Twin Towers Hype
By Michael S.
Shelton
16 October
2006
Updated 6
August 2014
The
Problem
There is an
increasing number of 9/11 skeptics who actually think the collapse of the twin
World Trade Center (WTC) towers was the result of an inside job, with the U.S.
government a popular bogeyman. Dr. Kevin
Barrett of the University of Wisconsin (Madison) has clearly stated that the
WTC towers’ destruction was the result of an inside job and they were brought
down as a controlled demolition. He is
not alone – he parrots many others and many parrot him. Please note that Dr. Barrett is not an
engineer – he is a language major and holds a PhD in Arabic with a focus on
Islamic Studies.
Wild
conspiracy stories and paranoia, unfortunately aided sometimes by well-meaning
but ignorant members of the media, have spread, and some are taking on the skin
of truth merely because they are repeated so often.
Due to
limited scope and time, I will address just one aspect of part of the 9/11
conspiracy hysteria, and that is this:
is the impact of a Boeing jetliner capable of causing sufficient damage
to the WTC towers (one airplane each) to bring about each tower’s
collapse? That is the premise from which
I will work here.
I made some
calculations based on ordinary physics and mathematics equations, obtained from
any good high school or college level textbook.
The reader can search the internet or textbooks for strength of
materials data and information concerning steel, alloys, iron, concrete, and
other such items. The burning properties
of jet fuel and specific heats / combustion theory – all that is easily
researched by anyone who seeks proper discernment of the facts.
The central
thesis here is looking at FACTS. Where I
see FACTS or make ordinary assumptions and calculations, I will make it
clear. Where I can only speculate
because I have either insufficient knowledge or insufficient expertise, I shall
also make that clear.
The
Premise
I’ll restate
my basic premise – “is the impact of a Boeing jetliner capable of causing
sufficient damage to the WTC towers (one airplane each) to bring about each
tower’s collapse?” Actually, it could
have been any large jumbo jet or large jet made by Airbus, Convair, the Brits,
or the Russians. But in the case of the
WTC towers, it was one Boeing 767 widebody jet that each hit the towers. AA Flight 11 was a 767-223ER (Extended Range)
and United Flight 175 was a 767-222. The
estimated gross weight of each aircraft was about 300,000 pounds at
impact. The ER could have been much
heavier, but 300K is good enough for this article. More later.
I have seen
several videos of the 767 impacts, from a variety of views. I have seen essentially the same videos
played again and again, whether they are on FOX News, CNN, ABC, Conservative
web sites, or Liberal / Far Left web sites.
Thus, a FACT: we have documented
video evidence and recorded times that a single B767 hit each tower. From the airline companies’ own data, we know
they were Boeing 767-200 variant aircraft.
Note:
there are a number of web sites and videos, with witness accounts, that state
the aircraft were military, with gray undersides, and were flown by remote
control. Numerous eyewitness accounts
stating that one or both airplanes had “gray undersides” or “gray bellies”
fuels some theories that the aircraft were NOT commercial jetliners, but
instead were military aircraft. The
reader will note that many military transport and tanker aircraft are based on
the same platform as the DC-10, the B707, the B737, the B747, and the B767. The USAF KC-135 and RC-135 use the B707
airframe. But the B707 is no longer in
use by U.S. airlines. The USAF KC-10
tanker uses the McDonnell Douglas (now Boeing) DC-10-30 airframe. The civilian version of the venerable old
workhorse, the C-130 Hercules, is the L-100 in 100-20 and 100-30 variants. Some U.S. airlines have gray paint schemes.
Also
note that eyewitness accounts of people who are not pilots or are not airplane
savvy are notoriously and historically inaccurate. It’s one thing to have eyewitness accounts
from different angles – these different aspects can help piece together the
puzzle of a crash. It’s another to
consider that a non-airplane person can provide accurate details of the paint
scheme and markings of a high-speed aircraft as it goes by before impact. Additionally, all TV news networks – all of
them, quickly gather aviation “experts” following a crash who often provide
conflicting “evidence” and speculative scenarios of what happened. The TV, radio, and print news networks are
notorious in reporting physical and dynamic attributes of plane crashes that
are physically impossible or have no technical merit.
The
Impact’s Effect
I mentioned earlier
that I estimate the gross weight of each of the B767s that hit the towers was 300,000
(referred to as 300K hereafter) pounds at impact. I refer to the Boeing “767 Airplane Characteristics for Airport Planning” (publication
D6-58328 of September 2005). Using the
tables for the –200 and –200ER, and making a best guess for takeoff weights and
fuel on board, I arrived at approximately 300K pounds for each airplane as each
impacted it’s respective north or south tower.
Those weights may be off plus or minus 10,000 pounds or so, but I
consider 300K to be a good ballpark.
For the
planned trip to the west coast, I estimate that each 767 had about
80,000-100,000 pounds of fuel onboard (about 15,000 gallons) at impact. The energy content of Jet A / A1 is approximately
118,000 BTUs per gallon, depending on the blend. For the reader, one can assume that the
average BTUs per pound for jet fuel is about 18,500 BTU/pound, which is typical
for petroleum-based fuels.
Assuming the
aircraft were doing about 400 knots true airspeed (460mph) at impact, and using
the standard Kinetic Energy equation of KE=(1/2)x(M)xv2, I calculate
the KE to be this number:
2,120,380,952
ft-lbsf
where M is
the mass of the airplane and v is the velocity.
That is, over
two BILLION foot pounds force of energy is what each tower was hit with. In scientific notation, that is 2.1204X109. To put this in perspective, the following
three objects are used to show comparable KE numbers:
(1)
A
standard baseball weighs about 5.25 ounces.
It would have to travel at 439,847 mph to have the same energy. At sea level, that’s about Mach 578, where
Mach One is the speed of sound (about 760 mph).
(2)
A
nominal weight for a bowling ball is about 15 pounds. The bowling ball would need to be moving at
65,053 mph, or about Mach 85.
(3)
A
2006 Cadillac STS at about 4233 pounds would need to travel at 3872 mph (Mach
5.1) to have the same energy.
Potential
Energy due to height is conserved if all the Kinetic Energy can be turned into
altitude. The Earth’s gravitational
strength varies inversely with the square of the radius from the center of the
Earth. However, for the moment, let’s
assume the gravitational pull remains constant.
In a perfect vacuum, the B767 would need to be dropped from a height of
1.34 miles (7068 feet) to impact the ground with the same speed and energy.
The Cadillac
STS? From 95 miles. That’s low earth orbit altitude. What about the 15-lb. bowling ball? That would be about 26,874 miles above the
earth’s surface.
The
baseball? Forget it – it’s way out
there. In reality, both the STS and the
bowling ball need considerably higher altitude for the drop because of the
decrease in the gravitational pull with altitude. But to avoid the messy math, I made it more
simple with a constant strength assumption.
The reader may pursue an astrodynamics / orbital mechanics textbook to
perform the calculations.
As further
contrast and perspective, an object must attain at least 25,200 mph to escape
Earth’s gravity. From the vicinity of
Earth’s orbit around the Sun, an object must attain at least 94,533 mph (26.3
miles per second) to escape our solar system and proceed out into interstellar
space. Our hypothetical bowling ball’s
speed is over 2/3 of the way there.
Pause
for Thought
At this
point, I hope the reader can grasp that the energy of each impact was
enormous. As I recall, the WTC towers
were designed for an impact of a Boeing 707 airliner WHILE IN THE LANDING /
TAKEOFF CONFIGURATION. This means slow
speeds, well below 250 knots. The 707 is
a considerably smaller and lighter jet.
About 170,000 pounds at say 190 knots produces far less KE than our
fast-moving and heavier 767. My point is
that the “smack” into each tower was very considerable in energy. Each tower’s ability to absorb the initial
impact is a testament to their design and engineering. One must understand what the definition of
“impact” means. Does this mean that the
above B707 in a slow-speed landing configuration would not knock the building
over? At what floor level? It would not cause internal structural damage
to precipitate a collapse? Exactly what
does “impact” mean?
So
What?
I don’t know
what the specific layout and configuration was of each tower at the impact
points. I do not have access to the WTC
tower floor plans, blueprints, structural design, and material specifications.
(By now, these are surely available to
anyone) Thus, I will make some
assumptions. The reader is free to
discern whether my assumptions, and conclusions thereof, are reasonable and
valid. From the few sketchy drawings and
videos that I have seen, it appears that each tower had major vertical support
beams in the center, and the steel outer shell structure that contained the
windows also contributed to the vertical, bending, and twisting loads
support. The main load-bearing design is
in compression. Someone with the proper
expertise can do a proper loads analysis.
That is beyond the scope and my expertise here.
However, I
can safely conclude that a B767, with a wingspan that was almost as wide as
each tower’s face, converted significant Kinetic Energy (KE) upon impact into
structural damage, heat, and debris. Any
residual jet fuel not burned would now contribute almost 118,000 BTUs per
gallon of energy if the fuel could be ignited further. In the few tenths of a second of the total
penetration into the face of the tower, encompassing several floors, the
airplane’s structure would disintegrate, with the fuselage hydraulicing and
exploding outward due to the rapid air pressure rise from ram effect as the
fuselage crushed nose to tail. I will
speculate that the B767s very robust and heavy major components, such as the
two engines, landing gear, and major wing box castings / forgings, may have quite
easily sliced through major building support structures. There would be localized intense temperature
areas as very rapidly-decelerating components hit other hard components, such
as steel beams.
In the form
of atomized fuel and destruction debris, there was considerable ejecta out the
other side of each tower. The ejecta
could have been considerably reduced if each jet had impacted in a steep dive,
which would have torn through more floors and imparted more destructive energy
to the tower. These ejecta represent some energy transfer and jet fuel thermal
loss that was not completely imparted to the building. Perhaps an assumption of about 20% loss could
be a good guess. That means that about
1.7 billion foot-pounds force of KE was still absorbed into the building. Within milliseconds. For the reader, that’s still a significant
impact.
Jet
Fuel Burning
I will
address this subject just briefly.
Extensive pontificated elaboration has been made concerning the fact
that free-burning jet fuel in the open atmosphere cannot melt steel. I’m not an expert in that particular area,
but I’ve read quite a few references and I will defer to the experts that this
is true. I found this simple fact on a
web site:
·
1535ºC (2795ºF) - melting point of iron
·
~1510ºC (2750ºF) - melting point of typical
structural steel
·
~825ºC (1517ºF) - maximum temperature of
hydrocarbon fires burning in the atmosphere without pressurization or
pre-heating (premixed fuel and air - blue flame)
The site goes on to
state:
·
Diffuse flames burn far cooler.
·
Oxygen-starved diffuse flames are
cooler yet.
·
The fires in the towers were diffuse
-- well below 800ºC.
·
Their dark smoke showed they were
oxygen-starved -- particularly in the South Tower.
I was
required to have firefighting training in the Navy on several occasions. The fact that most of the test sites and
“burning building” simulations are made of steel / concrete attests to the
notion that free-burning jet fuel in the atmosphere likely won’t melt
steel. However, the above last four
bullets are themselves stated from assumptions that may or may not be
valid. To my knowledge, we have ZERO
survivors who were witnesses in the vicinity of the actual impact and
blow-through of each B767. We have ZERO
witnesses to provide credible, professional engineering testimony to the ACTUAL
state of each tower’s structural damage and the character of the flames
inside. How does anyone know that EVERY
flame front / flame jet inside the area of impact was well below
800ºC? And the presence of dense smoke
DOES NOT automatically eliminate the possibility of localized intense-heat /
very high temperature flames.
I
invite the reader to view the following video produced by the Energetic Materials Research and
Testing Center (EMRTC) in New Mexico:
The
steel doesn’t melt. It merely is raised
to a temperature where the structural integrity is lost and the steel beam
bends. Is this what happened inside the
WTC towers? The answer is – nobody
knows. Only educated conjecture by the
real experts and uneducated wild imagination by the ignorant non-experts can be
given.
Structural Mayhem
I believe the key to the towers’ collapse is the
structural damage inside the building. I
don’t know what type(s) of steel were used for the main structure, but perhaps
a mixture of stainless and non-stainless steels. Perhaps high strength-low alloy (HSLA) steels
were used. Or dual-phase or maraging
steel. Were there large amounts of
martensite or austenite steels? These
specifications I am not privy to.
Were the steels properly quenched and hardened? Were the right amounts of carbon and cobalt
in the steel(s)? I don’t know. At the least, a solid, credible engineering
investigation should answer these questions.
Given the very high KE of the impact, and considering
that only 80% was perhaps imparted to the structure, and recognizing that the
second B767 impact was not as square a direct blow as the first B767 impact,
can one reasonably assume that extreme structural damage led to the eventual
collapse? I am convinced it did, based
on the limited data, information, and calculations I have. Yes, it is doubtful that the remaining
spilled jet fuel melted any steel, but the ensuing fire and cumulative heat
damage could only be adverse in the aftermath of the impacts. And no one knows if there were localized hot
jets of flame that were created from tunneling / narrowing of small channels,
and fed by forced air from unknown sources.
After all, the towers were well-ventilated after impact, and there was
wind. But we don’t know the internals
for sure.
We know that
the towers suffered significant compromise of the outer steel shell on at least
two faces of each tower. My limited
information shows that the outer structure was part of the vertical
load-bearing support for the towers.
Because the second B767 impacted lower, yet that tower collapsed first,
it logically follows that the additional mass above the damage would contribute
to a significantly-weakened load-bearing support structure. Very likely, the hot fires inside the
building, with the water sprinkler systems compromised or inactive, contributed
to the problem. All one has to do is
look at charts of Yield Strength vs. Temperature and Elastic Modulus vs.
Temperature for the alloy in question. Then
you will know exactly how much the strength and stiffness of the steel degrades
at any temperature. However, it is
acknowledged that there was no instrumentation; there were no thermocouples
inside the damaged areas, which provided real-time, accurate data.
If each tower had increasing “sag” or “buckling” at the
impact levels due to compression, then this means that the plastic yielding of
the steel eventually gave way to structural failure. The mostly vertical collapse and pancaking
downward of each tower fits this profile.
Controlled Demolition
This is one of the largest brazen theories stated by the
“Inside Job” believers. I saw and heard
with my own ears Dr. Kevin Barrett state this theory on TV. But this theory has not had any real facts
presented in a credible engineering investigation forum, and it would
presuppose at least the following:
·
Someone
or a team of people installed explosives, the timers, the detonators, and
sequencers in each tower, without the knowledge of the various oversight
agencies that monitor configuration management of the many engineering and
technical aspects of each tower (heating / AC / ventilation, electrical,
plumbing, emergency systems, conduits, computers, etc.). I find this very difficult to have been done
covertly
·
If
not covertly, then one or more people in the above oversight agencies knew and
were part of the sinister plot
·
The
suicide pilots of each B767 had to precisely hit their respective tower at the
right level. They had not practiced this
run in real life, only on paper and in armchair rehearsals. True, they may have had a proper sense of
direction, bearing line, and altitude.
But to hit a spot at say the 83rd or the 57th
floor in a heavy, fast-moving, slow-response jumbo jet is not believable. Were there outside, visible markers that
noted the floor levels of the towers? Or
a laser beam marking the spot? I doubt
it, but if someone has actual factual data, let’s see it. For any pilots who have been required to
accurately assess with high precision a target while moving at 400+ knots and
make last-minute corrections to flight path, you know the problem
·
We
know that each tower’s collapse commenced at the level where airplane impact
had occurred. Pre-positioned explosives
at those levels would have either been destroyed and / or already detonated. I have seen tower collapse videos many times
from different angles. I have not seen
any evidence of lower-level detonation.
One particular collapse view (I don’t recall which tower) showed a
significant outward puff / plume of dust / debris several floors down AFTER the
collapse commenced. This would be a very
logical “witness” event (or mark) as a result of the air pressure in the tower
below the collapse inauguration rapidly increasing and blowing out a window, or
air exiting suddenly from an already existing break. This same phenomenon can be seen as ships
sink, with many cases of air and spray bursting through vents and hull breaks
as the water forces the air out of the sinking vessel
·
Furthermore,
each collapse, as it moves downward, shows a strong upward and outward arcing
of dust and debris in all directions from the tower. Again, this is a logical consequence of “the
stuff has to go somewhere and it won’t be inward” air pressure rise at the
interface of the still-intact upper structure and the disintegrating lower
structure. In each case, at some point
in the collapse near the bottom, the upper structure had essentially fully
destroyed itself and the final few seconds of collapse would be characterized
by a mound of disintegrated rubble hitting bottom and then spilling out from
the mound of ground-level debris.
I would ask the following questions?
·
If
there were controlled explosives, why did the person holding the button delay
so long to initiate the explosives and thus the final collapse? Far more people would have died if the towers
had collapsed within seconds / minutes of the impacts.
·
Where
is the actual, factual forensic evidence of a controlled demolition
theory? This is similar to the bald
assertions by Lou Farrakhan of the Nation of Islam that the Government had
detonated explosives at the base of the New Orleans levees, causing the New
Orleans flooding following hurricane Katrina.
These allegations were made publicly several times, but the Nation of
Islam has never produced legal, forensic evidence. I ask for the same in the case of the WTC
towers’ collapse – where’s the evidence?
·
Who
is / are the person(s) in the Federal Government who would plan, engineer, and
orchestrate such a dastardly act, and for what purpose(s)?
Summary
I believe the towers collapsed following severe
structural damage from the impacts of each B767. Furthermore, the resultant fire, fed by
unknown amounts of jet fuel, surely did not help and likely contributed to
further weakening of the structure. I’m
convinced, unless there were unknown and untestable / non-verifiable hot flame
jets directly impinging on a steel beam, that the fires in each tower DID NOT
melt steel. Aluminum or lead, perhaps? Maybe.
But were there any structural contributions from lead or aluminum? Likely not.
I find it implausible that an “inside job” by agents of
the federal Government, or anyone else, could have installed and orchestrated a
controlled demolition of the towers. It
smacks of illogical idiocy to think so, and no one has produced investigative
forensic evidence of such a plot.
Please, for the Truthers skeptics, someone prove me wrong.
The B767-200 variants have about 10 specific engine
models from three manufacturers. A
thorough investigative engineering analysis would need proper simulation and
modeling of the deceleration characteristics as the large components of
engines, wing box, and landing gear ripped through the towers. If the Inside Job Conspiracy proponents
really want to come to reasoned, engineering conclusions, then a committee
composed of the proper team of professionals needs to do a complete impact
analysis that replicates the events of 9/11.
I believe I have presented a proper case that the mere impact of heavy jumbo-jet
wide body aircraft into a design such as the WTC towers is sufficient to bring
the building down just from the internal structural damage.
However, as an engineer, I too would like to see a
thorough and rigorous engineering analysis.
Perhaps, if the conclusions were as I think they would be, most (not
all, of course) of the 9/11 skeptics would finally blame Muslim radicals for
the destruction of the WTC towers, not Bush or Boeing or some other sinister
plot.
But who’s gonna fund this? It would be a very expensive
investigation. Perhaps Soros would put
his money where the leftist mouths are.
-------------------------------------------------------------------------------------------------------------------------------------
Michael
Shelton is a former Naval Aviator and fighter pilot. He has a BS and MS in Aerospace
Engineering. Although not a civil
engineer, nor an architect, nor does he claim high expertise in structures and
strength of materials, he nevertheless was required to take core courses in
structures and strength of materials that dealt with various metal alloys and
structure design. After all, good
airplane design requires good structural design and all U.S. transport aircraft
are built and tested to FARS 14 CFR Part 25 “Airworthiness Standards: Type Certificates for Transport Category
Airplanes.”
Michael is a
pilot with civilian and military flight time, with over 3500 flight hours, over
3100 of that in jets. He holds FAA
Airplane Single-Engine Land Commercial and Instrument Ratings, and Multi-Engine
Land Airline Transport Pilot (ATP) ratings.
