How Does Aluminum Cut Steel?

Originally posted by ULTIMA1

Originally posted by tep200377
And why is that? Why cant i compare aluminium/steel with water/steel, when my example is much more far out?

Your comparisons are way off.

First the water used to cut steel is traveling a lot faster then the planes was, also the water is comming out of a small nozzel so there is a smaller impact area.

When talking about the plane hititng the tower you are talking about the impact area being spread out over most of the building.

The plane impact wasn't "spread out over most of the building". Most of the impact energy was absorbed by the actual area where it impacted. That's why those areas were severely damaged by the impact, and other areas were not.

Originally posted by nicepants
The plane impact wasn't "spread out over most of the building". Most of the impact energy was absorbed by the actual area where it impacted. That's why those areas were severely damaged by the impact, and other areas were not.

No, the impact area was the hole cut into the side of the building, which covers most of the side of the building. So that means that the impact area was pretty much the entire side of the builidng.

Unless you stating the wings caused no impact, only the airframe?

This could possibly be the answer folks depending on whether the steel was high strength or regular structural steel.

Structural steel Ultimate strength = 400 MPa
High strength steel Ultimate strength = 760 MPa

Aluminum alloy Ultimate strength = 455 MPa

Source: en.wikipedia.org...

Note that this is tensile strength.

Shear could be different.

In general: ductile materials fail in shear (ex. aluminum), whereas brittle materials (ex. cast iron) fail in tension. See tensile strength.

en.wikipedia.org...

Actually, the steel would be under shear while the plane is under compression. Still looking to see if I can find easy numbers to verify.

But, I believe that since aluminum fails in shear that the Ultimate strength of aluminum would be in shear and since steel fails in tension first, the ultimate strength is in tension. So, the shear strength of steel could be higher. Still looking into it. It's been a while since I've had materials science.



From another thread that I just posted on.

reply to post by ULTIMA1



For ONCE read the OP title, and stop saying things you CANT back up! You do this every god damn time. You say things like a 8 year old boy that doesnt care if his wrong or right.

The OP title: HOW does aluminium cut steel?
My example: HOW does water cut steel?

The PRINCIPLE is JUST THE SAME!

Its pure mathematics, but it seems you only understand what you want to understand. And you just wont understand regular textbook principles like this..

Originally posted by ULTIMA1

Originally posted by nicepants
The plane impact wasn't "spread out over most of the building". Most of the impact energy was absorbed by the actual area where it impacted. That's why those areas were severely damaged by the impact, and other areas were not.

No, the impact area was the hole cut into the side of the building, which covers most of the side of the building. So that means that the impact area was pretty much the entire side of the builidng.

Unless you stating the wings caused no impact, only the airframe?

The impact area was not the entire side of the building. The side of the building goes from ground to roof, wall-to-wall. Only a small percentage of the total area was actually impacted by the plane.

Yes, the wings caused an impact, but again, this impact was not spread over the entire side of the building.

I believe Insolubrious was able to find this nice image of a plane shaped impact on the side of a WWII ship....on this very forum:
www.abovetopsecret.com...



A lightweight japanese fighter punching a hole into a steel hulled ship?



[edit on 20-11-2007 by Disclosed]

Originally posted by nicepants
Yes, the wings caused an impact, but again, this impact was not spread over the entire side of the building.

Let me try to explain this 1 more time.

The impact was spread out the hole length and heighth of the aircraft.

The length of the aircraft almost spead from side to side of the building from wing tip to wing tip.

Which means the impact area was spread out almost the entire width of the building.

quote]Originally posted by Disclosed
A lightweight japanese fighter punching a hole into a steel hulled ship?


Please tell me your not trying to compare a WWII fighter to a boeing 767?

SAY IT AINT SO !!!!!!!!!


[edit on 20-11-2007 by ULTIMA1]

Under enough pressure, solid metal becomes liquid. This happens whenever metal is forced to change shape without heating it.

Bending, scratching, puncturing all create regions within the metal where the pressure exceeds the limit of the atoms to hold themselves rigidly in relation to each other like in a solid. Essentially, they begin to flow as if it were a piece of liquid, but only enough to relieve the pressure. The instant the pressure is relieved, it's solid again.

Originally posted by dionysius9
Under enough pressure, solid metal becomes liquid. This happens whenever metal is forced to change shape without heating it.

Kind of like the molten aluminum you see comming out of the corner of the south tower.

Originally posted by ULTIMA1


Please tell me your not trying to compare a WWII fighter to a boeing 767?

SAY IT AINT SO !!!!!!!!!


[edit on 20-11-2007 by ULTIMA1]

Let me see if I can explain in simpler terms, so you can understand what we are discussing here.

The topic is "How Does Aluminum Cut Steel"...and they were questioning how aluminum could do that much damage to steel.
The Japaneze A6M Zero was built of T-7178 aluminum. The picture I linked had a hole cut thru the hull of the ship easily.

More information on the USS Hinsdale can be found here:

USS Hinsdale

While the skin of an aircraft is thin gauge aluminium alloy what is
underneath is not. In the wings are heavy structural spars and ribs.
On each wing are jet engines which weigh 2 tons each and are built of
high strenght alloys including titanium. The belly contains the landing
gear - again massive structural members weighing several tons. The
passenger cabin floor and cargo hold floor are reinforced to support
the weight above them. There are additional pieces in the aircraft
weighing hundereds if not thousands of pounds.

Go back 60 years to 1945 - a B25 bomber lost in the fog slams into
Empire State Building at 79th floor. The B25 is less than 1/10 the weight
traveling 1/3 the speed of the jet aircraft - impact forces are only 1%
( 1/100) that which the WTC towers. Yet one of the planes engines
punched through the building and landed on roof of neighboring building
Facade of ESB is 8" thick solid quarried limestone backed up by steel
structural members. So explain how the engine travelled through the
building? After all aluminium cant penetrate stone can it????

reply to post by ULTIMA1




Uh, no. The instant the pressure is relieved, the metal turns hard again.

And pressure doesn't heat metal. Bending it can warm it up a little, but a pair of scissors cutting through an aluminum can doesn't heat up the aluminum. What it does is create a highly focused pressure point allowing that point to become liquid. The area that is called "liquid" is microscopic, and immediately returns to a solid metal once the pressure is reduced back below the threshold of phase change.


As for aluminum looking bright yellow and flowing like a liquid, it just doesn't happen. All metals have a physical property called emissivity. It is a measurement of how much blackbody radiation they emit relative to temperature.

The color and behavior of that material seen flowing out of the WTC is entirely consistent with a metal consisting of at least 90% iron being heated to 2,750 F. As you all know, no hydrocarbon fuel can reach this temperature in a 21% oxygen atmosphere.


Blackbody radiation theory (which is well understood in physics) dictates that if a material has this emission spectrum (bright yellow) its temperature must be around 2750 F. This clearly presents a problem, because no common-sense answer is available to explain the existence of material at this temperature.


To get something this hot, you must provide an exothermic oxidation-reduction reaction capable of those temperatures. In other words, you need a fuel which can combine with oxygen and result in something very very hot. All burnable fuels that fall under the category of hydrocarbons (diesel fuel, gas, jet fuel, wood, plastic, paper, etc) will only reach a maximum of 1800 F in a 21% O2 atmosphere. If you want it even hotter, you gotta up the oxygen concentration and/or change what type of fuel you're burning.

If you take Iron III Oxide and let it combine with Aluminum, the oxygen on the Fe2O3 gets ripped off by the Al in a chemical reaction. In a sense, the rust is "burning" the aluminum. This chemical reaction allows a maximum temperature of about 4,500 F. This is the chemical combination in "Thermite". VERY hot.


If thermite was used in the WTC, then that would explain the source of oxidizer which would be needed to keep the hot spots hot weeks afterward.

If you take a candle and cover it, the flame goes out because it quickly uses up all the oxygen near it. At the bottom of the rubble pile in the WTC, burning materials would have done the same thing. They would have used up all the oxygen, and gone out like a candle flame before too long. But explaining how there could be so much heat down there so many weeks later is difficult, unless you add an oxygen source which can supply heat-creating chemical reactions the oxidizer they need to keep going, producing heat.

Originally posted by dionysius9
The area that is called "liquid" is microscopic, and immediately returns to a solid metal once the pressure is reduced back below the threshold of phase change.

Same principle as ice skating. Except instead of metal, it's ice obviously.

Originally posted by Griff

Originally posted by dionysius9
The area that is called "liquid" is microscopic, and immediately returns to a solid metal once the pressure is reduced back below the threshold of phase change.

Same principle as ice skating. Except instead of metal, it's ice obviously.

Bingo.

Excellent comments, it seems that Aluminum with enough speed behind it can indeed cut steel, however as shown from that picture of a zero going into the ship hull, it looks like the wings didn't make it in.

So basically since the full force of the speed is applied to the nose/front of the plane at impact, the kinetic energy would begin to drop on impact by the time the wings hit, it would have been reduced in theory. This also applies to the pentagon too.

So yes the nose & body pentrates and cuts, but how do the wings do it to?

Originally posted by Blue_Jay33
So yes the nose & body pentrates and cuts, but how do the wings do it to?

I would say that the skeleton (aluminum alloy or whatever) of the wing would hit a panel of columns and knock them all out together since they were connected together with spandrels at intervals. It looks that way to me at least. So, it would actually be the connections instead of the column itself that failed and allowed it to look like an airplane cartoon. Just my opinion of course.

Originally posted by Blue_Jay33
It has always troubled me how a lighter Aluminum alloy cut the external steel grid of the WTC like a hot knife going through butter. Watching the pictures of construction in the 70's those things were large and strong, the fascade was weak yes, but the steel behind it was thick and strong.
When you watch the second plane hit and go through it so easily, it just doesn't seem possible. I know some people will say kinetic energy did it.
But shouldn't the wings have snapped off like in other plane accidents.
This part of 9/11 baffles me. Thoughts?

[edit on 20-11-2007 by Blue_Jay33]

Damage done to jet engines by bird strikes. Now remember those fan blades are titanium alloy.

< en.wikipedia.org...:JT8D_Engine_after_Bird_Strike.jpg >
< www.flicklife.com... >

767 damaged by birds.

< www.airdisaster.com... >

reply to post by Griff


More importantly though, as commercial vehicles have certain "limiters" on them to prevent them from say going to fast. Dont these commercial jets have any kind of "limiters" on them to prevent some maniac pilot from flying the # out of his 757/767?? I figured this would be hard information to find, so Im sure one of the pilots here might know.

Originally posted by Stillresearchn911
reply to post by Griff

 

Dont these commercial jets have any kind of "limiters" on them to prevent some maniac pilot from flying the # out of his 757/767??

Exept from the "clacker" . a aural overspeed-warning there's nothing preventing the pilots from flying the aircraft into bits and pieces.

The so called 9/11 internet investigators are talking about a software limitation that prevents the aircraft from doing this and that, fact is: there's no such thing on any Boeing in manual flight.
There are several layers of speed-protection depending on the level of automation in use, but all it takes to disconnect it is a push of a button.

Originally posted by dionysius9
To get something this hot, you must provide an exothermic oxidation-reduction reaction capable of those temperatures. In other words, you need a fuel which can combine with oxygen and result in something very very hot.

Well you might look at too that molten aluminum comming into contact with,

Jet Fuel
Magnesium
Titanium
Oxygen tanks

And other hazmats from the plane.