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).

Pitot

I'm still waiting on the left canopy rail replacement part from Van's, so I haven't gotten much done lately.  I could completely move on to something else, like riveting the bottom wing skins, but setting up for something completely different is more trouble than it's worth.

I pulled the pitot off the shelf, figuring I could start figuring out where and how I want to mount it.  The pitot mast doesn't come attached to the pitot itself.  I laid out a few locations to drill the mast for screws.  Not sure what size of hole to drill for the 6-32 tap, I did a test hole in some scrap...and snapped my tap!  So a new tap is on order.

I was initially going to mount the pitot in the most common place - on the rib just outboard of the aileron bellcrank.  After looking at it though, I don't like how close it is to the tie down ring.  Widely spaced tie down ropes would come very close to hitting the pitot.  I looked up some discussion online and found that this is an issue and people do move the pitot one bay further outboard to give a little more room between it and the tiedown ring.  Easy, right?  All I needed to do was drill two more holes in the rib outboard of the bellcrank so the pitot and AOA lines can be run out one more bay.  I grabbed the unibit I bought not too long ago to make these same holes in the wing walk ribs.  It worked fine for those.  Not today!  My 10 second holes ended up being a 2 hour fix! That's building for you.

As I was enlarging the first hole, the unibit caught the rib material hard!  Usually when that happens it just digs in a little bit and you have to back it out and ease it through a little slower.  This time it caught and ripped a big gash in the rib.  I just stared at it in disbelief.  There was no way I was going to attempt to pull out the rib and rivet in a new one at this point.  Instead, I ground away the ripped material and smoothed it out.  Then I made a doubler for each side to sandwich the rib in between (does that make it a tripler?).  One on each side was overkill, but I wanted the sandwich to help flatten out the rib where it got ripped.  I still need to drill the second hole in the rib, but after dealing with this, I decided that's for another day after I've had a chance to count to 10.

Canopy Frame (6)

The name of the game for today was trying to improve the fit of the front canopy frame one step at a time.  I think it's going to be hard to get a consistent fit until things are actually riveted together.  Clecos have just enough give to allow for a lot of variation when removing and installing the frame over and over (which I did about 100 times today).

I riveted the hinge brackets to the front channel.  This alone really helped to stiffen things up, but unfortunately it also caused the fit of the skin to the aft round tube to be off now.  The skin had already been drilled to the aft tube, but the riveting of the hinge bracket pulled the whole welded structure forward enough to make 3 or 4 holes on the tube about a half hole off.  Luckily, I had only drilled those holes to #40, which means I still have some wiggle room to drill them to the final #30 size.  They are not structural and only get pop rivets to hold down the glare shield, so if the holes are a little oblong it won't be the end of the world.

Next up was trying to get each side aligned to the fuselage side skin. I pulled, pushed and twisted one side, then the other, then back, then back... Every tweak changed the other side.  How high the frame sets off of the longeron at the aft end really changes the angle at the front, so I spent some time figuring out what the appropriate height was based on where it put the edge of the skin.

I really don't like how the skin fits on the sides.  It's under so much tension that it flares out from the frame and won't line up with the side of the fuselage.  I taped a tube to the edge of the skin and rolled each side a little to pre-bend the skin to make it lay down a little better.  It did help, but in the end, the design is such that this portion of the frame is only going to get so good.  My guess is I'll have to do some body work on it with fiberglass once it's all put together.

With the sides sort of where they need to be (until I breathe on them and they move), the front skin joint is the next to deal with.  Van's says the front joint gap should be .032", but consensus of thousands of builders says that is way too tight and causes the skins to catch on each other when opening the canopy.  For starters, I just needed to see what the gap looked like, so put the frame in place with the skin on.  My previous oops where I ended up with the subpanels at slightly different positions than the plans called for is now showing itself.  It's not a big deal, but the slight differences in the subpanel positions causes the skins to not butt up against each other consistently across the whole span.  When the outside edges of the front gap is zero, the center is almost 1/8".  I pushed on the center of the frame to see if I could close that 1/8" and it turned out I couldn't.  I did some investigation and found that the hinges were actually hitting the aluminum spacers that they insert into.  I didn't feel like unbolting the entire front hinge assembly to trim those spacers, so instead I decided to trim some meat off of the hinges themselves.  I used the die grinder and knocked the front curved edge off.  That did the trick and now the center portion of the frame could move further forward.

With those hinges taken care of, I had a lot more flexibility with the skin gap.  Because of the subpanel issue, the outside 9 inches or so on each side had to be shaved down no matter what.  The question was how much?  Slowly but surely, I started sneaking up on opening up the outside edges with a file.

Once I got the gap on the outside portions close to where they need to be (still need more filing, but that will come later once things are all riveted together and solid), the next gotcha showed up.  The thin ledge that is riveted to the subpanel and that the weather stripping sets on was hitting the front frame channel and keeping it from moving forward the last tiny bit to close up the gap. I filed away the areas that were hitting and finally had a decent fit across the entire width of the frame.

The nerve wracking step of drilling the hinges was next.  It's not a hard step, just a point of no return.  I've read of too many builders who drilled the hinges, only to realize they misjudged things and didn't have good enough edge distance of the hinge hole.  The only choice if that happens is to weld the holes shut and try again or completely start over with a new frame.  With the skin clecoed back onto the frame for the millionth time, I duct taped the skins together to try to keep the gaps where I wanted them while drilling.  I also put a ratchet strap around everything to hold it down in the vertical plane so the tops of each skin matched up with the other.  All of this was to hopefully put the hinges exactly where they needed to be for drilling.

Drilling the hinges was a bit awkward.  Once the frame is in place, the hinges are hidden in between the UHMW and aluminum mounting blocks I made a while back (and everything is covered up by the front top fuselage skin).  There is a 1/4" hole in those blocks where the hinge pin slides through and captures the hinges.  I put a 1/4" drill bit in my angle drill, reached up through the cutout in the firewall and used that existing 1/4" hole as a guide to drill into the hinges.  The idea is not to drill through them but just drill enough to get a full 1/4" marking.  I pulled the frame off, and with a huge sigh, I saw that the holes were nearly dead center on the hinges.

I used a wood drill block clamped to the hinges to help get a good 1/4" hole, then slowly upsized the holes until they were 3/8".  I used my rivet squeezer to press fit brass inserts into the holes (this pic is before they were fit - they actually set flush with the face of the hinge).

Now that the hinges have the mounting holes, I can more reliably start to massage the fit of everything without worrying quite as much about the position shifting every time I take the frame off.  I temporarily bolted the latching mechanism on (it'll have to be removed again to allow me to rivet the top fuselage skin on).  It was pretty cool to see that the mechanism that inserts/removes the hinge pins works flawlessly.  When I tried to lift the frame up for the first time, it hit the center weather strip ledge as it rotated.  I hadn't filed down that center ledge earlier because it looked like it had a good gap.  It did have a gap in the closed position, but the opening motion pulls the frame channel forward into the ledge as it rotates.  So I chipped away at the ledge with a file until I got the clearance needed.

It felt really good to get all of this sorted out.  I know that once I rivet the skin onto the frame, the fit is likely to change and I'll have to do more tweaking, and then again once the side rails are fitted, and again once the canopy is fitted, but it's still a big step to have this part done!

Canopy Frame (5)

Back to the front of the canopy frame.  The big issue with this (well, one of the many big issues) is the fact that the skin has a huge gap on either side as it makes the corner from the top to the side of the frame.  The gapped area is where a line of rivets go, so it can't be left as-is.  I waffled between using epoxy and microballoons or epoxy putty.  For no great reason other than I wanted to try it out, I went with the epoxy putty.  I put packing tape on the skin to make the putty release from the skin but stick to the frame once it was cured.  I rolled out a snake of putty, put it in place and then just clecoed the skin down on top of it.  It squeezed into position pretty well with a little pressure.  After pulling the skin off, I hit it with sandpaper to smooth out the edges a little bit.  For the most part it will all be hidden, so I'm not going to fret over aesthetics.  The right side went great, but for whatever reason the putty on the left side didn't set up all the way, and it also stuck to the tape.  I had to scrape it all off and do it over.  The second time I rubbed some wax on the packing tape, which ended up making everything release really easily.

With the gap filled, I was able to finally drill the additional holes through the frame.

Next up is putting the frame back on the plane for a brief minute to snug everything down and match drill the brackets of the hinges to the front channel of the frame.  I neglected to get a picture of that.  It went okay, minus one hole that got away from me.  I'll have to check the result once I pull the frame back off.  I may just need to put an additional rivet in the bracket to make up for the subpar one.

Everybody says as soon as you think you have the frame perfect and drill or rivet something, it all goes to crap.  That's true.  I had all of the gaps and edges lined up nicely, but once the drilling was done, it looked like a toddler had worked on lining everything up.  I'll have to reset it all before the next step, at which point it will move again and be off somewhere else I'm sure.  That's just the name of the game because of the design.

Canopy Frame (4)

It's almost embarrassing to show a picture of today's progress.  Who would have thought that a couple of tiny wedges would make up my entire shop time today!  It's hard to describe where these go, but they are a part of where the canopy side rails connect to the front portion of the canopy frame.  They basically just act as a spacer where the angle of the frame changes as the longerons angle downwards.

They weren't hard to make, but they took a while.  The size of them meant they had to be cut out of a big aluminum bar (no manufactured bar stock has the 5/32" thickness). It was slow going because of how fast aluminum heats up when cut/sanded, not to mention how hard it was to hang onto these while sanding.  With work gloves doubled up under leather gloves, I could still only hold onto them for a few seconds at a time during sawing and sanding before I had to dunk them in water to cool them off.

Canopy Frame (3)

More work on the side rails.  Lots and lots of clamps on the right side to get everything lined up, then I drilled the rear piece of angle to the roll bar channel.  The one thing that bugs me is that Van's decided to put a tooling hole in the channel just at the edge of where one of the center holes gets drilled.  Once I upsize that hole to the size it needs to be for a bolt, I may have a figure 8 hole.  I'll cross that bridge when I come to it.  I may just be able to fill it with JB Weld or something.

The left side canopy rail is still giving me fits, but this time for a different reason.  The new part that Van's sent still doesn't fit up against the roll bar channel all that well, but I can work around that.  I decided I'll just put some epoxy putty in the space and clamp it for a while until it dries.  That'll make a nice, solid spacer to rivet through.  The problem I ran into tonight is the fact that the canopy rail doesn't follow the curve of the fuselage very well. I got the aft half in a decent shape, but the front half is giving me fits.  I tried fluting it like you would for most metal with a flange, but it's 1/16" thick material and the fluting pliers don't really move enough material to make a difference.  After an hour of squeezing until I was blue in the face, I still hadn't really budged the shape.  I'm taking a breather to think about it.  A metal shrinker would work, but most metal shrinkers won't even go up to 1/16" aluminum either.

Canopy Frame (2+)

The name of the game will be "canopy" for a while I think.  Given how fiddly it has been so far, I imagine it's going to take me a couple of months of work to finish it.  While most of the kit parts are fantastic, the canopy frame lives up to its reputation as something that should have been redesigned 30 years ago.

The instructions provide an outline of the order to build the frame in, but after reading a ton of build logs and seeing 100 different approaches, the plans approach just doesn't make much sense to me.  I'm going to bounce around in a different build order in an attempt to do things in a way that will hopefully make the fit slightly less frustrating to get right.

While I've been contemplating how to tackle the frame, I started making a bunch of the smaller parts that I'll eventually need, like the stack-up and mounting brackets for the hydraulic arms, splice plates for the frame, etc.

I put the riveted rear channel back on the roll bar with the wood spacers in between.  The fit isn't as great as I'd like, with some low spots on the top flange relative to the roll bar, but it's as good as it can get.  I've decided I'll use Sika to glue the canopy on.  By doing that instead of using screws/nuts, I have a little more wiggle room with the fit of the canopy to the flange.  The Sika glue requires a 1/8"(ish) gap between the parts, so a little uneven fit will easily be absorbed by the glue, whereas a screw/nut approach would require a much more consistent and tight fit across the entire length of the channel.

I did my best to get the flange bent to the right angle, as well as set at the right height to align to the roll bar.

The instructions would have me finishing the front canopy frame at this point, but I don't see how you can reliably get it set to the correct height for drilling without first knowing where the aft portion of it will set relative to the side rails.  I spent a couple of hours working on the side rails to get them to match up with the fuselage curve.  I put some .032" spacers on the outside to get the inset from the fuselage side skin correct.  The canopy skirt will attach to the side rail and if all goes well, will align with the fuselage skin when the canopy is closed.

Van's sent me a replacement left side rail because the first one was so badly manufactured.  This one is slightly better, but still not as good as the right side.  I think their jig may just be off for the left side, because they are welding the aluminum angle at a slight angle to the side rail.  Whereas my original part created a huge 3/8"+ gap with the rear channel, this one was only about 3/32".  I asked online, and a bunch of people said "yep, just like mine."  I ground some of the angle here, twisted a little there, and by the end got the gap down to a little under 1/16".  I'll either fill the gap with a shim or I'll just let the rear channel twist a little to mate up with the angle.  I THINK a tiny twist would be fine, so may just go that route.  I'll have to think about it.  Not shown in the pictures, I drilled the 6 reference holes in the angle that will later attach it to the rear channel.

It doesn't seem like much in pictures, but that was the better part of a day!  A lot of work for very little progress.

Canopy Frame - Rear Channel

After a few weeks off for vacation, it feels good to get back to the plane.  I did the back and forth dance with the canopy frame (the rear channel that nests against the roll bar) to get it untwisted and fairly flat.  That was a significant undertaking it itself.  Once I had each side as good as they were going to get, I drilled the splice plate to the right channel, primed the mating surfaces and riveted it all together.  I'll prime and paint the whole canopy assembly later once it's all fitted together.