WCT1 Near-Freefall not Evidence of CD

[GregoryUrich]

My latest submission to the Journal of 9/11 Studies.

...more truth from a "truther".

 

[einsteen]

You say near-freefall behaviour is no evidence of CD. Do you mean with this that only freefall is evidence of CD? If we look at wtc7 it was also no freefall, it was fast, more near g than wtc1,2 but no freefall. There is also no CD that goes with freefall. CDs are always near freefall, never freefall. I think that the point you are making is that the potential energy is sufficient, but we knew that already.

 

[Disbelief]

You say near-freefall behaviour is no evidence of CD. Do you mean with this that only freefall is evidence of CD? If we look at wtc7 it was also no freefall, it was fast, more near g than wtc1,2 but no freefall. There is also no CD that goes with freefall. CDs are always near freefall, never freefall. I think that the point you are making is that the potential energy is sufficient, but we knew that already.

What do you consider near freefall? Within 10%? 20%?

 

[Apollo20]

Gregory Urich:

I do not find your new JONES paper very convincing of anything!

You state WITHOUT PROOF (or any attempt at calculations) that 1.8 GJ per floor "can easily account for all energy requirements including breaking the structure, comminution of concrete, ejection of debris, air expulsion, adiabatic heating, and other less significant factors."

Well, it is precisely these energy requirements that have been called into question by many "truthers" - including you! Did you not recently claim you had a problem with concrete comminution at 8.5 m/s -the velocity of the first impact of the upper section of WTC 1.

Now I'm really confused....... Why the change of tune?

 

[einsteen]

What do you consider near freefall? Within 10%? 20%?

That doesn't matter, a CD always starts accelerating with a<g and the ratio depends on the mass/structure etc. If you compare the drop (as function of time) of an implosion with that of one of the three wtc towers you will see it all goes slower than g . Some time ago it seemed that even the Landmark and wtc1's drop were indistinguishable although the collapses were totally different.

 

[Dave Rogers]

Gregory,

I agree with Frank - the statement that "This amounts to 1.8 GJ per floor on average, which can easily account for all energy requirements including breaking the structure, comminution of concrete, ejection of debris, air expulsion, adiabatic heating, and other less significant factors" is too significant a result to quote without either derivation or reference. I think you need to justify the inequality. I'm a little surprised you didn't, because as far as I recall you've already done all these calculations. At the moment you've left JON-ES with a good reason to reject a paper that disagrees with its usual slant, whereas with the numbers for energy loss per floor in place I think you've got a solidly reasoned conclusion.

Dave

 

[MRC_Hans]

I don't think the collapse speed has anything to do with CD/non CD. In both cases, once the supporting structure is broken down, either by explosives or by whatever damage suffered, the collapse will commence at near free-fall. This is simply a property of a progressive, self-sustained collapse.

There are really, apart from an entirely hypothetical knife-edge scenario, only two scenarios:

1) Progressive collapse, where the descend of the upper part of the structure releases more energy than needed for maintaining the collapse.

2) Unprogressive collapse, where the released energy is insuffucient, and the collapse is halted.

Hans

 

[bofors]

Consequently, while it is reasonable to say that WTC1 fell at near freefall speed,
this is in no way indicative of assisted collapse. - Gregory Urich

Given that controlled demolitions usually proceed at near freefall speed and gravity-driven collapses do not, this statement is obviously false.

Furthermore, I would argue that the only time gravity-driven collapses approach free-fall speed is with a "pancaking" mechanism. Since the WTC twin towers did not "pancake", controlled demolition is indicated by the speed of their destruction alone.

 

[uk_dave]

Since the WTC twin towers did not "pancake", controlled demolition is indicated by the speed of their destruction alone.

Except that they did, just not at the collapse initiation.

Please do try to keep up.

 

[MRC_Hans]

Given that controlled demolitions usually proceed at near freefall speed and gravity-driven collapses do not, this statement is obviously false.

Circular argumentation. The WTC collapses did proceed at near freefall speed, and since you have not proven they were not gravity-driven, your statement falls.

Controlled demolitions are also gravity-driven, once the demolition charges have been detonated.

Hans

 

[Apollo20]

I think the important thing to note is that GU has only considered the energy requirements for a COMPLETE collapse of WTC 1. This is fine, but not the most important issue which is how much KE was available AT THE START of the collapse - say in the first 3 seconds. To determine this you need to consider the energy dissipation as a fraction of the KE available from a free fall drop of an upper block through a distance of 3.7 meters. If the post-impact KE is sufficient to keep the upper block moving, a self-sustaining progressive collapse is possible. After about 3 seconds into the destruction of WTC 1, a CD would be essentially indistinguishable from a gravity driven collapse!

 

[CHF]

Given that controlled demolitions usually proceed at near freefall speed and gravity-driven collapses do not...

What exactly are you comparing the WTC collapses to as a point of reference?

Furthermore, I would argue that the only time gravity-driven collapses approach free-fall speed is with a "pancaking" mechanism. Since the WTC twin towers did not "pancake", controlled demolition is indicated by the speed of their destruction alone.

Pancaking was ruled out as being what started the collapse.

 

[Newtons Bit]

Given that controlled demolitions usually proceed at near freefall speed and gravity-driven collapses do not, this statement is obviously false.

Prove it.

 

[Dave Rogers]

Consequently, while it is reasonable to say that WTC1 fell at near freefall speed,
this is in no way indicative of assisted collapse. - Gregory Urich

Given that controlled demolitions usually proceed at near freefall speed and gravity-driven collapses do not, this statement is obviously false.

You haven't defined "near-freefall", nor have you given any examples of gravity-driven collapses that proceed at speeds significantly different to freefall (where "significantly different" means not conforming to your definition of "near-freefall"). You're therefore committing yet another unevaluated inequality fallacy. And before you ask, I'm not going to get tired of saying that until you and the rest of the truth movement stop producing them.

Furthermore, I would argue that the only time gravity-driven collapses approach free-fall speed is with a "pancaking" mechanism.

So what you're saying is that gravity-driven pancake collapses proceed at near-freefall speeds whereas gravity-driven collapses don't proceed at near-freefall speeds, from which we can infer that you believe pancake collapses are not a subset of collapses. This is an utterly idiotic position.

Why do you persist in making such a fool of yourself in public?

Dave

 

[Disbelief]

That doesn't matter, a CD always starts accelerating with a<g and the ratio depends on the mass/structure etc. If you compare the drop (as function of time) of an implosion with that of one of the three wtc towers you will see it all goes slower than g . Some time ago it seemed that even the Landmark and wtc1's drop were indistinguishable although the collapses were totally different.

I understand completely, I was just trying to get a definition of near freefall, which I see thrown around alot. I think that a big problem with many CTists, is that they don't understand that within 4 seconds of freefall (which sounds close) is more than 40% slower than freefall.

 

[Apollo20]

Here are some MEASURED data for WTC 1, (taken from the Sauret video):

Time (s); Drop(m); Accel(m/s^2)

t d acc
------------------
0; 0; 0
0.5; 1.0; 8.0
1.0; 4.2; 8.4
1.5; 8.3; 7.4
2.0; 14.0; 7.0
2.5; 20.0; 6.4
3.0; 27.6; 6.1

Now is this near "free fall" or not?

 

[Dave Rogers]

Now is this near "free fall" or not?

Depends on your definition of "near". It's all within an order of magnitude, so if you're a cosmologist or a SIMS analyst that's not "near", it's "precisely equal to". None of it is within 10%, so if you're an engineer...

I just remembered who I'm talking to. Best not go there.

Dave

 

[Apollo20]

Dave Rogers:

Engineers!

Engineers are ok...... Gustave Eiffel was an engineer, and he was a genius!

The question is: could the WTC 1 collapse accelerations I quoted above be produced without the help of explosives/pyrotechnics?

The answer appears to be yes!

Certainly if you carry out a momentum transfer calculation for a progressive collapse of a WTC-type tower you can obtain numbers close to the accelerations I quoted.

 

[Disbelief]

Dave Rogers:

Engineers!

Engineers are ok...... Gustave Eiffel was an engineer, and he was a genius!

The question is: could the WTC 1 collapse accelerations I quoted above be produced without the help of explosives/pyrotechnics?

The answer appears to be yes!

Certainly if you carry out a momentum transfer calculation for a progressive collapse of a WTC-type tower you can obtain numbers close to the accelerations I quoted.

I still think the disconnect with the truth movement is that they do not comprehend what near free fall is. Like I said, they will say that it only took 4seconds longer than freefall (only 4seconds), instead of saying it was 40% slower. Understand why this might be an issue?

 

[GregoryUrich]

Gregory Urich:

I do not find your new JONES paper very convincing of anything!

You state WITHOUT PROOF (or any attempt at calculations) that 1.8 GJ per floor "can easily account for all energy requirements including breaking the structure, comminution of concrete, ejection of debris, air expulsion, adiabatic heating, and other less significant factors."?

I thought someone might call me on that. I'm finishing up the companion paper which has the energy estimates. Given my last OT regarding collapse continuation most of the energy factors are known. Air expulsion is the only one I'm no sure about yet. But, adding up everything we know for the 98th floor:

elastic energy 85 MJ
inelastic buckling 171 MJ
comminution of concrete 302 MJ
adiabatic compression 200 MJ
----------------------------
we get 758 MJ. Not even half of the budget for one floor. Plenty of energy left to expel air and wreck everthing else. I'll try to quantify everthing else but no way we are going to find 1000 GJ.

Well, it is precisely these energy requirements that have been called into question by many "truthers" - including you! Did you not recently claim you had a problem with concrete comminution at 8.5 m/s -the velocity of the first impact of the upper section of WTC 1.

Now I'm really confused....... Why the change of tune?

I was pointing out the problem with Ross's analysis in that he over-estimated pulverization on the first impacted floor. Are you suggesting there would be significant comminution (read pulverizing) at 8.5 m/s such that 302 MJ are consumed?

I don't think I have ever claimed there was a general energy deficit. If I did, I demonstrate my right and willingness to change my mind.