Merged No Planer calls for scientific study / Missiles of 9/11

tfk said:
Not quite true, MRC.

The upper ~60% of the fuselage is mostly air.

For an interesting psychological reason: people hate to be packed together like stacked cord wood. Or a NYC elevator, Japanese train, etc.

But "people density" means profit to airlines, so they go thru the exercise of packing as many people as conceivably possible into each flight.

This is the same reason that the towers were >90% air. But buildings have nowhere near the people density of airplanes. Imagine the hate & discontent if an office (or even a movie theater) packed people together as densely as airplanes do today.

Nonetheless, you're right. The upper ~60% is mostly air.

But the bottom 40% is not. Machines, equipment rack and luggage doesn't mind in the slightest being stacked like cord wood. And below that low density passenger deck is a VERY DENSELY packed volume of fuselage, filled with relatively heavy equipment.

People see the outside skin of the fuselage, and project in their mind what lies below the skin. Their projections are very, very wrong.

I've often thought that it would be useful to produce a diagram of a jet as "Isaac Newton" would see it. That is, as it would be "felt" by an impact, but replacing the contents with a "constant density" substitute.

In this view, the passenger deck would stay the same (because it is the only portion of a plane with which people are familiar. But the lower 40% of the fuselage would be drawn (my guess) 8 - 10 times longer, as would be the engine cores & the fuel tanks in the wings.

The wings themselves, along with the horizontal stabilizer & tail should be drawn (my guess) 2 to 5 times longer.

I've often thought that a plane, drawn this way, would give non-engineers a much better intuitive understanding of how it acts upon impact.
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You can't know this, but I'm in fact thoroughly familiar with aircraft constructions. However, I was just trying to make it simple for the kind of guys who can even contemplate comparing an aircraft fuselage with an empty beer can. :boggled:

It seems that the idea that aircraft are light and flimsy has somehow rooted itself in the minds of lay people since the early days of aviation, despite the fact that modern airplanes are in fact very sturdy and heavy. More sturdy and heavy than for instance cars.

Perhaps the notion is maintained by images of planes that have disintegrated in crashes. What people forget is that impacts at flight speeds could disintegrate a battleship. ....

Hans
 
Mikeys said:
We already had body, air, blast and now we can add fluid. You know what Hummo, tell your NIST experts to fill condoms with water and whack their foreheads with it.
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Ahh, OK. You have no serious idea what you are talking about, and you don't care. You don't even try to hide it. Fair enough, your choice.

You don't think the WTC collapse was started by airplane impacts. Fair enough, your choice.

You have no idea what did happen instead, and you don't really care. Fair enough, your choice.

OK, so tell me: Why should anybody give a hoot about what you think or don't think?

Hans
 
Mikeys said:
It finally decelerated when it hit the inner grid and platforms. In fact, it did what it should have done when it met the outer wall, that is stop and explode. It returned to the real world and started following Newtonian laws, which is something I wish believers did one day.
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Wrong.

The front-most portions of the plane decelerated as a direct result of tearing apart themselves & the external parts of the building.

"Slicing" takes very little energy compared to "compressing".

I invite you to prove this to yourself. Place your pinkie & ring finger on a cutting block. Fold your first & middle finger down along the side of the block to protect them. Take a potato masher & drop it repeatedly from greater & greater heights onto your pinkie & ring finger until they are mashed flat. Record the height required & the weight of the potato masher.

Next, place your 1st & middle finger onto the same chopping block. Repeat the experiment, only this time using a hatchet. You'll find that it takes far less energy with the hatchet than it does with the masher.

Ain't science fun...!

You can't see the deceleration of the front, shredded parts of the plane on the video because, surprise, there is a wall between the shredded parts and the camera.

The camera only sees the part of the plane that has not yet hit anything.

And for the rear portion of the plane to be slowed down by the deceleration of the front part, the skin (that very, very thin skin) would have to be strong enough to transmit the compressive forces without buckling.

Guess what. The skin ain't strong enough to do that. it buckles & tears instead.

The rear part of the plane enters a hole that has been created by the front part of the plane. Very little work is required to enter an "already created hole".

If somebody had a 1000 frame/sec camera very close to the point of impact (so that the plane's images took up many pixels), then I have little doubt that one would have been able to see dynamics in the wings & fuselage.

Unfortunately, the collision took place almost 900' in the air, and cameras were fractions of a mile to miles away, chugging away at 30 fps.

There is zero surprise that these details aren't visible in those few frames.
 
MRC_Hans said:
It seems that the idea that aircraft are light and flimsy has somehow rooted itself in the minds of lay people since the early days of aviation, despite the fact that modern airplanes are in fact very sturdy and heavy. More sturdy and heavy than for instance cars.
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I would strongly disagree with this statement.

If I were to back my car into another one at 5 mph, I would have no concern about driving away. (After I'd left my contact info, of course.)

If I were to back either a C172 or a 767 into another plane, then ... no way.

Cars are built far heavier & far sturdier. As this article posted by LSSBB states, a four seat car weights twice what a four seat airplane does.

As for "sturdy", it depends on the part. As mentioned above, there are no bumpers on planes, and the skin is far weaker than a car's.

I would expect by car's suspension to survive a 30 mph impact with a pothole. A plane's nose wheel? Nope.

However, the plane's main gear can absorb far more impact than a car's suspension. One doesn't design a car to withstand bad landings by student pilots.

All these are side points, tho. You're original point that the planes have an enormous mass - far more than most people appreciate - is absolutely accurate.

I was trying to point out that the mass is not evenly distributed across the cross section, as seen from the front of the plane.
 
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ElMondoHummus said:
That is not a substantive response. Address the core of the argument. At the speeds the jets were travelling, mass and momentum is far and away more important than strength and hardness. Your condom joke doesn't apply because it doesn't scale properly. The pressure-impluse curves showing at what points the core columns fail are published in NCSTAR 1-2B, chapter 10. The speed of the jets and the impulse they'd impart on impact is laid out there too, as well as in
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Everything is equally important, materials involved, speed, weight, shape, mass, density, etc.


I don't argue that the mass and momentum of the plane could fracture the wall, but about the physics of the impact. The plane was stopped by NOTHING at the outer wall,just as if the wall was not there. Look at the videos. Can you pick anything that acts on the plane when it meet the outer wall. ANYTHING. My theory is simple. A wall section was most likely unbolted or severed by other means. It was not part of the rigid frame when the plane came. The plane had to explode inside the building to pull it down
 
tfk said:
Wrong.

The front-most portions of the plane decelerated as a direct result of tearing apart themselves & the external parts of the building.
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If the front part got torn apart and failed to slow down the plane, how could it punch that hole?

"Slicing" takes very little energy compared to "compressing".

I invite you to prove this to yourself. Place your pinkie & ring finger on a cutting block. Fold your first & middle finger down along the side of the block to protect them. Take a potato masher & drop it repeatedly from greater & greater heights onto your pinkie & ring finger until they are mashed flat. Record the height required & the weight of the potato masher.

Next, place your 1st & middle finger onto the same chopping block. Repeat the experiment, only this time using a hatchet. You'll find that it takes far less energy with the hatchet than it does with the masher.

Ain't science fun...!
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Not all tools are designed for slicing, planes included.

You can't see the deceleration of the front, shredded parts of the plane on the video because, surprise, there is a wall between the shredded parts and the camera.
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It's about the deceleration of the whole plane, Pinkie

And for the rear portion of the plane to be slowed down by the deceleration of the front part, the skin (that very, very thin skin) would have to be strong enough to transmit the compressive forces without buckling.
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why not... if it was strong enough to demolish steel

The rear part of the plane enters a hole that has been created by the front part of the plane. Very little work is required to enter an "already created hole".
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me thinks you are all over the place, Pinkie.
[/QUOTE]
 
Mikeys said:
Everything is equally important, materials involved, speed, weight, shape, mass, density, etc.


I don't argue that the mass and momentum of the plane could fracture the wall, but about the physics of the impact. The plane was stopped by NOTHING at the outer wall,just as if the wall was not there. Look at the videos. Can you pick anything that acts on the plane when it meet the outer wall. ANYTHING. My theory is simple. A wall section was most likely unbolted or severed by other means. It was not part of the rigid frame when the plane came. The plane had to explode inside the building to pull it down
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Is your theory supported by the physics of what is understood by most experts who have studied the impacts? Do you think that there is a chance that your opinion of what should have happened is simply because you don't fully understand what happened?
 
Mikeys said:
...
It's about the deceleration of the whole plane, Pinkie
...Pinkie.
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Show the math. Make our day, present the math to prove your point. Do you have a point? You don't realize the plane was under thrust into the WTC with two running jet engines, each capable of putting out 50 to 60,000 pounds of thrust. You can't figure out the design of the WTC can only handle an impact of a plane with a KE of 187 pounds of TNT, and 11 and 175 had 1300 and 2093 pounds of TNT at impact.

You offer BS opinion, and have no math to go with your failed claims.

At 590 mph the nose section, the cockpit and nose gear entered the WTC with little resistance because the entire plane had 11 TIMES the energy required to ENTER the building.

A house stands up to a 70 mph, a 110 mph knocks off a few shingles and rips off parts of the roof - an F5 tornado destroys the house to the ground.

You are having problems understanding physics. It is sad.
 
Mikeys said:
We already had body, air, blast and now we can add fluid. You know what Hummo, tell your NIST experts to fill condoms with water and whack their foreheads with it.
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What do you mean 'add' fluid? You realize that from a scientific standpoint air is a fluid right?
 
Mikeys said:
I don't argue that the mass and momentum of the plane could fracture the wall, but about the physics of the impact. The plane was stopped by NOTHING at the outer wall,just as if the wall was not there. Look at the videos.
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One day you'll learn that your incredulity doesn't trump actual physics.
 
Mikeys said:
I don't argue that the mass and momentum of the plane could fracture the wall, but about the physics of the impact. n
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You have stated that you have never studied physics. What do you know about the physics of the impact? How can you know?
 
dafydd said:
You have stated that you have never studied physics. What do you know about the physics of the impact? How can you know?
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Because he just knows alright. How dare you question him about about his understanding.!!!

That's just bullying expecting him to know something!!:)
 
Mikeys said:
The plane was stopped by NOTHING at the outer wall,just as if the wall was not there. Look at the videos. Can you pick anything that acts on the plane when it meet the outer wall. ANYTHING.
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Out of curiosity, what did you expect to have happen when a fully laden jet airliner impacts at over 500 mph with a steel, aluminum and glass facade?
 
Mikeys said:
Everything is equally important, materials involved, speed, weight, shape, mass, density, etc.


I don't argue that the mass and momentum of the plane could fracture the wall, but about the physics of the impact. The plane was stopped by NOTHING at the outer wall,just as if the wall was not there. Look at the videos. Can you pick anything that acts on the plane when it meet the outer wall. ANYTHING. My theory is simple. A wall section was most likely unbolted or severed by other means. It was not part of the rigid frame when the plane came. The plane had to explode inside the building to pull it down
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This is not correct. Modeling and analysis by NIST, and separate analyses by Wedinger Associates as well as MIT has clearly shown that the dominant issues were indeed mass and momentum. That is laid out in the NIST reports. And the Purdue team that created independent computer modelings of the impacts accepted NIST's conclusions. The analyses conducted do take the factors you listed into account, and it was still shown that the mass of the jetliners and the momentum imparted by the speeds they were travelling at were the dominant factors. Those were the dominant factors precisely because they were so overwhelming that they provided several times more force than was necessary to not just penetrate the outer wall, but also sever core columns on the interior.

Please read NCSTAR 1-2B, chapter 10. And also, please read the link I provided to Ryan Mackey's presentation. He provides a simpler model that demonstrates the speeds involved were several times higher than necessary to penetrate the outer wall. You must familiarize yourself with that information before you can discuss this topic properly. Otherwise, you are not speaking from an informed position.
 
You know folks: Just because we're talking physics, I am reminded of a thread back in 2010. Just felt like reposting something from it.
ElMondoHummus said:
... I wanted to highlight something I really think is important:
Architect said:
Physics, in contrast, is a much wider field which can focuss on a huge range of issues. It does not, as a matter of course, include the kind of detailed analysis and interpretation of the structural performance of either individual elements or complex composite structures...

... I put it to you that a degree in physics no more equips one for such structural work than, say, a BA in Linguistics will mean you can speak French. It might give you an idea of a general framework or background, but does not provide the kind of detailed information one requires to rigorously interrogate or understand the topic at hand.
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Logically, what engineering amounts to is physics applied specifically to a field or set of problems. That is why Architect's post here is so relevant to the discussion of analyses regarding the Twin Towers collapses. Issues of how forces act on matter is still of course dominant, but applying basic, undergraduate physics to matters such as how a single constructed unit's worth of trusses, columns, braces, studs, etc. interact under loads is treading ground that was already trod decades ago (or longer). The field of engineering has been able to encapsulate all those individual interactions into an overall discipline and provided intellectual tools, so to speak, for how to deal with those myriad and complex calculations involved in dealing with all those interactions in a single, constructed unit.

That's why, when architects and engineers put up a basic framework for a building, they talk about analyzing a "moment frame": While each individual constituent element's reactions in the framework still follow the laws of physics, it's almost certain to drown a person in details if the analysis of the framework is conducted on the level of basic, elementary physics. You use the tools and processes generated over decades of experience shared in the field to conduct the analysis, instead of reinventing the wheel and starting from ground zero each time you're presented with a complex set of interactions in a structure.

And this is why I say that Architect's point is important, and must not get lost: When, for example, a truther talks about momentum (often phrasing their complaint as a violation of Newton's Second Law), you wonder if they either 1. Applied engineering principles to truly calculate how momentum came into play on elements of the overall structure, or 2. Took a laymans approach and calculated the myriad forces on each individual element of even a simplified model, then iterated those calculations over time as loads shifted. You wonder that, because you don't see any explanation beyond a broad stroke one, but more importantly, what you don't see is justification for why the analysis is superior to the more detailed ones conducted by NIST, Bazant and Zhou, Arup, University of Edinburgh, etc. You don't see any explanation of why or more importantly where the more detailed, more in-depth applications of physical laws - i.e. the engineering analysis - is flawed. You only see a broad stroke analysis with no reference to where knowledge gained over decades of engineering experience has been applied.

And that's why it's important to understand why this argument is being made, and also why it should not be construed as an Appeal to Authority. If a claim is made, then the background for such a claim can (and should, when demanded) be provided, but because human intellectual progress depends not only on the identification of fundamental principles, but the application of such principles and the cumulation of knowledge gained from such application, it is important to recognize why engineering instead of basic, fundamental "Physics 101", is the more correct discipline to use when analyzing the details of the Twin Towers collapses. It is not contradictory or incorrect to insist on engineering analyses instead of broad-stroke physics. Rather, it is a realization that physics as it's applied in practical construction is complex enough to where the knowledge gained from applying those fundamental principles absolutely must be taken into account. Using engineering as your analysis mode is the same thing as using physics. It's simply being smart about how you are applying it.
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I can't lie. I've committed one of the "sins" I listed back in 2010 in a post not too far above this one: I took a laymans approach and discussed a simplified calculation of a force on an individual element. In my defense, R.Mackey did it first, so I was just cribbing from him ;):D, but I did it for a reason. And that reason was to illustrate with a simple analysis why it was incorrect to merely presume that the forces imparted by the jetliner were insufficient to penetrate the towers (it's basically one of the same reasons Ryan did the analysis too... although credit where it's due: He did actually do the analysis, I merely copied and pasted it :o).

But on a broader note, why am I reposting this? Well, mainly to remind everyone - especially conspiracy peddlers - that no one needs to start from a position of ignorance on how the buildings performed on 9/11. As I noted above, we have NCSTAR 1-2B's discussion of column severing by jetliner impact. And the detailed analysis of the fuel slug impacts.

I really feel compelled to beat this into the ground: I want to remind everyone, but the conspiracy advocates specifically that these analyses exist and that objections must be grounded in the knowledge generated by them. Trying to claim, for example, that the jetliners could simply not have penetrated the towers stands in stark contradiction to the analyses performed not just by NIST, but by the Purdue modeling team. And incidentally, by the MIT team and Wedinger Associates working group that NIST compared their own findings to in their reports. Remember:
... more importantly, what you don't see is justification for why the analysis is superior to the more detailed ones conducted by NIST, Bazant and Zhou, Arup, University of Edinburgh, etc. You don't see any explanation of why or more importantly where the more detailed, more in-depth applications of physical laws - i.e. the engineering analysis - is flawed. You only see a broad stroke analysis with no reference to where knowledge gained over decades of engineering experience has been applied.
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For these contrarian arguments to have any traction, we need to see where these broad stroke references - such as the current one expressing doubt about the jetliners penetrating the exterior wall - are supposed to be superior to the already existing, in-depth analyses. So far, we're not being given that. And incredulity is a poor substitution for it.

Why are the current analyses wrong? It takes far more than just saying it couldn't happen.
 
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