How Does Aluminum Cut Steel?

Originally posted by ULTIMA1

Well yes that brings up the point that if small birds can put holes in the wings and airframe at slow speeds how can wings and airframe be strong enough to cut heavier, stronger steel?

It doesn't bring up a question ( point ), it reinforces the fact that an object - whether it be a bird or aluminum - can hit with enough energy at a single point to break apart another, harder substance - aluminum or steel.

BTW, thw bird didn't "cut" through the aluminum skin either, It broke it apart.

reply to post by Damocles


You are absolutely correct there, my friend. The aluminum skin that Ultima has so kindly shown being punctured by a bird isn't very thick to begin with. Most of the time, it's somewhere around .1" thick (mostly less).

It can be thin because the aluminum alloy is only used, like you stated, to create a smooth surface for air to flow over. For that purpose, it does not need to be obscenely thick. Any load is distributed over the entire surface of the aluminum sheet (and we all know those are some big sheets).

Now I have to correct Ultima there and say that his pictures do not show any of the actual solid frames under the skin being damaged to a significant amount.

He's been using those pictures and applying the terminology somewhat incorrectly. Some will include the skin as part of the airframe, but to me, they are two separate entities. It's like the bones and skin of your body. If you strip the skin away, the body itself can still "stand", as the bones are what allows it to do that.

Just like if you take the skin off the airplane, it's structure will still be intact and still stand. But I wouldn't want to take a flight in that!

And as Griff pointed out, the aluminum alloys that have been in use in the aerospace industry can be much stonger than construction structural steel.

I know you're going to repost that quote that you love so much, Ultima, but are you just going to take it at face value or actually do some research and find out what kind of aluminum alloy was used in 757s and 767s?

This isn't saying that the aluminum alloy won't take damage itself. There is enough initial mass from the airframe as a whole to break some steel beams before it starts being broken itself.

Another thing to consider for those of you that understand metallurgy is that steels are brittle, whereas aluminums are ductile. This means that once steel has reached a certain point, it will just break abruptly. This is in contrast with aluminum, which will plastically deform before breaking. This allows it to "squash up" (for a lack of a better term) against the steel and continue to apply pressure to it.

Also note that there are many beams in the 757 and 767 that are designed to take loads in the forward and aft directions. If you take a horizontal beam some 10 feet long and ram it into a vertical beam only maybe a foot or two thick in the horizontal direction (and remember, this vertical beam has an I shape to it, meaning it's not a solid square mass) at high velocities, that vertical beam is going to break. There's much more material resisting the force in the horizontal beam than in the vertical beam.

Mods, and everyone else, I apologize for the long post, but I had to say what was on my mind.

[edit on 15-6-2008 by HLR53K]

reply to post by ULTIMA1


The only problem I have with that quote is that it doesn't directly state which perimeter beams they were comparing to.

www.tms.org...

In contrast, the WTC structural plans specified steels that began at a minimum yield strength FY = 36 ksi and increased from FY = 40 ksi to FY = 85 ksi in 5 ksi (34.5 MPa) increments. Corner elements in the exterior wall often used FY = 100 ksi steels. Contemporaneous construction documents indicate that the lowest strength exterior wall column steels were supplied to the ASTM A 36 standard,...

We know the airplane didn't impact a corner element. So Ultima, which steel members was the journal comparing to?

Also, can you specify as to which of the FY = 36 ksi to FY = 85 ksi beams the airplane impacted? Since there is such a broad range of strengths in the exterior columns.

Originally posted by HLR53K
Also, can you specify as to which of the FY = 36 ksi to FY = 85 ksi beams the airplane impacted? Since there is such a broad range of strengths in the exterior columns.

Actually, this information is not known. Because as I keep harping about in thread after thread, the structural documentation isn't available. And I have not seen a quote from NIST where they state the specifics.

But, it's nice to see "ksi" when I remember someone questioning my engineering knowledge not long ago when I was talking ksi. They said "nah, uh, engineers use SI units". And it took me about 3 pages of argument to show this person that indeed structural engineers in the US still use the english system. Not you HLR53K.

Originally posted by Damocles
how slow is takeoff speed?

Takeoff is about 200 mph, about half the speed the planes that hit the towers were supposed to have been donig.

So if small birds can do that kind of damage, how much damage do you think the steel would do the wings and airframe?



[edit on 16-6-2008 by ULTIMA1]

Originally posted by HLR53KThe only problem I have with that quote is that it doesn't directly state which perimeter beams they were comparing to.

www.tms.org...

The only individual metal component of the aircraft that is comparable in strength to the box perimeter columns of the WTC is the keel beam at the bottom of the aircraft fuselage. While the aircraft impact undoubtedly destroyed several columns in the WTC perimeter wall, the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure.

[edit on 16-6-2008 by ULTIMA1]

reply to post by Griff


Haha! I've been brought up on both systems. Some of the college courses I took also had SI units mixing in with the English units.

The US might never move completely to the SI system because all of our tooling is in English and it would cost billions to switch.

Originally posted by ULTIMA1

www.tms.org...

The only individual metal component of the aircraft that is comparable in strength to the box perimeter columns of the WTC is the keel beam at the bottom of the aircraft fuselage. While the aircraft impact undoubtedly destroyed several columns in the WTC perimeter wall, the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure.

[edit on 16-6-2008 by ULTIMA1]

Ha! Didn't I call it that you would repost that generic quote?

Anyway, that still doesn't really tell me much. I want to see some numbers to compare to.

Or are you telling us that we should just accept that without questioning it (just because you posted it)?

Since I have posted that quote from another of their journals stating that a multitude of different strengths of steel (some of which have lower strengths than the nominal 7075 aluminum alloys used in aircraft) around the perimeter, it still bears asking which is correct.

For an individual structure, the "keel" (it's not a traditional one-piece keel) can be stronger than structural steel. But what about the combined assemblies of all the other components?

As for that fact, why did they ignore some of the titanium airframe items? Surely you can agree that a titanium structure will break steel much easier than aluminum.

Originally posted by ULTIMA1

Takeoff is about 200 mph, about half the speed the planes that hit the towers were supposed to have been donig.

So if small birds can do that kind of damage, how much damage do you think the steel would do the wings and airframe?

[edit on 16-6-2008 by ULTIMA1]

Where in those pictures does it show significant damage to the internal airframe? All I see is the outer skin being punctured. You still haven't answered me on that.

So you would have us believe that any airplane that's flown into a building (accidentally or not) would be like sending a vegetable through a screen mesh? Are you saying that the steel would not be damaged at all?

[edit on 16-6-2008 by HLR53K]

Originally posted by HLR53K
Haha! I've been brought up on both systems. Some of the college courses I took also had SI units mixing in with the English units.

The US might never move completely to the SI system because all of our tooling is in English and it would cost billions to switch.

In school we're taught both systems. Even on the PE (professional engineering) exam, there are problems with SI units. But, I think you are spot on about why we will never change.

Originally posted by HLR53K
Or are you telling us that we should just accept that without questioning it (just because you posted it)?

Well it seems you expect people to believe the official story just because you and others post it ?

I have posted more facts and evidence then most people on here, and will continue to find and post more facts and evidence.


[edit on 17-6-2008 by ULTIMA1]

Originally posted by HLR53K
So you would have us believe that any airplane that's flown into a building (accidentally or not) would be like sending a vegetable through a screen mesh? Are you saying that the steel would not be damaged at all?

All you have to do is look at the Purdue animation and you can see that the aluminum airframe and wings are shredded as soon as they enter the building.

Also if you look at the photos of the hole in the side of the towers you can clearly see that the wings barely made it in to the building, specially the wing tips.

Hmmm well how did ice puncture holes in steel then? Remember the Titanic. plain to see really. Or is that a conspiracy too? Like everything else!

reply to post by weenaman


Ice didn't punch holes in any steel. Inferior rivets were used to hold the steel hull plates together, and they failed allowing water to enter the hull.

NEW YORK (AP) -- The tragic sinking of the Titanic nearly a century ago can be blamed on low grade rivets that the ship's builders used on some parts of the ill-fated liner, two experts on metals conclude in a new book.

Source

reply to post by ANOK

The Titanic's hull had sixteen water- tight compartments. The iceberg punctured five compartments.

www.wicknet.org...'s/Warriner's18.h tm

On the bridge, the ship's First Officer gave the order to spin the wheel "Hard-a-starboard," while telegraphing to have the engines stopped and reversed. The bow of the ship eased to the left missing a head on collision, but below the water line, a rock-hard spur of ice punctured a large portion of the hull. From that moment, nothing could have saved the ship.

www.smokymountainsentinel.com...

The ten-second encounter with the iceberg had left six seemingly slight gashes in the ship's steel hull, but they were sufficient to puncture and flood six watertight compartments and thus sink the fabled vessel. Later metallurgical tests revealed that the ship's steel was overly brittle and thus prone to fracture because of an excess of slag used in its manufacture.

www.deathreference.com...

I also watched a program on discovery and the accepted official conclusion is that ice punctured holes in the STEEL hull of the Titanic which led to its demise, its fate was sealed.


[edit on 17-6-2008 by weenaman]

Originally posted by ULTIMA1

Well it seems you expect people to believe the official story just because you and others post it ?

I have posted more facts and evidence then most people on here, and will continue to find and post more facts and evidence.

[edit on 17-6-2008 by ULTIMA1]

This has nothing to do with why you think I'm trying to get people to believe in the "official story". I believe what science and the numbers tell me.

I'm not looking for people to believe the "official story". I'm here to make sure that people understand that an object with sufficient mass and velocity will be able to destroy somethat that in static conditions can be stronger than the moving mass.

Now, you yourself say that you require validation before completely believing in something. Are you going to post another independent source that can validate this journal? It seems like if you want all of us to accept this at face value just because either you posted it or because it's from a materials journal. Why can't they make mistakes? NIST and FEMA did.

Originally posted by ULTIMA1

All you have to do is look at the Purdue animation and you can see that the aluminum airframe and wings are shredded as soon as they enter the building.

Also if you look at the photos of the hole in the side of the towers you can clearly see that the wings barely made it in to the building, specially the wing tips.

No one here is arguing that the aluminum won't be destroyed after impacting several steel beams.

What we're saying is that those first few beams will break on impact because the airplane is still a whole mass and velocity at that point. Kinetic energy is something that's taught at a junior high school level.

KE = 1/2 * mass * velocity^2

You're using all these examples that hinge on a 767 impacting the WTC towers to further your argument so you must acknowledge that a pair of 767s hit the towers. The Perdue video also shows the steel beams breaking as the airplane initially impacted them.

But you still have failed to answer my question about that journal forgetting to acknowledge the titanium airframe structures in a 767.

reply to post by weenaman


Well use some logic there bud. What makes more sense? Ice punctured the steel or the rivets failed? The weakest link will always fail first.

Obviously a person on the ship at the time of the event wouldn't know about the rivets and assume the ice made a hole in the hull, which was the belief for years, but a recent study has shown it was the rivets.

Sorry it doesn't fit your illusion of steel being so easily damaged.

There is always a logical explanation for these events, except for the WTC buildings that is...

reply to post by ANOK


Just making sure that you're aware that what's poking up on the surface for an iceberg is only a tiny fraction of its real size. You can Google an image of one of many examples.

Another thing to remember is where the Titanic was traveling, close to the Arctic waters where the temperature is really cold. Steel becomes brittle at low temperatures, causing it to lose quite a bit of the elasticity it would have at normal temperatures, thus making it easier to puncture.

With something that massive underneath the waters, I wouldn't be surprised if it did rip gashes in the steel plate as well as cause the rivets to fail from the pressure against the hull.

Even the largest of ships today know to steer clear of icebergs. No matter how big the ships are, they'll always lose the mass war to an iceberg.

Originally posted by HLR53K
What we're saying is that those first few beams will break on impact.

So you do agree then the there were only a few beams broken on impact and that the towers did withstand the impacts of the planes?

But you still have failed to answer my question about that journal forgetting to acknowledge the titanium airframe structures in a 767.

So please tell us where and how many titanium strutures are in the 767 ?

By the way i can check your information.









[edit on 18-6-2008 by ULTIMA1]

[edit on 18-6-2008 by ULTIMA1]

reply to post by HLR53K


Well whatever, you guys just want to argue.

The point is the Titanic tragedy is irrelevant to the WTC building collapses, as apposed to say the Windsor Tower, or the Murrah building, or laws of physics for example...