Originally posted by ULTIMA1

Originally posted by jfj123
Unless of course you're saying that birds are stronger then aluminum and tempered glass? Let me know if this is the case.

No, what i am stating is the the aluminum airframe is fragile and cannot stand up to impact. The prove that the airframe is fragile is the fact that it can be easily damaged. So if the airframe were to hit steel it would be damaged.

If a bird made of flesh (softer then aluminum) can damage aluminum, then aluminum with enough force, can damage something harder (ie steel). Please read the last 4 posts from neformore as it explains things very well.



By the way, good job with the well organized, accurate, and logical posts neformore !!!!

Originally posted by jfj123
If a bird made of flesh (softer then aluminum) can damage aluminum, then aluminum with enough force, can damage something harder (ie steel).

But the aluminum did not have enough force. In fact very little of the over 60 tons of aluminum even make it far into the buildings.

Right.

I've tried to draw parallels. I've tried to explain things in clear terms. I've tried to be logical.

But now I realise I'm not dealing with people who can understand, or even want to understand the maths and physics of this.

What I'm dealing with is people who are clutching at straws. People who will use any little facile argument that they can to try and cling to their theory.

People who are - to be blunt - deliberately obtuse and cannot grasp the laws of physics as they are set out in front of them and can actually be observed in the world.

How many times have you seen or heard of vehicles involved in accidents smashing through brick walls? The walls have greater mass and weight than the vehicles, and yet it still happens. The vehicles are softer than the walls, and yet it happens - and yet there are people here arguing that it can't!

Hell you are even arguing that a bird can damage a plane - thats a relatively fragile object hitting something much stronger - and at the same time you are trying to argue that a relatively fragile object can't damage
something much stronger.....

Originally posted by neformore
But now I realise I'm not dealing with people who can understand, or even want to understand the maths and physics of this

So please tell me. How many steel beams do you think may have been cut by the aluminum airframe? Now how many steel beams make up the towers?

Do you actually think the thin aluminum airframe is going to take out enough steel beams to weaken the building enough for collapse?

Its nothing to do with math or physics.. its basic common sense. Something not many people on here seem to have.

Originally posted by ULTIMA1

Originally posted by neformore
But now I realise I'm not dealing with people who can understand, or even want to understand the maths and physics of this

So please tell me. How many steel beams do you think may have been cut by the aluminum airframe? Now how many steel beams make up the towers?

Do you actually think the thin aluminum airframe is going to take out enough steel beams to weaken the building enough for collapse?

Did the building fall down? If it did then between the fire and impact, you have your answer.

Its nothing to do with math or physics.. its basic common sense. Something not many people on here seem to have.

I can't believe you actually wrote "it has nothing to do with math or physics". I really don't know what to say to that as you couldn't be more wrong if you tried to be and I think you are trying. JUST MY OPINION!!

Your own arguments are proving you wrong but you refuse to get it. Are you deliberately screwing with people? Thats the only thing I can come up with ????

Originally posted by neformore
A bullet weighs a couple of ounces. A man weighs 210 pounds.

Fire a bullet at the man from distance.

Is the bullet going to bounce off the man?

No.

Its to do with the kinetic force of the impact.

What the .. ?

So, if you made the man out of "bullet material", and shot a flesh bullet at the "metal man", would it penetrate? After all, in your words the kinetic force of the impact would be the same?

You know the answer to this one, I know you do. I just can't understand why so many people are waving their hands at the physics involved here, with ambiguous and misleading statements like this. Bullets, believe it or not, are harder than "man", and Newtons 3rd law applies here just like in the WTC incidents. Also, this example is proving the point - to achieve penetration, the object impacting should be stronger than the object being impacted, not the other way round as seen on the WTC.

The force exerted upon both objects in a collision is the same, and the "stronger" object will come out on top every single time.

Originally posted by adjay

Originally posted by neformore
A bullet weighs a couple of ounces. A man weighs 210 pounds.

Fire a bullet at the man from distance.

Is the bullet going to bounce off the man?

No.

Its to do with the kinetic force of the impact.

to achieve penetration, the object impacting should be stronger than the object being impacted, not the other way round as seen on the WTC.

This is not necessarily true.
1. water is used to cut steel.
2. A 2" x 4" can go through a brick wall

there are plenty of other examples

Originally posted by neformore
How many times have you seen or heard of vehicles involved in accidents smashing through brick walls? The walls have greater mass and weight than the vehicles, and yet it still happens. The vehicles are softer than the walls, and yet it happens - and yet there are people here arguing that it can't!

Hell you are even arguing that a bird can damage a plane - thats a relatively fragile object hitting something much stronger - and at the same time you are trying to argue that a relatively fragile object can't damage
something much stronger.....

This is so selective I shouldn't really respond, but I will.

How many walls do you know that weigh a ton? That's the most ridiculous thing I ever heard! The entire building may weigh this, or more - but the impacted part of the wall would rarely, if ever weigh close to the car's weight. Check out Pillar 13 that the late Princess Diana's car crashed into, at quite some speed - nope it didn't collapse, or budge. Have you never seen a concertina wreck of a car?

And birds can damage planes - every picture I have seen showing this kind of damage always has the bird impacting a "soft" area. To say this is an example of a fragile object damaging something much stronger is absurd. Throw the same bird into the turbines, and you might get a fire (and wrecked fan blades!), but it won't punch a hole through it! Throw the same bird into the steel engine block and again, it won't punch a hole through it. Likewise if you threw the bird into the strong struts supporting the leading edges on plane wings, which I think is the reason most pictures show the birds "between" these, it still won't punch a hole through. At best, the bird vs. plane scenario is a good example of how fragile a plane really is, especially in the wing areas.

Originally posted by neformore
People who are - to be blunt - deliberately obtuse and cannot grasp the laws of physics as they are set out in front of them and can actually be observed in the world.

People who completely ignore (or fail to comprehend) Newton's 3rd Law of Motion, perhaps?

The unarguable point behind all of this, is that whatever speed the plane travelled at, whatever mass was behind it, all follows Newton's 3rd Law - which is the point of impact on the plane and tower both suffered exactly the same force, together, at the same time, in complete unison, so in order for the plane to "penetrate" and leave such a cartoon-like mark behind would mean the plane is stronger than the WTC.

Exactly how did you see copper cut through a 1.5 inch thick steel manway? Did they use a copper blade in a hacksaw? Please explain yourself clearly.

I think you meant you saw a CARBON ARC cut through steel. That has a copper cladding over carbon, using a high current to melt and compressed air to blow away the liquified puddle of steel. I know: I do.

How does a construction process using electricity compare to a plane hitting a building?

Now, you state "under some conditions aluminum is harder than steel." Perhaps there IS an aluminum alloy that is "harder" than some steel alloy, but that is not the case here.
Please stay focused on what you are talking about: a commercial jet plane hitting a skyscraper made on reinforced concrete and mild steel wide flange I-beams.

More comparable to a bird flying into the side of a brick house.

Get this clear: PHYSICS states that there is NO DIFFERENCE in results between a concrete building traveling 600mph falling on a jet plane, or that same plane hitting the building at 600MPH.

Capice? In other words, if you take an aluminum can and slam a concrete block into it at 600MPH, the same result will occur as if you took that same can and slammed it into said concrete block at 600MPH.

In both instances, the aluminum can gets flattened.

Yes, of course, the engines and landing gear are harder materials, and quite likely could penetrate the facade, but I SEE the ENTIRE plane "ghost" into the tower. Not possible. Kind of like watching Chik-Fil-A cows parachute into a football staduim: Looks real, but can not be. That's a clue, grab it.

You will notice, the Purdue simulation of the jet CAN NOT explain the COCKPIT emerging UNSCATHED from the other side of the tower. It shows it, quite properly, being sliced like a hard boiled egg through an egg slicer.

THAT cockpit "emerging" unscathed is quite impossible, and is the key to understanding the illusion perpetrated. That's another clue. Can you grasp it?

Originally posted by alupang
Capice? In other words, if you take an aluminum can and slam a concrete block into it at 600MPH, the same result will occur as if you took that same can and slammed it into said concrete block at 600MPH.

In both instances, the aluminum can gets flattened.

It's obvious that the physics on display here are hard to grasp. A 100 ton plane is considerably more than a thin empty shell.

Let's take that aluminium can and give it rigidity and boost its density up to the same as the 100 ton plane (in kg/m^3). Now armed with a collection of test cans we could propel them at increasing speeds into stationary 'solid' objects remembering the building was not solid either as there was lots of open space inside it and the most solid area was in fact at the centre, not the outer walls.

The kinetic energy of the projectile is proportional to the square of velocity so we should see the level of damage imparted to the solid target increasing along those lines as the velocity is increased. In fact, with sufficient velocity our can would go clean through the target despite its flimsy appearance in a stationary condition.

I'd like to see the 'mythbusters' have a go at this as it would definitely convince a lot of skeptics

Another analogy would be the karate master breaking a concrete block with his fist and he accomplishes it without any obvious physical damage to his fist or arm. It's all about velocity, and 1/2m.v^2 (kinetic energy) again. What would be the outcome if the concrete block were propelled into his stationary fist at the same velocity? clue - have paramedics and surgeons nearby.

From Department of Ocean Engineering, Impact & Crashworthiness Laboratory, Massachusetts Institute of Technology:

The problem of the airplane wing cutting through the exterior columns of the World Trade Center is treated analytically. The exterior columns are thin-walled box beam made of high strength steel. The complex structure of the airplane is lumped into another box, but it has been found that the equivalent thickness of the box is an order of magnitude larger than the column thickness. The problem can be then modeled as an impact of a rigid mass traveling with the velocity of 240 m/s into a hollow box-like vertical member. The deformation and failure process is very local and is broken into three phases: shearing of the impacting flange; tearing of side webs; and tensile fracture of the rear flange. Using the exact dynamic solution in the membrane deformation mode, the critical impact velocity to fracture the impacted flange was calculated to be 155 m/s for both flat and round impacting mass. Therefore, the wing would easily cut through the outer column. It was also found that the energy absorbed by plastic deformation and fracture of the ill-fated column is only 6.7% of the initial kinetic energy of the wing.

[edit on 23/11/2007 by Pilgrum]

Originally posted by jfj123
Did the building fall down? If it did then between the fire and impact, you have your answer.

But evidence suggest the impacts and fires were not enough to bring down the towers.

NIST, FEMA, and most other reports have stated the buildings withstood the planes impacts and the fires did not burn long enough or get hot enough to cause the collapse.

Originally posted by neformore
Rubbish.

I award you top marks for attempting to imply that Newton got it all wrong.

Originally posted by neformore
Bullets would never penetrate steel - that happens

Tanks would be obsolete, because their shells would never penetrate each other.

Lets get simpler and slower - Medieval longbow bolts used to be capable of piercing suits of armour.

To compare a ballistic projectile with a 767 is absurd. The reason projectiles penetrate is due to surface pressure, hence the reason the tips are sharp. This is also similar to how "water" cuts steel, and entirely different from an aluminium alloy plane impacting one of the strongest (if not the strongest) building in the world.

Originally posted by neformore
I guess we have nothing to fear from asteroids hitting the earth then, because the earths mass is so much higher, they'd bounce off?

This isn't even worth my time, and I merely quote this to show how ridiculous your line of reasoning is.

Originally posted by neformore
The person being selective here is you. You are croning on about Newtons third law like its the be all and end all of the argument, without even considering his second one.

I'm glad you bought up his 2nd Law.

The rate of change of momentum of a body is proportional to the resultant force acting on the body and is in the same direction.

How does this figure in this topic? Well, we can look at the deacceleration of each plane upon impact, to find how much force was acting upon the plane as it hit the building. To quote Dr. Morgan Reynolds:

Under Newton's 2d law, sometimes called the law of acceleration, if a force is applied at the front of an airplane, it must slow and the back or tail of that aircraft must slow too. Unless that is, the front is no longer in the way of the back of the plane because the front is no longer connected to the rear, and the disconnect occurred without loss of kinetic energy. Further, according to the 2d law deceleration must be proportional to the force applied. The steel/concrete Twin Towers would administer quite a force against an aluminum airplane flying at high speed.

Since NIST insists that a 159-foot-long Boeing 767 disappeared into the north tower within 0.25 seconds and into the south tower within a corrected 0.23 seconds, almost the same as their speeds in the air, no force was impressed on these planes according to Newton's second law. ΣF = ma and if a = 0, then no net force was applied. When was Newton's 2nd law repealed? I did not get the memo. If the 2d law still applies, and I believe it does, then NIST cannot possibly be right and any gashes or holes in the towers that appeared at 8:46 a.m. and 9:03 a.m. on 9/11 must have been impressed by some method other than by a no-deceleration airplane. NIST apparently forgot the lecture on the first day in engineering mechanics class.

Originally posted by neformore
You are assuming that a 218,000lb plane hit the towers acting as individual parts instead of as a single mass moving in unison.

Funny, because that's exactly what happened. The impact force may be calculated, but each individual part hitting the tower will act differently! The impact force will act the same upon the part hitting the tower, and the tower hitting the part, and in the case of a steel engine compared to some light aluminium, there will be drastic differences in the collisions! Imagine the plane was made out of paper, with steel engines - do you honestly believe the paper will cut through the steel tower the same way the engine would?

Originally posted by neformore
You are assuming that the plane hit the whole building mass at the same time, which it didn't. It hit part of it. You are also assuming the building is totally solid.

No, I'm not. I included it would only hit over 5 floors, and not every part of that, by reducing it to 1/3rd (which I think is very conservative given the cut-out shapes we are left with). You on the other hand, merely assume the plane imparts this impact force into the tower, then follows neatly into the space given by the retreating steel construction.

Originally posted by neformore
You are completely failing to grasp the notion that a body in motion has kinetic energy that multiplies its impact force.

I am fully aware of the effect of kinetic energy, but you fully do not understand Newton's Laws of Motion! The figures you gave were off slightly for one, and you act as if this is the force impacted upon the towers - it is not! It is the force impacted upon both objects! If you think it is more than enough to damage/penetrate the tower, what do you think it may do to a 767? Increase the plane speed by double, the impact force still affects both objects!

Originally posted by neformore
In short, you do not know what you are talking about because what you are saying is that this can't happen

When did I say that? Of course this can happen. Since when was a 767 designed to penetrate steel? The last I heard, they designed the noses aerodynamically to reduce drag and increase stability, not to increase the surface pressure to punch holes through armoured targets, like bullets, arrows, or bolts.

Originally posted by ULTIMA1

Originally posted by jfj123
Did the building fall down? If it did then between the fire and impact, you have your answer.

But evidence suggest the impacts and fires were not enough to bring down the towers.

NIST, FEMA, and most other reports have stated the buildings withstood the planes impacts and the fires did not burn long enough or get hot enough to cause the collapse.

If that were really the case, wouldn't the buildings still be standing?
Just because the fires and damage didn't cause the buildings to immediately collapse, doesn't mean they weren't the cause. MY OPINION.

Originally posted by jfj123
If that were really the case, wouldn't the buildings still be standing?
Just because the fires and damage didn't cause the buildings to immediately collapse, doesn't mean they weren't the cause. MY OPINION.

You would certainly think so! I would too, and I assume many others!

I tried to look at your second statement many times, from many different angles, before coming to the conclusion that if the fire and damage did not cause the building to collapse, then they did not cause the building to collapse, no matter how much time passes.

Either it is the cause, or it isn't. If it's a time delayed cause, then it's still a cause.

There are 3 major defiances of physics that day. Newton's 3rd Law missing upon plane impact (both towers), Newton's 2nd Law missing when the planes should deaccelerate after impact (again, both towers), and conservation of momentum being ignored as the towers fell (on all 3 towers, even the one that wasn't hit by a plane!). Details can be argued all day, but these three things glare defiantly in the face of physics as we know it, and to accept "hand waving" in place of scientific fact bodes grimly for the future of man on this planet.

Maybe I can present it in a different context

Let's say a sphere with a mass of 100 tons at a density of 2T/m^3 (which works out to be 4.5m or ~15' diameter) is propelled into the building dead centre with an impact velocity of 220 m/s (500mph). What damage would be expected?

No-one could seriously suggest that it would bounce off. In all likelyhood this object would go clean through the whole structure with energy to spare.

The amount of initial penetration is dependant on:
The kinetic energy of the moving object (massive in this case)
The surface area of inital contact which determines the actual contact pressure (huge even if we take into account the deformation of the wing down to the high tensile main longitudinal spars).
The tensile strength of the building outer wall sections impacted.

The MIT study determined that the wings only used up ~1/15th of their kinetic energy in penetrating the outer steel columns which is why the planes entered the buildings so easily with sufficient energy left over to fatally damage the central core structure as well. And all that without considering the exploding fuel and subsequent fire damage.

The planes did decellerate - they actually came to a standstill from 500mph in 100' or less and remained inside the buildings except for a few parts that got through to the other side. This is what delivers the kinetic energy so Newton's laws are still safe

[edit on 23/11/2007 by Pilgrum]