structural engineer leslie robertson interview

Originally posted by Pilgrum
The hardness of a material is associated with molecular bonding and crystalline structures within the material and is fairly independant of actual mass.

But that is part of what constitutes its mass, how the atoms bound together, the molecular bonding, so how is it independent of it?

...The mass of an amount of matter in a chemical substance is determined in part by the number and type of atoms or molecules it contains, and in part by the energy involved in binding it together...

Yes I am trying to make it very simple, it's too much to explain in detail.
According to Newtons laws when objects collide the force on each object is equal, what is not equal is the amount of deceleration each object receives.
The object with more mass will decelerate more than the other, this is where the damage happens, the more deceleration the less damage. The object with the lesser mass will decelerate less and thus receive more damage.

There are a lot of variables as you say, but the main point I'm trying to make with this is two colliding objects cannot destroy each other. As in the F-4 and the concrete, different mass, one object was destroyed. They can damage each other, but in the case of the WTC towers and the pentagoon both objects are completely destroyed. In fact we are expected to believe not only did the planes go though one steel wall, but then still had enough energy to sever through the massive core columns. You don't need any variables on simple physics to see this is not a very probable outcome. Especially in WTC2 where the plane didn't even hit the central core.

Originally posted by ANOK

Originally posted by Pilgrum
The hardness of a material is associated with molecular bonding and crystalline structures within the material and is fairly independant of actual mass.

But that is part of what constitutes its mass, how the atoms bound together, the molecular bonding, so how is it independent of it?

The best examples I can think of off-hand would be diamond at 3.5g/cc and lead at 11.3g/cc. The diamond is far harder than lead but has less atomic particles per unit volume and the hardness is more a function of internal structure than pure mass. The same is true of alloys which are specialised to have maximum hardness/strength for minimum actual mass.

Hardness is a factor in collisons because it determines the degree of deformation which affects the surface area of contact that produces the peak pressure of the impact making a harder projectile more likely to penetrate. A softer projectile can compensate by going a little faster.

Originally posted by ANOK

Originally posted by thedman

 

The fuel which penetrated the elevator shafts dispersed as an aerosol as
it fell down the shaft - the fuel aerosol mixed with air and formed an
explosive mix. Same principal as automobile engine - mix of fuel vapors
and air when ignited explodes

You keep saying this as if it's fact.

How did the fuel disperse as an aerosol?

No it's not the same as a car engine. It would have to be a diesel engine (jet fuel is diesel), so as well as atomising, through special jets, the fuel also has to be compressed, thus jet engines have compressor sections to compress the air before the fuel is added, car engines a piston.

How did the fuel get atomized in open air?. And even if the fuel did ignite it would not explode unless under pressure (compressed), how did the oxygen and fuel get compressed? This is a silly and impossible hypothesis.

I challenge you the dman, to go get some diesel fuel, or even jet fuel if you can, and see if you can get it to ignite and explode in open air.
To be a theory it has to be testable and that test repeatable. Until you can do that I'd drop this silly argument.

[edit on 3/21/2009 by ANOK]

YOU DONT REPEAT DONT have to compress diesel to get it to light I have seen a video of a fire test in a tunnel a steel bath filled with a mixture of water and DIESEL FUEL was mixed to simulate spillage after a mutiple vehicle crash it was set alight with a FLAMING TORCH NO COMPRESSION!!!!!!!!!!!!!!!!!!!!
This experiment was to test fireproofing in a road tunnel!

reply to post by ANOK


How did fuel get dispersed ?- when the fuel tanks ruptured at 500 mph the liquid fuel was broken into droplets by air resistence and by contact with solid materials. Ever spray water from hose ? Notice how the liquid
is broken up into droplets and then to mists. The fuel from American 11
fell down the elevator shafts from the 93-96 floors, a thousand foot drop
The resulting mist cloud when ignited creates a violent explosion

Notice the fireball from the aircraft impact ? This is the violent burning
of the aerosol cloud of jet fuel

Checking my copy of the NFPA handbook states that a fuel mist-air mixture when ignited has an overpressure of 8 x initial (20 x fuel/oxygen)

Under normal conditions jet fuel is not explosive, is even difficult to
ignite, Yet when dispersed into fine droplets/mist becomes explosive

ANY COMBUSTIBLE substance, even solids, if finely divided and suspended in air becomes explosive when ignited. This accounts for
grain elevator/coal mine explosions when flour dust or coal powder
explodes. Has sufficent force to level a grain silo and hurl chunks of
concrete for hundreds of yards. Often are multiple explosions as first
explosions dislodges and disperses more dust which explodes.

A grain dust explosion caused extensive damage to a half-mile-long grain elevator facility. It also resulted in the deaths of seven employees. Ten employees were injured, and three employees are still in critical condition.

Urban Search and Rescue Team (USAR) personnel, many of whom had also worked on the scene of the Oklahoma City federal courthouse bombing, were faced with the daunting task of locating survivors and recovering bodies in an unstable structure filled with more than six million bushels of grain, the dust from which could explode again at any time.

For a dust explosion to occur, several factors must come together, according to Dust Explosions in Process Industries by Rolf K. Eckhoff. First, there must be fuel, or grain dust. The critical parameter for grain particle size is 0.1 mm or smaller. As the size of the particle decreases, the risk of a deflagration or explosion increases.

The dust concentration contributes to the dust’s flammability. In order for a dust explosion to take place, the concentration must be between 40 grams per cubic meter and 4000 grams per cubic meter. The actual limits may vary based upon particle size and composition.

Jet fuel aerosol explosions

Aerosols hazards are primary related to the widespread use of combustible fluids (i.e jet and diesel fuels) but also of heat transfer fluids (i.e. hydraulic fluid, lube oil) in process and manufacturing industries. Such fluids, that are normally thought safe since theirhigh boiling point, usually operate at elevated temperatures and pressures thatdramatically increase their risk of being aerosolized and becoming flammable. A great number of study has been focused on the fundamental ignition and combustion characteristics of aerosolized fuel with the aim of designing efficient combustion systems. On the other hand the flammability properties of these liquids in the form of aerosols is only addressed to a limited extent with respect to a safety point of view. The flammability of hydrocarbon liquids in aerosols form is very different from that inthe form of a liquid pool which is dictated by the flash point or vapor pressure (Willauer et al. 2007), since, aerosols can explode at temperatures well below their flash points

My copy of the EMERGENCY RESPONDER GUIDE states jet fuels and related materials are explosion hazards indoors/outdoors and in sewers

Jet Fuel is not Diesel

JA1 (called JP5 in the millitary)

Diesel

Diesel was used in older porp driven planes for, jet they use a heavily kerosene based fuel

Originally posted by ANOK
Regardless aluminium has less mass than steel. Aircraft aluminium included. If they were to make it stronger than steel it would be too heavy for aircraft use. If they could use steel they would but it's too heavy.

Sorry ANOK, I usually agree with you but:

www.wicksaircraft.com...=8082/index.html

One of the highest strength alloys available 7075 is ideally suited for high stress parts and is commonly used in aircraft structures. Arc or gas welding is not recommended. It is available in "Alclad" which improves corrosion resistance with only a minor reduction in strength. Use where highest strength is needed such as bearing housing and retention plates in rotor hubs. The accompanying charts indicate the characteristics of aluminum alloy plate and sheet that are suitable for aircraft construction. The most commonly used grades for structural components are 2024T3, 6061T6, and 7075T6. Tensile strength is listed in thousands of pounds per square inch (PSI) Bend radius is expressed in thicknesses of sheet and plate material. As an example 2t-4t denotes the minimum radius of a 1/4 inch plates should be 1/2 to 1 inch.

7075-T6

7075 tech sheet T6 temper 7075 has an ultimate tensile strength of 74,000 - 78,000 psi (510 - 538 MPa) and yield strength of at least 63,000 - 69,000 psi (434-476 MPa). It has elongation of 5-8%.

[edit] 7075-T651

T651 temper 7075 has an ultimate tensile strength of at least 67,000 - 78,000 psi (462 - 538 MPa) and yield strength of 54,000 - 67,000 psi (372-462 MPa). It has elongation of 3-9%.

7075 is widely used for construction of aircraft structures, such as wings and fuselages.

en.wikipedia.org...

Just as a comparison, A-36 steel has an ultimate tensile strength somewhere around 54,000 psi and a yield strength of 36,000 psi.

Far below the strengths listed for these aircraft aluminum alloys.

Can we put this argument to rest now?

Originally posted by CameronFox

* There are no reports of anyone being killed by the blast. The principal danger was fire.

What happened to the reports posted by you Cameron of the guy with his clothes burnt off with his toungue on the floor or the woman who was still at her desk with her clothes burnt off as if she were still typing away?

I would consider those people "being killed by the blast", so therefore I can only conclude that Mr. Mackey is full of it.

reply to post by thedman


You need to go look up what the definition of "aerosol" is. Fuel in a gas tank is not aerosol, nor will it turn into an aerosol if the fuel tank is busted open in the air. You need a fine, pressurized mist to have an aerosol and busting open a fuel tank will not pressurize fuel and turn it into a fine mist. Large droplets, but not aerosol.

Further, as soon as the plane's fuel tanks were busted open inside the tower, the fuel became instantly ignited, hence the large fireball. There wouldn't have been a single drop of jet fuel that could've travelled a quarter mile away from impact and escape ignition.

Since the jet fuel was instantly ignited upon impact, do you realize how fast the fuel would have to travel away from the fireball to keep from being ignited? Your logic is so ridiculous it's not even worth wasting any more time on.

Giving you the benefit of the doubt for just one second, even if the fuel somehow magically compressed itself into an aerosol form and travelled a quarter mile down the tower at such a speed to escape the fireball, it:

1.) wouldn't have been enough to cause damage on as many lower floors as it did

2.) although explosive, the power of the explosion wouldn't even come close to causing the heavy devastation in the parking garage and the other basement levels as in the pictures I posted

But as we all know, that's impossible because even the links you posted said jet fuel is difficult to ignite, yet aerosoled jet fuel ignites much quicker than it's flash point, therefore there would be no possible way an aerosol could've escaped the fireball.

Pooring liquid fuel down an elevator shaft will not pressurize or compress it and turn it into an aerosol.


[edit on 22-3-2009 by _BoneZ_]

Originally posted by Griff


What happened to the reports posted by you Cameron of the guy with his clothes burnt off with his toungue on the floor or the woman who was still at her desk with her clothes burnt off as if she were still typing away?

I would consider those people "being killed by the blast", so therefore I can only conclude that Mr. Mackey is full of it.

While I can not speak for him, the injuries that I have posted are consistent with burns from a fire ball. Not an explosive. As I have stated in the past, if you are close enough to a detonated bomb to get burned, you will have more than burns as your injuries.

Originally posted by _BoneZ_



1.) wouldn't have been enough to cause damage on as many lower floors as it did

2.) although explosive, the power of the explosion wouldn't even come close to causing the heavy devastation in the parking garage and the other basement levels as in the pictures I posted

Bonez... please go back one page to this post:

www.abovetopsecret.com...

thank you

reply to post by CameronFox


Ohh, you must've missed this:

www.journalof911studies.com...

Definition of aerosol

2

3

Note that one definition is a small partilce of liquid in a gas

Fuel droplets in air fit that definition.

Originally posted by CameronFox
While I can not speak for him, the injuries that I have posted are consistent with burns from a fire ball. Not an explosive. As I have stated in the past, if you are close enough to a detonated bomb to get burned, you will have more than burns as your injuries.

How did the man lose his tongue? Fire would not do that IMO.

Originally posted by Achorwrath
Fuel droplets in air fit that definition.

Actually it does not fit. You took it out of context. It explicitly says FINE solid particles or FINE liquid droplets as from something pressurized or compressed.

Originally posted by _BoneZ_

Originally posted by Achorwrath
Fuel droplets in air fit that definition.

Actually it does not fit. You took it out of context. It explicitly says FINE solid particles or FINE liquid droplets as from something pressurized or compressed.

Link 3

A small particle or a liquid suspended in air

Fourth one down

reply to post by Achorwrath


Exactly, small as in fine partical or liquid in air. You won't get that with breaking open a fuel tank. Instead of making post after post after post, why don't you take a glass of water and throw it in the air and watch it come down. You will never get aerosoled anything without compression or pressure.

And it won't matter how many times you throw the water in the air, it will never become aerosolized unless you add some kind of pressure or compression to it.

What it all boils down to is whatever YOU have to make up to help YOURSELF sleep at night and not have to believe the real facts and evidence.

Bonez,
that example is not fuel taks rupturing at 400+ MPH
what would happen then?

A better example would be pour water out of the glass then smack the falling water with your hand.

Instead of making post after post with comparisons that do not fit the event try looking at it with all the data to hand.

Plane hits bulding, breaks outer columns, fuel tanks rupture but of course due to Newton's First law the liquid wants to keep going, it will imapct other objects that will break up its form ... including the initial explosion.

That is the point I am making with my posts,

You post true information, but that information is not accurate or true at the time of event.

If you have ever seen a water barrel hit the water inside is sprayed in fine droplets and large ones too.

Actually my example above is not accurate either, take the same glass of water and throw it at a wall or tree.

does it maintain the shape? no it spatters

[edit on 22-3-2009 by Achorwrath]

[edit on 22-3-2009 by Achorwrath]

Originally posted by Achorwrath
Actually my example above is not accurate either, take the same glass of water and throw it at a wall or tree. does it maintain the shape? no it spatters

You're still not understanding aerosolized liquids. The only example I can give you is in an aerosol can. When the can is sprayed, the liquid is turned into very FINE droplets. As one of the definition sources you posted "sub-microscopic droplets".

Any type of fine powder or fine mist of fuel will be explosive. But without compression or being pressurized, there will be no aerosol.

Further, if the fuel were to magically aerosolize and somehow magically escape being ignited (even though it has a much lower flashpoint than it's liquid form) and it somehow was able to make it into one or both of the only 2 elevator shafts that ran to the basement, the aerosolized fuel would have evaporated in the air or stuck to the sides of the elevator shafts on it's quarter-mile journey to the bottom.

No matter how you dice it, all of your hypotheses come up short.

I don't understand why it's so hard to believe what the facts tell you. That massive explosions took place in the lower levels completely obliterating the parking garage and severely damaging the other sub levels including the lobby, explosive detonations seen going off down the sides of both towers as they were falling, and the buildings falling at near free-fall speed into the MOST resistance (against the laws of physics unless demolition was involved). Every single piece of evidence points to demolition and you are reaching as far as you possibly can to explain away things that have an easier and more likey explanation.

[edit on 22-3-2009 by _BoneZ_]

I am not sure how you cannot grasp that the fuel would be boken up on impact.

Like I said throw a bucket or glass of water against a wall and see how much of it becomes fine mist.

Look at highspeed impacts of water tanks or the saftey barrels on the roads.

when they are impacted the water's sruface tension breaks up and it becomes a fine mist.

You example has nothing to do with the event.

An aerisol can is also presurised and the nosel is designed to break up the stream.

But you can acheive the same effect with colision into a solid object.

take a look at these,
The quality is terrible and the Fire Cracker is not the same force as the impact but look what happens to the water in the bottles.
at first it breaks up.

source

it is not a solid mass like you are saying it would be. you do not need a mist you just need smaller droplets to ignite.

But no matter it would still be broken into small droplest combined with mist.


Here is highspeed photo of a water ballon Link notice the mist on the edges?
The fine droplets?


[edit on 22-3-2009 by Achorwrath]

I do not believe I ever said it went to the lobby

I did say that fires broke out on lower floors (I think 55th and 24th)

But I never said Lobby

But as we know the flames from the initial impact expanded out on almost all sides how is is beyond belief that it did not also travel down the shafts?