with some skin "character."

Right Wing - Bottom Skin (2)

More work on the right wing today.  It's slow going, but I finished up the top 1/3 of rivets.  I'm guessing the rest will go a little faster.  Small bite size chunks will get it done.  It can get a little monotonous (you can't see the shop heads, so you have to rivet, then feel with your finger, rivet again, feel, etc).  My "well duh" moment for today was the fact that I can't just finish the outboard skin and then slide the inboard skin underneath at the joint.  I mean, I can, but then I won't be able to bend up the inboard skin to rivet the top rivets!  Duh.  So I need to make more room by pulling out my grinding bench so I can get at the inboard portion and do it in conjunction with the outboard skin.  My grand plan was originally just to do the outboard skins, then swing the stand around to do the inboard.  I realized I never dimpled the inboard skins, so that'll be the next step tomorrow.  That means I need to do some cleaning so I have a place to dimple.  The shop is a mess!

The access holes still needed to have the dimples done for the screws and nutplates riveted on.  Easy enough.

Right Wing - Bottom Skin

I need to do a little more research about how I want to put the pitot tube in (mostly how I want to route the tubing around the bellcrank and to the hard pitot lines).  I decided I may as well move on to something else for a bit since I'm still waiting for my canopy parts as well.  I ordered a whole mess of electrical supplies this week.  I figure making wiring harnesses will be a pretty good cold weather kind of task this fall/winter.

Most people are adamant riveting bottom wing skins is a two person job, but I've also heard quite a few people say they did most of it themselves.  Why not give it a shot! I still have to install the pitot in the left wing and the autopilot servo in the right wing.  I already have the servo bracket in place on the right, so the servo itself can easily be installed after the wing is closed (it's right behind an access panel).  It'll be easier to finish up with the pitot routing without the skin permanently installed though, so I'll wait to close the left side up until the pitot is done.

The instructions say to lay the wing down flat on a table and have a riveting partner stand over the wing on one side while the bucker reaches inside from the other. I can see that working well for two people, but it seems like it would be a tough position solo. I don't want to completely overhaul my space to move the wings to the workbenches either.  The only way I want to move on to riveting the wings is if I can do it without moving them around too much. I slid my workbenches out of the way just enough to get to the right wing.  The outboard skin was clecoed on at the rear spar and about 1/3 of the way forward.  It's too far to reach under the flat skin to buck and shoot, but if the skin is bent up a little, it's supposedly doable for us long arm folk.  I laid a piece of scrap across the aileron hinge brackets to strap to, clamped some wood to the bottom edge of the skin and used straps to roll the skin up.

I won't say it's super easy to rivet, but it's actually not as bad as I thought it would be.  I started near the center of the skin and worked my way out and down.  It's slow going and tough on the arms, but I managed to get a small section done.  I don't think it's something I can do for hours at a time, but if I chip away at it in between other tasks I'll eventually get it done.  I was originally going to start with the inboard skin since it goes underneath the outboard skin at the joint, but the instructions are pretty clear to do the outboard first (then slide the inboard under).

Autopilot Brackets

I'm trying to find random things I can accomplish while I'm waiting for my back ordered primer.  I installed the Dynon pitch servo bracket on the elevator bellcrank rib.  Ignore the lovely primer scribbles on the vertical rib - I had to cover up a bunch of scratches to the Rustoleum primer where I looked at it funny.  Hence the reason I'm not a huge fan of the spray can primer.

The roll servo gets installed in the right wing.  Most of the original brackets say in place, but Dynon adds in a few pieces to accommodate the servo.  Here's the original setup:

I replaced the bottom bracket, as well as added a diagonal rear bracket arm (hard to see in the picture, but it's by the arrow) that will support the servo itself.  To allow the servo to connect to the bellcrank, a spacer and plate is added to the bellcrank.  This will eventually get a pushrod that connects the two.  For now, this is all that I'll put together though.  I'll buy the servos when I'm ready to start doing a lot of the wiring in the plane.

Right Flap (6)

Time to finish up the right flap and clean up the shop so I have bench space to inventory the fuselage when it arrives (hopefully in the next few days).  The next step was to rivet the bottom skins to the spar, so I flipped the flap top side down.  The ribs need to be held flat against the bench.  Last time I laid pieces of wood on the ribs and weighed them down with weights, but the weights kind of got in the way of riveting.  This time I just put the wood on the ribs and screwed them down, basically pinching the rib to the bench. To try to keep the skin somewhat flat, I did the same with some wider boards.

Riveting the bottom skins to the spar went fairly quick this time around.  I went up one rivet length, just like I did on the left flap because of the dimpled vs countersunk spar.  Once the spar was done, I put the weights on the bottom skin and clecoed the skin to the ribs.  I also put the trailing edge wedge in and clecoed it together.  Last time I clecoed it to the table and waited for the tape to set, but with the method of squeezing the rivets with clecos in place, I skipped this step. I didn't really need to use the tape, but I put it in anyway, just because it helps to hold the rivets in the holes while I'm squeezing them.

I pop-riveted the main ribs to the skin and moved on to the trailing edge.  This is what the rivets look like partially squeezed.  This worked out great again.  There was no back and forth and back and forth to try to keep the edge straight.  I just kept the weights in place with the edge just off the table, then squeezed every other rivet, removed clecos, and did the rest.  I did use 3-3.5 rivets again, even though the 3-3 is what is called for.  The 3-3 is a little too short for my liking.

I flipped the flap over and finished up the edge using the mushroom set and the big back rivet plate.  Just one second of riveting is all that was necessary to flatten the rivets the rest of the way.  The trailing edge ended up perfectly straight again.  I sure wish I had known about this technique when working on all of the other trailing edges!

I threw the flap up on the wing just to see what it looks like.

It nests down into the rear of the wing.  The top wing skin projects over the front of the flap, and the flap gap fairing keeps there from being too much of a space for air to sneak through.  The flap was just sitting there for this picture, so it won't sit down on the rear wing spar like this when it's bolted on.

All of the control surfaces are done now.  I'm not going to bother fitting the flaps to the wing until much later in the build.  I don't see any reason to fit anything just to take it apart and then final fit it again down the road (after final fitting it still has to be taken apart for painting).  That's why I didn't fit the tail surfaces together yet.  I'll do that once the fuselage is largely done.

Right Flap (5)

I haven't heard from the shipping company itself yet, but I got word from Van's that my fuselage kit will be picked up tomorrow and head this way!  Gotta get the last flap done so I can clear a bunch of room!

With freshly primed parts, it was time to start assembling everything.  Everything had to be dimpled still, so that was first up, following by riveting the nose ribs and hinges.

After the individual hinges were put together I started riveting them to the spar. You'd think I'd remember all of the ins and outs of doing this since I just did it on the left flap not too long ago.  Enough steps have passed since then I guess, because I still had to do some trial and error to figure out the easiest way to rivet everything together.  There just isn't much room to get at a lot of these rivets, so it takes some back and forth with different squeezer yokes, rivet gun sets, bucking bar types, etc to land on the easiest way.  I guess in defense of my awful memory, each hinge assembly (and even each side of each hinge) takes a slightly different setup to get at the rivets.  I suppose shy of writing down what combination works for every single group of rivets, I shouldn't be surprised that I don't remember what I did last time.

The inboard angle kind of gave me some fits initially.  I just couldn't set the rivets nicely, no matter which method I tried.  That is, until I took a step back and realized that there must have been some longer rivets in the bin vs the size I thought they were.  They were so long that I just kept bending them over with the squeezer.  Things went better with the right length of rivet.

After the nose ribs were finished, then the main ribs were riveted to the spar, followed by clecoing on the top skin.

The top side of the nose skins were clecoed on next.  The skin/nose rib holes were up-sized to 7/64" holes and riveted with pop rivets.

Back into the cradle it all goes!  This part I definitely learned my lesson on last time, so getting the nose skins squeezed together in the cradles and clecoed was far easier this time around.

Last up for today was riveting the skin to the spar.  I also got about half of the rivets for the skin and main ribs set.  Even though I know the wave in the skin is normal, it's still disconcerting to see!  I stopped riveting the main spars when I reached about 2/3 of the way towards the tips.  I was having an awful time setting the last few without clinching them.  I have to use a narrow bucking bar, which makes it hard to keep parallel to the rivet head.  I'll try again tomorrow.  Like I did on the left flap, I'm not even going to bother to use a solid rivet in the last hole of the trailing end.  With a super tiny bucking bar (a lot of people use a wood chisel with a bucking bar taped to it for the mass), I know I could ultimately get the rivets set, but it's not worth the hassle.  I used pop rivets on the left flap, and I'm going to do the same on the right flap.  It's just not worth the frustration otherwise.  I've been told that before paint, just put a dab of epoxy/micro in each hole of the pop rivets (they're flush style) and you'll have a hard time ever telling them apart from regular solid rivets.  They are slightly raised and not perfectly flush just because that's how they squeeze, but I don't care enough to spend hours cussing trying to set rivets in this small area - rivets that in all likelihood would come out sub-par anyway.

Right Flap (4)

Not many pictures to share, but a lot of work.  I scuffed and cleaned all of the right flap parts and shot primer.  I was almost out of primer from my original gallon, so I bought one more quart of the same Ekoprime, plus one quart of the Ekopoxy.  My plan is to spray the tail cone with the Ekoprime, then I will spray the cockpit area (baggage compartment forward) with the Ekopoxy.  I think one quart of each should be enough, but time will tell.  I'm switching to Ekopoxy for the cockpit simply because it's a lot tougher than the Ekoprime - important in an area that will get a lot of wear.  It's still a waterborne primer, so not toxic like most other epoxy primers, but it's still a two part epoxy.  The downside is it means it has a pot life and the extra can't be saved once it's mixed, unlike the Ekoprime.  I decided to go one shade lighter for the cockpit area - smoke grey vs charcoal grey - since the lighter color will give the feeling of slightly more room.  That being said, I'm fairly certain I'm going to end up putting up side panels in the cockpit and probably cover most of the floor with carpet, so there won't be much of the primer to see in the end anyway.  The other option was to prime and paint the interior and leave it at that, but I think my important passenger will want the "comfy" factor of upholstered panels and floors.

There aren't a ton of parts in the flaps, but the ribs are small and awkward to scuff, so prepping and priming took about 3 hours.  At least I'm done with priming for a little while now.  Unfortunately, I think the timing will work out so that I'll have to prime the bulk of the fuselage parts during the winter, which is never easy.

Left Flat Assembly (6) & Right Flap (3)

I tackled the trailing edge riveting a little differently this time around.  The "normal" way of doing it is to tape or proseal the wedge in place, then partially set the rivets (just enough to swell and stay put) using a back rivet set, then flip everything over and use a mushroom set and the back rivet plate to finish setting the rivets.  This works fine, but it can be kind of difficult to keep the edge straight and flat, and requires some finesse with the back rivet set to keep from dinging the skin since you have to start vertical and then angle it to match the skin angle.  Instead of using the back rivet set, I decided to use the squeezer to do the initial partial set of the rivets.  Because I didn't need the back rivet plate at this first stage using this method, it meant I could leave clecos in the trailing edge to keep the wave from causing a headache.  I slid the flap off the edge of the bench just enough to allow me to get the squeezer in position.  To try to protect from a wavy edge even more, I put a board and weights on the flap to keep it all flat to the table while I riveted.

Van's calls out 3-3 rivets for the trailing edge, but those seemed short to me.  I used 3-3.5s instead, which were maybe a little on the long side, but still worked better than the 3-3s would have I think.  I set the squeezer to just squeeze the rivets to the point where the rivet set would almost touch the skin at it's widest angle, which left quite a bit of the rivet still protruding.  Because the clecos were holding everything in place and the weights were keeping it flat, I just went down the line with the squeezer.  When doing this the typical way, you have to bounce back and forth every 6-10 rivets or so to keep from creating a hook in the trailing edge by doing too many rivets in one place at once.

Once done with squeezing, I flipped everything over and finished by using the mushroom set and back rivet plate.  The shop head (that was partially set) went down against the back rivet plate, and the mushroom set hit the manufactured head.  It didn't take much to set the rivets the remainder of the way.  In the end, the edge turned out amazingly straight with no noticeable wave in it.  It's kind of hard to take a picture to show the edge.  It kind of looks like a transparent flap here.

Here's what the shop heads look like using this technique.  Very clean and flat.  I probably could have gotten away with the smaller 3-3 rivets, but I think I'll still use 3-3.5s on the other flap.

So the left flap is largely done now.  I still have a couple of rivets to set on the end ribs, but I'm waiting for a new tool to get here to do those.  It's too tight for the squeezer, and I was told that a great tool to have for awkward places is the parallel jaw Knipex pliers.  Apparently they work great for squeezing size 3 rivets in places where bucking isn't ideal and a squeezer is too big.

On to the right flap again!  Everything is fit and ready for the assembly, so that means lots and lots of deburring needs to be done.

Left Flap Assembly (5) & Right Flap (2)

I finished up match drilling everything on the right flap, including the trailing edge wedge.

I noticed that the inboard piece of angle has one hole that is just a touch too close to the edge, so doesn't meet normal edge distance rules.  This is because the instructions for putting this angle in place to match drill just say to center it on the spar.  I obviously didn't get it perfectly centered.  I emailed Van's to see if it's okay or needs to be remade.  It's not uncommon for even some of Van's predrilled parts to not have "by the book" edge distance, but they do it in places where the engineering says it doesn't matter.  We'll see what they say about this part.

Since I was done using the left flap wedge for the spacing of the right one, I put it into place in the left flap (with the VHB tape - although I'm not convinced it really helps much) and finished pop riveting the bottom skin to ribs.

Left Flap Assembly (4) & Right Flap

I clecoed the left flap bottom skin to the ribs.  I couldn't finish by inserting and clecoing the trailing edge wedge though, because I need the wedge as a spacer to set the distance of the trailing edge wedge on the right flap (I can't remember if I showed that before - the plans say to lay one wedge against the aft ends of the ribs, then slide the permanent wedge up against that.  This sets the wedge where it needs to be for drilling).  So with the left flap finished up until the point of riveting the bottom skin to the ribs and riveting the trailing wedge, I moved to the right flap.  Even though I've been told that the wave in the flap trailing edge is normal and will flatten out when the wedge is riveted, it's still a little disconcerting to see.

Now that I have the one main rib I was missing for the right flap, I can finally finish it up.  I clecoed the nose rib and hinges to the spar, the main ribs to the top and bottom skins, and match drilled everything.

I learned from the other flap and had a much easier time putting on the nose rib skins for the right flap.  I used the ratchet strap in the middle to start clecoing it to the spar, then moved the strap out towards the edges.  I was lazy and didn't feel like going out to the shed to grab a long 2x2 to hold the ribs flat while I put the nose skins on, so instead I just used shorter pieces that I weighted down.  I think this might actually work better, since they're flatter (shorter distance) and the weight just needs to span a couple of ribs at a time while working on the nose skin.

Wing Misc.

After being sick for the last week, I needed to get back out to the garage to keep my boredom from doing me in.  I still don't have a lot of energy, so just did a few odd jobs.  I just couldn't get up the motivation to jump back into the flaps yet.  From what I can gather, there shouldn't be any reason that I'd need to pull the fuel tanks off of the wings again, so I went ahead and put all of the Z bracket bolts in and torqued them (I still need to install the bolts on the inboard bracket, but that's too hard to do with the wings in the cradle since those go in from the front side of the spar).

I'm not going to pull wire for a while, but while the bottom skins are off I am putting conduit through the ribs.  It's ribbed, so is a real pain to pull through the holes I drilled.  

I got it pulled through the right wing, but still need to put either proseal or RTV at each hole.  Apparently vibration can chop through the conduit over time if it's not protected.

It'll still be a while before any of the aileron pushrods will get permanently installed, but they need to be put in place so the general rigging of the aileron can be done.  I think this is to just get each aileron set in a neutral position.  Once the wings are on the fuselage, I'm sure there is more to do to ensure that the right amount of deflection is there.

I just got the right aileron set in place.  Next I'll need to pull out the aileron rigging tool I made months ago as part of the wing build.  It's just a long piece of angle that has some reference holes drilled in it to align the trailing edge of the aileron (I'm assuming with the wing chord).