Was WTC Brought Down By The Controlled Demolition?, 9 minutes video, which shows a lot Options

[SPreston]

So I'm appologizing to all who losed their time with this bogus story.

Nobody lost any time. We just corrected an error and got that much closer to the the truth with your help, and it was a very interesting dialogue. It is valuable information when it appears someone is creating red herrings. We have to be cautious, even when we are taking several weeks to work it out. Thank you.

[dMz]

[I posted this at another board after a post about aircraft aluminum and heat claimed by NIST, but some here might want to see my conclusions. My thanks to the other poster for originating this line of questioning.]
-----------BEGIN QUOTED
That's a very good point. "Thermal mass" is a concept understood by few, and a Boeing transport airliner will bring a LOT of it to the party. Have you ever sat on aluminum football stadium bleachers in early winter? For simplicity's sake let's just call it aluminum mass * the specific heat of aluminum (in applicable units). Let's subtract out the engine masses, since they have very little aluminum and are quite hot already.

From my records, AA11 was reported to be:
B767-223ER #N334AA Boeing# 22332, GE CF6-80A2, Mode 3A 1443 off 08:20:38 EDT

From GE:
http://www.geae.com/engines/commercial/cf6/cf6-80c2.html

Fan/Compressor Stages: 1F/3LPC/14HPC
Low-Pressure Turbine/High-Pressure Turbine Stages: 5/2
Max Diameter (Inches): 106
Length (Inches): 168

Dry Weight (Lb.): 9,480 - 9,860

Okay, let's average the engine at 9670 lbs. 2 of these are 19,340 lbs. Let's not be morbid and consider the passenger specifics, but the Jet A thermal mass also should be considered in a better estimate.

From:
http://www.airliners.net/info/stats.main?id=103

767-200ER - Empty with PW4056s 76,566kg (168,800lb), with CF680C2B4s 76,476kg (168,600lb), operating empty with PW4056s 84,415kg (186,100lb), with CF680C2B4Fs 84,370kg (186,000lb). Max takeoff with PW4056s or CF680C2B4Fs 175,540kg (387,000lb).

From:
http://www.janes.com/aerospace/civil/news/...oeing_767.shtml

"Structure
Fail-safe structure. Conventional aluminium structure augmented by graphite ailerons, spoilers, elevators, rudder and floor panels; advanced aluminium alloy keel beam chords and wing skins; composites engine cowlings, wing/fuselage fairing and rear wing panels; CFRP landing gear doors; and aramid flaps and engine pylon fairings.
Subcontractors include Boeing Military Aircraft (wing fixed leading-edges); Northrop Grumman (wing centre-section and adjacent lower fuselage section; fuselage bulkheads); Vought Aircraft (horizontal tail); Canadair (rear fuselage); Alenia (wing control surfaces, flaps and leading-edge slats, wingtips, elevators, fin and rudder, nose radome); Fuji (wing/body fairings and main landing gear doors); Kawasaki (forward and centre fuselage; exit hatches; wing in-spar ribs); Mitsubishi (rear fuselage body panels and rear fuselage doors). "

All right, fuel will come out of the maximum takeoff weight- let's ignore it though. If we take off 2 engines 186,000 - 19,340 = 166,660 lbs. Let's assume 80% of this figure is aluminum, since most of those other aerospace materials are quite light and most of the structure is aluminum. This gives 133, 328 lbs of aluminum for AA11/North Tower WTC1.

From
http://hyperphysics.phy-astr.gsu.edu/Hbase/tables/sphtt.html

Specific heat of aluminum (c_Al) = 0.215 BTU/lb * deg_F = 0.900 J/g*K = 24.3 J/mol*K

So, the thermal mass would be 133,328 lb * 0.215 BTU/lb * deg_F = 28665.52 BTU/deg_F. Now thermal coupling is fairly tricky business, but as you pointed out, aluminum is used extensively for its "heat sink" properties. The NIST FAQ #7 claims a maximum air temp of 1800 F, but let's use the melting point of aluminum instead here.

http://www.chemicalelements.com/elements/al.html
Melting Point: 660.37 °C (933.52 K, 1220.666 °F)

Okay, let's assume we heat the thermal mass above from 70F to 1221 F, or +1151 deg_F. 28665.52 BTU/deg_F * 1151 deg_F = 32994013.52 BTU = 3.30E7 BTU to [nearly] melt AA11. That's 33 million BTU's of heat for just AA11.

EDIT: The above was not finished. To MELT the aluminum, we would need the heat of fusion of aluminum added in.

http://www.engineeringtoolbox.com/fusion-h...als-d_1266.html

For aluminum, the above gives 398 kJ/kg ~= 171.11 BTU/lb. 133,328 lb aluminum * 171.11 BTU/lb = 22813754.08 = 2.28E07 additional BTU needed to change the +1221 deg_F aluminum into the liquid phase, or 55.8 million BTU's needed altogether to melt AA11 (from +70F- but the planes were likely much colder from high altitude flight).
------
My records for UA175 show:
B767-222 #N612UA Boeing # 21873, PW JT9D-7R4D, Mode 3A 1470 > 3020 > 3321

I don't really like Wikipedia, but they came up first for the JT9's:
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT9D

JT9D-7R4D/D1
8905 lb, 132.7 in long, 93.4 in diameter fan, 48 000 lbf Static Thrust

From the page above:
http://www.airliners.net/info/stats.main?id=103

" 767-200 - Empty with JT9Ds 74,752kg (164,800lb), with CF6s 74,344kg (163,900lb). Operating empty with JT9Ds 80,920kg (178,400lb), with CF6s 80,510kg (177,500lb). Max takeoff 136,078kg (300,000lb), medium range max takeoff 142,881kg (315,000lb)."

178,400 - (2 * 8905) = 160,590 lb. Again assuming 80% Al, this gives 128,472 lbs of aluminum.

128,472 lb * 0.215 BTU/lb * deg_F = 27621.48 BTU/deg_F for UA175/WTC2 South.

27621.48 BTU/deg_F * +1151 deg_F = 31792323.48 BTU = 3.20E7 BTU to [nearly] melt UA175. That's 32 million BTU's. I think [other poster] and now I are the first to even look at these considerable heat sinks that I'm aware of.

EDIT2: adding the heat of fusion of aluminum, 128,472 lbs * 171.11 BTU/lb = 21982843.92 BTU = additional 2.20E07 BTU. The total would actually be 54 million BTU's to melt UA175 (from +70F or about +23C). Now a BTU is the amount of latent heat needed to raise 1 lb of water 1 deg_F in temperature. 54 million BTU's would heat 1,080,000 lbs (or approx. 135,000 gallons) of water +50 deg_F.

According to:
http://www.onlineconversion.com/energy.htm

54 000 000 Btu = 56.973 024 gigajoule (GJ)
-------------------------------------
But wait, there was WATER in those buildings for sprinklers and restrooms, etc. I even recall hearing of water tanks to maintain pressure. Now I think nearly everyone knows that automobile engines usually use water for cooling, although they may not be aware of its extremely high specific heat capacity.

From:
http://www.sciencebyjones.com/specific_heat1.htm

Relative to aluminum, water has a specific heat capacity of 1.00/0.217 = 4.6082949309 times.

Relative to steel:
http://www.ac.wwu.edu/~vawter/PhysicsNet/T...atCapTable.html

1.00/0.108 = 9.2592592593 times higher for water than steel.

Looking at aluminum's thermal conductivity,
http://hyperphysics.phy-astr.gsu.edu/hbase/tables/thrcn.html

it is 205.0/50.2 or 4.0836653386 times that of steel. Relative to concrete, 205.0/0.8 =256.25 times. It is 205.0/0.6 or 341.6666666667 times that of water at 20 deg_C.

Okay, for the laymen out there, this says the majority of the heat will likely flow to aluminum first (and melt it if hot enough), then steel, then concrete, then water.

Even the NIST FAQ says:
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm
"8. We know that the sprinkler systems were activated because survivors reported water in the stairwells. If the sprinklers were working, how could there be a 'raging inferno' in the WTC towers?

Both the NIST calculations and interviews with survivors and firefighters indicated that the aircraft impacts severed the water pipes that carried the water to the sprinkler systems. The sprinklers were not operating on the principal fire floors.

However, there were ample sources of the water in the stairwells. The water pipes ran vertically within the stairwells. Moreover, there would have been copious water from the broken restroom supply lines and from the water tanks that supplied the initial water for the sprinklers. Thus, it is not surprising that evacuating occupants encountered a lot of water.

..."

Now while the water is much less thermally conductive, I don't think that the incredible thermal mass of an unknown "bath" of water can be ignored in a proper accounting of WTC heat sinks. I haven't even mentioned the high heat of vaporization of water, but I think anyone who has boiled a pan of water knows what I'm getting at here.

There is also some interesting info about water and fuel tanks over at:
http://www.whatreallyhappened.com/fema_report.html

d

This post has been edited by dMole: Feb 17 2008, 12:58 AM