Chapter 18 - Step 3

This step has you make and install the TB-1 bulkhead. You also add the drip rail.

Drip rail measuring April 24, 2004. Here are two boards used to measure the location of the drip rail.

Drip rail marking 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.

Drip rail tape 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.

Drip rail foam 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.

Drip rail foam tape April 24, 2004. Here is the drip rail after adding more tape on the foam.

Drip rail glassed 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.

Drip rail glassed April 24, 2004. A full shot of the drip rail after glassing. I used peel ply to cover the edge.

Raw bulkhead 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 :)

Bulkhead template 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.

Completed bulkhead 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.

Taped bulkhead 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.