Canopy Latch (4)

It's no lie that when you deviate from the plans, the time involved goes up exponentially!  Had I gone with the standard seat back brace, between it and the latch, it probably would have taken just a few hours.  Since I changed the seat back brace, I'm guessing I'm at least at 50 hours of work modifying everything to make it work.  It'll be worth it in the end, and I actually enjoy having to do more than just follow that plans at times, but it's a lot of extra work!

I wasn't sure how I wanted to make the standoff for the left side teleflex cable.  At first I thought of just doing something super quick and basic, but I want it to look somewhat finished in the end and not like an afterthought. Now that I'm done, I can think of a number of ways I could have made it better of course.

I went through a bunch of paper templates and finally came up with something workable.  I made the top portion out of fairly thick sheet, which was kind of a nightmare to bend well without a metal brake.

I made the bottom portion out of thinner material, which was much easier to work with.  By the time it's all put together I think it'll be plenty stiff.

I wanted to use existing hardware or rivets in the bulkhead if at all possible.  The top brace is bolted to the bulkhead using two bolts in the latch setup.  The bottom brace will be attached with a couple of rivets used in the latch mechanism as well.

To give it a bit of a finished look and stiffen it up a little more, I made a cover that will attach with screws.

On the right side, the cable has to attach higher up and on the opposite side of the pivot of the latch hook.  That puts the hole in the bulkhead quite a bit higher and in kind of an awkward location (it has to go through the thick piece of angle on the back side of the bulkhead.  Figuring out exactly where to drill the hole was easier said than done since the clevis for the cable moves through quite a bit of an arc.

I drilled the hole through the bulkhead, then hit it with the dremel until it was opened up enough (I think).  Next up will be figuring out the standoff for this side.  I think it'll be far simpler though.  Because the cable sets up so high, I'll probably just make a super simple angle bracket that is screwed to the seat back brace.  I did some quick tests and everything works pretty well.  The cable has a little slack in it though, so the throw on the right side is a little less than the left side (because the left side hook action is directly connected to the handle, but by the time it transfers through all of the connections of the cable it's a little more sluggish and limited on the right side).  I think once I get the right side mounted solidly, the range of movement for the hook will be enough to clear the canopy connection and also lock it closed. 

Canopy Latch (3)

I had a couple of minutes to putter around the garage, so I kept working on the canopy latch.  I cut the push tube to length (well, I kept it about 1/4" longer than the plans called for - I've had too many instances of Van's making things too short).  I upsized the hole in the last inch of each end and tapped each end.  One end gets a bearing and bolt to attach to the handle arm, and the other end has a clevis that attaches to the rear mechanism.  With that all done and adjusted, I took some measurements for the standoff I'll make for the teleflex cable. 

Canopy Latch (2)

The handle mechanism for the canopy latch is pretty simple, but could use a little tweaking.  The long arm with the handle latches with the teeth on the smaller arm.  The smaller arm has a guide wire that sticks into a hole in the bulkhead cover.  The wire's purpose is to keep a spring in line.  The spring pushes the arm back to keep it engaged with the long arm's teeth.  Opening the canopy can be done with just one hand - when you grab the ball on the long arm, you can slide your fingers in front of it, which is enough to push the small arm forward and disengage the teeth.

The mechanism is a great, simple design, but the way the spring interfaces with the arm needs some thought.  It rides up over the edge of the arm and gets caught on top, making the action sticky.  It needs to have a larger, flat surface to butt up against.  I think if I make some sort of clevis that attaches to the arm, that would be better than the wire.

The standard design for the actual latch itself that locks the canopy frame down is a tube with hooks on each side.  Because I modified the seat back brace, the connection between the two sides has to be changed.  I chopped the hooks off of the tube.  I'm going to mount each hook independently, then connect them using a teleflex cable.

The front side handle connects to the rear latch using a pushrod.  The hooks are normally attached to the bulkhead with a UHMW block.  I put the provided one in place and drilled/bolted it.

Here's the latch mechanism and how it connects to the hook.  The pushrod arm and the hook are at different angles, so I had to twist and bend the thin steel connecting pieces until they matched the hook angle.

Now is where the design really diverges from the plans.  There has to be a way to translate movement of the left hook to the right side.  I figured out where (I hope) to drill the hole to connect to the teleflex cable.

I bought a slab of 3/4" UHMW on Amazon and cut blocks for the inside of each hook.  I had to hollow out a few spots on the back to make room for the rivets.  The action of the hooks is kind of stiff with both blocks in place, but I'm guessing it'll free up the more it moves.

I drilled holes in the two baggage bulkheads and routed the cable through (I'll have to pull it back out to paint, so won't go overboard on attaching everything).  The right side attachment to the hook is going to need a little more surgery than the left side just because the cable has to connect much higher up on the right hook.  It has to be equidistant above the central pivot point to translate the pull on one side and the subsequent pull on the other side into the same hook motion.  If the cable is in the standard spot, the hooks will move opposite of each other.  The right side is going to be a little more trouble to drill through the seatback bulkhead because of how much higher the cable sets.  It will have to go through the big piece of angle that makes up the top of the bulkhead.

Front Deck Riveting

One more round of priming done.  There really aren't that many more parts that are going to need priming, aside from the canopy frame and a few odds and ends.  Granted, there's still the interior painting to do, and let's not forget the fact that the entire plane has to be painted, but other than that...

I riveted the weather seal strips to the outer and center subpanels.  Once I'm done fiddling around with all of the structure, I'll have to go back and put some proseal on the top and bottom between the strips and the subpanels.  There's also a known issue in that there is no strip for the rubber seal to set on in the gaps where the canopy hinges are.  I need to see how the hinges work before I can decide what to do there.  I've seen other builders rivet in a little filler that connects the weather strips as well as goes up and over the hinge area and under the top skin.  I'm sure it'll become clear once I see it all together.

I'm leaving the piece at the bottom of the center subpanel clecoed on for now.  That's what the control cables attach to as they make their way to the instrument panel.  They get attached with adel clamps which use nutplates and screws.  Since I don't know exactly where my cables will route yet, it'll be easier to be able to pull this piece out and attach nutplates on the bench later.  You can see where I cut off the ribs that originally went from the firewall all the way to the instrument panel.  Those locations won't work for glass displays in the panel.  After I lay out the panel, I'll rivet the ribs back on in a new location using a piece of aluminum angle, then screw them to the panel (makes the panel removable).

I stood back and proudly looked at my work from today.  Then it hit me.  I forgot that all of the rivets that attach the ribs to the firewall are flat head rivets.  I forgot to dimple the rib flanges and the firewall before I put everything in place.  There's no easy way to do it with everything in the plane, so I'm going to have to pull it all back out just to dimple a dozen holes.

Canopy Latch

It looks like the weather tomorrow should be okay for priming, so I started today by deburring and prepping the front deck and subpanel parts.  I'll prime those tomorrow so I can move ahead with riveting it all together and moving on to the tip-up mechanism.

I can't start the canopy frame itself until that front deck is all riveted together, so I skipped ahead to the canopy latch.  It's tough to explain and hard to even visualize from the plans.  Like most things, it'll make  more sense once it's actually complete.  The latch requires two cutouts in the side skin.  I located a template, checked that it was right about 50 times, then drilled the rivet holes that will hold a couple pieces of angle in the mechanism.  I drilled holes at the ends of the slots, then used the dremel and small cutoff disk to cut the slots themselves.  That was nerve wracking.  One slip would really mess up the skin.

The initial cutouts went pretty well.  I snuck up on the right dimensions with files.

The main part of the latch is made up of two 1/8" thick pieces that have interlocking teeth when the latch is in the closed position.  The long piece had a bit of a bow to it from being punched out, so I straightened it and then smoothed all of the edges out.

The latch bars get sandwiched between two pieces of angle, which get riveted to the side skin.

I had to take a second stab at the lower angle.  Even though the first one sure seemed perfect in terms of the dimensions, the two bolt holes must have just been the tiniest fraction off - the teeth of the latches wouldn't disengage.  The second angle worked out better, although I think I'll still have to round off the teeth a little bit so they slide over each other easier.

I temporarily bolted everything together, sandwiching the latches in between the two pieces of angle.  The instructions say it works best put UHMW film on each angle face to allow the latch to slide easier, so I put some shims in place to give room for that down the road.  With all of that clamped together, I match drilled it to the holes I had drilled in the skin. 

Front Deck (6)

One of the last steps for the front deck is getting the tip-up weather seal strip in place and match drilled to the sub-panels.  The strip is nothing more than a thin piece of aluminum angle that is riveted to the panels to create a shelf for the rubber seal.  The awkward part of it all is the fact that it needs to set 1/8" below the sub-panel flange to give the rubber seal some room.  The center section was relatively straight forward since it's fairly flat, although there is just enough of a curve at the sides that I needed to flute the strip to allow it to match the curve.  To get the 1/8" offset, I clamped a piece of bar to the sub-panel flange and then clamped a 1/8" thick bar to that to butt the angle up against.  Since the sub-panel isn't flat though, I had to do it little by little, moving the reference pieces every few inches to accommodate the curve.

It turned out pretty well with a consistent offset from the flange.

The outside sub-panels were a different story because of the big curve they have.  Actually, the curve itself probably wouldn't have been all that bad to deal with.  The issue with it was the fact that the sub-panel flanges are horribly made.  They are really wavy, even after a lot of effort spent flattening them out.  I think it's just a product of the aggressive curve and thick material.  Either that, or the Van's employee came to work a little tipsy that day.  I think I was still able to get a pretty decent 1/8" offset, but it's definitely not as consistent as the flatter, center section.  As long as the rubber weather seal I use has a decent working range, it should be okay.  General consensus from other builders is to find some weather seal to use in place of what Van's sends.  Apparently it's terrible and doesn't do much good.

That finishes up the main structure of the front deck.  Technically I should get it all riveted together and installed on the fuselage now, but I'll wait for another window of nice weather to make it easier to prime the parts.  In the meantime, there are plenty of other things to do.

The standard plastic air vents that Van's sells are known for being kind of useless because they don't seal well, so I bit the bullet and upgraded to some nice aluminum eyeball vents.  The are pricey, but get great reviews.  The vents attach at the outside lower corners of the instrument panel.  A single screw/nut attaches each vent to the panel, then a bracket is fabricated that gets riveted to the side skin and attaches to the vent with two more screws.  The vent mounts are square, which doesn't allow them to fit in the panel cutout, so one corner has to be cut away so that the bend at the bottom of the panel doesn't interfere.

It's a little nerve wracking to grind away at an expensive part, but it worked out.  I rounded off the corner until the vent would lay flat against the panel.  It's a little hard to see in the picture, but I also had to grind the plastic adapter to match the same shape (the adapter sets behind the vent and allows it to connect to SCAT tube from the air intake.  Then I made the angle bracket for the outside vent screws and skin attachment.

From behind, you can see the white plastic adapter and the outside bracket against the skin (not match drilled completely to the skin yet).

As usual, the second vent went twice as fast.  Once fitted, I pulled them out and boxed them up for later.

Lately I've noticed that my air compressor seemed to be taking a lot longer to come up to pressure.  I felt around while it was running, and sure enough there was a huge amount of air coming out near the top gasket.  It looks like it'll be fairly easy to replace, assuming I can find the right replacement gasket.

Front Deck (5)

More work on the front deck today.  I don't love how the panel fits at the sides, but there's not much that can be done about it.  The cutout leaves a 1/8" gap on each side that will show the attach bracket behind the panel.  I did some research, and it looks like it's hit or miss.  For some people the panel fits perfectly, and for others it has this gap.  I have no idea why the difference.  Some people go so far as to cut their own panel blank to make it fit better, but I don't quite care THAT much. Once I decide what color the panel will be, I'll paint the bracket the same color.  Hopefully that'll help hide the gap.

Each side of the panel is attached with two screws into two pieces of angle.  I remember reading blogs that said these little brackets took a ridiculous amount of time to finish.  They are two little tiny brackets!  How hard can it be?  Well, they were right.  Two tiny brackets on each side took me 2 hours to finish!  There is nothing complicated about the setup, but it requires a lot of putting things together, taking them apart, putting them together, etc.

This is the result of my 2 hours of effort:

I have a bunch of random things to do to finish up the front deck.  The center rib is attached to the firewall with a piece of angle.  I peeled back the skin and clamped the angle in place so I could match drill it to the rib and firewall.  In typical fashion, I had to take the center rib out and rivet the angle to it then reinstall it so I could drill the firewall holes.

After this I pulled the skin all the way off because I need to prep and prime parts.  The skin won't be riveted in place until after my avionics are wired up, but I'll have to put it back on to build the canopy frame.

I hit all of the firewall flange holes with the die grinder to deburr them.  That stainless steel is sharp and tough!

The outside ribs of the front deck (the ones that go from the firewall all the way back to the panel) won't work as-is because they will interfere with where the glass displays will go in the panel.  Van's designed this plane before glass panels were a thing, so reworking these ribs is pretty much a standard modification these days.  The portion of the rib that is between the subpanel and instrument panel is just there for support of the instrument panel and isn't structural.  I cut each rib just aft of the subpanel.  I will still use the cut off portion - once my instrument panel is laid out, these ribs will be reattached to the subpanel using a piece of angle.  I'll just move them side to side depending on where the glass panels and radio stack land.  I'll probably put the ribs towards the center of the panel and use them as supports for the center stack mounting racks.

The last thing I need to do on the front deck before I prime parts and put it all together is make the two weather seal angles that are riveted to the curved portions of the subpanel (basically a tiny shelf that weather seal sets on and the canopy front skin seals against when closed).  Simple parts, but very time consuming to make.  I got one done.  The second will have to wait for tomorrow.