1/72 Scale Los Angeles Class Submarine Build, Part IV

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The central core of the 688 SSN model is made from a 30 inch (76.2 cm) section of 5″ PVC well casing.  The outer diameter of this pipe is 5.563″ or 14.13 cm.  The stated hull diameter of the Los Angeles class is 33 feet (10.1 meters) so the pipe is oversized by 0.063″ or 1.6 mm, although this is mitigated by the addition of rubberized hull coatings designed to absorb sound so i am happy with it.  I also constructed a work stand from scrap lumber, necessary to prevent the hull from rolling around the work bench.
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A lip was made from a 1 inch (25 mm) band of scrap plastic to increase the bonding area for the vacuform bow and stern sections.  This band was built up with additional strips of scrap until the outer surfaces of the finished pieces were level.  MEK from the hardware store was used to glue all these pieces, it reacts well to both the PVC in the pipe and in the sheet and ensures an outstanding bond.  It is the active component of most thin hobby glues, only much, much cheaper when bought in bulk.
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The vacuforming process stretches and thins the sides of the formed plastic, so additional spacers were added to compensate on the hull sides.  The 0.060″ sheet had thinned to 0.040 – 0.045″ on the sides.  Easier to get things level now than to file and fill later, although that is inevitable in modeling.
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The bow and stern sections were cut loose from the backing sheets and trimmed to fit as best as possible.  The seams were backed with more scrap strip.  Here is the stern section with the strip clamped in place while the MEK sets up.  I found that this did not take long, I was able to alternate between the bow and stern assemblies and keep working.  Note the screw head on the pipe in the picture.  This will be one of the anchoring points for the base.  Inside the pipe a nut and washer have been epoxied in place and the long screw is  tightened down while the epoxy sets.
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Here the halves of the bow sections have been joined in place and are taped to the hull while the glue sets.  I kept the bow and stern sections removable at this point to allow me to fill the ends of the pieces with casting resin.  This helps solidify the assemblies at their weakest points and prevent any splitting while sanding.  If you use this method you must make certain that the pieces are completely sealed, as the resin will find even the slightest gap and leak out.
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The completed sections are test fit and posed with the sail master.  Alongside is the Mobeus Skipjack for comparison.  The Los Angeles boats are longer and have a greater hull volume, but also have a much smaller sail structure.
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