keep it real keep it real keep it real keep it real

September 27, 2004 7:44 AM

IF jetplane + wall == dust THEN wow(windowsmedia)
Hunt the Boeing my arse.
posted by Pretty_Generic (41 comments total)

Fortunately, the pilot walked away with only a few bumps and bruises and a broken right arm.

?!
posted by jpoulos at 7:48 AM on September 27, 2004

I think the boys at big-boys.om are just making up captions as they go. The video itself states the jet is completely destroyed.

I've noticed big-boys.com are not sticklers for accuracy.
posted by jazon at 8:02 AM on September 27, 2004

Fortunately, the pilot walked away with only a few bumps and bruises and a broken right arm.

Like hell he did.

If there were a live human in the cockpit of that thing, there wouldn't be enough tissue left for any kind of meaningful autopsy.
posted by alumshubby at 8:06 AM on September 27, 2004

if (f4 != 747 OR wall != pentagon) then
continue speculation
end

I guess the pilot was really lucky, I got a few bruises myself while picking sea buckthorn berries last weekend. But the video is amazing. The concrete wall is taking some damage, but it's almost as if the planes vanishes through the wall.
posted by ikalliom at 8:08 AM on September 27, 2004

"Fortunately, the pilot walked away with only a few bumps and bruises and a broken right arm." is a joke, there was no pilot, end subject.
posted by Pretty_Generic at 8:11 AM on September 27, 2004

I wish they had shown the impact once at full speed.
posted by wsg at 8:17 AM on September 27, 2004

Fortunately, the pilot walked away with only a few bumps and bruises and a broken right arm.

Ahh, a good landing, then.
posted by eriko at 8:18 AM on September 27, 2004

Fortunately, the pilot walked away with only a few bumps and bruises and a broken right arm.

But he vowed that he would never again fly for the Texas Air National Guard.
posted by eatitlive at 8:37 AM on September 27, 2004

That's $18,000,000 (USD) worth of airplane dust, there. F4s are, um, cher.
posted by Shane at 8:47 AM on September 27, 2004

*rimshot*
(for eatitlive)
posted by KevinSkomsvold at 8:48 AM on September 27, 2004

Weird... I ran this on coolgov yesterday. Here's the page where it originally came from... There are some pretty spectacular still shots on that site.

As a side note, does anyone know anything about the Muto Institute of Structural Mechanics -- Sandia labs' partner on this project?
posted by ph00dz at 9:13 AM on September 27, 2004

If there were a live human in the cockpit of that thing, there wouldn't be enough tissue left for any kind of meaningful autopsy.

Autopsies on a live person is usually not tolerated.
posted by substrate at 9:29 AM on September 27, 2004

Wow, that's horrible english, even for me.
posted by substrate at 9:31 AM on September 27, 2004

Shostakovich
posted by Pretty_Generic at 9:52 AM on September 27, 2004

wsg, that's what I was going to say. I'd love to see this impact at full speed. Around 700 feet per second. That's hella fast.
posted by tomplus2 at 10:09 AM on September 27, 2004

"Mr. Dent. Have you any idea how much damage that concrete wall would suffer, if I were to let you fly right into it?"

"No, how much?"

"None at all."
posted by Civil_Disobedient at 10:24 AM on September 27, 2004

Wow. That's an impressive video. Talk about wholesale pulverization. Very cool.
posted by five fresh fish at 10:29 AM on September 27, 2004

Think about the application of this to the scrap metal recycling industry! No more expensive crushers and grinders, just build one of these walls and get yourself a rocket sled and badda-bing, badda-boom, you've got sortable scrap. I'd like to see them try this with a car, like an old Buick, at 500 mph.
posted by Pollomacho at 12:31 PM on September 27, 2004

Scrap metal industry? You name an industry that *wouldn't* benefit from a concrete wall and a rocket sled.
posted by Krrrlson at 1:32 PM on September 27, 2004

P_G: I'm not sure what you're trying to get at.

If reinforced concrete can grind a plane moving at full speed into dust, then it would suggest a plane did not hit the Pentagon, as it caused massive damage.

If reinforced concrete can NOT grind a plane moving at full speed into dust, then it would suggest a plane did not hit the Pentagon, as there were no plane parts left.

I'm not sure I'm buying that it both atomized it AND suffered incredible structural damage. Too big of a leap.

(Disclaimer: I personally believe that a plane hit the Pentagon. But I believe the explanation to people's "questions" lies elsewhere, not here.)
posted by Ynoxas at 2:16 PM on September 27, 2004

Built during the early years of World War II, it is still thought of as one of the most efficient office buildings in the world. Despite 17.5 miles (28 km) of corridors it takes a maximum of seven minutes to walk between any two points in the building.

It was built from 680,000 tons of sand and gravel dredged from the nearby Potomac River that were processed into 435,000 cubic yards (330,000 m³) of concrete and molded into the pentagon shape. Very little steel was used in its design due to the needs of the war effort.

It sounds like the pentagon wasn't built of reinforced concrete due to the demands of the second world war. I'm not a physicast, but weak concrete + airplane full of fuel could result in the destruction of both.
posted by b1tr0t at 2:33 PM on September 27, 2004

if (f4 != 747 OR wall != pentagon) then
continue speculation
end

Bingo, didn't anyone else read the text on the page pointing out that the test wall was specifically reinforced for post-nuclear military applications?

Another big difference: Windows.
posted by KirkJobSluder at 3:05 PM on September 27, 2004

You say that as if having a wall that's some 40% windows could conceivably weaken the wall's structural integrity in event of catacalysmic force. Pshaw, I say, pshaw!
posted by five fresh fish at 3:54 PM on September 27, 2004

If the pentagon runs windows, you would not even need an airplane to crash it.
posted by Kwantsar at 6:13 PM on September 27, 2004

IF jetplane + wall == dust THEN wow

Except for that one bit that didn't turn to dust. That one bit that not only didn't turn to dust, but magically went thru 5 or 6 walls of the Pentagon building.
posted by uncanny hengeman at 8:49 PM on September 27, 2004

You can see a bit of the plane's right wing just fly right on past the edge of the wall.

Remind me not to be in a crashing plane, mmkay?
posted by ikkyu2 at 9:15 PM on September 27, 2004

jesus christ, hearing people argue about wether a plane hit the pentagon or not just makes my bones squeal in pain. why the hell is it that people REALLY think there is no difference between 6 feet of concrete and 1 feet of concrete....i mean shit, i know most people haven't studied physics but isn't there something to be said for simple common sense?!

ok, so here's the thing. the pentagon has (probably) walls of 1 foot thick reinforced concrete (it's built to be a warehouse with 150psf live loads (pretty heavy stuff)). This is a pretty rigid structure (compared to the WTC) but absolutely nothing compared to the regidity of that 6 foot wall shown in the video. Add to that that there's also an issue of basic momentum. The airplane carries allot of speed and a bit of mass...but the wall has an INCREDIBLE amoutn of mass (lets say the plane weights 9 tons, well that wall if 10' thick and 35' wide and 20' tall then it has a mass (well weight) of 5250 tons). If the wall didn't damage at all (and it does based on the video) by energy alone we know that moment is constant (so if the plane has a velocity of 600 mph then the wall would have a velocity of 1 mph (note: i know this isn't right but it gives you an idea of what the difference in mass means)). Of course, the energy loss is the plane shredding to pieces (we also don't see how the wall damages...whcih it must have).

Another thing people don't understand is that planes are thin shells where the exterior skin is a major part of the structure...something akin to a exoskeleton. it's not like hitting a wall with a bullet, it's quite fragile. more like running an egg shell into the floor with your foot.

As for the wall in the pentagon that actually failed because it was much thinner, had less mass, and the plane was much bigger.

so PLEASE FOR THE LOVE OF GOD stop being shit heads and use your brain dammit!

that said, never expect that there is something a structural engineer can build that someone can't come along and destroy (we build targets, not weapons).
posted by NGnerd at 10:35 PM on September 27, 2004

Eh. We do one of these on the Playa every year.

/sarcasm

HOLY FUCKING SCHWAZZAZ!!
posted by scarabic at 11:17 PM on September 27, 2004

Another thing people don't understand is that planes are thin shells where the exterior skin is a major part of the structure...something akin to a exoskeleton. it's not like hitting a wall with a bullet, it's quite fragile. more like running an egg shell into the floor with your foot.

As for the wall in the pentagon that actually failed because it was much thinner, had less mass, and the plane was much bigger.

So, by your analogy, it would be like running an egg shell into the floor with your foot, compared to running a bigger egg shell into a thinner floor with your foot.

Hmmm, yes. I can see how the floor would get damaged in that instance.

And you still haven't explained the MAGICAL object that travelled through 3 rings of the Pentagon.
posted by uncanny hengeman at 11:20 PM on September 27, 2004

Bugger. Those first 2 paras should be italicised. I wuz quoting a previous post.
posted by uncanny hengeman at 11:22 PM on September 27, 2004

And you still haven't explained the MAGICAL object that travelled through 3 rings of the Pentagon.

Your lack of comprehension of basic physics combined with your jumping to conclusions is...disturbing.

Empty weight of an f4 - 29,535 lbs
Gross weight of a 747 - 775,000 - 833,000 lbs

28 times the mass at the same speed equals 28 times the kinetic energy. It doesn't matter how the plane is constructed, all that energy has to go somewhere, and that somewhere is pulverising concrete.
posted by TungstenChef at 5:05 AM on September 28, 2004

Oh man, some people have fantastic jobs! Seriously. Here I am sitting at a computer all day in a dingy office dealing with annoying users, and yet there are guys out there strapping jet fighters to sleds and slamming them into walls at 500mph under a beautiful blue desert sky.

I chose the wrong career. Sob.
posted by Meridian at 5:44 AM on September 28, 2004

I'd like to see a few still photos of the test crash's aftermath. That wall might still be standing, but it's probably got one hella chunk out of the middle of it.
posted by alumshubby at 6:55 AM on September 28, 2004

Surely some of you can understand why some people at least question what happened.

It seems pretty simple to me.

Either the pentagon is so tough that it almost vaporized a 747, or it is weak enough that it could be severely damaged by a mere thin metal shell.

It can't be both. Interestingly, it also can't be neither.

Planes crash into mountains and the ground all the time (by comparison). I don't know the mass of the pentagon, but I know it is less than the earth.

Even when a plane flies straight down into the earth, there are still pieces of "plane" left on the ground. Take the 9/11 plane that crashed. There was still pieces of "plane" left on the ground. It was recognizable as a plane crash.

But, at the Pentagon, there was quite considerable damage, but yet, no "plane" parts.

So, you have a paradox. Either the plane was tough enough to cause massive damage, or the Pentagon was tough enough to vaporize it.

As I said above, I think there is some other explanation, as I do believe it was a plane that hit the Pentagon.

But this has no relevance to what happened to the Pentagon on 9/11. It has a "gee whiz" factor, but this does not explain anything about the Pentagon + Airplane situation.
posted by Ynoxas at 10:34 AM on September 28, 2004

Either the pentagon is so tough that it almost vaporized a 747, or it is weak enough that it could be severely damaged by a mere thin metal shell.

It can't be both. Interestingly, it also can't be neither.

Please provide some information to backup your assertions. We saw a pair of Boeing 767s crash into the WTC. Recall that most of the WTC's structure came from the steel beams on the outside of the tower, not from an interior latticework like the Empire State Building. Despite the fact that these aircraft are made of eggshell-thin aluminum foil, they managed to punch aircraft-shaped holes into the two towers. The damage from these holes extends all the way to the aircraft's wingtips.

How can this be?

Recall that force is directly proportional to mass times the square of velocity:
Force = Mass * Velocity²

Even though the airplanes are vey light, they had a full load of fuel and were traveling at close to 500 miles per hour.

Incidentally, the flight that crashed into the pentagon was a Boeing 757, NOT a Boeing 747. The 757 is somewhat smaller and lighter than the 767s that hit the WTC. Both the 767 and 757 are substantially smaller and lighter than the 747.

Ynoxas claims claims that the Pentagon MUST have EITHER vaporized the aircraft, or the aircraft destroyed the pentagon. It is claimed that BOTH destruction of the pentagon AND airplane is not possible. Why is this?

A bomb dropped on a target destroys both itself and some portion of the target. An airliner full of fuel is a very slow-bruning bomb. We can see from the relationship between Force, Mass, and Velocity that the eggshell-thin airliner can impart significant force upon its target (the Pentagon) if it travels at a sufficient velocity. From previous links, it is clear that the Pentagon is made of wartime-grade concrete prior to the cold-war era. I have no trouble believing that an aircraft crashing into the pentagon could both damage the pentagon and vaporize itself.

That having been said, some of the details of the pentagon crash are suspicious. It would be both interesting and relevant to national and urban security to deeply investigate both the WTC and Pentagon attacks.
posted by b1tr0t at 1:12 PM on September 28, 2004

Next you'll be trying to tell us that water can cut metal.
posted by five fresh fish at 1:58 PM on September 28, 2004

b1tr0t - you mean energy, not force, and it's E=0.5*m*v² (and by the way it was built of reinforced concrete - the remark about steel for the war effort is trying to explain why they used reinforced concrete instead of rolled steel beams and columns.) Force is mass*acceleration (in this case, negative acceleration: deceleration). TungstenChef is onto it above.

Folks, "common sense" cannot explain everything and answer all questions. If it could, there would be no need for scientists, engineers, and other thinkers.

Read the report (pdf). And there were pieces of the plane left behind, including the front landing gear and the flight data recorder (not to mention human remains of passengers...)
posted by pitchblende at 3:08 PM on September 28, 2004

You are correct pitchblende, energy is the relevant quantity for this discussion, not force. I took the data from the airliners.net links that I provided above and plugged them in to E=0.5*M*V². I took the results of those computations and compared them with the force of a single ton of TNT and two conventional bombs from the US arsenal. The results are very interesting. Please note that I don't take the explosive action of fuel in a confined space or the flammability of aluminum in to account. The numbers that follow are likely to be an underestimate of the energy that was expended at the Pentagon crash site.

A Boeing 757 with no passengers, no luggage and no fuel traveling at its cruise speed will impart as much energy as 0.39 tons of TNT, 4 MK-82 bombs or 0.8 MK-84 bombs if it hits something. The same aircraft with a full load of fuel, passengers and luggage carries as much energy as 0.77 tons of TNT, 8 MK-82 bombs or 1.6 MK-84 bombs.

A Boeing 767 with no passengers, luggage or fuel traveling at its cruise speed carries as much energy as 0.5 tons of TNT, 5 MK-82 bombs or 1.6 MK-84 bombs. A fully loaded 767 carries as much energy as 1.2 tons of TNT, 12 MK-82 bombs or 2.5 MK-84 bombs.

The 757 that hit the Pentagon is not concentrated into a small package, so it would be unfair to compare its impact with that of the large MK-84 bomb. It is more reasonable to think of the 757 as between 4 and 8 of the much smaller MK-82 bombs. If we assumed 6 MK-82s, we could use one to simulate each of the 757's engines. That leaves four bombs to simulate the aircraft's fuselage.

I'm going to guess again and say that the construction quality of the pentagon is probably similar to other 40's-era concrete apartment or office buildings, adjusted for the Pentagon's PSF loading requirements. There is ample evidence of what bombs can do to such buildings in the actions of terrorists and civil wars in the last decade alone.
posted by b1tr0t at 6:22 PM on September 28, 2004

If you feel like throwing these numbers into your calculations: The building report I linked above estimates the amount of fuel in the airplane at impact as 36,200 pounds (about 5300 gallons of Jet A fuel) They think about 4900 pounds of it was burned up in the immediate impact fireball outside the building, leaving 30,400 lbs of fuel to burn inside the Pentagon.

They calculate that the maximum possible energy that could have been released by the burning of this fuel to be about 575 million BTU (or 607,000 MJ).

Also, the pentagon was built a bit better than other typical concrete buildings of the time (if you want to get technical, the spirally-tied columns and the large amount of continuous bottom reinforcing in the concrete beams and girders is somewhat atypical and helped the pentagon survive a bit better than one might have expected.)
posted by pitchblende at 7:51 PM on September 28, 2004

Your lack of comprehension of basic physics combined with your jumping to conclusions is...disturbing.

Can you please help me with the "disturbing" conclusion I came to?

I was directly quoting from NGnerd’s analogy.

The 757 is either an eggshell or it ain’t. Ya can’t have it both ways (which is what he was saying).
posted by uncanny hengeman at 10:04 PM on September 28, 2004

Sure you can have it both ways. It can be an eggshell in that it offers no meaningful integrity as far as maintaining its own shape, but then you're still dealing with an enormous high speed mass slamming into a fixed structure.

And my brother-in-law was there, in a nearby Navy building, and both saw and heard the plane pass right overhead before hitting the Pentagon. It really happened.
posted by NortonDC at 6:29 PM on September 29, 2004