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Old 01-02-2012, 03:32 PM
Join Date: Jun 2005
Location: Princeton Junction, NJ
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Default RE: 1/4 Scale Pfalz DrI

Thanks David - Something important about the spiral sheeting method I didn't mention: Since each half springs back (twists) a little as the stressed strips try to straighten-out, you need to layout the halves with the spiral pattern mirrored (like "book-matched" veneer, say down-and-back on both sides). Then both tend to pull each other back together when you glue the halves together and line up straight. If you laid them out in the same spiral direction (like down-and-back on one side, and down-and-forward on the other), the spring-back on one half would follow the spring back on the other - gluing together with a back permanent twist.

If you're really picky, its good to try and build each half the same - same angle, similar density strips, same widths, at least in roughly the same locations, etc. It's not all that sensitive, but little things help. I also used 1/8 balsa spacers (glued to the board and longerons) to lift the top/bottom longerons and bulkheads above the board, so strips and bulkheads don't accidentally get glued to the board, and the longerons overhang the edge of the board, so the strip lengths don't need to be trimmed carefully while gluing. To separate the shell, just cut the spacers, then trim the ends of the strips. A few of the strips need to be spiled (tapered ends) to lay flat. That slows down the layup, but it shouldn't need too many.