Merged Fireballs and Backdraft in WTC1 Basement and Lobby

[Norseman]

After doing a bit of research the last days, here are some thoughts on why the jet fuel fireballs on sublevel B4 and in the lobby of WTC 1 could be so destructive.

The keyword is backdraft. The burning jet fuel cascading/raining down the elevator shafts of car number 6,7 and 50 would consume all available oxygen in the shaft on its way down. Behind the burning front of the fireball, in the shafts, there would follow a cloud of expanding hot gasses including evaporated jet fuel, CO and likely pyrolyzed jet fuel, all lacking oxygen to combust.

When the fireball shot out of the shafts at the bottom, all the unburned gasses mixed with fresh air and rapidly deflagrated, causing the overpressure that blew out walls and windows.

Normally backdraft occurs in fires when fresh air suddenly enters the confined space of an oxygen starved fire. The principle would be the same for an oxygen starved fireball that shoots in to a room filled with fresh air.

Here is a YouTube video from Uruguay showing the effect of a backdraft. And it also gives an impression of what it would have looked like when the fireballs shot out of the elevator shafts.

Here is an artificially created backdraft.

According to this article by Vincent Dunn moderate amounts of over-pressure can fail walls. Here is another article discussing violent fire deflagrations including backdraft.

Regarding the time for the fireballs to reach the bottom of the shafts witness Edward McCabe gives the following account:

I was in the refrigeration plant in tower 1 sub basement 4.I was passing through when I felt a slight shifting of the building.I froze right where I stood and listened....nothing.. about 30 seconds past and to my left about 30 feet from me was a stairway leading up to a door. this door explodes off its hinges and white smoke came into the plant.

According to Wikipedia large raindrops impacts ground with a speed of 9 m/s. This gives a fall time for a fuel drop from the impact area to the bottom of the shafts of about 40 seconds. But the time would very likely be somewhat shorter due to down draught from falling elevators and expanding fire-gasses. So the timing of Edward McCabe looks very reasonable. By the way, evaporated/pyrolyzed jet fuel creates white smoke.

Nothing earth shattering, but hopefully it gives a better understanding of the events.

Norseman

 

[jhunter1163]

This is the kind of thing you'd never see a Twoofer do. A carefully explained, scientifically sound explanation of an event on 9/11. Perhaps not earth shattering, but orders of magnitude more plausible than anything any Twoofer could come up with. Nicely done.

 

[R.Mackey]

According to Wikipedia large raindrops impacts ground with a speed of 9 m/s. This gives a fall time for a fuel drop from the impact area to the bottom of the shafts of about 40 seconds. But the time would very likely be somewhat shorter due to down draught from falling elevators and expanding fire-gasses. So the timing of Edward McCabe looks very reasonable. By the way, evaporated/pyrolyzed jet fuel creates white smoke.

Just to add to your useful and perfectly reasonable comments,

We expect the "droplets" of jet fuel to be much, much larger than rain droplets. The jet fuel is not all coalescing out of vapor phase. Instead, the droplet size will be driven by Plateau-Rayleigh instability, which states that the droplet radius will be approximately equal to the radius of the original stream of fluid -- potentially quite large. Larger droplets would fall much faster.

I would actually expect the rate of fuel travel to be limited by wetting effects on the sides of elevator shafts, rather than aerodynamic considerations. Not sure how to estimate this without conducting an experiment. In any event, the timing seems plausible to me.

 

[cloudshipsrule]

Planted explosives are much more sinister, therefore more plausible to the truth avoiders.

Here's the thing. If it was explosives what was their purpose? The towers didn't collapse for another hour, so they obviously didn't initiate collapse. Maybe they were planted and blown because the perps didn't think flying airliners into the towers at 500 mph would scare people enough? "Sir, one or two extra sticks of TNT might be just enough to cause panic."

 

[Norseman]

Just to add to your useful and perfectly reasonable comments,

Thanks. And just to elaborate a little bit more.

We expect the "droplets" of jet fuel to be much, much larger than rain droplets. The jet fuel is not all coalescing out of vapor phase. Instead, the droplet size will be driven by Plateau-Rayleigh instability, which states that the droplet radius will be approximately equal to the radius of the original stream of fluid -- potentially quite large. Larger droplets would fall much faster.

That would be correct initially, but when the speed increases water droplets with a size above 5 mm becomes unstable, and breaks up in to droplets of smaller diameters. Here is an interesting AMS article from 1970 about this that I found, where they started with a water flowing under zero pressure from a hose 60 meters above the ground. And here is an illustration of rain droplet breakup. At exactly what size jet fuel droplets breakup, in situations comparable to rain, I have not found, but this should be within the ballpark.

I would actually expect the rate of fuel travel to be limited by wetting effects on the sides of elevator shafts, rather than aerodynamic considerations. Not sure how to estimate this without conducting an experiment.

If I understand you correctly, some amount of droplets should be picked up by the shaft sides on the way down. Yes, that should definitely be a limiting factor. Considering this it seems likely that no liquid jet fuel traveled all the way to the bottom, just the gasses. Therefore the fall rate of liquid droplets would possibly not be an reliable indicator to time the fireball with. Then we would have to consider how fast the fire gasses could expand downward in the shafts. But as you say, I guess we would need an experiment or an elaborate simulation to give us any exact answers on this.

 

[R.Mackey]

Thanks. And just to elaborate a little bit more.

That would be correct initially, but when the speed increases water droplets with a size above 5 mm becomes unstable, and breaks up in to droplets of smaller diameters. Here is an interesting AMS article from 1970 about this that I found, where they started with a water flowing under zero pressure from a hose 60 meters above the ground. And here is an illustration of rain droplet breakup. At exactly what size jet fuel droplets breakup, in situations comparable to rain, I have not found, but this should be within the ballpark.

Also correct. The conditions in the WTC Towers would be quite complicated...

One interesting scenario would be for jet fuel to "pool" on or around a large elevator, say the main freight elevator, about the time said elevator had its cables cut by the impact. The fuel would then fall with the elevator at "virtually free-fall" speeds , resulting in a fireball in the sublevels only a few seconds after impact.

Lots of possibilities.

 

[peteweaver]

R mackey, lifts, tend to have an anti fall device fitted, so that if the cables snap, restraining bolts spring out, catching the lift... So its doubtful that any lifts would have fallen, however, there are gaps and burning fuel would 1 pass into the lift itself (if it found an opening), and two, some of it would go around the lift, following the path of the least resistance.

 

[R.Mackey]

R mackey, lifts, tend to have an anti fall device fitted, so that if the cables snap, restraining bolts spring out, catching the lift... So its doubtful that any lifts would have fallen, however, there are gaps and burning fuel would 1 pass into the lift itself (if it found an opening), and two, some of it would go around the lift, following the path of the least resistance.

Anti-falling devices notwithstanding, there were lifts that did fall. I wouldn't have suggested this otherwise. The huge fireball in the sublevels cited by William Rodriguez did, in fact, issue from a freight elevator shaft after the elevator fell due to the impacts.

 

[leftysergeant]

Anti-falling devices notwithstanding, there were lifts that did fall. I wouldn't have suggested this otherwise. The huge fireball in the sublevels cited by William Rodriguez did, in fact, issue from a freight elevator shaft after the elevator fell due to the impacts.

I should think that there would be a set speed at which the brakes would engage, and that there would be some provision for graduated deceleration so that passengers are not driven out the bottom of the elevator car when it stops.

At any rate, the fuel travelling into the basement would have been highly aerosolized and quite probably oxygenated to a point that it would create quite a blast in the basements, if it hit a source of ignition. I am sure that there are plenty such sources on a mechanical floor. However, I would further not expect all available fuel to have been consumed in one god-awful WHOOF! Some of it may have also been forced into other areas to ignite later. I am not sure where, but I recall reading a narrative in which a team of fire fighters heard "something shifting and thumping" on one of the mechanical floors. Quite likely, it seems to me, some of the fuel exploded and knocked equipment driven by electric motors out of its mountings, but did not cut off electrical supplies. There is also a clip somewhere on YouTube of a young man who opened a door and was met by a major explosion. No question in my mind what that would have been.

 

[Arkan_Wolfshade]

Elevator braking devices only work if the elevators remain on their guiderails.

 

[peteweaver]

Fair points, I stand corrected.

 

[Norseman]

At any rate, the fuel travelling into the basement would have been highly aerosolized and quite probably oxygenated to a point that it would create quite a blast in the basements, if it hit a source of ignition. I am sure that there are plenty such sources on a mechanical floor.

Could be, but I still think that the backdraft scenario with a burning front, that I described in the opening post of this thread, best fits the available witness accounts I have read so far. But I will keep it in mind when I elaborate further on the issue. The ignition source in your scenario could also be the fireball traveling down the shafts behind the front of the fuel droplets, while it sustains itself on the falling fuel. Good input.

I am not sure where, but I recall reading a narrative in which a team of fire fighters heard "something shifting and thumping" on one of the mechanical floors. Quite likely, it seems to me, some of the fuel exploded and knocked equipment driven by electric motors out of its mountings, but did not cut off electrical supplies.

This account from WTC1 was given by Joseph Shearin:

The 41st-floor mechanical room had sustained considerable damage – equipment formerly located in the ceiling was down on the floor and water was gushing from crushed pipes.

In addition to likely fuel or fireball entering the mechanical room causing damage, I also find it very likely that vibrations and swaying of the building from the airplane impact could also cause serious damage to the mounting of heavy equipment.

 

[PhantomWolf]

Just for some excitement, here's another backdraft explosion

 

[WildCat]

My oh my, the silence from the truthers is deafening in this thread.

 

[Swing Dangler]

While checking a PDF I have on file for the number of ABM employees who died on 9/11 (17: see page 12), I came across an account that I'd somehow missed before. It's the story of James Barrett, like Rodriguez an ABM janitor, who was in the north tower basement when both planes hit. I don't know what level he was on. His account is notable for several reasons:

1) He didn't hear either plane impact, wasn't aware of any explosions, and didn't know anything was wrong until he went up to the plaza level on routine business.

2) He is the one who helped Rodriguez rescue the men in the north tower freight elevator who had sprinkler water pouring on them. Before today, I'd never known his identity. Rodriguez says he met this man in the north tower.

3) His account makes an interesting addition to the accounts of people who didn't hear the impacts. On this page I quote several people in each tower who were closer to the impact zones than was Rodriguez and who felt, but didn't hear, the impacts. Below, I've reprinted part of the accounts of Edward McCabe, on the B-4 level, who felt a slight shift of the building and about 30 seconds later saw a door blow off its hinges, followed by white smoke; and Mike Pecoraro, on the B-6 level, who felt and saw nothing, but whose co-worker noticed the lights flicker, then they saw white smoke that smelled like kerosene.

4) I think Barrett's account illustrates the localized nature of the jet fuel explosion in the basement core, and lends credence to the idea that Rodriguez didn't hear flight 11's impact.

See also Salvatore Giambanco's corroboration of the elevator rescue on this page, and the Port Authority radio transcripts on this page.

Other interesting basement stories (more here):

Oh god, not this jet fuel basement explosion thing again....this has been analyzed to death and found without merit.

Start here for one of the most throughouh analysis: Basement Explosion

As a follow up you can read more here: North Tower Basement Explosion.

For true believers perhaps you can explain the following issues:

1. Simply trace the route of the jet fuel, in liquid or fireball form from the initial impact to the basement areas.

2. Determine how the fireball, if that is what you truly think caused the damage in the basement areas, had enough energy to cause the local destruction witnessed at impact, and yet not destroy the shafts on the way down to the basement, and then have the energy to destroy parts of the basement areas underneath both towers.

3. Explain how people closest to impact survived the initial blast and jet fuel explosion and then explain how parts of the basement, furthest away from impact, did not.

4. List the accounts of survivors who witnessed pools of jet fuel streaming down the shafts and/or puddling in the area.

5. Find witnesses who were not later TOLD what had happened. I point this out as Gravy uses Ed's account but he, like many if not all of the people in the basement, were later TOLD what happened.

6. And what about Jenny Carr's audio record of the day? Can you explain that loud sound just prior to the apparent impact of the plane?

 

[bonavada]

Oh god, not this jet fuel basement explosion thing again....this has been analyzed to death and found without merit.

where exactly do you think the "basement explosions" originated?
straight-forward answer please.

BV

 

[gumboot]

1. Simply trace the route of the jet fuel, in liquid or fireball form from the initial impact to the basement areas.

Down the freight elevator shaft. Thanks.

2. Determine how the fireball, if that is what you truly think caused the damage in the basement areas, had enough energy to cause the local destruction witnessed at impact, and yet not destroy the shafts on the way down to the basement, and then have the energy to destroy parts of the basement areas underneath both towers.

The fireball was created at the bottom of the shaft.

3. Explain how people closest to impact survived the initial blast and jet fuel explosion and then explain how parts of the basement, furthest away from impact, did not.

The damaged basement survived the initial explosion fine. It was the secondary explosion caused by jet fuel spilling down shafts that did it.

4. List the accounts of survivors who witnessed pools of jet fuel streaming down the shafts and/or puddling in the area.

WTF would anyone be doing in the elevator shaft? (And not in an elevator).

6. And what about Jenny Carr's audio record of the day? Can you explain that loud sound just prior to the apparent impact of the plane?

Judging by most of the other Truther "explosion" evidence, I'd guess it's probably fake.

-Gumboot

 

[Quad4_72]

Oh god, not this jet fuel basement explosion thing again....this has been analyzed to death and found without merit.

Start here for one of the most throughouh analysis: Basement Explosion

As a follow up you can read more here: North Tower Basement Explosion.

For true believers perhaps you can explain the following issues:

1. Simply trace the route of the jet fuel, in liquid or fireball form from the initial impact to the basement areas.

2. Determine how the fireball, if that is what you truly think caused the damage in the basement areas, had enough energy to cause the local destruction witnessed at impact, and yet not destroy the shafts on the way down to the basement, and then have the energy to destroy parts of the basement areas underneath both towers.

3. Explain how people closest to impact survived the initial blast and jet fuel explosion and then explain how parts of the basement, furthest away from impact, did not.

4. List the accounts of survivors who witnessed pools of jet fuel streaming down the shafts and/or puddling in the area.

5. Find witnesses who were not later TOLD what had happened. I point this out as Gravy uses Ed's account but he, like many if not all of the people in the basement, were later TOLD what happened.

6. And what about Jenny Carr's audio record of the day? Can you explain that loud sound just prior to the apparent impact of the plane?

So you are suggesting that there were secondary explosive devices planted in the basement? What purpose did they serve, seeing as how the towers collapsed from the top down?

 

[BenBurch]

You know, when firefighters entered the building, there was a stench of Kerosene and people by the elevators burnt to death where they stood (or sat in the case of the guard.)

I suppose Thermite explains that?

 

[Swing Dangler]

So you are suggesting that there were secondary explosive devices planted in the basement? What purpose did they serve, seeing as how the towers collapsed from the top down?

cloudshipsrule Planted explosives are much more sinister, therefore more plausible to the truth avoiders.
Here's the thing. If it was explosives what was their purpose? The towers didn't collapse for another hour, so they obviously didn't initiate collapse. Maybe they were planted and blown because the perps didn't think flying airliners into the towers at 500 mph would scare people enough? "Sir, one or two extra sticks of TNT might be just enough to cause panic.

1. To destroy the pumping system that would help fight the fire in the upper parts of the tower.

2. To split the firefighting and rescue efforts.

3. A secondary attack on the structure in case they didn't suffer global collapse.

Gumboot
Originally Posted by Swing Dangler View Post
1. Simply trace the route of the jet fuel, in liquid or fireball form from the initial impact to the basement areas.

Down the freight elevator shaft. Thanks.

Down the elevator shaft? Which one? And how does that correspond with the survivors in the elevator? On a graphic of the elevator layout, please show this route.

6. And what about Jenny Carr's audio record of the day? Can you explain that loud sound just prior to the apparent impact of the plane?
Judging by most of the other Truther "explosion" evidence, I'd guess it's probably fake.

ROFLMAO! Ok. Take that up with Jenny Carr. I don't think calling it a fake is going to get you out of this one. Please provide scientific evidence proving the recording is a fake.
The interesting thing on the tape is that the first explosion(sound) sounds nearly identical to the plane impact explosion.

bonavada
Originally Posted by Swing Dangler View Post
Oh god, not this jet fuel basement explosion thing again....this has been analyzed to death and found without merit.
where exactly do you think the "basement explosions" originated?
straight-forward answer please.

BV

Parking garage.

R.Mackey
Anti-falling devices notwithstanding, there were lifts that did fall. I wouldn't have suggested this otherwise. The huge fireball in the sublevels cited by William Rodriguez did, in fact, issue from a freight elevator shaft after the elevator fell due to the impacts.

Can you please accurately source the information for the elevator fell due to impacts? Thanks. We know the elevator fell, but it didn't fall into the elevator pit areas. That is pure speculation on NIST's part which has no evidence to support their assumption.

Norseman
Fireballs and Backdraft in WTC1 Basement and Lobby
After doing a bit of research the last days, here are some thoughts on why the jet fuel fireballs on sublevel B4 and in the lobby of WTC 1 could be so destructive.

The keyword is backdraft. The burning jet fuel cascading/raining down the elevator shafts of car number 6,7 and 50 would consume all available oxygen in the shaft on its way down. Behind the burning front of the fireball, in the shafts, there would follow a cloud of expanding hot gasses including evaporated jet fuel, CO and likely pyrolyzed jet fuel, all lacking oxygen to combust.

No, the key word is energy. How much energy needs to be expended to cause the damage on some many basement levels. Here is a hint, it isn't from jet fuel.

Regarding the time for the fireballs to reach the bottom of the shafts witness Edward McCabe gives the following account:
Quote:
I was in the refrigeration plant in tower 1 sub basement 4.I was passing through when I felt a slight shifting of the building.I froze right where I stood and listened....nothing.. about 30 seconds past and to my left about 30 feet from me was a stairway leading up to a door. this door explodes off its hinges and white smoke came into the plant.
According to Wikipedia large raindrops impacts ground with a speed of 9 m/s. This gives a fall time for a fuel drop from the impact area to the bottom of the shafts of about 40 seconds. But the time would very likely be somewhat shorter due to down draught from falling elevators and expanding fire-gasses. So the timing of Edward McCabe looks very reasonable. By the way, evaporated/pyrolyzed jet fuel creates white smoke.

Unfortunately you are assuming that it was jet fuel that caused the explosion and white smoke. Ed is TOLD what it was later. And as far as that jet fuel falling down the shafts, there is going to be something in the way...the elevator itself. And for the jet fuel vapor being white, what you need to do now is explain the process in relation to the environment of how that jet fuel went to liquid then unstable vapor form in the alloted time frame.
So your theory is now dependent upon the size of a rain drop? LOL!