Earlier, (Lou Parker) wrote:

Anyone know of any downfalls to using
liquid nails to glue spars together?

Here's the data sheet for the most common formulation of Liquid Nails,
the one called Liquid Nails for Projects:

http://www.liquidnails.com/datasheets/ln601ds.pdf

It shows a best shear strength, achieved after 4 days of cure time, of
"Exceeds 400 psi." I suspect that's like 99-cent deer nuts being under
a buck. And there's no data about how reliably you can count on that
figure.

In comparison, most aircraft-use epoxies will give you a shear
strength of better than 2000 psi, of which you can consistenly enough
count on 1000 psi. Check out the epoxy strength curves on this Sequoia
Aircraft page:

http://seqair.com/skunkworks/Glues/Notes/Notes.html

That said, I've always got a tub or tube of Liquid Nails for Projects
up at the shop. The last time I used a lot of it was to glue on a
canopy for my HP-18. So far, it's held up better than the earlier two
glues that were used for that job.

Thanks, and best regards to all

Bob "never argue with the data sheet" K.