Sheeting Foam Wings with Gorilla Glue Polyurethane
For years Iíve used 3M Super 77 to bond the wing skins on my foam wings. But at long last, Iíve found what I believe is a better way.
polyurethane is an adhesive that foams slightly and cures in
the presence of moisture. This makes it great for sheeting
foam wings, since it makes a strong bond and also fills any
gaps that might exist between the core and the skins.
The glue looks like honey, and it's applied to the prepped and cleaned wing skins much like laminating epoxy; dribble on a little and spread it with a squeegee. You want the surface of the wing skin to have a uniform sheen of glue on it.
Once the glue is applied to the wing skins, the wing core is wiped with a wet sponge to make it slightly damp. The water is the catalyst that will cause the glue to foam and cure, so donít forget this step.
Next the whole
works is laid up in the wing beds - bed/skin/core/skin/bed -
and stacked up with weights. Be careful of the
alignment, as this will determine how straight the wing will
be. Itís almost impossible to use too much weight.
Allow the stack to dry at least 24 hours. The moisture on the cores will cause the glue to foam just slightly and then cure. I've been impressed with how aggressively the skins adhere to the cores. Once the panels cure, you can proceed with assembly.
This method is
well-suited to vacuum bagging, but it also works fine if you
don't have the equipment to bag wings. Good luck!