To interject a translation of the above - not very.
The polyurethane has the same basic properties as Clark-Foam, the material commonly used for surfboards. It ends up with a brittle, fryable surface (it damages easily) and the whole makup of the glue ends up being realtively susceptible to shock and vibration, at which point it just disintegrates and comes apart.
It's use on parts that are not subject to repeated loads and/or vibration is OK, but of course that's not an airplane.
The Liquid Nails would probably work ok on something like attaching foam ribs to plywood when building an ultralight. Other than that, no.
If you are thinking about trying to save $$ on glues when building something like a "real" airplane with a decent size engine, you aren't going to save much. The cost of glue for a wood airplane is a small percentage of the complete expense.
For wood, use T-88 epoxy or whatever the plans call for. You will sleep better at night knowing it won't be a failed glue joint that "bites" you.
Oh, are you asking what liquid nails is made of? Just re-read your post. I think it is an organic adhesive refered to generally as mastic. I am sure someone else will know.
Money isn't really a concern for me. I'm more looking at availablity and ease of use. I don't think you can get T-88 at the hardware store.
What does anyone think about Aircraft Spruce's "All-Purpose Structural Adhesive?" It claims "similar" properties to T-88 but is available in a slower gel time (up to 2.5 hours). Is there any disadvantge to this product in the end result?
I've used T88, APCO, resorcinol, and West System epoxy as glue at different times. They all work well, with resorcinol being the most critical of conditions and fit of parts.
The APCO you ask about is easy to use and shares the T88's tolerance for temperature, and is cheaper to boot. I've always liked it.
Right now I use West System. It's not as viscous as the others, but can be thickened by adding SMALL amounts of colloidal sylica. West seems to be pretty available locally at least in larger metro areas. For me, the West is easier to work with and makes for an easier cleanup of squeezed out glue. Since it has several hardeners it can be used for glueing, laminating of fiberglass, and protective coating.
Your mileage may vary so far as ease of use is concerned, but if you use good techniques, I think any of the epoxies mentioned will do a good job for you.
Epoxy or Resorcinol. According to AC 43.13.1b Resorcinol is the only approved adhesive. But the Epoxy adhesives are mentioned as being acceptable. Resorcinol requires the parts to fit very tightly, with no sanding to fit.