NIST recognises a 2.25 second period of free-fall1 but as we agree econ41 the model does not proceed to this point in the collapse sequence2 . For now I will suggest that it concerns me because freefall acceleration is without doubt a feature of the collapse that has raised questions and is a frequent focus of objections to NIST's conclusions3 ; it cannot be disputed that this aspect of the collapse is not explained by the model4 . The "realistic advantage" as you put it would be to demonstrate with a model5 (to the "layperson", if you will6 ) that this controversial and unique aspect of the collapse has indeed been fully understood7 , as is claimed8 .
However, I would prefer to focus on the collapse sequence of the Towers,9 as there are no successful models of this of any kind, to my knowledge10.
My apology for the delay - pragmatics of real life intruded. Some preliminary points - we are mostly in agrement so far.
1, 2, 3, 4 - Agreed
5, 6 - Agreed - "layperson" however my aim is to explain to you and to show why a model is not the best way of doing it. In fact it may not be possible AND the objective is to address your concerns which I assert can be best done by explanation rather than model.
7 - understood by who? there is a lot of confusion - my aim is to clear up any confusion you may have NOT solve all the confusions for everybody involved. (Not at this satge - that
may come later
)
8 - false claim I suggest.
9 - that is what I will focus on.
10 - My understanding also.
OK, now my offer was specific and focussed:
You appear to think that you could benefit from extended modelling. So our viewpoints are some distance apart - we need to bridge the gap. If that is the situation we can progress discussion. Otherwise show me what I have misunderstood and I'll try again.
...other members are continuing discussion on a range of related issues. I could contribute to those discussions but to facilitate
our discussion I will stay focussed on the issues
we are discussing. And since our discussion is dead centre on the topic of this thread - use of models - I don't think we need to shift to another thread. Guidance welcomed - and we could relocate if appropriate.
So the issues I will explore with you Cube Radio are:
1) The relevance of free fall as a factor in explaining the collapse mechanisms of the Twin Towers collapses which actually occurred on 9/11 (your preferred starting point)
2) The suitability of modelling as a tool of explanation for lay persons AND whether modelling can fulfil that purpose better than well structured explanation. I will come from the position that it cannot and will explain why as we progress.
3) The possible involvement of Malicious Human Interventions ("MHI") (other than planes and unfought fires) AKA "CD". The approach I will take is strictly neutral to the CD factor - I will comment explicitly on CD if and when it becomes necessary OR assists the explanation.
So lets see if we can agree the context for discussions.
A) The Setting is Collapse of Either "Twin Tower" - we can distinguish 1 from 2 if and when we need to.
B) I will treat the collapse initially as three distinct phases viz:
(i) "Initiation" - what happened from impact to "Top Block" starts to fall. (And
not discounting CD as a possible factor at this stage.)
(ii) "Transition" - How the collapse changed from (i) "Initiation" to (iii) "Progression".
(iii) "Progression" - the rapid falling of the Global collapse of each tower. (Again n
ot discounting CD as a possible factor at this stage.)
IMO (iii) is the one we need to focus on - it is the one with fall rates arguably approaching or a large proportion of "free fall" - without me getting all pedantic about "acceleration' v "velocity" OR getting lost in all the confusions we see posted on forums.
So - process check - have I adequately described the "start line" for further discussion?
1) Do you agree with my outline of the context?
2) Are you comfortable with the "three stages" of collapse as I have defined them?
3) Do you agree that "(iii) Progression" is the stage for which I need to explain free fall and modelling as per your expressed concerns?
Then - so I know where to start fleshing out explanations:
Are you familiar with the acronym "ROOSD" and what it refers to? Do you object if I use it? If you do I will avoid it. Otherwise it is useful "shorthand".
Are you familiar with my "Three Mechanisms" explanation of the progressive collapse stage for WTC1 ans WTC2? If not I will summarise. It has been posted on other forums but not here where I am a "newbie"
Those two are the foundations for understanding the collapse progression mechanism - therefore they are the foundations for understanding free fall related concepts in this setting AND for deciding whether modelling is a better tool than "explaining".
Cheers
Econ41