Working on the turtleback
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July 6, 2013: Here you can see the first strip being applied to the turtleback frame. Jean-Pierre ALAGNOUX made the turtleback frame and sized it for the texas cozy canopy. He also has a raised leading edge but kept the rear to the standard shape so that we can use the normal engine cowling. The foam is H60; not called out for but should still work. I checked the mechanical properties and they are sufficiently close so that I am not worried about the substitution. Why the substition? I had this foam left over from another foam shipment. In fact, they used this foam to protect the other foam. Some of this foam was damaged but not the pieces I used. |
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July 6, 2013: The pieces of foam were not long enough so I had to glue some end to end using the old hinge technique which we first found out about in Chapter 4. The first strip went on nicely. I then used the first strip to mark and trim the second strip and so on. |
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July 7, 2013: Slowly coming together. |
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July 14, 2013 : Almost all together. A little trimming is required. You can also see some gaps between the strips which need to be filled. I chose to fill them with small strips of foam and then later on some dry micro. |
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July 14, 2013: In this photo you can see some of the small strips of foam for gap filling between the large strips. You can also see that I chose to hold down the strips of foam with screws. I had heard about using string, plastic coated wire and so on. In the end, this method ended up being the easiest. I thought I would have very small gaps so I didn't put the aluminum strip between the strips of the foam as called out in the manual. This was a bit of a mistake. The gaps were small and I had no epoxy leaks. On the other hand, they ended up making little bumps between the strips. Easy enough (sort of) to sand off on the outside: on the inside, I still have the bumps. |
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July 14, 2013: The other problem I had was at some of the butt joints to make the long strips, the curvature changed right by the butt joint. I ended up trying to hold these in place with small brads but even with that, it was a problem. |
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July 14, 2013 : Here are the small brads. |
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August 15, 2013: All the foam is in place, some of the gaps have been filled. |
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August 15, 2013: Rounded edges at the flanges. |
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September 14, 2013: The inside of the turtleback has been glassed. Marking the centerline. |
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September 14, 2013: Marking the cut line for separating the front and back of the turtleback. |
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February 2, 2014: Big gap in construction but this seems to happen. Here I have installed the TB1 piece. I had to modify it extensively from what is called out for in the plans to account for the extra width of the texas cozy canaopy. You can see the rain tray for stopping drips in the background. |
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February 2, 2014: Rain drip tray. |
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February 9, 2014: Just have flipped the turtleback frame, getting ready to take it out. In fact, there were very few epoxy leakages between the strips. Still took a little work to get it out of the frame. |
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February 22, 2014: Getting ready to make all the joggles: I made a special tool for sanding 1/16th of an inch joggles. Removing the foam down to the glass was first done with a boxcutter knife and then some quick sanding to ensure glass to glass contact at the area where the canopy will be floxed onto the turtleback. |
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February 22, 2014: Lots of work sanding to get the contours just right. A little filling was required in certain places. I spent a lot of time doing this to ensure that it would look nice. |
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February 27, 2014: 5 hours to put on the fiberglass to the outside of the turtleback (with two people!). I was careful to make sur that the joggles sat properly and that there were no 90° intersections. (I filleted those with dry micro) |
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February 28, 2014: Just another view. You can see the rest of the fuselage and the texas cozy canopy in the background. |
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March 8, 2014 : Starting to lay out the openings for the windows in the turtleback. The texas sized cozy canopy came with bigger rear windows as well. In the end, there is not a whole lot of changes in the dimensions that you can do. In the rear, you have things mounted on the firewall and the wingspar which jut forward about 6 inches forward of the firewall. In the front, you have the turtleback "former", TB1, which establishes a forward limit for the rear windows. The bottom of the rear windows can not be moved to much because of the fairing that will be added later. In the end, the only modification that I made was to extend the rear windows up by about 1 inch. The photo on the left shows the two possibilities, per plans and slightly larger. |
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March 8, 2014: Here I have taped the windos in place. They will have to be trimmed to size but the curvature is correct. |
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March 8, 2014 : Here the sidewindow cutouts have been made in the pilots's side. Really nervewracking to do this. I used a Fein Multimaster for the straightlines, a rotozip for the radii and cleaned the radii up with a circular file (1 inch in diameter). Things are looking good. |
