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Funding sought to crash 747 into derelict building

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Funding sought to crash 747 into derelict building

Old 7th Jul 2016, 21:07
  #321 (permalink)  
 
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Originally Posted by Geordie_Expat View Post
Where would we be without Hitchhikers ?
Merely Eddie's in the space-time continuum.
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Old 7th Jul 2016, 22:44
  #322 (permalink)  
 
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Is he? What's he doing there - setting demolition charges?

PDR
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Old 7th Jul 2016, 22:56
  #323 (permalink)  
 
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KenV,
The mass of structural steel on one floor is estimated to be 900,000 kg in which case Ee(steel) for one floor is 51.3 MJ.
Ed = Ee(steel) + Ee(concrete) + Ep(steel) + Ef(concrete)
where,
Ee(steel) is the elastic strain energy stored by the structural steel up to its yield point. Ee(concrete) is the elastic strain energy stored by the concrete up to its yield point. Ep(steel) is the plastic strain energy dissipated by buckling of the structural steel. Ef(concrete) is the fracture energy associated with the crushing of the concrete.
Summarizing all the contributions to the WTC 1 energy decrement term Ed for a damage zone of one floor we have:
Ee(steel) = 51 MJ Ee(concrete) = 34 MJ Ep(steel) = 284MJ Ef(concrete) = 234MJ Total=Ed =603MJ
Keep in mind these are estimates based on the best technical data available at the time, but as each floor impacted the floor below, the kinetic energy increased. There certainly was no shortage of energy. The release of energy (fire) from the jet fuel only had to heat the steel to 500F for the yield strength to begin to decline. The biggest enemy of structural steel is fire.
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Old 8th Jul 2016, 14:40
  #324 (permalink)  
 
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The weight of steel in one floor, taken from Turbine D's post would add to each floor as the columns gave way due to heat, so at first top floor impact would be 900t..2nd impact of that by then double floor would be 1800t plus 50% simply due to the Kinetics of the drop, and so on, as it went down the towers it would reach a mass that didn't need or rely on any form of heat, it would just crush by impact simply by mass plus Kinetics plus the ever increasing weight, that would create air pressure to blow out windows underneath in lower levels..
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Old 8th Jul 2016, 17:06
  #325 (permalink)  
 
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Thanks TD for the additional data. The bottom line is that there was more than enough energy available and released to destroy the towers without having to resort to weird conspiracy theories about explosives.
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Old 9th Jul 2016, 08:05
  #326 (permalink)  
 
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Hi,

that would create air pressure to blow out windows underneath in lower levels..
Physical impossibility that air is compressed and certainly not in the lower floors
For compressing air .. it is necessary that the volume in which it is either reduced
Or in the case of towers volumes of each stage are at their désintingration brought into contact with the external atmosphere
therefore no compression effect as it happens in a combustion chamber of an engine e.g.
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Old 9th Jul 2016, 10:15
  #327 (permalink)  
 
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How is it a physical impossibility? The floors above are collapsing and the air within the building has to go somewhere as each floor collapses. Why couldn't it be forced through internal vents, shafts and doors into lower floors?
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Old 9th Jul 2016, 11:17
  #328 (permalink)  
 
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Hi,

each floor collapses
Desintegration is a better word instead collapse !!
The air is no trapped as it's in direct contact with the atmosphere !
You can't compresse air in a not closed volume
The NIST do not make a scientific analysis of the "collapse" itself .. it's a page "blank" in the NIST final report
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Old 9th Jul 2016, 11:58
  #329 (permalink)  
 
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You don't need a perfectly sealed container to produce pressure. The inertia of the air is enough to produce an imperfectly sealed container. How do you think the transmission of sound through a gas works?

Drop a moderately heavy perforated plate on table and observe the air forced out sideways. Better still drop it on another perforated plate and observe the air forced through the holes in the bottom plate and sideways. Use a bucket of sand or assorted sized gravel if you want to persist with the disintegration idea.

Disintegrated or not the material falling from above will compress the air underneath.
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Old 9th Jul 2016, 14:25
  #330 (permalink)  
 
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Hi,

Disintegrated or not the material falling from above will compress the air underneath.
Even .. if a part of air is compressed .. this air will escape by the easiest way .. and it's by the sides of the crushed floors and not to below by any apertures
And that's what you see in the videos ..
With you principle .. you will build up a big air pressure along the fall of the floors ..
That's not what videos shows
And I repeat .. the NIST have no scientific analysis in their final report about the collapse itself ... the 10 or more seconds of the collapse are not documented
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Old 9th Jul 2016, 15:40
  #331 (permalink)  
 
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Originally Posted by jcjeant View Post
Hi,
The air is no trapped as it's in direct contact with the atmosphere !
You can't compresse air in a not closed volume
Oh dear - someone had better go and tell all those ramjets to stop working then. Not to mention all those barometric VSIs...

To increase pressure all that is needed is for the volume to be reducing more quickly than the air can escape through the holes in the container.

PDR
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Old 9th Jul 2016, 16:28
  #332 (permalink)  
 
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Ehh no jcjeant, it will exit via wherever the pressure is lower, so out the sides, up and down. Noting the pressure will be highest in the centre.

Why would you get a big pressure build up? See the above exit rules.
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Old 10th Jul 2016, 00:02
  #333 (permalink)  
 
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Original quote by PDR1
To increase pressure all that is needed is for the volume to be reducing more quickly than the air can escape through the holes in the container.
And in essence, that is what happened on floors below the damage zone as they were sequentially impacted down to ground level.

From NIST in answer to a question:
9. Weren't the puffs of smoke that were seen, as the collapse of each WTC tower starts, evidence of controlled demolition explosions?
No. As stated in Section 6.14.4 of NIST NCSTAR 1, the falling mass of the building compressed the air ahead of it—much like the action of a piston—forcing smoke and debris out the windows as the stories below failed sequentially.
These puffs were observed at many locations as the towers collapsed. In all cases, they had the appearance of jets of gas being pushed from the building through windows or between columns on the mechanical floors. Such jets are expected since the air inside the building is compressed as the tower falls and must flow somewhere as the pressure builds. It is significant that similar “puffs” were observed numerous times on the fire floors in both towers prior to their collapses, perhaps due to falling walls or portions of a floor. Puffs from WTC 1 were even observed when WTC 2 was struck by the aircraft. These observations confirm that even minor overpressure were transmitted through the towers and forced smoke and debris from the building.
The volume of air in the building was ~85% of the total Tower volume. The floors below the damage zone were sound meaning that air pressure built up to the point where windows failed.
Original quote by jcjeant: The NIST do not make a scientific analysis of the "collapse" itself .. it's a page "blank" in the NIST final report
That doesn't mean they didn't do it, it just means they didn't publish it. I suspect that was in deference to the victims and the families of victims as the details would have been gruesome. NIST did do an analysis of the collapse of WTC Building 7, it was vacant resulting in no fatalities at the time of total collapse.
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Old 10th Jul 2016, 01:09
  #334 (permalink)  
 
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Hi,

I suspect that was in deference to the victims and the families of victims as the details would have been gruesome
There we are again ..
Used argument ad nauseam when something is missing or is not supposedly published
For an important event like the fall of the two towers .. it's a bit light as argument
Especially that alot of victims families are asking questions remained unanswered until now
On the other hand .... the word "piston" used by NIST does not seem appropriate to me
My two cents
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Old 10th Jul 2016, 01:31
  #335 (permalink)  
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https://youtu.be/cIV7F5QiiCQ

Forensic record video of exposed ceiling trusses, made in March 2001 during renovation of the 85th floor.
It reveals patchy application of original insulation and that the insulation of this type can be knocked/scrapped off in chunks. It's unlikely to survive the mechanical action of a 500mph metal scraper!

Mickjoebill
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Old 10th Jul 2016, 09:49
  #336 (permalink)  
 
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How many floors were there in the individual towers, and were the windows Plate glass or toughed safety glass..?
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Old 10th Jul 2016, 11:22
  #337 (permalink)  
 
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110 storeys, laminated safety glass.
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Old 10th Jul 2016, 16:04
  #338 (permalink)  
 
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Thank you Gouli for the 110 storeys and glass info

I have carried out a fair amount of investigation with weights and impact loads on HGVs here in the UK. putting it into a simple easy case,..If 1 tonne travelling at 30 MPH unfettered meets with an instant dead stop, at that point,.. the 1 tonne carries an impact weight of 15 tonne's, not actual weight but Kinetic energy increase due to forward speed at the point of the dead stop.

So take the 900t weight of steel in the falling top floor of a 110 floor building the initial impact of floor 110 would be 900t plus 50% of a drop speed say that was 30 mph that would be 44 ft per second, 900 tonnes actual plus the effect of the kinetic energy/weight increase due to falling would make an impact value of weigh 1350 t for that one floor.

so the next floor to collapse would be Floor 109 @900t(steel only)
plus the weight of floor 110 1800 t (steel only)
Plus the kinetic weight of impact this would be equiv + 900t
So total weight impact on floor 108 would be 2700 t (steel only)

Kinetic weight is only energy released by movement, but the impact target in this case the next lower floor feels this as though total additional weight, that would be possibly why the towers seemed to accelerate when seen from the many camera angles as were shown, at about floor 60 there was an almost continuous impact type of noise akin to a train wheel going over a cracked or broken rail line.
My conjecture is the windows were blown out,.. not by expolsives, but by the huge increase in the dropping of the multiple floor weight(s) which increased higher and higher simply due to Newtons Law which then brought into play Kinetic weight impact as well. allied to the speed of the compression of the lower level floors.. this simply blew out any entrance doors or windows that were there .
P R-B

Last edited by Peter-RB; 10th Jul 2016 at 16:06. Reason: alteration
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Old 10th Jul 2016, 16:23
  #339 (permalink)  
 
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We are surrounded by air at 15 pounds pressure per square inch. We are generally completely unaware of the air pressure forces acting against us until we try standing in a gale force wind or cycle into a headwind. But those forces are always present. The human body can resist quite significant changes in air pressure without harm because we are essentially squishy.

Five pounds per square inch of over pressure is sufficient to destroy most man made structures. A sheet of A4 paper measures roughly 8x11 inches or 88 square inches. So 5 psi over pressure would impose a load of 440 pounds on an area the size of a sheet of paper.

Easy to demonstrate how the excess air pressure during the collapse sequence would not only blow out windows, but would also apply sufficient side loads to shatter concrete.

The only point I would like to make is that it most probably wasn't a single 900 ton floor that dropped to initiate the collapse, probably several floors gave way simultaneously, so the initial collapse loading on the intact floors would have been several times your initial figure, perhaps even as much as the entire mass of the remaining intact structure above the impact level.

The forces involved were well beyond any normal experience in building design.
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Old 10th Jul 2016, 16:51
  #340 (permalink)  
 
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jcjeant,
Original quote by jcjeant: The NIST do not make a scientific analysis of the "collapse" itself .. it's a page "blank" in the NIST final report
What exactly would you like to know in the seconds it took (11 for WTC1) & (9 for WTC2) for the centers to collapse to the ground? Isn't it obvious what took place during those time spans by looking at photos and videos?

From NIST:
Why didn’t NIST fully model the collapse initiation and propagation of the WTC towers?
The first objective of the NIST WTC investigation included determining why and how WTC 1 and WTC 2 collapsed following the initial impacts of the aircraft (see NIST NCSTAR 1). Determining the sequence of events leading up to collapse initiation was critical to fulfilling this objective. Once the collapse had begun, the propagation of the collapse was readily explained without the same complexity of modeling.
I just want to remind you again, there is a human aspect to this beyond the "blank page" scientific analysis. Next weekend is the anniversary of the TWA 800 explosion and crash, 20 years ago:
Twenty years after the Boeing 747 exploded in a fireball off Long Island, killing all 230 aboard, the passage of time has been a salve for some, but others will never get over the heartache. "Let it go," says John Seaman, whose niece died in the crash; he has led an organization of victims' families since the crash.
"It's time to take a deep breath and reflect," he said. "I think the passage of time is helpful. It allows some of us to forget a lot of the details. The loved ones are not forgotten. To us, it’s about healing."

Last edited by Turbine D; 10th Jul 2016 at 18:18. Reason: added paragraph
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