Physical Impact Model Video

  • Thread starter Thread starter psikeyhackr
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N320AW said:
Sure, thats not a problem.

Many aircraft that were not designed for flight above the sound barrier, have either intentionally or un-intentionally exceed the speed of sound. The German ME-262 for example.

When you said " survive " I took that to mean the structural integrity of the aircraft was at issue. The problem which most aircraft have in approaching and transitioning above the speed of sound (transonic) is one of possible un-controlability. Buffeting is frequently encountered, but the biggest problem is the AC's tendency to nose down, sometimes to the point of the pilot not being able to recover from the dive.

Some aircraft today have what is known as a mach trim system. This system will automatically introduce the proper amount of elevator trim to compensate for the aircraft's nose down characteristics when at high speed.

By the way, the B757 has the system . . . the B767 does not!
 
Transonic Wave Drag

psikeyhackr said:
Would the aircraft survive breaking the sound barrier?

The Concord SST was shaped somewhat differently than a 767.

psik

Hi psik,

The airfoil shape certianly comes into play in subsonic, transonic, and supersonic drag. I just located the following information on "wave drag" (Wikipedia is NOT one of my preferred sources, but this information looked legitimate to me). And AuGgie, I'm already sensing a 1980's transvestite joke coming here. ;)

From:
http://en.wikipedia.org/wiki/Supersonic_travel

"Below supersonic speeds the energy radiated to drag is roughly proportional to the square of airspeed and the density of the air. However, as speeds approach the speed of sound, the phenomenon of wave drag appears. This is a powerful form of drag that starts at about Mach 0.8 and ends around Mach 1.2, (transonic speeds). Between these speeds the coefficient of drag (Cd) is approximately tripled. Above the transonic range Cd drops dramatically again, although it remains 30 to 50% higher than at subsonic speeds. This means that a supersonic aircraft has to have considerable extra power to overcome wave drag, although cruising performance above that speed is more efficient."

From:
http://en.wikipedia.org/wiki/Wave_drag

"Wave drag is caused by the formation of shock waves around the aircraft. Shock waves radiate away a considerable amount of energy, energy that is experienced by the aircraft as drag. Although shock waves are typically associated with supersonic flow, they can form at much lower speeds at areas on the aircraft where, according Bernoulli's principle, local airflow accelerates to supersonic speeds over curved areas. The effect is typically seen at speeds of about Mach 0.8, but it is possible to notice the problem at any speed over that of the critical Mach of that aircraft's wing. The magnitude of the rise in drag is impressive, typically peaking at about four times the normal subsonic drag. It is so powerful that it was thought for some time that engines would not be able to provide enough power to easily overcome the effect, which led to the concept of a "sound barrier".

See also:
http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Flow/TH19.htm

http://en.wikipedia.org/wiki/Aeroelasticity

The increased "wave drag" makes me wonder how much velocity above Mach 0.86 at various altitudes the applicable Boeing high bypass turbofan pairs are ACTUALLY capable of generating...

A retired Royal Navy aerospace engineer (with decades of experience with subsonic, transonic, and supersonic naval aircraft including the supersonic F4 Phantom fighter) provided me with the following excellent Concorde SST engine link:

http://www.concordesst.com/powerplant.html

NOTE: Rapid reheat or "reheat" is termed "afterburner" in US aerospace circles. Also note the variable ramps to restrict and slow incoming airflow in the 4 Concorde Rolls-Royce/SNECMA engine air intakes.

All of my research so far points to the jet engines being the upper velocity limiting factor for high-bypass subsonic/low transonic Boeing turbofans built by either GE, Pratt Whitney, or Rolls-Royce (in the 757 case). Considerable engineering work has obviously gone into the supersonic Concorde engines to overcome transonic and supersonic challenges, and the Boeing engines are missing nearly ALL of these design adaptations. My research is confirmed by the retired Royal Navy engineer at:

http://z9.invisionfree.com/Pilots_For_Truth/index.php?showtopic=9179&view=findpost&p=10265987

Research is being done on supercritical airfoils and supercritical turbofan blades, but I didn't find many sources on these two that didn't require a subscription service.

d
 
Correction

dMole said:
Do you know of any PUBLICLY available FAA radar data as of Dec 2001 to cross-check against the USAF RADES data? I don't...

Correction past "edit thirty": make that PUBLICLY available FAA radar data as of Dec 2007.
 
Comparative Boeing Analysis

psikeyhackr said:
These are videos of large aircraft at low altitudes:

Low Pass

Hot Dog

So if the planes in the videos were doing 300 mph and drag is proportional to the square of velocity.

300 * 300 = 90,000 500 * 500 = 250,000

250,000/90,000 = 2.8

Going from 300 mph to 500 mph at the same altitude means 2.8 times as much drag. But going from 700 feet to 30,000 feet means 1/4th as much drag.

2.8 * 0.25 = 0.7

So doing 500 mph at 30,000 feet is less drag on the planes than 300 mph at 700 feet. So if the engines were only using 50% of their maximum thrust when cruising at 30,000 feet they could not produce enough thrust to do 500 mph at 700 feet. I think there is a very good chance that ex-Boeing engineer is correct. Since MIT says the plane that hit the south tower was doing 503 mph this makes 9/11 look very weird.
...
psikey

Also see this New Zealand 757 video:

http://www.youtube.com/watch?v=50BRFzVxDH8&NR=1

All 3 planes looked "flapped" to the stops IMHO, and the 757 had landing gear extended in one pass (increased drag), but they looked MUCH closer to stall or landing speeds than 500mph (or even 300mph) to me. I grew up near the Bonneville Salt Flats speedway, so I've seen several 400+ mph ~4100 feet ASL "low altitude" "cars" and nearly 300mph top-fuel "1/4 mile" dragsters live, but perhaps I can't estimate velocity...:burnout:

I'd bet that all 3 planes were EXTREMELY "light" (i.e. NO passengers and small flight crew) for lower-liability "stunt" flying. I doubt the fuel load was much either for logistics and risk reasons (but fuel "slosh" is a common problem in aerospace engineering). Less weight = less lift needed, no?

I'm fairly certain that the Boeing 727 has a much smaller moment of inertia (and MUCH higher roll rates) than a 757/767 due to the 727's three engines being MUCH closer to the fuselage centerline than the 2 massive wing-mounted engines for a B757/B767 (or B777 and B787 for that matter).

B727 shows a "Zero fuel weight" of 100,000 lb / 45,360 kg

http://en.wikipedia.org/wiki/Boeing_727#Specifications

B757 shows an "Operating empty" weight of roughly 128,000 lb / 58,000 kg

http://www.airliners.net/info/stats.main?id=101

B767-200 shows "Empty weight" of 176,650 lb / 80,130 kg

B767-200ER shows "Empty weight" of 181,610 lb / 82,380 kg

http://en.wikipedia.org/wiki/Boeing_767#Specifications

B707-120B shows "Operating empty weight" of 122,533 lb / 55,589 kg

B707-320B lists "Operating empty weight" of 146,400 lb / 66,406 kg

http://www.airliners.net/info/stats.main?id=87

Based on my physics, I'd say your older B727 and B707 are the "sporty" Boeing models, with the B757 getting an honorable mention. Of course, we would need to add a reasonable amount for fuel load and a minimal flight crew to each of the above numbers, based upon my 2 assumptions about "stunt" flying above.

As an aside that indicates Boeing could likely answer our "low altitude" speed questions, NASA says of the B767-200:

"Although of conventional configuration, the detailed aerodynamic design of the 767-200 is highly refined, as might be expected by the nearly 25 000 hours of wind-tunnel time required in the development of the aircraft. To place this wind-tunnel effort in perspective, 14 000 and 4000 wind-tunnel hours were expended in developing the Boeing 747 and 727, respectively."

http://www.hq.nasa.gov/pao/History/SP-468/ch13-6.htm
 
dMole said:
Hi psik,

The airfoil shape certianly comes into play in subsonic, transonic, and supersonic drag. I just located the following information on "wave drag" (Wikipedia is NOT one of my preferred sources, but this information looked legitimate to me). And AuGgie, I'm already sensing a 1980's transvestite joke coming here. ;)

d
Thanks dMole.

What about the aircraft as a whole?

I am not a pilot or knowledgable about aerodynamics but my "gut" reaction is that a 767 would be destroyed trying to make the transition to supersonic. I have doubts about it being able to handle 500 mph at 1000 feet but I am not sure.

psik
 
Sorry- FAST n loose terminology

Yes Psik, you are correct. Most people consider the wings (and horizontal tail sections) as the "airfoil" per se.

Two decades of studying military aircraft, missiles, and rockets makes me think of flattened things like F-15, F-22, B-2, F-117, SR-71, etc. as a "cumulative" airfoil. I also have an off-n-on, 20+ year, "loose" history with the USAF, so my perception of "aircraft capabilities" is admittedly not from a commercial airliner perspective- those scare me a little. No comment from me on "spacecraft," however. ;)

If you replace my generic use of "airfoil" with "entire Boeing airframe [to include 2 high-bypass turbofan engines]", you'll probably like my statement a little better.

EDIT: add the F-14 Tomcat (with its movable wings) to the above list- one HELL of an interceptor design there, but my sources tell me Tommy's soon bound for pasture...
 
ASCE/ J. Eng. Mech Simulation Article Found

Hi psik,

My searching found the following Univ. of Akron article, but you'd need a subscription service to get a copy. I usually check local university and city libraries, and engineering, electronics, physics, and chemistry departments for tech. articles to copy before purchasing.

http://scitation.aip.org/getabs/ser...00131000010001066000001&idtype=cvips&gifs=yes

My BS detector already went off from the abstract:

"Accepted 1 December 2004) A numerical simulation of the aircraft impact into the exterior columns of the World Trade Center (WTC) was done using LS-DYNA. For simplification, the fuselage was modeled as a thin-walled cylinder, the wings were modeled as box beams with a fuel pocket, and the engines were represented as rigid cylinders. The exterior columns of the WTC were represented as box beams. Actual masses, material properties and dimensions of the Boeing 767 aircraft and the exterior columns of the WTC were used in this analysis. It was found that about 46% of the initial kinetic energy of the aircraft was used to damage columns. The minimum impact velocity of the aircraft to just penetrate the exterior columns would be 130 m/s. It was also found that a Boeing 767 traveling at top speed would not penetrate exterior columns of the WTC if the columns were thicker than 20 mm."

My immediate issues with this:

1. The 2 high bypass turbofan engines were highly energetic rotating complex physical shapes ( E_rot = 1/2 * I * omega^2), NOT rigid cylinders. The complicated moment of inertia and subsequent collision dynamics are likely very different than that of a simple cylinder (and I didn't see whether the rigid cylinder model was hollow or solid either).

2. I recall the perimeter columns being structurally modified with 4 external "ribs" to resist wind load bending, NOT simple box beams, which are generally more prone to crushing, twisting, and bending. The "trapeziodal" taper in the 47 core columns, in addition to their considerable thickness, likely compensated for box beam limitations.

http://911research.wtc7.net/wtc/arch/perimeter.html

From:

http://www.911research.com/papers/trumpman/CoreAnalysisFinal.htm

" In a 2004 presentation NIST asserts that the 47 core columns had a factor of safety of about 2.25. The 236 perimeter columns had a factor of safety of about 5.0 (it has been asserted that the higher factor of safety for the perimeter columns was to handle wind loads). It has been asserted that the core columns, the main load bearing columns, carried 60% of the building load, and the perimeter columns supported 40% of the building load. This was a big building, like a rock in Lower Manhattan for 30 years."

"The factor of safety is based upon the dead load (building materials) of the building and the intended live load (people, office furniture, and similar). The dead load of a floor was 1,818 tons. The floor area was rated 40-150 psf (1.9-7.18 kPa), depending on what the area was going to be used for. Higher load ratings generally were for areas that would support larger than normal loads such as mechanical equipment. Below are floor load estimates based on a review of WTC data contained in a 2005 NIST report. This report contained select scanned images of original WTC specification documents. Because of contradictions in the NIST final report this paper relied on the original WTC specification documents. Data was incomplete so inferences had to be made. The load rating for columns in the perimeter area was 50 psf. The load rating for the core area was up to 100 psf. This comes out to be an estimated 75 psf average for an office floor. The load ratings for floors 110-94 average out to be about 82 psf (3.9 kPa) per floor. On average, a floor's design live load was 1,488 tons. The estimated total weight of a floor, dead load plus live load, is 3,306 tons. Add the factor of safety and the building structure could handle multiple times this load. It is estimated that the average factor of safety for a floor was 3.35. This means a floor could handle a total of 11,075 tons before failing. To visualize, imagine 5,500 2-ton cars stacked in a square about 1/3 of a city block."

To reiterate: 236 perimeter columns at ~5.0 "safety factor"
47 core columns at ~2.25 "safety factor"

Also from the same on ASTM A36 steel:

"We need to account for weakening by heat. Earlier it was calculated that the average air temperature on a floor with fire was 148 C at the time of collapse. Using a general steel strength versus temperature chart, one finds that the steel would have lost about 2% of its strength if it was heated to this temperature. Adjusting our figure we get 466 MPa." "We also have to account for weakening by the plane impact. In a 2004 presentation NIST asserts from its "modeling" that in the "Realistic Case", 3 core columns were severed, 10 were damaged. In this same presentation the "Realistic Case" for the perimeter columns was 34 severed columns and 5 damaged."
 
2 more JOM articles- suspect ones at that.

I found 2 more that have some good info (and considerable suspect info IMHO in a quick scan of them).

http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html

" To a structural engineer, a skyscraper is modeled as a large cantilever vertical column. Each tower was 64 m square, standing 411 m above street level and 21 m below grade. This produces a height-to-width ratio of 6.8. The total weight of the structure was roughly 500,000 t, but wind load, rather than the gravity load, dominated the design. The building is a huge sail that must resist a 225 km/h hurricane. It was designed to resist a wind load of 2 kPa—a total of lateral load of 5,000 t."

[Ed: I recall the wind at JFK being about 5mph at sea level around 09:00 on 9-11-2001. I haven't seen any data on winds aloft, but the smoke in the photos and videos indicates DAMN LITTLE.]

"Inside this outer tube there was a 27 m × 40 m core, which was designed to support the weight of the tower"

[Ed: Ummm, one "core", NOT 47 core columns- hmmmm... Also, the perimeter supported a lesser portion of "the weight of the tower"]

" The only individual metal component of the aircraft that is comparable in strength to the box perimeter columns of the WTC is the keel beam at the bottom of the aircraft fuselage. While the aircraft impact undoubtedly destroyed several columns in the WTC perimeter wall, the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure. Of equal or even greater significance during this initial impact was the explosion when 90,000 L gallons of jet fuel, comprising nearly 1/3 of the aircraft’s weight, ignited. The ensuing fire was clearly the principal cause of the collapse (Figure 4)."

[Ed: Where does the fuel number come from? What is so "clearly" about fire causing the collapse? Thermal data is where?]

-------------ARTICLE 2
http://www.tms.org/pubs/journals/JOM/0711/banovic-0711.html

" During the recovery effort after September 11, and before NIST began its collapse investigation, volunteers from FEMA, ASCE, NIST, the National Science Foundation (NSF), and the Structural Engineers Association of New York (SEAoNY) worked at the four steel recycling facilities to identify and collect steel members important to the investigation. They focused on identifying pieces that the aircraft struck or were obviously burned, as well as pieces from the fire and impact zone. The National Institute of Standards and Technology arranged to have these pieces shipped to its facility in Gaithersburg, Maryland."

[Ed: NO intact, uncompromised beams were focused on??? The article in the post above indicates that the vast MAJORITY of columns were not compromised. Also, exactly how do you get steel members to "burn?"]

"
In all, NIST cataloged 236 structural steel elements:



  • [*] Ninety exterior column panels, of which 42 were unambiguously identified. Of those identified, 26 came from the fire and impact floors, and four of these had been struck by the airplane that hit WTC 1.
    [*] Fifty-five core columns, of which 12 were unambiguously identified. Four of the identified columns came from the fire and impact zones.
    [*] Twenty-three pieces of floor truss. Unfortunately, these elements had no identifying marks, so their original location in the towers is unknown.
    [*] Twenty-five pieces of the channel that supported the floor trusses at the core; all are of unknown location."
[Ed: So 26/42 of the perimeter colums were impact/fire damaged, and 4/42 of those were "impact columns". But the earlier JOM article stated: "the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure". 4/55 core column sections were fire/imact damaged. The uncompromised?? steel was NOT focused on, and QUICKLY shipped overseas for "recycling," in conflict with typical crime-scene SOPs. Hmmm... I'll let the reader calculate his own percentages here]

" Although many of the individual recovered elements are rather large, the collection represents less than 0.5 % of the more than 200,000 tons of steel used in the buildings. It does include, however, representative samples of all the relevant steels necessary for estimating properties for the impact and collapse models. Given the difficulties in locating, identifying, and safeguarding elements in the field, the extent of the collection is impressive."

[Ed: take the 22/42 fire perimeter, 4/42 WTC1 impact perimeter, and 4/55 fire/impact damaged core percentages above and multiply by 0.005 to get a representative percentage of the fire/impact damaged steel actually recovered from the Towers- it is going to be QUITE small. I think the article meant "Given the difficulties in having your crime scene compromised and evidence shipped overseas for destruction, the extent of the collection is impressive." (But I'm just going from the observed facts from the last 6 years of federal "investigation" here). Were the investigating agencies picking steel evidence or cherries on Manhattan Island? My $0.02]



EDIT: 2 more UNREVIEWED articles at JOM:
http://www.tms.org/pubs/journals/JOM/0112/Marechaux/Marechaux-0112.html


http://www.tms.org/pubs/journals/JOM/0112/Biederman/Biederman-0112.html
 
Composite vs. Aluminum Boeings

Here are a few links on the Boeing 787 composite fuselage testing (also has a little info on aluminum B757/B767 fuselages and "skins").

http://seattletimes.nwsource.com/html/boeingaerospace/2003612251_boeing111.html

http://seattletimes.nwsource.com/html/businesstechnology/2003612251_boeing111.html

" Why build a plastic jet?
dot_grey808080.gif

dot_clear.gif

Carbon-fiber reinforced plastic has advantages over aluminum:

Strong: Carbon fiber laid in precise configurations provides optimal strength where loads are heaviest.

Light: The plastic construction is up to 30 percent lighter than aluminum. Less weight means the plane burns less fuel.

Doesn't corrode or fatigue: Metal fatigues because of repeated stress over time, and it corrodes with exposure to moisture. Plastic does neither. [Ed: Aluminum metal fatigue? The MSM/OCT mentions this how often? Hmmm....]


Reduces maintenance: Without corrosion and metal fatigue, a 787 will require a full heavy-maintenance check every 12 years, Boeing estimates, compared with every six years for a metal jet such as the 767. [Ed: this maintenance check data for B757 & B767 is where exactly?]


Allows fabrication of huge pieces: A one-piece fuselage section replaces 1,500 sheets of aluminum and eliminates as many as 50,000 fasteners.

Nicer air, a better view for passengers: Boeing says it can keep the air that passengers breathe moister and more pressurized because the one-piece plastic fuselage sections are stronger, sealed more tightly and won't be damaged by humidity. The strength of the structure also allows bigger windows.

Source: Boeing

[Boeing 787 fuselage test- interesting comments]

http://boeingblogs.com/randy/archives/2007/09/testing_testing.html

http://seattlepi.nwsource.com/business/175791_composites01.html
 
Empire State B-25 Impact in 1945

Some interesting articles on the 1945 B-25 bomber impact with the Empire State Bldg. in the fog:

http://www.tms.org/pubs/journals/JOM/0112/News/News8-0112.html

"At 9:40 a.m., as workers went about their business in the Catholic War Relief Office on the 79th floor, the B-25 crashed into that office at 322 kilometers per hour. The impact reportedly tore off the bomber’s wings, leaving a five meter by six meter hole in the building. One engine was catapulted through the Empire State Building, emerging on the opposite side and crashing through the roof of a neighboring building. The second engine and part of the bomber’s landing gear fell through an elevator shaft. When the plane hit, its fuel tanks were reported to have exploded, engulfing the 79th floor in flames.

The 102-story building shook with the initial impact, according to witnesses, but within three months, the damage was repaired at a cost of about $1 million. Smith died in the crash, along with two other crew members. Eleven workers died in the Catholic War Relief Office, and at least two dozen people were injured."

From:
http://www.withthecommand.com/2002-Jan/NY-empireplane.html

"It is believed that the planes speed at this time was 225 mph. Within seconds the plane was closing rapidly on the Empire State Building. Col. Smith attempted to veer away from the structure but his proximity to the building would not allow for such an evasive maneuver. The plane impacted the 78th and 79th floors on the towers north end.
The impact of the plane created an 18 x 20 foot hole in the side of the tower. This crash caused extensive damage to the masonry exterior and the interior steel structure of the building. The 102-foot building was rocked by the impact. Many people who were in the street at the time saw flames shooting from the point of impact, which was at the 913-foot level. The impact was heard as far as two miles away. Flames and dense smoke obscured the top of the structure. Later on a wing was found on Madison Avenue, one block away.
empire%201.jpg
Nearby buildings were damaged by fragments of the impact and one of the planes engines was found on the South side of the building in the top of a twelve story building. The engine had flown over thirty-third St. and had crashed through a skylight in a penthouse."

From:

http://www.cosmik.com/aa-april02/dj82.html

"Colonel Smith banked away to the west just in time. How he got around the next few buildings is anybody's guess, but the one thing we do know is that despite his efforts to climb and bank away, he flew his plane, along with his two-man crew, into the north side of the 79th floor of the Empire State Building at 9:49 AM.

Inside the building there was only a small work force that day. On the 79th floor, in the offices of The National Catholic Welfare Service (now known as Catholic Relief Services), faith was put to a severe test as 11 workers were killed, some burned to death at their desks. The impact was thunderous, leading many, both inside and outside the building, to believe that New York City was being bombed. Debris was raining down from over 900 feet in the sky, much of it burning. Naturally, panic ensued.

dj4.jpg
Back on the 79th floor, a fire was burning. The 78th floor was involved, as well, and there were other problems. On impact, the plane's fuel had exploded, sending a fireball down the side of the building and through the inside via hallways and stairwells. The fireball reached all the way to the 75th floor. One of the plane's engines, broken loose from the wreckage, shot through the building, tearing through several walls and finally out a south side window, finally coming to rest on the roof of a 12-story building across 33rd Street. Miraculously, none of the tragedy's victims were killed by the giant engine.

The saga of engine number two is just as dramatic. It, too, broke loose from the plane on impact, but instead of exiting the building it flew directly into an elevator shaft and on top of an elevator car, which began to fall rapidly with two terrified women inside. Even in 1945 elevators were equipped with hydraulic "slowing" devices for emergencies like... well, nobody ever dreamed of emergencies like this one, but for emergencies, nonetheless. When a rescue crew finally reached what was left of the elevator car at the bottom of the shaft, they were amazed to find living, breathing women with one hell of a story to tell their grandchildren.

Back on 79, surviving office workers would have sadder stories to tell their grandchildren. Two of the ladies from the office saw their supervisor, Joe Fountain, standing upright and still in the flames. They called to him and he eventually walked to them, but the damage had been done and he died just a few days later. They'd never shake that vision. Nobody who was near the Empire State Building that morning would ever be able to forget the sight of that burning plane wedged in the side of the building, the black billowing smoke partially obscuring the upper floors from view"


[Ed: yes this was a much smaller, slower propeller-driven aircraft and a "conventional" steel & masonry skyscraper. Let's consider what we do find though.

1. Two OF TWO engines survive and are torn off the aircraft, one penetrating all of the way through the building and flying across the street.
2. A section of wing is torn off and found a block away on Madison Avenue
3. The WTC Towers were an "open" floor plan, increasing the probablity that at least ONE of the two the UA175 WTC2So engines should have penetrated through the Tower, with the starboard engine being very close to the perimeter columns.
4. Not even partial building collapse with 4 floors of aircraft fuel fire.]
 
Late EDIT

dMole said:
[Ed: take the 22/42 fire perimeter, 4/42 WTC1 impact perimeter, and 4/55 fire/impact damaged core percentages above and multiply by 0.005 to get a representative percentage of the fire/impact damaged steel actually recovered from the Towers- it is going to be QUITE small.

Late EDIT: Make that 26/42 fire perimeter, ... above
 
I researched the B-25 a little and some place said the stall speed was 130 mph. I have always heard that story as their being lost in the fog so I figured if the stall speed was 130 they would have been going slower than 200.

psik
 
JOM Authors

Upon closer inspection, 2 of the moderately-informative articles that I posted above were authored by NIST and MIT personnel.

Hmmmmm.....
 
FEA Research Update

Hi Psik,

I've been searching for WTC Finite Element Analysis (FEA) simulation information lately. :dilbert: I'd prefer to not peruse the NIST report again right now, but here's who landed the simulation/consulting NIST contracts:

http://wtc.nist.gov/solicitations/

I found these gems over at MSC.Software, who did the FEMA/ASCE/NSF Finite Element Analysis (FEA) animation/study:

-----BEGIN QUOTED
CREATING THE MODEL
Because of the limited time available to provide an initial
analysis, a search of MSC.Software’s past projects turned up
the public domain geometry of a Boeing 747 with partially
meshed wings and engines. MSC.Patran was used to add the
fuselage and stiffeners, tail section, flooring and other major
components, completing the finite element model of the B747.
Concentrated masses were added in specific locations along
the aircraft to represent the cargo, passenger weight
distribution and fuel. The total weight of the aircraft was
304,000 kg.
A full mockup of the building was unnecessary, because of
time limitations and the actual structural data had not yet been
made available. Therefore, a generic six-story steel structure
was constructed with tubular beams and columns. The gravity
loading was applied to the entire structure and the dead weight
of the building was added through the floorings located on the
top-two and bottom-two floors of the structure. Floors were
not added to the impact area, which facilitated the study of the
failure pattern of both the aircraft and the beam-column
connections. The foundation of the building was rigidly fixed.
Approximately 61,000 elements were used to construct the
entire model of the building and B747.
-----END QUOTED
http://www.mscsoftware.com/support/library/wp/pdf/wtc_collapse.pdf

I'll let you count the problems in the two paragraphs above.

Also, there may be something helpful in these NIST papers from j911s (but I've only read a few of them so far, but I found some information on the NIST simulations):

http://www.journalof911studies.com/volume/200704/SzambotiSustainabilityofControlledDemolitionHypothesisForDestructionofTwinTowers.pdf

http://www.journalof911studies.com/volume/200612/NIST-WTC-Investigation.pdf

http://www.journalof911studies.com/volume/200704/NISTandDrBazant-SimultaneousFailure-WTCCollapseAnalysis2.pdf

http://www.journalof911studies.com/volume/200704/RFCtoNISTbyMcIlvaineDoyleJonesRyanGageSTJ.pdf

http://www.journalof911studies.com/volume/2007/NISTresponseToRequestForCorrectionGourleyEtal2.pdf

[Ed: NIST says "Blame it on Taguchi/Design of Experiments"]
http://www.journalof911studies.com/volume/2007/AppealLetterToNISTGourleyEtAl.pdf

December 2007 papers
http://www.journalof911studies.com/volume/200703/GUrich/MassAndPeWtc.pdf

http://www.journalof911studies.com/volume/200703/Sudden_collapse_initiation_impossible.pdf

I'm not betting that you've heard back from Purdue yet.
 
Floors were not added to the impact area, which facilitated the study of the failure pattern of both the aircraft and the beam-column connections. The foundation of the building was rigidly fixed. Approximately 61,000 elements were used to construct the entire model of the building and B747.
I'll let you count the problems in the two paragraphs above.

ROFLMAO

I'm content to stop at two because they are so BIG.

One relates directly to my model.

Years ago I read someone claiming that the impact energy of the plane was 95% of the maximum wind force the building was designed to handle. But the wind doesn't do localized structural damage to a skyscraper, it causes the whole thing to sway.

But the energy of the plane impact affected the towers in two ways. Localized damage and oscillation of the entire building. I have always wondered how they separated those two, the more of one the less of the other. So if they ran the simulation with those few floors and a rigid foundation they would get a lot more impact damage from the simulation than actually occurred.

Also without floor slabs the perimeter columns would bend more and the fuselage and wings wouldn't get sliced and diced by the concrete and trusses of the floors and probably hit the core harder.

Sounds like a delusional simulation to me.

So it is back to my distribution of mass business. That info plus the amount of movement of the building would be necessary to compute how much kinetic energy just rocked the entire building and how much did damage.

Thanks dMole

psikey

PS - It sure is a pain having to do so much work just to find people are talking BULLSHIT!
 
Psik,

I've had a few more thoughts on this.

1. How do we know that the passenger mass was DIRECTLY coupled to the airplane's momentum? Do we know the seat belts were on and tight? Weren't the pilots and some passengers injured/bleeding/dead in the "back of the plane" according to the "phone calls?" There is also considerable question about gate assignments and the actual passenger count over at Pilotsfortruth.org.

2. I'm pretty certain that the 110-story towers were on seismic mounts (like the skyscrapers in Japan). Seismic (and their smaller cousins, kinematic) mounts ARE NOT stationary. These are loosely related to gyroscopic systems and the "Steadicam" used to dampen movie camera oscillations.

3. A 1000+ foot long intermediately-loaded cantilevered beam (vertical skyscraper) does what exactly when a [impulse] driving force is applied? You've already alluded to this quite well in your physical model, I believe. Yours is the only physical model that I've seen, by the way. It does look like NIST did some questionable, overly-aspirated "fire experiments" from what I read of the papers linked above.

http://www.efunda.com/formulae/solid_mechanics/beams/casestudy_display.cfm?case=cantilever_interload

http://www.efunda.com/formulae/solid_mechanics/beams/casestudy_bc_cantilever.cfm

4. We might be able to glean something from the seismic data- I haven't looked at that for a few years.

d
 
1. How do we know that the passenger mass was DIRECTLY coupled to the airplane's momentum? Do we know the seat belts were on and tight?

I have heard that people can be cut in two by seat belts in automobile accidents. I don't think seat belts would matter when decelerating from 500 mph to ZERO in 200 feet or less.

If the planes were switched wouldn't the flight crews of 175 and 11 have to be in on it?

psik
 
I'm agnostic on Judy Wood (and most other things I don't know firsthand), but I'll try to listen to the MP3s if I get time.

I do know she is rather taboo in most 9/11TM circles however.

d
 
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