Chap 8 – Seat back

Today I awoke to what was supposed to be a nasty day, but turned out to be a beautiful day for flying.  I was getting together with my lifelong friend Kevin, who stayed with me a bunch in Germany and helped me glass the left wing.  Kevin just got back into town permanently after having done the multi-year contractor gig over in Pakistan since about the time I was returning to Germany from Tampa in April 2013.  Long story short, I took him flying on a hop over the Chesapeake Bay to Cambridge, Maryland where we did a few touch-n-goes and a couple of landings before heading back.   Amazing how a forecasted crappy day turned out to be almost as perfect as you could ask for to fly.

Back in the shop, I went into planning mode.  With just a couple small odd-n-end things to do on the headrest, I turned my sights to the seat back configuration.  As I said in my video, the seat back will be close to the original plans in that there will be about a 4″ wide glass shelf, or headrest base, that meets the seat back at the aft side, will traverse across the fuselage from longeron to longeron, with the forward edge abutting the rectangular 4130 steel crossbar that will make up the primary base of the roll bar.  The rectangular crossbar is 1.75″ wide, so add that to the 4″ glass base that sits directly aft of it, and we get an overall flat surface area going across the back of the seat of 5.8″ wide.

Coincidentally (or not), the headrest assembly is 5.8″ deep at the base.  I don’t have any pictures of all this yet, but you can see that the aft 2/3 of the headrest will sit on the 4″ glass base, with the forward 1/3 of the headrest sitting on the rectangular crossbar.  Two (2) screws will secure the headrest to the glass base, and two (2) screws will secure the headrest to the rectangular crossbar, for a total of 4 screws securing the headrest to the base structure of the seat back.

So tonight was all about figuring out the composite structure for the seat back area.  If you take Burt’s original headrest configuration, and lopped off the triangular headrest so that you were just left with the base of it, you would essentially have what I am designing right now.  One other key modification that you would have to do to the original plan’s seat back, is to make a notch 1″ down and 1.75″ deep/wide at the front corner of the plan’s headrest base to allow for my rectangular metal crossbar to fit in there.

I accounted for every piece I was going to need, while assessing the pieces I had already made during the Summer of 2012 in Germany.  I will also need to widen one of my 3/8″ foam pieces that I have glassed on one side, and cut out some foam pieces that will be wide enough to go across the fuselage.  I pulled some 3/4″ & 3/8″ sheets of Divinycell out of storage in preparation for the seat back construction and confirmed I had all the materials required on hand.

Obviously once I get the headrest base/seat back glassed I can start actually welding the 4130 steel rollover assembly together.

My goal is to have Chapter 8 completed by the end of March.

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