I was wondering if someone could point me to an article that discusses the BTU and horsepower effect on the WTC towers.....any help would be greatly appreciated :)

forgive my ignorance but what is the btu and horsepower effect? BTU generally refers to a unit of thermal energy, 1055.5 or so joules. a rating for heat output. horsepower... well we all know what that unit of measurement is for. basically thrust.

so wanna elaborate any?

I dont know what he means either.

BTU can be converted to horsepower hour. Basically what im looking for is this. A 757 has 11,451 gallons of fuel, or there abouts. The BTU per gallon is 128,500 I believe. So multiply that and you get 1,471,453,500 BTU, which is, needless to say, alot. Convert that to horsepower hour and you get 578 303.006 087 551 horsepower hour. Thus, my question is, is there an article written that goes over the effect of that much horsepower hitting the WTC buildings. Or anything relating to horsepower hitting the WTC buildings :) Any help would be appreciated.

Paladin, there are a variety of sites that provide calculators for converting various items. Here is one I found with a few moments Googling and there are probably more detailed ones than that out there.

I know of no article specifically that discusses the effect of that energy, but I conccur that it is worth investigating.

one horsepower provided over one hour; equal to 0.745 kilowatt-hour or 2,545 Btu.

think of it like this
35 MJ per L (jet fuel)
40000 L
1 400 000 000 000 J

I would estimate, a fair bit over 70/80% of that energy in the first/second cases respectively was lost outside in the immediate fireballs. Lets be generous and say 50%

that leaves around 700Giga joules. Divide that between 5 floors, 150 gigajoules, each floor weighes somehting like 3000 tonnes, thats 50 KJ per kg floor material and concrete specific heat is 0.88 joules per g per K =

average temperature rise of (very roughly) 50 K / 50 degrees C.

not exactly steel melting temperatures. (in fact I could be off by a factor of 30 and still not melt steel....)

your request for horsepower is a bit strange(its not a car, why do we care?) but just icase you want to know, the fema report (i think it was that one) thought it (the jet fuel) would have all pretty much been gone in the first 10 minutes, so we are talking
1400GJ in 10 mins (600 seconds) = about 2 gigawatts, total, 50% lost immediately leaves 1 gigawatts, spread over about 5 floors = 200 MW a floor
each floor is 65 *65 = about 4000 square metres area. therefore there was around 20KW per square meter, not exactly cool, but not exactly the biggest fire ever either

now this is mostly a very conservative estimate (ie the real average temperature rise due to jet fuel would probably be a fair bit lower)(most of the heat would have escapes in the fireball/or in the smoke, ignores specific heat of the actual fuel (though this is probably negligable in comarison) etc etc, except for two things:

- most of the heat actually absorbed into the building from the fuel fires (which is a small fraction of that released) would be concentrated near the surface, at least for the first 10 minutes while thes fires where actually burning. This doesnt really matter though, since th ebuilding didnt collapse in the first ten minutes, and the fires seemed to gradually burn out over the next hour, any steel that did somehow lose structural integrity at the start should have been regaining most of it back by the end, so if it was going to fall unaided by explosives, should have fallen near the start, when it was hottest.

- the office material also burned, probably adding a decent amount more, but still not even reaching the ferocity of what Id call a quite large building fire, and nowhere near as bad as some other highrise fires which havent caused collapses.


Basically: firstly the jet fuel was pretty much irrelevant except as a firestarter (as fema said), 50 degrees extra just isnt going to matter, and secondly, because of this it was basically a normal medium/low intensity office fire, with some structural damage within design specifications, so why both collapsed is unknown unless due to other causes (explosives)

that help you much?

the total energy, considering fuel AND kinetic energy of the airplane, is worth considering.

as far as heating STEEL -- you need directed energy. When steel is heated for treatment, it is not merely placed in a room where there is an active office fire, no, heat is applied DIRECTLY, from a blowtorch, or blast furnace -- a concentrated energy field.

otherwise, the heat will disperse through air, and radiant, convective, and conductive losses will make it impossible to heat the steel significantly.

if the air temperature of a hydrocarbon fueld office fire might heat the air to a theoretical 1200F, or even 1500F, how hot do you suppose the steel could get, assuming passive transfer, through air, of that heat energy (which is just as happy to vent up and out the windows)

you begin to see the difficulty in the 'weakening steel due to heat' hypothesis

Jack

you are correct in that the majority of the heat (my pulled out my bottom estimate is >90%) would not actually be transfered into the steel but carried out the windows in the smoke/lost in the fireball

as to the kinetic energy involved:

E = 1/2MV^2 = 0.5*~100000* (~200Ms^-1)^2 = ~2GJoules.

only about 1/1000th of the energy content of the fuel burned, and a large portion of it went into making the tower sway back and forth, therefore was spread out over the length of the tower (and especially the base)

basically: the kinetic energy involved was unimportant from a heat/temperature point of view (though obviously it caused some physical damage)

how much 'directed energy' can we even begin to postulate went into steel column heating? And which columns?

In any real investigation of a disaster or fire, the first task of investigators would be to idenfity the elements that failed, and triggered other failures.

That would mean finding the core columns that 'failed' -- etc - particularly from the WTC1 north tower where collapse initiated from the interior (antenna fell first) --

since no such investigation was done, we are left to hypothesize.

Energy, part 2: after taking into account the spent energy from jet fuel and impact, what would be the necessary energy input to fracture and pulverize the concrete from floor pans, and from core column, to micron size? this involves significant water heating (water latent in concrete) -- and we can only estimate the temperature of dust clouds -- Hoffman's calculations suggest that the energy input for concrete pulverization alone was 10 times more energy , at a minumum, than gravitiational reserves contained. again, how is collapse energy able to both pancake floors, AND superheat concrete to dust?

where the hell did all the thermal inputs come from?

I agree and remember from one of my long ago physics or chem lectures a discussion on this topic, and the energies involved in fracturing solid materials (since to farcture you have to break whatever bond is holding the material together, and to do that normally involves the addition of energy, and this energy is proportional to the new surface area exposed. I tried to look it up but couldnt find it on the net, cant remember what the law is called. What I do know is this energy would NOT have been negligable, and there is no way that a gravity collapse could both pulverise AND fall quickly (in fact it could do neither, but you get my point)

anyone know the equations involved?

You seem to know quite a bit.[worthy]

Do you happen to know how much BTU of atomic bomb?
Hiroshima Dome vs WTC