darrenf
resident denizen
The impact yes, not the impact with post crash fire from loaded tanks.
United 93 - Accident Investigation
- Thread starter hambone
- Start date
The impact yes, not the impact with post crash fire from loaded tanks.
Brian29
Well-Known Member
I If I am correct, I believe that the Towers were quite unusual in their design in that the load bearing structure was the outside facade. The age-old and common design of hi-rise buildings is to place the load bearing structures within the interior of the building and stack it to some extent similar to a deck of cards. The Towers were constructed with the exterior structure comprising the bulk of the load bearing structure in order to maximize the available usable space on each floor. The more classic design restricts the amount of usable floor space since so much more space is taken up by the load bearing columns.
With the large gashes/hole blown into the face of each tower by the impact of the aircraft I would imagine that the load bearing capacity was severely diminished.
This is how the construction of the WTC was explained to me well before 9/11 and this is how I understand it.
hambone
Well-Known Member
+1 The outside of the building was what carried the load. So when the planes took out the load bearing parts of the building, it was only a matter of time before they came down. Thats the reason that the second building to get hit came down first. It was hit much lower than the first, so the load on a weakened structure. And the steel truss that spanned the inside had nearly all of the fire insulation knocked off. Even still, with the amount of fire in the buildings, no amount of insulation could have kept the heat out. There are some interesting videos out there that show what a steel beam will do when exposed to a Jet A fire.
SeanD
Well-Known Member
There was an interesting show on last night. Something about debunking many of the conspiracy theories. One test was igniting jet fuel under a steel beam. The beam started to bend within 3 minutes. Another was a demolition of an old 8 story building which took 3 days to prepare. They say it would take at least 100 men and 3 months if not longer to prep a 100+ story building.
WacoFan
Bigly
I remembered that John Deakin wrote an interesting article about the energy of the the wrecks after it happened.
Here is the full article written December of 2001: http://www.warmkessel.com/jr/flying/td/jd/48.jsp
Here is the full article written December of 2001: http://www.warmkessel.com/jr/flying/td/jd/48.jsp
Kinetic Energy
My first thought was of the B-25 that crashed into the Empire State Building in 1945. That accident (they were lost, in weather) caused a small handful of deaths (about a dozen), and about a million dollars in damage, which was serious enough, and big news at the time. The structure of the Empire State Building was not seriously damaged, and since the WTC buildings were still standing after the airliners struck them, I figured the big twin towers would probably be okay, too.
The B-25 grosses at 28,000 pounds, and the 767s at roughly 250,000, depending on the model. Roughly ten times the weight, so ten times the kinetic energy. Taking a wild guess at the speed at impact, assuming the B-25 hit at 150 knots and the 767s at 600 knots, that's four times the speed. Yes, redline indicated airspeed for a 767 is under 400, but I doubt they were paying much attention to the manual, or limitations, and they were MOVING. Energy varies with the square of the speed, so that's 16 times the energy from speed, or a total of 160 times the energy of the B-25 that slammed into the Empire State Building. With those numbers in mind, I wondered how the buildings were still standing after the impact.
For some perspective, take a look at this chart:
Click for larger image.
I have assumed a weight of 20,000 pounds for the B-25, and an impact speed of 150 knots for that actual incident. I do not know what the real figures were, but that's close enough to establish an approximate data point, and by the time we look at the higher speeds and weight, any small errors will be lost in the noise.
This compares an actual accident (the B-25), with three other airplanes used as weapons. Note the relatively small energy of a Bonanza, even at 300 knots. It's about half that of the B-25, which is six times heavier. Both absolutely pale in comparison with the big jets. I cannot help but wonder, if we're so worried about future terrorist incidents, why were the big airplanes flying, and the small ones grounded?
Boeing 747 409,684,764,222 800,000 600 Boeing 767 128,186,722,222 250,000 600 B-25 640,933,611 20,000 150 Bonanza 384,560,167 3,000 300
Aircraft TypeKinetic Energy foot-poundsWeight poundsSpeed knots
But what difference does all that make? Those who hate airplanes, or who don't understand how important general aviation is, will take the attitude they don't even want RC models flying around, for fear they may be used as weapons. Few outside our small community see small airplanes as anything but toys for the rich, and I'm not sure we'll ever convince anyone otherwise. Pity.
The HorrorThe fire, that awful fire, clearly visible even from a great distance, kept burning on multiple floors, and I began to wonder what was burning. Then I thought of the thermal energy contained in 10,000 gallons of jet fuel, guessing at the amount, not really knowing how much they were carrying. That could vary greatly with the flight plan distance, which I didn't know.
I began to realize with mounting horror that those buildings were doomed, and were coming down. It was just a matter of time until the steel structure heated up enough to weaken just enough to begin bending, and once that happened, it would be all over. Watching them come down numbed me to the soul. I believed at first that there might have been 100,000 deaths. Without knowing anything about the buildings, I guessed at 200 people per floor, or 40,000 within the towers, plus probably an equal number in the surrounding very large buildings.
I am so glad I was wrong on that. It could have been that bad, but for several fortunate circumstances (if we can call anything about this event "fortunate"). The first one hit high, killing "only" those on and above those floors. That gave precious time for those lower in the building and most in the second tower to get out, saving tens of thousands. The second impact was lower than the first, but by then, most people on and above those floors were already below that point.
We'll never know for sure how many died that day. Authorities began talking of "hundreds," and reluctantly raised it in steps to the current number approaching 7,000. For a little perspective, we kill about seven times that number every year on the highway. No, I know, that doesn't help me, either.
Pilots and Politicians
Click for larger image.
Bandit_Driver
Gold Member
From everything I've seen and read the Trade Towers fell do to structural damage, intense fires weakening the metal, and ended up colapsing under their own weight. Once the floors started falling it was a domino effect as each floor below couldn't pick up the weight of the ones above it. Jet-A wasn't exactly buring in an open space. It was in a confined spaced. The insulation on a lot of the beams was taken off during the impact.
Deakin said:
Killed on 9/11 = < 3,000
Number of US people killed since 9/11 by drunk drivers = ~ 150,000
More food for thought:
Number of US soldiers killed in Iraq and Afghanistan = 6230
Total casualties in Iraq and Afghanistan = ??? (Maybe 200 to 300 TIMES as many people as died on 9/11?)
Just trying to add some big picture perspective.
Additional thought: I refuse to acknowledge conspiracy theories as having any basis in reality.
boondr
Penalty Vectorer
Get your own website if you want to make inside jokes.
Cptnchia
Dissatisfied Customer
ASpilot2be
Qbicle seat warmer
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Bumblebee
Commodore
our great computers, fill these hallowed halls...
Qutch
Question everything
Comparing the number of views-to-posts in this mean thread, I presume that there are a lot of silent readers wondering what the hell is going on here. . Two opposing camps, with many posters unwilling to give an inch, or even willing to listen to an alternative viewpoint . .
My time in the Air Force was spent working in Aviation Psychology, Human Factors Engineering. . Specifically, I worked in an R&D lab on the development of advanced flight control and navigation techniques. . These techniques were not recycled techno-procedures. . They were completely different approaches, requiring the pilots to employ completely new problem solving mindsets (without going into detail, it required the pilot to abandon "procedures" and use an intuition based subconscious process instead). . Pilots able to make the thought-shift were able to radically outperform computers, teams of pilot/navigators working together, or all three working together. . We found that all UPT student lab rats introduced to these techniques by qualified instructors were able to quickly make the leap, but very few of their IPs could. . Some pilots could adjust, partially, but for most test-subjects the mind-shift needed to take place before too much flight "experience" had accrued. . Pilots with too much "experience" clung to their familiar methods. . What I found intriguing was, they were not only resistant to learning the new technique, some exhibited hostility at even being asked to try the new thought process . . Initially I theorized that a demonstration by the resistant IPs' own students, who easily outperformed their instructors, would open their minds, but it didn't. . It sometimes embarrassed them, and seemed to threaten them, but it still didn't allow them to "see" what their students saw. . Many IPs clung to their procedures, even after watching their students complete complex intricate testing maneuvers that the IPs themselves found impossible to perform . . Some IPs argued that this new thought process might be a dangerous threat to training traditions, cohesiveness and standardization, regardless of how well it worked. . For most "experienced" pilots, their brains were already wired. . We were too far outside their comfort zone. . They weren’t listening.
The 911 issue raised in this thread is still upsetting, even 10 years later. . I've seen this before. . Some people have made up their minds. . They don't want them changed. Many don't even want the subject discussed. . I've never seen this many insults in a thread. . Clearly, many are not ready to discuss the subject civilly . . What fascinates me is …...why?
To me, it has nothing to do with blindly believing the government. I don't believe that an AA 757 hit the Pentagon because the government tells me that's what happened, I believe an AA 757 hit the Pentagon because I was an AA F/A at the time and I saw the a/c removed from the fleet list, I saw the flight number and crew list be removed from FOS, the pax record be removed from RES, I saw the crew's names later and yes these were REAL people, REAL AA crew members who were based at a VERY small, very tight-knit base. It happened. Not because the government says so, but because I saw tangible proof. So when people try to say that it wasn't an airplane that hit the Pentagon, I dismiss it. Not because I'm closed minded or not able to think for myself, but because I AM able to think for myself, and I know what I saw, having worked for the airline involved at the time it happened.
flyingbum
Needz Re-Edjamacayshun
Don't forget about the thousands of first responders that are being denied medical care. They are dying from toxic dust from the WTC collapse. We have the money to fight multiple wars and no money to provide heath care to the 9/11 first responders. Firefighters, police, medical responders etc etc... The real bummer is they are not allowed to be present at the 10 year ceremony. Probably because over 50% of them are "truthers". We easily respect the already dead, how about some respect for those who are still suffering and dying.
Stryker172
Well-Known Member