Finally, after all the preparation work, I bonded the first fuselage parts together. The entire
setup was partially disassembled to gain access to the main longerons. The bonding itself was
straightforward and uneventful. At each bulkhead station, the position had already been marked;
more importantly, wooden positioning blocks were screwed to the lateral beams to make alignment
and clamping repeatable.
I used Sicomin GP33 with a 50/50 mix of SD4771 and SD4775 hardeners, since it was quite warm in
the workshop. The slower SD4771 hardener significantly extends the pot life. The epoxy was heavily
thickened with flox.
As in earlier work, I used disposable pastry bags to apply the epoxy. They make it easy to lay down
a controlled adhesive bead, and they are simple, clean, and inexpensive to use.
Only the 30x30 main longerons remain on the strongback. Everything has been checked several times; the lateral and longitudinal dimensions are as accurate as I can make them.
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Only the 30x30 main longerons remain on the strongback. Everything has been checked several times; the lateral and longitudinal dimensions are as accurate as I can make them.
The first beads of flox-thickened epoxy for bonding the 30x10 strips that make up the 30x30 longerons. The disposable pastry bags work very well and keep the job tidy.
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The first beads of flox-thickened epoxy for bonding the 30x10 strips that make up the 30x30 longerons. The disposable pastry bags work very well and keep the job tidy.
The epoxy is heavily thickened with flox. I tested the required adhesive bead size with scrap 30x10 pieces before applying it to the actual longeron.
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The epoxy is heavily thickened with flox. I tested the required adhesive bead size with scrap 30x10 pieces before applying it to the actual longeron.
The first 30x10 strip bonded and clamped in position on the strongback.
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The first 30x10 strip bonded and clamped in position on the strongback.
Both 30x10 strips bonded. Excess epoxy has been wiped off and everything is clamped in place while curing.
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Both 30x10 strips bonded. Excess epoxy has been wiped off and everything is clamped in place while curing.
View at C10C on the tailwheel version, with the freshly bonded longeron passing through the bulkhead notch.
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View at C10C on the tailwheel version, with the freshly bonded longeron passing through the bulkhead notch.
Spring clamps hold the laminated strips together while the thickened epoxy cures.
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Spring clamps hold the laminated strips together while the thickened epoxy cures.
The middle strip protruded slightly, so the upper surface was not completely flush at first. I clamped it down as well, although I did not take photos of that step. In the end the surface came out perfectly flush.
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The middle strip protruded slightly, so the upper surface was not completely flush at first. I clamped it down as well, although I did not take photos of that step. In the end the surface came out perfectly flush.
