FOAM CORE INFORMATION:
Note 1: Some foam cores may have a bow in the foam. This is NOT a problem with the cores
themselves because when they are cut the foam is pressed flat. Bows in foam often occur when the
big blocks are cut, releasing internal tension, similar to what happens with wood. After you install the
spars per directions in the Construction Manual the foam cores will be and will remain perfectly
straight.
Note 2: Foam cores for the Boxer 60, 90, and 120 have been made by laminating two layers of
foam using spray adhesive. This joint is at the center line of the airfoil where bending moments are
zero. This joint will not effect the strength of the foam core, which if one thinks about it, is never
much since foam is hardly a strong material. Virtually all the strength of sheeted wings comes from
the balsa sheeting, spars, and center joint fiberglass reinforcing.
Gus Ozols
Boxer 90
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