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This step has you make and install the TB-1 bulkhead. You also add the drip rail.
April 24, 2004. Here are two boards used to measure the location of the drip rail.
April 24, 2004. I decided to use my handy little laser level to mark the location of the drip rail. The neat part
of this trick is that once you get the boards in the correct places, you can slide the laser level around on the board
and point it anywhere on the turtleback - it will always point to a spot along the driprail line.
To get the boards in place I marked a center line in the "bottom" of the turtleback. On this line are marked the
17" dimension. I also marked the 27.75" (or whatever it is) dimension up on the "shelf" of the turtleback. Now the
trick is that you need to position the boards so the laser will end up pointing to these marks. Due to the thickness
of the boards and the thickness of the laser, you need to move the boards back an appropriate amount. This is hard
to describe but is very obvious when you have all this in place. Once you have the boards located properly, simply
set the laser in place and rotate it a little at a time so you can make a mark along the curve every 1" or so. Easy
and accurate.
April 24, 2004. After making all the marks with a pen, I got out the drill and a 1/16" drill bit and made a little
hole at every mark. Once done with that I added the duct tape along the drill marks. The duct tape follows the
compound curve fairly well - at least the forward half that matters. You will get some wrinkles on the other half
but it doesn't matter since you don't glass over that part.
April 24, 2004. The next task was adding the driprail foam. I cut the strips with the 45° angle. The strips are
narrow enough that they will follow the compound curve with a little force. The trick is holding them in place, with
the correct curve and twist, while the 5-minute epoxy cures. The trick I used that worked well was to cut the foam
strips into lengths about 12" long. At that length I could hold a single piece down with both hands with fingers
spread. I premarked all the strips indicating where the glue should go. Then, one piece at a time, I added the
5-minute epoxy, waited until about 4 minutes had elapsed since mixing, then but the piece in place, force the curve,
and held it down until the epoxy set enough to hold it by itself - maybe 2 minutes. I repeated this for all the
pieces. The downside is that it takes nearly an hour but it gives good results.
April 24, 2004. Here is the drip rail after adding more tape on the foam.
April 24, 2004. Here is the drip rail after adding the 2 BID and 1 UNI. I wet out all the glass in place due to
the compound curves. I just didn't see how this would work if I wet it out on plastic first - especially the UNI.
This was a pain because the BID deformed a bunch as I tried to lay it in place and wet it out. Lots of time spent
fixing the shape.
April 24, 2004. A full shot of the drip rail after glassing. I used peel ply to cover the edge.
April 25, 2004. Here is the TB-1 bulkhead after glassing both sides and trimming to shape to fit in place. I'm glad
I added this after doing the drip rail - reverse from plans. If this was in place first, the drip rail would have
been much harder to do. Boy, the rear passengers aren't going to have much of a view :)
April 25, 2004. Since my turtleback is higher than plans, I made my own template for the bulkhead. Basically the
curve along the top and the straight section on the bottom are the same thickness as shown in the plans. I then just
traced my headrests in the correct location for the rest.
April 25, 2004. Here is the bulkhead inplace after cutting the holes. I left some extra along the headrest sections.
This will allow me to trim it to a perfect match later after the turtleback and headrests are installed in the
fuselage.
April 27, 2004. And here is the turtleback fresh out of the jig after taping the bulhead in place. It's amazing how
light this thing is at this point.
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