Why 4130 tube?

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?

Ron Webb wrote:
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/summit2001/DAY_1_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.

The stuff in my garage doesn't seem to notice any difference. It is
more than happy to rust if I don't do anything to protect it. It could
be that it happens slower; I haven't done any sort of scientific testing
to see. But the bottom line is that rusty is rusty.

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Del Rawlins-
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But the bottom line is that rusty is rusty.



Agreed...but if it took 30 years to rust out the back of the longerons on
your new float equipped Bearhawk to the point of them being unsafe, since
they are .049" 4130 - but it would take 100 years to do the same thing to
..063 1010 --that might be enough to tip the scales if the weight differance
was 20 pounds or so...

OK, I'll admit it...I made the longerons on my MoHawk out of 1/2 x.032
4130 too, just like the plans say...but there are MANY things I'd do
differently if I was starting over...like start with a set of Bearhawk plans
for instance;^}

In Ron Webb wrote:

Agreed...but if it took 30 years to rust out the back of the longerons
on your new float equipped Bearhawk to the point of them being unsafe,
since they are .049" 4130 - but it would take 100 years to do the same
thing to ..063 1010 --that might be enough to tip the scales if the
weight differance was 20 pounds or so...

My position is that if the lower longerons are getting rusty, there are
other parts in there that I need to be just as concerned about. Beefing
up parts doesn't make the airframe any stronger necessarily, it only
shifts the weak point elsewhere. I would expect that to be true of
corrosion issues as well as overall strength. I would rather go the
extra mile with corrosion protection measures NOW while the plane is
under construction, than add a bunch of unneeded weight by making
everything thicker. In 20-30 years I will most likely want to tear the
fabric off and inspect everything closely no matter what anyway. I've
got a sandblaster and I'm not afraid to use it.

OK, I'll admit it...I made the longerons on my MoHawk out of 1/2 x.
032 4130 too, just like the plans say...but there are MANY things I'd
do differently if I was starting over...like start with a set of
Bearhawk plans for instance;^}

I hear that a lot. 8^)

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Del Rawlins-
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A building material that is less expensive and more available may in
practice end up building a lighter airframe. The reason is that
you're more likely to be able to use the exact right stock instead of
just over building because you couldn't find or afford the expense to
buy a special piece of the lighter guage material.

Bend versus break. Old cars were build on rigid chassis, the safety
argument was that you want something really strong. But modern cars
are generally built uni-body designated crush zones to dissipate some
of the energy instead of transfering it to the passengers.

"In theory, practice and theory are the same. But in practice, they
are often very different."

In Jay wrote:
A building material that is less expensive and more available may in
practice end up building a lighter airframe. The reason is that
you're more likely to be able to use the exact right stock instead of
just over building because you couldn't find or afford the expense to
buy a special piece of the lighter guage material.

Speak for yourself. If my plans call for a specific material, that is
what I use. On the couple of occasions where I have deviated, I placed
long distance calls to the designer to get his okay on the changes.

Bend versus break. Old cars were build on rigid chassis, the safety
argument was that you want something really strong. But modern cars
are generally built uni-body designated crush zones to dissipate some
of the energy instead of transfering it to the passengers.

I'm all in favor of less rigidly constructed car chassis for other
people. That way, when I get into a collision with one of them, they
will serve as a crush zone for my rigid chassis and heavy duty bumpers.
If I get into an accident where (for example) my '73 pickup truck isn't
sufficient to protect me, chances are I wouldn't want to survive that
anyway. Not to say I won't try to improve my chances where it makes
sense; I just finished fabricating a set of brackets to convert the old
beast from lap belts only to lap with shoulder belts.

"In theory, practice and theory are the same. But in practice, they
are often very different."

"No plan survives contact with the enemy intact."

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/