I'm taking a step back in time to try to get caught up on entries for all of the work that's happened over the last week. This is the last day I worked on the plane before Dad arrived. I really wanted to get the firewall insulation to a point where it wouldn't hold us up if we were to work fast enough that we could get the engine hung.
Using my template, I cut out the fiberfrax, and as best as I could, I punched holes at (ok, near) the locations for the penetrations. The fiberfrax and stainless foil only came in 2' widths, so I had to get a little extra of each to go all of the way to the top of the firewall. My seam, which will allow for outgassing of the fiberfrax in the event of a fire, is about 8" or so from the top of the firewall. Once the fiberfrax was fit and gave me some confidence that the size was right, I moved on to the .005" stainless. Cutting the outside lines of the stainless was easy enough with shop scissors, but the interior holes weren't as easy. Regardless of which tool I used, the holes just couldn't be cut smoothly. Tin snips worked the best though.
I laid the fiberfrax on the firewall and held it in place while I put on the stainless. I used a couple of rare earth magnets to help hold it all together. That's where I stopped before Dad got here to help. The picture below was taken a few days later when I had laid out and drilled holes for the stainless pop rivets. While all edges will get fire sealant (as much for protecting unsuspecting fingers from being sliced off as for fire protection), the foil and fiberfrax need to be held on mechanically as well. In the very unlikely case of a fire, the sealant expands and chars, so it will not hold the insulation in place all on its own after it's heated to that extreme.
This part of the plane has by far the most blood given in sacrifice of the build. That stainless foil is essentially razor blade material, and it lives up that. I don't have a specific picture of it, but we spent a considerable amount of time figuring out the origami required to wrap the firewall recess too.
