Why 4130 tube?

Richard Lamb wrote:

Leon McAtee wrote:

You know how hard it is to pull 20 pounds off of a bare airframe?

Or a girlfriend?

Richard

Off of a dressed girlfriend is easy off a bare one is tought!

"Rich S." wrote in message ...

'Course this would never happen with that 1000 series steel from XYZ
company.

Rich "Mebbe you could save a buck on the leather jacket and silk scarf" S.

Money saving is not my main motivation. In fact the local rusty stuff
purveyor wants - more - for local 10XX tube than AS+S 4130 W/shipping
would cost. From what I have been able to gleen from the Internet
1026 DOM looses a good bit of strength when welded (normalized state)
but something like 1040 DOM ends up with 92% of the yeild strength of
4130 N after application of fusing heat.

The down side of the 1040 seems to be that post heating is recomended
- the same as 4130 (says one Internet source). Does this mean that
1040 has similar problems with embrittlement in the HAZ as 4130? This
seems kind of odd considering the stuff is originally resistance
welded during fabrication. The same source says nothing about post
heating of 1020.

===================
Leon McAtee

Leon McAtee wrote:

Richard Lamb wrote in message ...
You know how hard it is to pull 20 pounds off of a bare airframe?

Or a girlfriend?

Richard

Depends on the girl............. one simple comment can do the job -
if your willing to be the recipient of the other reactions as wellG

20 pounds may seem like a lot on a bare airframe but in the grand
scheme it's not really significant. My Aeronca for example lost a LOT
more than that with the change from Linen to Dacron. With the other
modern materials available to us now, that 20 lbs (if that) can be
made up for elsewhere. I know guys that have more than 20 lbs of junk
stashed in their planes that they haven't even looked at for years.

Other than weight - IS - there a reason not to use 1026 DOM? This
assumes of course that the design is based on the slightly lesser
strength and/or has adequate design margins to begins with.

==================
Leon McAtee

I think it's the last assumption that won't let me let go here, Leon.
WAS that structure originally designed for mild steel of 4130.


Also, there is a subtlety here that only applies to airplanes.

Building a truss structure with heavier tube probably doesn't ring
bells and wave red flags for you, but it really should.

It's not the actual increase in weight that's the issue, but the
distribution of that weight.

(everybody look blank for a moment and say "huh?")

But wouldn't the increased weight would be evenly distributed?
Very true.

The extra weight in the cockpit section is hardly noticeable
BECAUSE
it's all close to the center of lift.

But.

The longerons, verticals, diags, tail feathers, etc. in the aft section
all weigh more too.

And THAT increased weight can be a real serious BALANCE issue.

(Sorry for the caps, but I get loud when I preach
the Gospel according to Weight and Balance)

Can I get an Amen?


Richard

In Ron Webb wrote:

Lessee...20 pounds heavier, but not as brittle or corrosive...cheaper
to acquire, and easier to work with...

There is no difference between mild steel and 4130 as far as corrosion
resistance is concerned, and in a traditional welded tube aircraft
structure any increase in brittleness is going to be a non-issue. If
you hit something hard enough to break (not just bend) it, you probably
wouldn't have survived anyway. I've flown in an aircraft with a 4130
tube fuselage that was rebuilt following a stall/incipient spin incident
from (very) low altitude. Some tubes were bent but as I recall nothing
actually separated. Pilot and passenger both walked away.

----------------------------------------------------
Del Rawlins-
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On 17 Mar 2004 18:19:11 -0800, (Leon McAtee)
wrote:

The "mild
steels" can be welded using MIG or TIG with little worries about HAZ
and since we are not heat treating the 4130 to obtain its strength
advantage it seems to me to actually be a poorer choice for amateur
aircraft construction.

To add to Corky's comments, 4130 can be TIG welded with little worry
about the HAZ as well, which is how I am welding the steel components of
my Bearhawk together. I may do some stress relief of critical clusters
and attach points using a rosebud torch, not because I think it is
necessary, but only because it is easy and I haven't seen a convincing
argument that it hurts anything to do so. MIG welding of aircraft steel
components is generally not recommended, not because of the alloy so
much as it is difficult to control the heat applied throughout the weld.
What an amateur can end up with using MIG, is a weld that starts cold
and finishes burning through. It is also possible to lay down a nice
looking bead with MIG that doesn't have any real strength to it. This
is less likely with TIG, and darn near impossible with oxy/acetylene
welding.

While it is true that we don't typically heat treat 4130 to obtain the
ultimate stength that it is capable of, the normalized condition that it
is generally supplied in is a heat treat which is optimized to provide a
good compromise between strength and toughness. This is what makes a
steel tube fuselage hold together and protect its occupants during an
accident.

Finally, any cost difference to be had using mild steel instead of 4130
is totally insignificant compared to other costs incurred during a
homebuilt project. The 4130 for my fuselage should run a little over
$1000, while I may end up spending 20 to 30 grand on an engine package.
Even if it only saves me 20 pounds, that is 20 pounds that I won't have
to carry for the life of my airplane. That is also 20 pounds more of
gear, fuel, or whatever than I can carry for the life of the airframe.
I don't know about you, but I'm planning on keeping my plane for a long
time, considering the trouble I am going to in order to build it.
Figure that I am 29 now, hope to fly it before I turn 35, and plan to
fly it as long as I am medically able to do so. I'd have to truly be a
retard to want to skimp on materials in this fashion, even if the parts
were resized to maintain equal strength.

----------------------------------------------------
Del Rawlins-
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Unofficial Bearhawk FAQ website:
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Del Rawlins wrote in message ...

To add to Corky's comments, 4130 can be TIG welded with little worry
about the HAZ as well, which is how I am welding the steel components of
my Bearhawk together. I may do some stress relief of critical clusters
and attach points using a rosebud torch,

Seems to be a contradiction here. If TIG works so well why bother
with the "stress relief of critical clusters and attach points"? This
either implies that the welding process is not completely acceptable,
or the rest of the structure has been over built and less than ideal
welds are acceptable. If the later is the case why not use something
like 1026 DOM and forget the post heat alltogether?

I'm not from Missouri but I still need to be shown that TIG is truly
acceptable for welding 4130. (I have a TIG and could use it, but
don't) I know some certified plane builders do it this way, and have
heard that at least one uses MIG, but to me it seems that heat is
heat, no matter how it is introduced to the metal. From my limited
understanding of metallurgy it's not the quantity of the energy put
into the metal it's the energy density, or peak heat, that is the
determining factor, coupled with the rate of cooling. The HAZ may be
smaller and closer to the weld with TIG but it - is - still there.
Isn't it? Maybe because the TIG HAZ is closer to the weld, and
therefore has a larger area than than the HAZ would have after being
chased out into the tube, one can get a stronger overall stucture by
not post heating a TIG weld?

Just to clear up a possible misconception from another poster - I am
NOT suggesting to, or wishing to, substitute ERW DOM mild steel for
4130 in an existing design. I'm well aware of the cascade effect of
changing something on an existing design.

If TIG, or MIG (I'm real good at MIG of thin metal, done lots of it)
welding of 4130 results in an overall better airframe then I'll stick
to 4130. But if there is a substitute, like 1040 DOM, that has a
strength only slightly less than 4130 N, that can be welded with out
any worry of developing a critical HAZ (not 100% sure about this),
then to me that would seem to be a better option for the average
homebuilder.

I'm not trying to be argumentative and have no desire to ignite any
flame here. I do like to occasionally challenge the accepted
traditions to see if there might be a "better" way of doing things.
Even if there isn't a better way I, and maybe some others, will get a
better understanding of just why "we do it that way".

=================
Leon McAtee

"Leon McAtee" wrote in message
om...

I'm not trying to be argumentative and have no desire to ignite any
flame here. I do like to occasionally challenge the accepted
traditions to see if there might be a "better" way of doing things.
Even if there isn't a better way I, and maybe some others, will get a
better understanding of just why "we do it that way".

Understand where you are coming from, Leon. It seems that you are walking
awfully close to the line between "builder" and "designer" - one which I
avoid like STD's. )

The pitfalls of changing a design are many and legendary. One thing seems to
lead to another and it is my opinion that it takes an aeronautical design
engineer who is specifically trained in the field of homebuilt light
aircraft to fully comprehend and integrate changes to proven designs. You
say, "it's only 20 pounds"; but that may have far-reaching effects which are
not evident to a builder.

That being said, I would think that a change from 4130 steel to 2024
Aluminum would have many more advantages than from 4130 --- 1026. I was
given the option on the plans for my airplane to use either 1/4" 4130 or
3/8" 2024 Al for the wing joining plates. The 2024 was stronger and lighter,
so I chose to use aluminum. The difference here was that it was written
right there in the plans. I would not have elected to do this myself.

From what I've heard, the builder of John Denver's Long Eze had a better
idea for the location of the fuel selector valve. . .

Regards,
Rich S.

In Leon McAtee wrote:
Del Rawlins wrote in message
...

To add to Corky's comments, 4130 can be TIG welded with little worry
about the HAZ as well, which is how I am welding the steel components
of my Bearhawk together. I may do some stress relief of critical
clusters and attach points using a rosebud torch,

Seems to be a contradiction here. If TIG works so well why bother
with the "stress relief of critical clusters and attach points"? This
either implies that the welding process is not completely acceptable,
or the rest of the structure has been over built and less than ideal
welds are acceptable. If the later is the case why not use something
like 1026 DOM and forget the post heat alltogether?

No contradiction. I haven't been convinced that stress relief is
necessary, but neither have I been convinced that it hurts anything, and
it only takes all of a few minutes to accomplish. From what I can tell,
even experienced welders can't agree on whether or not it is desirable.

I'm not from Missouri but I still need to be shown that TIG is truly
acceptable for welding 4130.

Over and above 50 odd years of experience in the aerospace industry?
I'm going to say Arkansas, but that's only a guess.

(I have a TIG and could use it, but
don't) I know some certified plane builders do it this way, and have
heard that at least one uses MIG, but to me it seems that heat is
heat, no matter how it is introduced to the metal. From my limited
understanding of metallurgy it's not the quantity of the energy put
into the metal it's the energy density, or peak heat, that is the
determining factor, coupled with the rate of cooling.

Speaking of contradictions, if heat is heat, why do you still need to be
shown that TIG is acceptable for welding 4130?

The HAZ may be
smaller and closer to the weld with TIG but it - is - still there.
Isn't it? Maybe because the TIG HAZ is closer to the weld, and
therefore has a larger area than than the HAZ would have after being
chased out into the tube, one can get a stronger overall stucture by
not post heating a TIG weld?

That's possible, I don't know.

Just to clear up a possible misconception from another poster - I am
NOT suggesting to, or wishing to, substitute ERW DOM mild steel for
4130 in an existing design. I'm well aware of the cascade effect of
changing something on an existing design.

If TIG, or MIG (I'm real good at MIG of thin metal, done lots of it)
welding of 4130 results in an overall better airframe then I'll stick
to 4130. But if there is a substitute, like 1040 DOM, that has a
strength only slightly less than 4130 N, that can be welded with out
any worry of developing a critical HAZ (not 100% sure about this),
then to me that would seem to be a better option for the average
homebuilder.

To play devil's advocate, I would like to be shown instances where
amateur TIG welding of 4130N resulted in homebuilt aircraft falling out
of the sky. Also, before deciding to switch from 4130 to something else
based on price, check out the prices at Dillsburg Aero in Pennsylvania.
Members of the Bearhawk list who live nearby to ACS in California, have
reported that it is still significantly cheaper to have 4130 shipped
from Charlie Vogelsong at Dillsburg than to buy it locally at ACS.

I'm not trying to be argumentative and have no desire to ignite any
flame here. I do like to occasionally challenge the accepted
traditions to see if there might be a "better" way of doing things.
Even if there isn't a better way I, and maybe some others, will get a
better understanding of just why "we do it that way".

Understood. As a relative newcomer to aviation, I get sick and tired of
the deeply held beliefs of many of the mechanics and pilots I encounter,
which often have no basis in reality, or are based on obsolete
information.

----------------------------------------------------
Del Rawlins-
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Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

Del Rawlins wrote:
In Leon McAtee wrote:

Del Rawlins wrote in message
...


To add to Corky's comments, 4130 can be TIG welded with little worry
about the HAZ as well, which is how I am welding the steel components
of my Bearhawk together. I may do some stress relief of critical
clusters and attach points using a rosebud torch,

Seems to be a contradiction here. If TIG works so well why bother
with the "stress relief of critical clusters and attach points"? This
either implies that the welding process is not completely acceptable,
or the rest of the structure has been over built and less than ideal
welds are acceptable. If the later is the case why not use something
like 1026 DOM and forget the post heat alltogether?


No contradiction. I haven't been convinced that stress relief is
necessary, but neither have I been convinced that it hurts anything, and
it only takes all of a few minutes to accomplish. From what I can tell,
even experienced welders can't agree on whether or not it is desirable.


I'm not from Missouri but I still need to be shown that TIG is truly
acceptable for welding 4130.


Over and above 50 odd years of experience in the aerospace industry?
I'm going to say Arkansas, but that's only a guess.



It was my understanding that the problem with TIG is that it doesn't put
in ENOUGH heat. That is, it melts the steel at only a very limited
section, as soon as you move on all the surround steel sucks the heat
out, basically quenching the weld and making 4130 brittle.

Don't know if it was my lack of skill, the cheap TIG contraption I was
using, or misaligned stars, but the few test pieces I TIGed together
came apart with my bare hands. I'm strong, but not like that. I
decided to stick with OcyAcet.

Luckily, I'm almost done with it.

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

There is no difference between mild steel and 4130 as far as corrosion
resistance is concerned,

Now you have got my curiosity in gear. As I said, my personal experience is
that I have seen a significant differance.

I went looking for some quantized data on the subject. I have not found what
I was looking for on the net, and may run up to the University library later
on. For now I found
http://www.armycorrosion.com/summit2...PM/schario.pdf

It does not have much in the way of quantized data, comparing 1010 to 4130
corrosion properties, but there is enough to refute the claim that there is
no differance.

Anybody got a link that does a better job with this?