There's an article in the Kitplanes issue I just got in the mail (March, 2019) about using a mixture of polyurethane glue (e.g Gorilla GLue) and water-based spackle. The author (Vince Homer) mixed Gorillla Glue and Sherwin Williams Shrink-Free Spackling in various proportions, and added flox to some samples, then compared sandability and strength to the foam itself, to epoxy + micro, and epoxy + flox. The goal was to get something as strong as the epoxy mixes, but which sands easier (so the glue line won't sit above the nearby foam after sanding the core to get it ready for lamination)
It's worth reading if you plan to be gluing foam together. He founds 2 parts Gorilla Glue + 1 part spackle gave bending strength about equal to epoxy+micro and epoxy+ flox, but with improved sandability. Add flox and the strength of the bond is about 50% greater than epoxy+flox, and approaches the strength of the XPS.
The use looks pretty straightforward: mix the PU glue and the spackle, the water in spackle gets the PU glue frothing. Apply with stick/spreader. He says it can be used to glue foam chunks together or to fill dents, voids, etc. The article said several times this was for non-structural applications (molds, wingtips, fairings, wheel pants, etc). I don't know if that was the lawyers talking or not.
My main question/concern would be about durability over time. Folks who have used spray foam (Great Stuff) as core material have been surprised when it proved to be dimensionally unstable over long time periods.
Anyway, interesting.
A shout-out to Ron Wantaja on the good article on comparison in E-AB accident rates and causes between builders and those who bought their plane from the builder.
It's worth reading if you plan to be gluing foam together. He founds 2 parts Gorilla Glue + 1 part spackle gave bending strength about equal to epoxy+micro and epoxy+ flox, but with improved sandability. Add flox and the strength of the bond is about 50% greater than epoxy+flox, and approaches the strength of the XPS.
The use looks pretty straightforward: mix the PU glue and the spackle, the water in spackle gets the PU glue frothing. Apply with stick/spreader. He says it can be used to glue foam chunks together or to fill dents, voids, etc. The article said several times this was for non-structural applications (molds, wingtips, fairings, wheel pants, etc). I don't know if that was the lawyers talking or not.
My main question/concern would be about durability over time. Folks who have used spray foam (Great Stuff) as core material have been surprised when it proved to be dimensionally unstable over long time periods.
Anyway, interesting.
A shout-out to Ron Wantaja on the good article on comparison in E-AB accident rates and causes between builders and those who bought their plane from the builder.
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