Panel (2)

I test fit the radio, G5 and AP panel, got it all squared away and drilled the holes for the screws.  The picture makes it look funky, but it all turned out nice and square.

I made the cutout for the PMA450 audio panel next.  I shot off an email to AFS to see if they can tell me what the cutout should be for the Garmin GNC 355 that will go right below it.  I think instead of leaving the PMA450 hole the size that it is, I can probably just expand it to be big enough for the GNC rack as well.  The GNC will come with a rack that supports the GPS (just like the PMA has as well), so the panel doesn't really do much in terms of supporting the unit.  I'll see what they say, since it's something they do all the time.

After measuring 100 times, I bit the bullet and made the cut for the PFD.  There really won't be much meat left to the panel after all of the cuts are made!

Sweet success!  I drilled the screw holes, but still need to install all of the nutplates.

Cowl Jig and Panel Cuts

I'm going to be bouncing back and forth between the cowl and other work for a while, just because that's the only way that I'll keep my sanity while working with the cowl.  I can't remember if I posted a picture of how the cowl jig works.  Basically, the black 3D printed spacer is bolted to the prop flange and sets the appropriate distance for the front of the cowl.  The disc gets attached to the front of the cowl and slides over the center dowel to ensure the cowl is consistently placed every time it comes off and on (which I'm assured by others will be at least 100 times).

I spent a few hours trimming and sanding the front edge of the top and bottom cowl.  They still don't fit together, but at least it's a little bit closer.  Many more hours of trimming to come (followed by a lot of additive fiberglass after it's all said and done to fill in spaces and mismatched surfaces).  I was running out of room to work, so I put the top cowl in place just to get it out of the way.  It's starting to look like a plane!

Change of scenery - back to the panel!  The other day I had gotten the big hole drilled for the Garmin G5, but still needed to drill 3 screw holes around that for mounting the attach bracket.  The bracket gets screwed to the panel and then the G5 slides onto it.  The unit has a pin on the back side at the top that slides into the bracket as a reference point, then it's made solid by screwing in a small allen head screw from the front.  Thankfully, all of my measuring paid off, and all of the screw holes landed in the right places to make the G5 set square.  Every other instrument in the center stack will reference off of this, so it was pretty important to get it right.

Next up was the radio and autopilot panels.  Those will flank either side of the G5.  Because the G5 does stick out from the panel, I decided to bump the radio and AP panel out 1/4" from the edges of the G5, just to give me a little more room to reach everything without feeling like I was having to work around the G5.  Laying this out involved a ridiculous amount of measuring and double checking squareness.  It doesn't help that the shapes of the panels are odd (at least they're both the same).

I pulled out the die grinder and went to town.  This is thick aluminum, so it took a little longer than I anticipated to make the plunge cuts each time.  I started hand filing the AP panel (right), but ran out of steam.  I'll continue with that next time.  I'm sure I'll have to sneak up on the lines a little at a time to get the fit right.  I need to order mini nutplates that can fit in those tiny corners.  That's what the units will screw into.  Thankfully, there's about a 1/16" lip on the units, so the cutouts will be hidden and don't have to be perfect. The important part will be getting the nutplates in the perfect position to make everything square.  now I see why people often get the panels cut by CNC.  It would definitely take some of the anxiety out of layouts.  Really though, these top three devices are the worst of the bunch.  Otherwise it's just a bunch of big rectangles and circles.

Panel Planning

I went to Home Depot and grabbed a small piece of 1/4" underlayment to make the cowl jig disc out of (1/2" would have been stiffer, but the clecos won't go through anything that thick).  The wood is plenty flat, but fairly soft, so I decided to play around with fiberglass to give it a little more strength for drilling holes and holding clecos.  The other reason I pulled out the fiberglass was to see if the epoxy I had was still good.  I bought a bunch of fiberglass stuff from the guy I got the wing kit from, so it's been sitting in the garage for many years.

I just put one layer of fiberglass over the front of the disc, then brushed the remaining epoxy onto the back side.  The epoxy is clear and seems to be setting up ok, so I think it's still fine to use.  I'll have to wait until tomorrow for it to fully cure (the hardener I have is the slow cure stuff).

I received my avionics order, which means it's time to play with the panel now!  They did mess up one part of the order though.  They sent me two autopilot control panels vs one autopilot and one radio control panel.  They're shipping me the radio, then I'll send back the extra autopilot panel.  I'll post more pictures of the actual units later when I start putting them in the panel.

I've gone back and forth on the panel design, but I think I've landed on my final design.  I'll have power and engine start toggles on the left (plus an alternate static toggle under a protective cover), and the rest of the switches in the center.  I waffled on whether to put the Garmin G5 in the center of the center stack between the radio and AP or on the left side of the center stack.  It's my backup attitude indicator if the primary screen fails, so I want it close to my line of site.  In the end, I decided to keep it in the very center.  It's designed so that it doesn't mount flush with the panel, but sticks out a half inch or so.  If I put the radio to the right of it, I was afraid it would be an annoying visual obstruction.  Since I'll use the radio all of the time and the G5 is just there as a backup, I decided to give the radio top billing.  In reality, the G5 is still only slid over an extra 2".  It will stick out over the AP panel, but I did a little role playing, and it should be fine.  There is a flush mount kit for the G5, which I initially planned on using.  The problem is it would require me to drop it down another 1/2" from the top and have at least 1/2" in between it and the next device below it.  I don't have the panel space to do that, so unfortunately I have to live with the non-flush mount.  I won't notice it after the first 5 minutes of flying with it, especially since the audio panel and GPS below it also stick out the same amount.

I will put the audio panel in right away, but the bottom GPS is just a space filler for now.  I'm going to cut the hole in the panel and put a cover on it.  That way when I do decide to go IFR and buy the GPS, at least I don't have to pull the panel out to cut it again.  We'll see if that ends up working!

As my final check, I printed out some actual size pictures (although they aren't actual size - just close enough to get an idea).  I couldn't find a picture of the audio panel, so white it is.  It sure looks like everything will fit!

Scary, but I cut my first hole!  The non-flush G5 actually fits in a standard 3 1/8" instrument hole, which is why it's such a popular retrofit item for older planes.  I measured about 50 times to make sure I had a true center line on the panel.  That's easier said than done given its odd shape.  This is the only 3 1/8" hole I need to make, so I just used the fly cutter instead of spending ridiculous money on a hole saw or a punch.  I still need to drill holes around this one for mounting screws.

Cowl Jig

Given how bad the cowl fit is and how many times I'm likely going to need to take it on and off, I think making a jig to help reliably get it on the crankshaft centerline will pay off.  The manufactured jigs for this purpose are machined metal ones.  I'm sure they're nice, but for a one time use, I'm not about to spend $400 on one!  Basically, the way the jig works is once you get the top and lower cowls somewhat matched up, you drill and cleco a round disc to the nose bowl to create a consistent reference point. Basically, like this:

I'm not sure what I'll make the disc out of.  Probably either just a nice flat piece of plywood or a sheet of hard plastic.

With that in place, you can work with the cowl halves separately (you have to work with them individually to get them trimmed to match the fuselage).  The second part of the jig is a spacer that bolts to the prop flange of the engine.  It has a tube extending from the center that the disc can then slide over as a reference every time you take the cowl on and off for measuring.  That means you get the cowl in the same position every time.  Without the jig, you have to measure, prop up and clamp the cowls every time you move them.

This is the $400 jig.  Looks beautiful, but seem like overkill for what it does.

I don't know if it'll work or not, but I drew up a similar jig in CAD and am going to 3D print it.  $10 in filament to save $400 seems worth the attempt! I have a scrap 1" dowel that I'll stick into the center hole for my locator pin that will mate with the disc that clecos to the cowl.  The big question to be answered is did I get the depth of the spacer correct?  The normal prop spacer is 2.25", but then I had to take into account the spinner backplate and how it sets, plus leaving about 1/4" between it and the cowl.  That ended up requiring the spacer to be 1.4375" thick (so that when the disc slides in place and up against the spacer, the cowl is sitting in a location that will ultimately be 1/4" behind the spinner).  Time will tell if I got that right.

Back At It

I need to get caught up on all of the small things I've done over the last few weeks.  I haven't had a lot of time to tackle anything big, but I'm trying to remember that everything has to get done, and small tasks are still progress.

Since the humidity is going to start rising soon and it'll be at least a year before the engine fires up, I decided to pull out the engine dehydrator I built.  I never got the 3D printed valve I was using to be air tight, so I just pulled it out of the loop for now.  I may try to come up with a new valve design at some point, but for now I'm just keeping the dehydrator in the "closed loop" position all of the time.  The air pump pumps air into the oil dipstick tube, then pulls it out from the oil breather line and sends it through a canister of desiccant beads before sending it back to the air pump.  By keeping this a closed loop (vs pumping fresh air through the beads and not having a return line back to the pump), the desiccant will last a lot longer before I have to dry it out.  I will eventually need to get some rubber stoppers to connect the tubing to the engine, but since I don't have any and the dehydrator will stay in place for a long time, I just wrapped the tubing with plastic and taped it in place.  I also taped off the exhaust and air intake to minimize leakage of ambient air into the engine.  So far, the humidity level inside the engine is staying between 20-25%.  From what I've gathered, corrosion pretty much flatlines when humidity is below 40%, so if I keep the dehydrator running, I should be fairly safe to have the engine just sit for a while.

My propeller arrived this week!  This is the Sensenich ground adjustable prop.

There is a spacer that bolts to the prop flange of the engine, then the prop hub bolts on top of the spacer.  The prop blades insert into the hub and the pitch of each blade is set by inserting a pitch pin into the hub and turning each blade until they bump into the pin (each blade has a steel pin sticking out of the base).  It's a far simpler system than most ground adjustable designs, which usually require hours of fiddling with blades and protractors.

I temporarily mounted the spacer and base of the hub (with the spinner back plate), because I need to have a reference for where the front of the cowls need to rest.

Before I get to work on the cowls themselves, I needed to finish the hinge on the right side of the firewall.  The bottom two rivets on both left and right side hinges are buried right next to the engine mount and were next to impossible to buck, so I took the easy way out and used pop rivets there.

Now that I have the prop spacer and know the distance to the spinner back plate, I can finally get to work on the cowls.  I decided to start with something easy - I laid out and cut the oil dipstick door.  It's just a rough cut for now.  I won't finalize it until I'm done with everything else.

True to the internet stories of the last 20 years, Van's fiberglass is a disaster.  The finish isn't horrible, but the fit is amazingly bad.  They outsource the fiberglass parts, and I don't think the molds have ever been right.  I've never heard of anyone who didn't have to do a ton of work on all of the fiberglass parts.  It's so bad that it's pretty confusing about where to start.  I'm doing as much reading as I can.  I'll just have to jump in though.  At least I know that fiberglass can always be fixed.

Just putting the top and bottom cowls together, you can see how off everything is.  I think my first step will be to create a round jig the size of the spinner and get the round nose bowl the right size and shape.  That will guide how much I have to cut off at the sides to get the two pieces to nest together.  In all likelihood, there will be a lot of additive finishing that has to happen once I have it all fit.  Once I have the front fitting, then I'll cut and fit the top cowl to the fuselage, then fit the bottom cowl to both.  I have absolutely no idea what I'm doing.  Should be fun!