veedubber what do your ribs weigh?

On Wed, 31 Dec 2008 00:11:01 -0700, wrote:

Thanks for this info. As well, I wanted to see if an ammonia solution
could be used instead of bicarbonate, so I did some googling, and found
a discussion of the chemistry involved. Turns out that various bases or
basic salts can be used resulting in, I suppose, various chemical
properties of the casein glue since it specifically mentions that casein
glue formed using lime has a known assoiation with aviation related wood
gluing. Here is the link
http://www.dotapea.com/english/chap03casein.htm

There's another article on casein linked from that page, but needs
translating from French.

A.L.

casein if protected from fungal attack is still an acceptable glue for
some aircraft work. typically gliders in dry climates that are not
left out in the rain.

the chemistry of the glue is one thing but what really matters is the
long term stability of the chemistry in the overall joint.

resorcinal formaldehyde, invented in the early 1930's, is the oldest
glue for aircraft use. the need for near perfect joint gaps, 70psi
jointing pressure and about 70degrees F jointing temperature make it
more difficult to use than the new boy on the blocks Epoxy Resin.
(dont sue me on the numbers, they're from memory)

some glues have disgraced themselves along the way by failing in
service.
acid catalysed phenolics like Selleys 308 are not usable for aircraft
because too much formic acid in the joint gradually destroys the wood
layer abutting the joint leading to in service failures.
PVA glues become thermoplastic at high temperature and will fail
underload.

just be carefull with aircraft glues. what you want is a glue that
forms a chemically stable compound after achieveing the joint
strength. it is never just a matter of sticking stuff together.
Stealth Pilot

Dear Stealth, et al,

Some of the people who have written to me asking for assistance are so
far behind the financial power curve that it's difficult for others to
appreciate. At least one correspondent is/was in China. (He vanished
just when things were getting interesting.) Others have been in
India, where disposable income appears to be less of a problem. One
was in Afghanistan, A number in Pakistan.

In most cases they seek explanation of a single term or phrase, the
next most common is those seeing information regarding adhesives,
which lead to a lengthy exchange covering the making & testing of
casein glue.

It is difficult for me to imagine having to make my own glue; more
difficult to imagine riding a bicycle 60 kilometers each way for the
mere CHANCE of getting on the internet to see if I have responded to
his last message.

Language can be a problem, as are perceptions. In most cases I am
wealthy in their terms, whereas we're barely scraping by relative to
American standards.

These people are heros to me. Imagine having to learn another
language, then how to TYPE in that language, then riding 30 miles on a
bicycle to play work-up, hoping to get even a few minutes of computer
access --- then to find I've suffered a medical problem that kept me
away from the computer for several months.

Making acetylene gas the Old Fashioned Way (ie, carbide pellets into a
tank of water). Using 'bicycle tubing' to fabricate a fuselage. Four
bicycle wheels as your landing gear. Having to make your own rib-
stitching needles.

Most of these people are better educated than me, often asking
questions that are far over my head. I am forced to solve problem
empirically -- to make a part then test it to destruction. They do
not have that option; they must do their calculations so that they can
make the thing ONCE... and hope they get it right.

I worry about the glue... and most everything else. I wonder if the
wiser course would be for me to stuff a sock in it; to let them find
another source of information.

-Bob