Peter Dohm wrote:
clare at snyder dot ontario dot canada wrote in message
...
On Wed, 19 Mar 2008 21:04:46 -0400, John
wrote:

Does anybody still do the old technique of drilling holes before tacking
tubes together to interconnect them for oiling the fuse when it's
finished? I've been told that's not done any more, because of the
realization that as long as the welds are air tight, the oxygen trapped
in the tube is consumed in a small amount of oxydation of the metal
surface inside until all that's left is nitrogen and then it's fine
without any oil inside.

Comments?

John
We drilled ours.
If you are 100% confident all your welds are perfectly air-tight the
oxygen arguement is true. Some guys stuff washed steel wool into the
tube as a sacrificial element.

We are thinking of putting a guage and valve on ours to see if it IS
airtight and possibly argon fill it.

--
I've heard of that being done with acrobatic birds, although it might have
been with nitrogen. A loss of pressure is evidence of structural damage.

Peter

I drilled all of mine,put half of an 1/8" pipe coupling in each top longeron at the rear,
a pc on on the lower front cross member (near one side) elevated the
tail about a foot, put a valve, small catch bottle & vacuum pump on the
rear--a hose & valve on the front, and stuck the hose down in a gallon
can of linseed oil--boiled or raw, don't make no difference. Pulled a
29" vacuum on the system--let it set a while --if no loss of vac, open
the lower valve & fill with oil. close valves. roll 1/4 turn each morn
& eve until all 4 sides have been on the bottom 8-12 hrs. (measure oil
consumed!!)
Place in initial position, open valve into oil can, apply slight
pressure with argon, neon, nitrogen, & drain out oil while filling with
inert gas. It helps to pull a vacuum on the linseed oil,Prior to
putting in the fuselage, as it will have some dissolved air in it.

otherwise you get some foaming into the catch bottle when it nears being
full.
Doesn't take very long to computs the volume inside the tubes--then
you"ll know how much to expect to use. Jerry †