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

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.

--
Posted via a free Usenet account from http://www.teranews.com

<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

On Thu, 20 Mar 2008 02:32:24 -0400, "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
>
We would likely use Argon only because the Tig Welder that was used to
weld it has a nice big tank of Argon readily available.

--
Posted via a free Usenet account from http://www.teranews.com

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 †

clare at snyder dot ontario dot canada wrote:
> 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.
>

Aerospatial Llama helicopters do that. Dry nitrogen would be fine.

Or, use a vacuum pump and evacuate the truss, with a vacuum gauge to
monitor it.

John

One thing to consider, at least on shorter length tubes is that as you
weld, the air inside the tube will be expanding with the increasing
temperature, if the tube cannot "breath" a bit it will cause a blow
hole in your bead just as you finish it. If I were doing my project
again I would weld it tight, pressurize it, and make a habit of
checking the gauge for pressure loss on preflight like the aerobatic
guys do. More work but negligible extra weight and great indicator of
cracking.

<clare at snyder dot ontario dot canada> wrote in message
...
> On Thu, 20 Mar 2008 02:32:24 -0400, "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
>>
> We would likely use Argon only because the Tig Welder that was used to
> weld it has a nice big tank of Argon readily available.
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>
Given the same situation, I would do the same.

BTW, I am curious whether you used argon it in the tires as discussed in an
earlier thread and, if so, how well it has held pressure. My recollection
is that I had expressed the possibility that it might have slightly more
leakage than nitrogen due to a smaller molecule.

Peter

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


my old Auster had a section where the drain holes in the fabric had
been forgotten.
the rudder particularly had been flying around for years with about 9"
of water in the bottom of it. there were lots and lots and lots of
tide marks in the fabric where the rusty water had partially dried out
then refilled.
needless to say the entire lower tube frame of the rudder was corroded
through in a number of places.
when we cut the corroded section away and looked into the tube, an
eighth of an inch away from the rusted through area on into the rest
of the tube the tube was pristine.
the poms had swabbed out the inside of the tube with lanoline.

skimp on the little eighth inch holes all you like and dont bother to
put tube seal in the tubes. they're such a bother.

....might just bite you in the arse one day.

soaking all the auster fuselage tubes took less than half a can of
tube seal and even with our import costs was under $20.
for that I have a totally corrosion free fuselage and it will stay
that way.

experimenting is such fun. go for it.

Stealth Pilot