Firewall ready for hammering...

Firewall
I decided to make the firewall in one piece. The material is stainless steel 0.018. A buddy will be guiding me when it comes to shrinking and stretching the material as I form the flange around the perimeter. I started to use the original firewall that I acquired with my salvaged Skybolt, but it soon became apparent that it was not symmetrical  :0|. So I decided to use one half of the old firewall as a pattern, then flipped it over for the other half. The initial pattern was from 1/4 ply. This pattern was used as a router guide, from which I routered out a final template out of 3/4" MDF. I then added a 1/8 round-over to the template with the router. For spring-back when bending the flange, I slightly beveled the edge of the 3/4" template. That part was actually pretty tricky: I made a jig for the bed of the router to angle it somewhat, but I couldn't get it to not interfer with the 1/8 radius previously cut. I couldn't add the 1/8 radius afterwards, since the bearing guide would make contact with the lower region of the 3/4 MDF (which would be angled in slightly), resulting in the cutter going deeper into the template (the end result would have been a round over with a 'small step'). So, I did it the artisan way...I scored a pencil line around the template right at where the round-over starts, then I colored in the area below that line (bevel area) with pencil. I setup the bench mounted disc sander at the required angle and gradually worked my way around the template, sanding, until I removed the shaded pencil area. All seemed to come out OK.

The steel sheet was then cut out with some overlap, for now. I then made another cloned template from 3/4" MDF. This had no bevel/round-over etc. This piece sits on top of the primary template, with the steel sheet sandwiched in the middle. This was all then clamped together using 6,000,013 C-clamps (in the UK we call em G-clamps...they do look more like a G...). the top template is there to keep the steel sheet down while the hammering goes on. For final locking reference point, I drilled the top two engine mount locating bolt holes through the whole sandwich. Now I need my buddy to continue with the hammering/shrinking/stretching...

Heel Rails
I decided to keep the flooring to a bare minimum, so heel rails it was to be. These were made from 6061-T6 x 0.063. The most tedious part was fabricating and welding in the attachment tabs. I used 3-sided tabs for where there was no inherent support from the fuselage structure, and simple flat tabs where the tubes would take the weight. An annoying mistake I made on the first two tabs, was to align the tabs flush at the top of the tubes, which is fine - as long as all the tubes are the same diameter :0|. These tubes are like, 7/8, 3/4, 1 1/8 etc. Luckily I only did two before I caught on. I am considering powder coating these heel rails...

Heel rails locked down...

Engine mount torsion strap...