Chapter 15       Firewall
 
Chapter 15. What can I say? You've probably already been here during earlier chapters we decided to make some of your pulley is in brackets and whatnot. This is the chapter for you to learn all about various fittings sleeves to being and other head scratching, wall pounding, and otherwise frustrating minutia. For being only two pages long, it's really action-packed. The Plan's call for covering the firewall with 1/8" fiberfax and .016" aluminum, but at present, I'm looking at other options. Stainless steel seems to be the way to go if you check the archives, but there are other people were using the new "fabric" type firewalls. But, thankfully, there has been no on-site testing in an actual situation where we have an engine fire. (which DOESN"T help me with my decision.)
I just ordered about $200 worth of fittings and stuff, and am really looking forward to drilling holes in my nice, neat firewall.
If you've gotten this far, you probably already know how the chapters tend to run into each other. As time goes on, I feel more like a juggler than an airplane builder. At this point, I would guess the most important thing is to plan out where you're going to place the various components. And don't forget those nice add-ons like roll trim, autopilot, remote oil filter, and such.

6/16/08

I agonized for a long time, trying to figure out how I wanted to go with the firewall material. The plans call for .016 aluminum. But the general consensus was that aluminum melts relatively easily. Also, I understand that Burt Rutan recommends stainless steel. Another canard builder used nothing but intumescent on his firewall. I liked the idea of that, except for the fact that you lose any insulation properties afforded by the Fiberfrax insulation from normal engine compartment heat. Stainless steel adds weight, but it really ends a lot of safety when you consider it does not melt as easy as aluminum. I decided to go with the Fiberfrax and .016 stainless steel. It'll probably had about 4 1/2 pounds to my installation. It is more difficult to work with stainless steel then aluminum, but I think it was worth the extra effort.

Here you see where I first made a template out of construction paper. Then, I transferred the shape to the aluminum, (which I bought long ago). I then made the trial fit to the firewall. Once I got it the way I liked it, I transferred the final shape to the stainless steel. Stainless steel is much more difficult to work with aluminum. But, I had a product called the Rodman Nibbler. It made pretty good work for the compound shapes that I needed to carve.

Next, I glued the Fiberfrax to the firewall in accordance with the Plans. This stuff cuts really easy with a box knife or scissors. The glue reminds me of sand milkweed sap with a grainy texture. Not something that you would instinctively choose to glue insulation onto a firewall. But I used it anyway.

Next, comes the laborious process of putting everything back on the firewall. (Hopefully for the very last time.) I'm also finding that I half to reject the fit of the Cowlings. The firewall insulation and the stainless steel adds that maybe 1/4 of an inch. Looks pretty good, if I say so myself

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