Wiring Continues

It was a little tough to get a picture, but if you squint just right, you can see the work I did on the battery.  The first issue with the battery is the fact that it is a new lithium design (not the spontaneously combust kind, but aviation specific lithium chemistry), which means it's a different size than the old school battery.  The bar that holds the battery down doesn't fit very well with this design, so I modified the thickness of it.  I also had to buy some modified terminals that screw to the standard terminals and allow the wires to be attached from the front side vs the top (since the hold down strap covers the standard terminal location - had I know this battery was a different size, I would have changed the entire Van's design to make the hold down strap work better).  The hold down strap sits about 1/16" above the brass bar that relocates the terminal.  I don't love that.  It seems ripe for a short from a dropped screw or washer.  I think I'll pull the strap off and paint some plastidip over that brass bar.

I used 2 AWG welding wire for the positive and negative battery connections.

My wire connectors arrived this afternoon, which allowed me to finish up the switch wiring.  The last thing to do before pulling everything off the panel and painting is to figure out the length of the switch wire harness.  I put the panel back in the plane to sort that out.

I decided to make the harness really close to the exact length necessary vs adding in extra length for a service loop.  The area behind the panel is going to fill up very quickly, and for a harness this simple, I don't think the extra wire is necessary.  If there's ever an issue and I need to replace wires, the access is not a problem and swapping wires would be pretty easy.

The remaining switches either don't run through the ACM (ex: PMags and Master) or tie into other connectors on the ACM (the passenger PTT and starter switch).  All of that can be done with the panel in place.  I pulled all of the switches out, so now I'm ready to prime and paint the panel.  If the weather holds tomorrow, I might actually get that done!  My dry transfer labels are supposed to arrive early next week, but I'll give the paint a week or so to cure before I start messing with the labels.

Panel Wiring

 Before jumping into more of the panel tonight, I decided to do something I've been putting off for months and months.  When I originally put the firewall insulation and stainless foil in place, I made a template and cut it to the exact size of the firewall.  I THOUGHT that the cowl hinges that are riveted to the firewall flanges would be able to be put in place with the insulation trapped behind it.  It turns out the insulation is just a smidge too thick, so it pushes the hinge out far enough that it can't be riveted where it needs to be.  So all of that "get it the perfect size" energy was for nothing.  The only option is to cut the insulation and foil away from the firewall flange about 1/8" so the hinge can slip back against the firewall.  That seems like no big deal, but let me tell you, getting to the foil and cutting it with snips was nasty business!  I finally got it inch by inch and then ran a wood dowel over the upturned and ragged foil edge to squish it back down.  It's pretty ragged looking, but once I have the hinges riveted on with the top skin, a bead of fire barrier will cover the exposed edges and clean it up a bit.

Back to the panel.  I finished up the shelf for the com transceiver and backup battery.  I needed to see how far back the MFD display would project behind the panel to know where to locate the transceiver, so I put the MFD in place.  It's starting to look like a real panel!

The MFD is fairly shallow, and also has a few inches on the bottom side, so I was able to set the transceiver relatively close to the panel underneath the bottom edge of the MFD.  I needed to sneak it forward like that so I could also fit the battery on the shelf.  The pictures are a little deceiving.  It looks like the battery could have been slid further outboard, but if I did that it would trap the transponder on the subpanel in place.  One thing I did do with the battery was flip it end on end so the cables come into it from the outboard side.  It would have been nice to have them come in from the inboard side to make the run to the ACM shorter, but that would put them uncomfortably close to the center stack and make it all fit tighter than it needs to.

I connected the cables to the MFD just to verify I had clearance for everything.  There's obviously a lot of cable management that's going to have to happen once everything is in place.

I'm at the point where I can start wiring the switches on the panel.  I'm going to wire the switches in place, then remove them all and paint the panel.  I figured there'd be less destruction of paint that way vs flipping the panel around on the bench after it is painted.  I loosely inserted all of the switches.  I was originally just going to have the alternate static air toggle (upper left corner) left open just like the rest.  It's very sensitive and easy to flip up though, so I think I'll put the red guard on it.  While unknowingly bumping to the cabin air source wouldn't be the end of the world, it would throw instruments off enough to be a little confusing, especially if flying IFR.

The switches are a combination of spade connectors, screws for ring terminals, and solder on (for the cheaper non-aviation specific stuff).

The ACM only has 4 ground pins in the connector for the switches.  I would need 3 or 4 times that many if I grounded everything separately.  I verified with AFS that the switches carry very little current, since they are just used to send the signal to the ACM, which then does the heavy lifting of opening and closing circuits (not all switches go through the ACM - the master relay and PMag switches work differently and carry the full loads).  That means that I can combine a bunch of the grounds together to consolidate them on just a few of the connector's ground pins.  AFS suggested daisy chaining switches together to cut down on the amount of wire needed.  All of the center stack switches can easily share a single ground this way.  I chained the center switches together, then started running the power wires as well.  Unfortunately I ran out of spade connectors and had to stop.  I had originally thought that most of the switches would need ring connectors, so I ordered a ton of those and very few of the spade connectors.  Got that backwards!  These connectors fit a lot tighter than the automotive ones I have, so I'm going to order more vs just grabbing some locally.

Panel Supports

The next step to finishing up the panel was to cut the center stack opening for the IFR GPS.  It'll be a minor miracle if all of this is accurate enough to not require some additional surgery down the road, but hopefully it'll be fairly close.  The standard cutout dimensions that Garmin provides must assume that the panel is being cut by machine, because the tolerances are miniscule. Cut just a hair off the mark and the bevel of the face plate won't cover up the cutout.  Because I'm cutting by hand, I modified the dimensions so the rack will set behind the panel face instead of inside the cutout space.  This will allow more wiggle room so the face plate will cover any less than perfect cut lines.  Now that I've experienced panel cutting, I can say for sure that it'll be worth a few bucks to have my next panel cut by CNC.

The audio panel and GPS are deep enough that the subpanel has to have a cutout as well.  I made the cut just a hair larger than the racks will require, then made an aluminum doubler to go behind the subpanel to stiffen the area up a little.

The racks need a way to attach to both the panel and the subpanel.  Because my cutouts were made by hand and not perfect, getting two pieces of angle where they needed to be so the audio panel face is square and flush was easier said than done. 

The audio panel rack has holes for two screws on each side that will attach to the angle on the panel.  There is also a single screw on each side towards the back of the rack. This rack was kind of a nightmare to fit.  I emailed the company to see if I got a bogus rack, but never heard back.  The dimensions are such that there's literally no way to set the rack against the panel and still have the audio panel itself cover up the hole. This seems to be a common theme with panels!  They essentially make the outside rack dimension the exact same dimension as the face plate of the unit.  Why they don't make the unit 1/16" bigger all the way around is beyond me.  I'll probably regret it later, but I made my cuts to ensure all of the cutouts would be hidden.  That meant making a smaller cutout and offsetting the racks behind the panel instead of thru the panel, as normal.  It makes getting everything square a lot more difficult, but worth it in the end.

Like on the panel side, I made a a couple of angle brackets for the subpanel side.  Then, measured 100x to figure out how to create angle brackets that go from the panel to subpanel.  These brackets have to set at a slight angle to capture one of the rack's front screws, then the back screw, then the subpanel bracket, so it took a bit of experimenting to get them right.  The GPS rack is larger and will also need some sort of support, but until I have the actual rack, it's just too hard to fabricate anything ahead of time.  I'll just have to suck it up and deal with the pain down the road when I add the GPS.

I pulled out the center stack to give myself a little more room to work on other panel related stuff.  Next up is finding a home for the com transceiver, fuse block and backup battery for the PFD/MFD.  I was initially going to put the com transceiver on the subpanel, but they've changed models since I first laid everything out.  The newer transceiver is not as deep, but it's taller and wider.  It just doesn't fit very well on the subpanel.  So instead, I'm putting the fuse block on the subpanel.  Here you can see it next to the big subpanel cutout.

Since the transceiver lost its home on the subpanel, I need to make a tray of some sort to mount it and the battery in between the panel and subpanel.  I screwed a couple of pieces of angle to the bottom of the panel/subpanel.  I've got some spare 1/16" sheet that I'll rivet to these to make a tray to hold the transceiver and battery.  The transceiver is just shallow enough that it can set on the tray without interfering with the back side of the MFD.

Defrost Fans and Panel Fit

A couple of days to catch up on...

Rose helped me pull the canopy off and get it to the bench so I could see what kind of a mess I'd made with the Sika.  For the most part, it turned out pretty well.  As expected, most of the joints still need to have a finishing bead of Sika put on them just to give a more even line though.  I taped up the aft canopy brace on both sides and ran a new bead on each side.  That made a big difference and gave it a nicer finished look.  The canopy side skirts and the inside canopy to frame joint is a little messier and harder to deal with because it's already a pretty tight joint.  It's just wide enough that I do need to fill it with a tiny bead of Sika though.  The Sika had gotten underneath the tape on the outside, so I had to spend quite a while cleaning it off of the plexi.  Luckily it doesn't stick very well to areas that weren't primed (but boy does it stick to anything that got primer!).  I think eventually I'll need to use a little polish on the plexi around those side skirts.  Just in cleaning up the Sika I managed to get some tiny scratches.  At least they're barely noticeable and nothing that some polish won't clean up.  I think I'll have to get used to polishing out scratches on the canopy every handful of years.  It's not exactly like a Cessna where you can just pop in a new window when one gets old!  I ran out of the glue, so can't finish the side skirts until I get more.

With the canopy off, it's a good time to cut the holes in the glare shield for the defroster fans.  I waffled on putting fans in, since they are so small and won't really move a ton of air, but I finally decided that it's so easy to put them in now that I may as well.  Even if they don't actually work for defogging the canopy when on the ground, they'll be great for pulling hot air away from the back side of the panel and keeping the avionics a little cooler.  I ordered two 50mm CPU fans on Amazon, thankful for experimental aviation.  I'm sure if I needed a fan for a certified plane, I'd be out hundreds of dollars, not $8 for two!

Considering I'm drilling into a finished canopy frame that took months of work, I decided to draw up a drilling template in Fusion 360 vs just marking sharpie lines on the glare shield and hoping I was close enough.

The slider canopy frames allow for much larger fans to be used, but the tipup has a very small space between where the panel sets and where the canopy frame braces are.  That's why 50mm is about as big as I could go.  Most fans that size are only 10mm deep, but I found some that are 20mm deep and move a lot more air because of it.  The drilling was pretty uneventful.  The large hole is an odd size though, so I had to use a fly cutter in a hand drill to make it.  That's actually very easy to do, and a lot less scary than using a fly cutter in the drill press.  I just went very, very slowly and with very little pressure on each pass.

Since I had already drawn up the basic dimensions in Fusion 360, I had a little fun and made a quick design for a fan grill and 3D printed them.  They will go on top of the glare shield and be held in place by the screws that mount the fans.  I have a feeling the filament I used may not be up able to stand up to the heat of a cockpit sitting on a hot ramp during the day, but we'll see.  I used PETG, which starts to deform around 160 degrees.  If I find it gets soft, I may just send the file over to sendcutsend.com and have it cut out of aluminum.  I loaded the file for a quote, and it's only $5 for each grill to do that (except $20 in shipping of course, unless I come up with another $20 in stuff I want them to make - I'll sit on it and see what else I come up with before I'm done).

The next thing I need to figure out is where to make the cutouts for the center stack audio panel and GPS in the subpanel.  Those two units are too deep to fit in between the panel and subpanel.  Avionics have changed a bit in the 25 years since Van's designed the RV9!  I measured about 100 times and marked where I think the hole in the subpanel needs to be.  I'll cut the hole and then put some angle bracing around it.  I do still need to cut the panel for the IFR GPS as well.  I'm really waffling on that - I hate to cut it, not knowing for sure if I'll ever get my IFR ticket or not.  But I think I'll hate it even more if one day I decide to put an IFR GPS in and have to pull the whole panel out to cut a new hole!

Because of the big glass screens, I had to chop off the panel to subpanel support ribs a long time ago.  I need to put those back in somewhere to make the panel a bit more solid for button pushing.  I started playing around with them to see where they could go.  I'm going to have to do some research.  I'm thinking it may just be easier to make my own braces that will serve double duty and support the avionics racks in the center stack as well.  If I use the original ribs, I'll still have to cobble together some bracing that sets in between them at the right width for the audio panel and GPS racks.  I think that will get a little busy and hard to work around, so bracing from scratch may be the best way to go.  I'll mull that over more tomorrow.

Panel Switches (2)

I've spent gobs of time thinking about switch layouts and drawing out various setups.  I finally landed on a design that I think makes logical sense, so I bit the bullet and drilled the holes for the switches.  I now have the entire panel cut, with two exceptions: I still need to put a hole in for a keyed switch and I also need to cut the opening for the future IFR GPS.

I wasn't going to use a keyed switch, since most planes that use electronic ignition these days don't bother with them, but I decided that in this day and age of lawsuits, it probably makes sense to put one in as a legal buffer.  The key won't control the mags like in a traditional setup.  It will simply be in series with the starter button, so the starter can't be engaged without the key.  It's completely unnecessary since the master also has to be turned on for the starter to work, but I just shudder to think of my plane sitting on a ramp somewhere and a "the world is all about me" parent letting their kid get into the plane and push buttons.  Without a key, the right combo of flipped switches will energize the starter, which can kick over the prop and hurt someone, even though the engine wouldn't likely fire.  Of course that would be my fault somehow.  So the keyed switch is simply my way of getting a slight edge up on an unscrupulous lawyer.

Here's the layout, pretty much set in stone at this point:

On the left are the engine and avionics related switches (Master, Avionics, Alternator, Pmags and Auto Pilot).  I put the AP switch here, because it needs to be turned on before the master is turned on in order to initialize the servos.  Above that block of 6 switches is a single toggle for an alternate static source.  This will probably be off for the life of the plane, but who knows.  It's a toggle with a 1/8 port for the static line from the back of the plane and an opening to cabin air.  If the static ports of the plane get plugged, I can flip the switch and change to getting static air pressure from inside the cabin.  That obviously throws instruments off a bit in terms of accuracy, but still allows them to function well enough to get the plane on the ground.

Below the engine/power switches are the key switch (still not drilled) and the push button starter.  Then below that are the headset jacks.  I plan on using a headset with a lemo plug (gets active noise reduction power from the plane vs battery packs), but decided to go ahead and put the lemo jack plus the traditional 2 plug jacks in, just in case I ever switch headsets.  The audio panel harness that AFS built came with both setups already wired, so aside from drilling two more holes, it was no more effort to just include them in the panel.

In the center of the panel are the "flight" related switches, grouped by functional use.  On the left are the boost pump and flaps, in the middle are lights (navigation, landing, taxi), and on the right are pitot heat and defrost.  The defrost is going to control a couple of small computer fans on the glare shield.  Defrost is probably the wrong descriptor - it's more like a defog function when sitting on the ground and the humidity is high enough to fog up the canopy before takeoff.  In reality, I'll probably have this switch on all of the time, since I think the more useful use of these fans will be to pull hot air from behind the panel to keep the avionics a little cooler.

On the right side of the panel are random things that the pilot won't need access to most of the time.  On top is the ELT activation/test panel, then a small push to talk button for passenger use if ever needed (the passenger stick has a PTT button, but I decided not to connect it since I'd rather the stick be removable without having to deal with wire connections).  Below that is a 3 port USB charger, then the passenger headset jacks.

Panel Switches & Canopy Sika

 I need to catch up from the last coupe of days of work.  I cut out the second big hole for the MFD, squared it up to the first one, and drilled the screw holes.  With that, all of the major cutouts are made in the panel.  I still have to drill the holes for the switches, the future GPS (once I figure out the size) and the ELT control panel.

I pulled out all of my switches and did an inventory to make sure I have what I need.  I think I do, but that usually means I'm one short of something.  All of the main power types of switches will be grouped to the left of the PFD.  All of the lights and other "in flight" kinds of switches will be in the center below the center stack.

I wasn't sure what spacing would work best for the switches, so I did a quick mockup.  The military standard is apparently about 1" between switches, and that felt fine.

I've been putting off gluing the canopy down for far too long, so today was the day to finally get it done.  I cleaned all of the edges and applied the Sika primer, then let it dry for about 30 minutes.

The canopy was primed, as well as the frame itself.

After the primer dried, I ran a bead of Sika 295 UV around the perimeter of the frame, and Rose came out to help me drop the canopy in place.  With it on, I put Sika on the side skirt pieces and clecoed them on.  Just to try to snug the side skirts up as much as possible, I put a few ratchet straps on.  On the advice of others, I ran an extra line of Sika around the front of the canopy.  The purpose is simply to help fill in the gap that exists so you have to do a little less filling with fiberglass.  Sika sands very easily once it's dried, so there was no reason to make this portion neat, especially since I was on the clock to get the rest done before the Sika started to skin over (60 min).

I climbed inside and smoothed out all of the squeeze out.  Unfortunately, I wasn't able to go fast enough to pull all of the tape before the Sika started to skin over.  So my nice fillets got pulled up and turned kind of ugly.  I'm not sure what I'll do to clean up the look.  I will let the canopy stay in place for a few days, then take it off to get a better look at the inside.  With it off I can probably beautify it a little easier.