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Post by papageno on Oct 3, 2006 20:25:38 GMT -4
I am currently discussing the 911 conspiracy theories on an Italian forum.
The only new idea I had not heard before, was that the light poles should have cut the wings of the Boeing 757 before hitting the Pentagon.
The guy proposing the idea keeps repeating "but I showed that the poles would exert a load of 2300 kg/mm^2 on the leading edge of the wings, and it is much more than necessary to break aluminium". Despite his claims of being an aeronautic engineer, he has not been able to explain how exactly the poles would be able to cut the wings.
So, I have a question for the experts: What would it take for a common street light pole in steel to cut the wing of a commercial airplane like the Boeing 757? Would it be possible, or would the potential damage be other than a simple cut (assuming the pole keeps standing long enough)?
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Post by LunarOrbit on Oct 3, 2006 21:55:32 GMT -4
Light poles are designed to snap off at the base when hit by cars (I'm assuming this is to ensure they fall away from the car instead of on top of it). I imagine an airplane wing would knock the pole over rather than the pole slicing through the wing.
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Post by sts60 on Oct 3, 2006 22:02:56 GMT -4
I don't know about the light poles in the Pentagon parking lot. But I've grabbed and moved light poles out of the street at accident scenes by myself with little effort, after a car hit the poles and they broke away as LO mentioned.
What does he mean by using kg as a unit of force anyway?
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Post by LunarOrbit on Oct 4, 2006 0:00:29 GMT -4
Isn't it odd how CT's claim that the airplane's wing should have sliced through the reinforced walls of the Pentagon AND that the light poles should have sliced off the wings. The wings must somehow be both super strong and pathetically weak at the same time.
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Post by gwiz on Oct 4, 2006 3:00:19 GMT -4
I doubt if a light pole would stand up to the main wing structure, though it would damage the leading edge. You find quite substantial trees cut through at crash sites. There is also the question of whether the impact would propagate down the pole to the designed snap-off point before the top of the pole was sheared off.
Aluminium wings certainly cut through steel walls at the WTC, or does your CT think that was a hologram?
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lenbrazil
Saturn
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Post by lenbrazil on Oct 4, 2006 7:50:36 GMT -4
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Post by papageno on Oct 4, 2006 14:51:32 GMT -4
Thanks for the replies.
However, I put the thread in "General Discussions" because I was not looking for a confutation of the CT's argument.
I had a picture in my mind of what would happen in the impact between a steel pole and a plane wing. But, not being an expert of the field, I could not tell whether my picture was accurate.
LunarOrbit: "I imagine an airplane wing would knock the pole over rather than the pole slicing through the wing."
This is what it looks like from the pictures (but most of them are not very clear).
sts60: "What does he mean by using kg as a unit of force anyway?" I think that the force should be given by y N = x kg * g.
gwiz: "Aluminium wings certainly cut through steel walls at the WTC, or does your CT think that was a hologram?"
He does not even bother to try and substantiate his claims anymore. He tried to throw some technobabble at me, but then he realized that I was not impressed.
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Post by phunk on Oct 4, 2006 15:03:20 GMT -4
Are light poles steel? I always figured they were aluminum.
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Al Johnston
"Cheer up!" they said, "It could be worse!" So I did, and it was.
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Post by Al Johnston on Oct 4, 2006 15:29:15 GMT -4
Steel: it's a lot cheaper
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Post by PhantomWolf on Oct 4, 2006 16:19:26 GMT -4
Steel: it's a lot cheaperWell I can't speak for Washington DC, but the breakaway ones we have here appear to mostly be aluminium (the non-breakaway ones tend to be concrete and or steel) and according to this list, it seems most approved US poles are either Aluminium or fibreglass. With the bolts at the base, the force required to shear them would be far less when it is applied to the top of the pole (from a plane) than what would need to be applied at the base (from a car.) It's a basic lever principle. So if it requires 2300N to shear the bolts from a strike at 0.5m above the bolts (our car's bumper), then at 3m, it'd take just 384N (at least if I'm recalling my lever physics right.) Of course this makes the assumptions that it requires 2300N to shear it from a bumper hit, I can't find any actual figures currently.
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Jason
Pluto
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Post by Jason on Oct 4, 2006 18:17:52 GMT -4
There are probably one or two photos on the internet that show if light poles were sheered off, bent, or broken off at the bolts by the plane.
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Post by LunarOrbit on Oct 4, 2006 19:32:26 GMT -4
Like this one? It looks like that one snapped off at the base as well as breaking and twisting in multiple other places.
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lenbrazil
Saturn
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Post by lenbrazil on Oct 4, 2006 21:07:54 GMT -4
Steel: it's a lot cheaperWell I can't speak for Washington DC, but the breakaway ones we have here appear to mostly be aluminium (the non-breakaway ones tend to be concrete and or steel) and according to this list, it seems most approved US poles are either Aluminium or fibreglass. With the bolts at the base, the force required to shear them would be far less when it is applied to the top of the pole (from a plane) than what would need to be applied at the base (from a car.) It's a basic lever principle. So if it requires 2300N to shear the bolts from a strike at 0.5m above the bolts (our car's bumper), then at 3m, it'd take just 384N (at least if I'm recalling my lever physics right.) Of course this makes the assumptions that it requires 2300N to shear it from a bumper hit, I can't find any actual figures currently. I made similar calculations see the linked post with figures from a CT site based on info the webmaster got from the Virginia DoT.
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Post by papageno on Oct 5, 2006 6:25:17 GMT -4
Thanks, LunarOrbit. That's the kind of picture I have been trying to get from the CT without success. I showed it to him and pointed out that the exterior panels of WTC 1 and 2 were cut by the wings (thanks, gwiz!). Yet the CT claims victory. He obviously does not realize that he's never proved anything in support of his theory.
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Post by sts60 on Oct 5, 2006 8:50:25 GMT -4
FWIW, that's Montgomery County (Cabin John Park VFD) Medic 309 on the left. I've mentioned elsewhere that I know guys from the county urban search and rescue team that were there picking pieces of bodies and 757 out of the Pentagon that day. I mentioned the "no-plane" hoax idea (it doesn't consitute a theory) to one and he just rolled his eyes.
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