Spar gluing

BOb

You got to remember that your panels are basically supported by the
glue in a shear situation. Even kids white glue will do pretty good in
shear.

When you put things in peal you get a different result so don't lead
the neophytes astray.

Bob, you got to remember that some of the young'uns don't have any
experience with the hot hide glues like they used to build the
'Jennys' G

Big John
++++++++++++++++++++++++++++++++++++++

Heavens to Betsy, alpha dawg:

When I tell neophytes to stay the hell away from
auto conversions in the strongest terms known
to man and beast....who takes me seriously?
The neophytes?
HELL NO - I get roasted, toasted, sliced and diced.

When I post lite hearted tongue in cheek horse****,
what do I get? Yep... your post.

Can't win. g

P.S.
Outta' time. Gotta' go now....
and test fly my 300 mph Crazy Glue & Styrofoam special.
I'm having issues with the GM locomotive 2 stroke diesel.

P.P.S.
eBay Brooklyn Bridge reserve still not met


Barnyard BOb -- Union Pacific RR - tired and retired

BOb

Guess 'hot glue' was really before your time? (tongue in cheek) G

I expected a dissertation on it and its properties and uses on
aircraft.

And here's an Irish toast to thee.

Always remember to forget
the friends that proved untrue.
But never forget to remember
those that have stuck by you...


Always remember to forget
The troubles that passed away.
But never forget to remember
the BLESSINGS that come each day...


May the Lord keep you in His hand
and never close His fist too tight...


HERE'S TO A HAPPY & SAFE HOLIDAY SEASON!
STARTING WITH THANKSGIVING

Big John



On Fri, 21 Nov 2003 10:03:54 -0600, - Barnyard BOb -
wrote:


BOb

You got to remember that your panels are basically supported by the
glue in a shear situation. Even kids white glue will do pretty good in
shear.

When you put things in peal you get a different result so don't lead
the neophytes astray.

Bob, you got to remember that some of the young'uns don't have any
experience with the hot hide glues like they used to build the
'Jennys' G

Big John
++++++++++++++++++++++++++++++++++++++

Heavens to Betsy, alpha dawg:

When I tell neophytes to stay the hell away from
auto conversions in the strongest terms known
to man and beast....who takes me seriously?
The neophytes?
HELL NO - I get roasted, toasted, sliced and diced.

When I post lite hearted tongue in cheek horse****,
what do I get? Yep... your post.

Can't win. g

P.S.
Outta' time. Gotta' go now....
and test fly my 300 mph Crazy Glue & Styrofoam special.
I'm having issues with the GM locomotive 2 stroke diesel.

P.P.S.
eBay Brooklyn Bridge reserve still not met


Barnyard BOb -- Union Pacific RR - tired and retired

On 19 Nov 2003 09:01 AM, Lou Parker posted the following:
Anyone know of any downfalls to using liquid nails to glue spars

Interesting choice of words.

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

Don't do it. Liquid Nail (brand name) is not strong enough in the ways that
count for spars.
There's a reason why 30 minute (or longer) epoxy has been used for this
purpose for so long.
I'd give you a smart ass answer too but I can't think of one at the moment.

MJC

"Lou Parker" wrote in message
om...
Anyone know of any downfalls to using liquid nails to glue spars together?
And yes, I expect the usual ignorant smart asses, who really don't have an
answer.
Lou

On Wed, 19 Nov 2003 15:57:07 -0600, "MJC" wrote:

Don't do it. Liquid Nail (brand name) is not strong enough in the ways that
count for spars.
There's a reason why 30 minute (or longer) epoxy has been used for this
purpose for so long.
I'd give you a smart ass answer too but I can't think of one at the moment.

MJC


MJC,

A question like that does not deserve even a smart ass answer.

O-ring

On 19 Nov 2003 10:01:51 -0800, (Lou Parker) wrote:

:Anyone know of any downfalls to using liquid nails to glue spars together?
:And yes, I expect the usual ignorant smart asses, who really don't have an answer.
: Lou

Unless you're talking about tacking things together with liquid nails
while the real glue cures, the glue joint will be very, very weak in
comparison with the underlying material, and subject to creep. So you
will have to size up the material significantly. Probably to the
point where no amount of power will get you off the ground. Or,
accept a safety factor under 1. Better to use almost anything else,
even white glue from the drugstore.

Other problems -
Screaming on your way to the ground can irritate the throat
The crash may cause the surrounding brush to catch fire
A shameful waste of a perfectly good engine and instruments
Increased accident rates make EVERYONE's insurance rates go up

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.

"Bob Kuykendall" wrote

...like 99-cent deer nuts being under
a buck....


You owe me a keyboard Bob.

Earlier, "Gig Giacona" wrote:

You owe me a keyboard Bob.

I'm sure glad somebody got that one.

Here's the full riddle:

What's the difference between beer nuts and deer nuts?

Beer nuts are $1.39, but deer nuts are under a buck.

Thanks, and best regards to all

Bob K.

On 19 Nov 2003 10:01:51 -0800, (Lou Parker) wrote:

Anyone know of any downfalls to using liquid nails to glue spars together?
And yes, I expect the usual ignorant smart asses, who really don't have an answer.
Lou

maybe I'll be the only one to give you a serious answer.

aircraft wood glues have a number of requirements on them that the
usual off the shelf glues cant satisfy.

wings out in the sun get quite hot and they may be in the air under
load in this condition. this means that thermo softening glues, such
as liquid nails, pva etc cant be used because they WILL fail under
load when hot.

wood will expand and shrink slightly with different moisture
conditions, sometimes one side of the joint can be moist and one side
relatively dry. this may seem insignificant but in actual fact is one
situation which anything but the best of joints will be destroyed by
over time. the differential wood expansion sets up large sheer
stresses across the glue joint. if you have a weak glue you may just
end up with only half of it remaining and half of it showing cracking
from the stresses. for this reason varnishing to water proof the wood
is essential for any glue, as is making the glue joint with wood that
has the same moisture content.

aeroplanes (wonderful word that) last quite a while so it is essential
that the glue last longer than the life of the aircraft. Acid
catalysed phenolics (like Selleys 308 in australia ) use formic acid
applied to one side of the joint to set off the resin mix applied to
the other side of the joint (it sets off when they are put together)
this acid catalyst has been found to continue working as an acid after
the cure and has led to wood failures beside the glue joint. people
have died in structural breakups of aircraft because of it.

currently there are two basic wood glues that have stood the test of
time in aircraft structures. they are Resorcinol Formaldehyde which
was developed all the way back in the 1930's and wood compatible epoxy
resin. (not all epoxys are suitable)

It doesnt cost anything more to use a wood glue that will last the
distance so I would implore you to use a proper, tested by time, wood
glue.

Both of the glues I mentioned as suitable have little factors in their
use which need to be understood. I'll leave it to you to research
those.

Btw I asked Australia's CSIRO about modern glue research a few years
ago for my work with the SAAA. "yeah we're doing lots of it but under
contract so I cant show you the results of the tests. I will tell you
that Queensland Hoop Pine is exceptionally easy to glue (it's not much
different from spruce) and in all of our tests to destruction
Resorcinol Formaldehyde glues have outlasted the wood."

I should mention casein glue in passing. it works but is eaten by
bacteria if it ever gets moist an is unreliable over the life of the
vaerage aircraft.

Hope that helps.
simple as it is it is critical that you get glueing right.
Stealth Pilot