Rust inhibitor?

On Wed, 27 Aug 2003 16:53:15 GMT, "Steve Thomas"
wrote:

When you guys weld up your 4130 airframes do you use any type of rust
inhibitor in the tubes? I have read about some that you spray in the tubes
ait crawls up the walls to coat the whole inside, and it is supppose to leak
out of any weldment that had a pinhole in it. I am just curious if you use
anything like this or not. Thanks!

--
Have a good one!

Steve
www.americanspiritppc.com

Once again, I'm breaking from tradition regarding this building
method. What method do I use? Absolutely nothing.

Here's the way I figure it. I'm 55 now. I've welded this fuselage
together to the best of my ability and have closed off all openings.
Is it air tight? Proably not, there my be a pinhole somewhere. But
the fuselage will be sandblasted, at which time I get to inspect it
one more time, than it will be coated with primer and then coated with
paint. By the time all this is done, there will be precious few
places for water to get into, and that's without the fabric covering.

With the fabric covering, almost no water will be able to reach the
tubes. And even if it could, there would be very very few places for
it to get inside the tube. Did I mention that the fuselage sits level
rather than tail down? Well that's a factor too.

Finally, even if I somehow left a gaping hole for moisture to enter
the tubing, which isn't the case but for argument's sake let's assume
so, it still won't matter much in my lifetime.

So I decided not to painstakingly drill a hole through every joint so
that linseed oil or whatever could be poured into it and then roll the
fuselage around to slosh each tube, then drain it out, sort of. I
mean sheesh, what a mess to deal with and how much added weight would
this be? All for no good reason that I could see. The entire
fuselage doesn't rust out from the inside, never has. Only a few
tubes that were improperly welded and were tail down ever rusted much
and then it took 30 or 40 years to do so.

Corky Scott

Corky Scott wrote:

Once again, I'm breaking from tradition regarding this building
method. What method do I use? Absolutely nothing.

Here's the way I figure it. I'm 55 now. I've welded this fuselage
together to the best of my ability and have closed off all openings.
Is it air tight? Proably not, there my be a pinhole somewhere. But
the fuselage will be sandblasted, at which time I get to inspect it
one more time, than it will be coated with primer and then coated with
paint. By the time all this is done, there will be precious few
places for water to get into, and that's without the fabric covering.

With the fabric covering, almost no water will be able to reach the
tubes. And even if it could, there would be very very few places for
it to get inside the tube. Did I mention that the fuselage sits level
rather than tail down? Well that's a factor too.

Finally, even if I somehow left a gaping hole for moisture to enter
the tubing, which isn't the case but for argument's sake let's assume
so, it still won't matter much in my lifetime.

So I decided not to painstakingly drill a hole through every joint so
that linseed oil or whatever could be poured into it and then roll the
fuselage around to slosh each tube, then drain it out, sort of. I
mean sheesh, what a mess to deal with and how much added weight would
this be? All for no good reason that I could see. The entire
fuselage doesn't rust out from the inside, never has. Only a few
tubes that were improperly welded and were tail down ever rusted much
and then it took 30 or 40 years to do so.

Corky Scott


Corky, you're better off drilling a 1/8" hole in a low spot than to
leave just one small pinhole.

Used to drive a 18wheeler. Air brakes with big air tanks that had to be
bled, ie a short piece of rope is tied to a valve on the bottom of the
tank. If not bled regularly (every day), when you pull the rope all
sorts of dark brown gunk get blown out the bottom.

There was a spare tank sitting over in the yard that no one had used
for a year or two. I went over one day and pulled the rope on it.
Wasn't much pressure in it, but it squirted a slow steady stream of
water for a minute or so before petering out.

Here's the process. Airframe (which is acting as a tank here) get hot
during the day. The air pressure rises and forces humidity out of the
small amout of air in the tubes before the air gets squeezed out the
pinhole. Leaves maybe 0.1oz of water.

Night comes and the airframe cools. Very slowly, air, wet with evening
dew is drawn into the tube (with it's 0.1oz of water), where it waits to
start the cycle again the next day.

Paint won't help. If there's a pinhole, the paint will get blown off
when the pressure rises (the linseed oil runs into the hole from the
other side and acts as a plug, not a patch).

My unrequested advice: Either close it, and close it properly, or leave
it all the way open.

--
----Because I can----
http://www.ernest.isa-geek.org/
------------------------

On Fri, 29 Aug 2003 00:07:15 GMT, Ernest Christley
wrote:

Corky Scott wrote:

Once again, I'm breaking from tradition regarding this building
method. What method do I use? Absolutely nothing.

Here's the way I figure it. I'm 55 now. I've welded this fuselage
together to the best of my ability and have closed off all openings.
Is it air tight? Proably not, there my be a pinhole somewhere. But
the fuselage will be sandblasted, at which time I get to inspect it
one more time, than it will be coated with primer and then coated with
paint. By the time all this is done, there will be precious few
places for water to get into, and that's without the fabric covering.


Corky,
It's not the water you see that hurts, it's the water in the air rhat
gets sucked in and out of those tubes as they heat and cool. As the
tubes cool they suck damp air in, and the moisture condenses out into
the tubes.
If you don't drain them at the low point the water builds up and it
WILL rust the tubes. Better to leave both ends wide open, and allow
the structure to breath, than to leave a few pinholes and not protect
the tubing.

With the fabric covering, almost no water will be able to reach the
tubes. And even if it could, there would be very very few places for
it to get inside the tube. Did I mention that the fuselage sits level
rather than tail down? Well that's a factor too.

Finally, even if I somehow left a gaping hole for moisture to enter
the tubing, which isn't the case but for argument's sake let's assume
so, it still won't matter much in my lifetime.

So I decided not to painstakingly drill a hole through every joint so
that linseed oil or whatever could be poured into it and then roll the
fuselage around to slosh each tube, then drain it out, sort of. I
mean sheesh, what a mess to deal with and how much added weight would
this be? All for no good reason that I could see. The entire
fuselage doesn't rust out from the inside, never has. Only a few
tubes that were improperly welded and were tail down ever rusted much
and then it took 30 or 40 years to do so.

Corky Scott


Corky, you're better off drilling a 1/8" hole in a low spot than to
leave just one small pinhole.

Used to drive a 18wheeler. Air brakes with big air tanks that had to be
bled, ie a short piece of rope is tied to a valve on the bottom of the
tank. If not bled regularly (every day), when you pull the rope all
sorts of dark brown gunk get blown out the bottom.

There was a spare tank sitting over in the yard that no one had used
for a year or two. I went over one day and pulled the rope on it.
Wasn't much pressure in it, but it squirted a slow steady stream of
water for a minute or so before petering out.

Here's the process. Airframe (which is acting as a tank here) get hot
during the day. The air pressure rises and forces humidity out of the
small amout of air in the tubes before the air gets squeezed out the
pinhole. Leaves maybe 0.1oz of water.

Night comes and the airframe cools. Very slowly, air, wet with evening
dew is drawn into the tube (with it's 0.1oz of water), where it waits to
start the cycle again the next day.

Paint won't help. If there's a pinhole, the paint will get blown off
when the pressure rises (the linseed oil runs into the hole from the
other side and acts as a plug, not a patch).

My unrequested advice: Either close it, and close it properly, or leave
it all the way open.

One more comment , if you please---If you seal it up, haveplugs in each end,
and pressure test it before you fly it----If you prang it kinda hard one day
&
wonder if you cracked a weld--simply pressure it up-(nitrogen, argon,etc)
then see if it bleeds down----If it does, pressure it up with Freon, and go
sniffin with a leak detector. Saw back a few years ago where a guy left it
pressured up, and put a small gage in the ftg. ---one more thing to
pre-flight.
clare, @, snyder.on, .ca wrote:

On Fri, 29 Aug 2003 00:07:15 GMT, Ernest Christley
wrote:

Corky Scott wrote:

Once again, I'm breaking from tradition regarding this building
method. What method do I use? Absolutely nothing.

Here's the way I figure it. I'm 55 now. I've welded this fuselage
together to the best of my ability and have closed off all openings.
Is it air tight? Proably not, there my be a pinhole somewhere. But
the fuselage will be sandblasted, at which time I get to inspect it
one more time, than it will be coated with primer and then coated with
paint. By the time all this is done, there will be precious few
places for water to get into, and that's without the fabric covering.


Corky,
It's not the water you see that hurts, it's the water in the air rhat
gets sucked in and out of those tubes as they heat and cool. As the
tubes cool they suck damp air in, and the moisture condenses out into
the tubes.
If you don't drain them at the low point the water builds up and it
WILL rust the tubes. Better to leave both ends wide open, and allow
the structure to breath, than to leave a few pinholes and not protect
the tubing.

With the fabric covering, almost no water will be able to reach the
tubes. And even if it could, there would be very very few places for
it to get inside the tube. Did I mention that the fuselage sits level
rather than tail down? Well that's a factor too.

Finally, even if I somehow left a gaping hole for moisture to enter
the tubing, which isn't the case but for argument's sake let's assume
so, it still won't matter much in my lifetime.

So I decided not to painstakingly drill a hole through every joint so
that linseed oil or whatever could be poured into it and then roll the
fuselage around to slosh each tube, then drain it out, sort of. I
mean sheesh, what a mess to deal with and how much added weight would
this be? All for no good reason that I could see. The entire
fuselage doesn't rust out from the inside, never has. Only a few
tubes that were improperly welded and were tail down ever rusted much
and then it took 30 or 40 years to do so.

Corky Scott


Corky, you're better off drilling a 1/8" hole in a low spot than to
leave just one small pinhole.

Used to drive a 18wheeler. Air brakes with big air tanks that had to be
bled, ie a short piece of rope is tied to a valve on the bottom of the
tank. If not bled regularly (every day), when you pull the rope all
sorts of dark brown gunk get blown out the bottom.

There was a spare tank sitting over in the yard that no one had used
for a year or two. I went over one day and pulled the rope on it.
Wasn't much pressure in it, but it squirted a slow steady stream of
water for a minute or so before petering out.

Here's the process. Airframe (which is acting as a tank here) get hot
during the day. The air pressure rises and forces humidity out of the
small amout of air in the tubes before the air gets squeezed out the
pinhole. Leaves maybe 0.1oz of water.

Night comes and the airframe cools. Very slowly, air, wet with evening
dew is drawn into the tube (with it's 0.1oz of water), where it waits to
start the cycle again the next day.

Paint won't help. If there's a pinhole, the paint will get blown off
when the pressure rises (the linseed oil runs into the hole from the
other side and acts as a plug, not a patch).

My unrequested advice: Either close it, and close it properly, or leave
it all the way open.

One more comment , if you please---If you seal it up, haveplugs in each end,
and pressure test it before you fly it----If you prang it kinda hard one day
&
wonder if you cracked a weld--simply pressure it up-(nitrogen, argon,etc)
then see if it bleeds down----If it does, pressure it up with Freon, and go
sniffin with a leak detector. Saw back a few years ago where a guy left it
pressured up, and put a small gage in the ftg. ---one more thing to
preflight.

The CH7 (?) Angel homebuilt helicopter has a pressurized frame with gauge if
I'm not mistaken.

I'm kinda with Corky on the longevity of the tubing, but on my aircraft I
definitely like having raw linseed in the tubes to indicate frame cracks. That
stuff will leak out and leave a red indicator before the crack is noticeable to
the naked eye. It will also snitch on cracks under paint. That alone is worth
the oil to me. More than once it was the stitch in time that saved nine.

On Fri, 29 Aug 2003 02:33:04 GMT, clare @ snyder.on .ca wrote:


Corky,
It's not the water you see that hurts, it's the water in the air rhat
gets sucked in and out of those tubes as they heat and cool. As the
tubes cool they suck damp air in, and the moisture condenses out into
the tubes.
If you don't drain them at the low point the water builds up and it
WILL rust the tubes. Better to leave both ends wide open, and allow
the structure to breath, than to leave a few pinholes and not protect
the tubing.

Well that's good information, thanks Clare. Don't think it will
change my mind at this point but it's nice to know how the process
works.

The Christavia has so many tubes and they are of such thickness that
I'm reasonably sure the airframe will outlive me and my son, as long
as I don't create new openings by gronking it against a mountain or
something.

I compared the fuselage to a Wag-Aero 2+2 and was shocked to see how
beefy the Christavia was by comparison. The problem is that the
beefiness comes at the cost of additional weight I wish I did not have
to deal with.

Corky Scott

On Fri, 29 Aug 2003 13:20:57 GMT,
(Corky Scott) wrote:


The Christavia has so many tubes and they are of such thickness that
I'm reasonably sure the airframe will outlive me and my son, as long
as I don't create new openings by gronking it against a mountain or
something.

I compared the fuselage to a Wag-Aero 2+2 and was shocked to see how
beefy the Christavia was by comparison. The problem is that the
beefiness comes at the cost of additional weight I wish I did not have
to deal with.

Corky Scott
The christavia was designed so that it could be built with mild steel
and still be strong enough to fly safely.
Our Pegazair has about the same amount of tube, and EVERY joint has
been drilled. It is being Tigged, and just for the "Halibut" we will
do a pressure test. My partner says it WILL be oiled, even if he
decides to pressurize it with Argon or Nitrogen as well.