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manon, I'm certainly not the instant-reply type, I do my research, as it happens I was doing it just to reply your other comment downthread.

One plane crash is not the other if velocity and fuel level is the same, the impacted medium and impact angle also count.  But I asked you specifically about speed, too.

what makes you so eminently qualified to judge events?

Of the two of us it wasn't me who tried to use the argument from authority.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Sep 15th, 2006 at 03:49:03 PM EST
[ Parent ]
speed can be vectored as horizontal and vertical components and thus the angle of impact isn't really important

as for the impacted medium, I have already told you that that was a variable, but if you know it's physical properties, you can extrapolate from one medium to another

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 03:53:53 PM EST
[ Parent ]
Write a technical diary, DoDo is an astrophysicist so you know what level of technical detail to shoot for.

Those whom the Gods wish to destroy They first make mad. — Euripides
by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 03:55:38 PM EST
[ Parent ]
gotcha

I just finished a gig at an observatory filled with wannabee mechanical engineers with astrophysics degrees

not the same thing in the least

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 04:01:31 PM EST
[ Parent ]
Trained astrophysicist working as a railway engineer, to be exact. The point is not about being the same, but about an audience with what education you should tilor your technical arguments for.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Fri Sep 15th, 2006 at 04:06:41 PM EST
[ Parent ]
I mean, I have a physics degree too. I can follow materials science arguments.

Those whom the Gods wish to destroy They first make mad. — Euripides
by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:07:52 PM EST
[ Parent ]
and you can troll rate as well, I noticed

material science? really?  how about destructive testing?  do any of that?

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 04:14:59 PM EST
[ Parent ]
No, I can give you and Colman each a warning. I'm the one who gets troll-rated around here on a regular basis.

Look, all I'm saying is feel free to write a technical diary about this. DoDo is sceptical, I'm actually interested. We're both physicists. That doesn't mean we know better but you know what to expect us to know or be able to understand.

Everyone getting defensive doesn't help.

Those whom the Gods wish to destroy They first make mad. — Euripides

by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:18:17 PM EST
[ Parent ]
perhaps the problem is that you are physicists

you approach this with a bias that is more appropriate to the birth process of stars than to metallurgical failures due to impact

come on, you're talking about 9 m/sec/sec acceleration versus a 520 mph thrust forward

you're also arguing against the established facts -  no aircraft has sustained this type of damage from an impact of any kind in history. EVER.  and people are questioning it.  doesn't that ring any bells for you?

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 04:24:47 PM EST
[ Parent ]
No, I can understand that gravity is irrelevant. Point to a comment of mine where I mention gravity.

Those whom the Gods wish to destroy They first make mad. — Euripides
by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:27:45 PM EST
[ Parent ]
The problem is that you replace technical arguments with innuendo and argument from authority or argument from incredulity, plus some out-of-context argument and misrepresentation (like that about g and 520 mph). You're the expert, you could educate us instead.

That no plane sustained this kind of damage is paralleled by the fact that no plane suffered this kind of impact. You were navigating around that point for several rounds. You were not responding to any queries about to what kind of experience you have with impacts, not even kinds of impact that could be extrapolated for the case of the Pentagon.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Sep 15th, 2006 at 04:31:37 PM EST
[ Parent ]
but that is EXTREMELY important

how do people in engineering design things?  from previous experience

how do they know how things behave in certain conditions?  from previous experience

I once had to test a certain type of bearing seal called an air seal that exists in the hot part of the engine and supports the power shaft in some turboshaft engines.  The seal worked most of the time, but nobody who had worked with it over years and years could tell me where the high pressure and low pressure areas were, ie, how the seal actually worked.  It worked, that's all.  

A lot of engineering is like that - you design something and hope it works.  You don't necessarily put instruments all over the place and figure out how it works.

Same thing when something ruptures.  Most engineers don't care about anything at the molecular level.  They just want to know under what conditions it will happen.

So the fact that it has never happened before, and it happened TWICE, both times on 9-11, and not anytime since then, when planes have hit buildings before, makes it extremely suspicious and that is what should be investigated, not the 10,000 times or more that it didn't happen.

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 05:06:42 PM EST
[ Parent ]
This is a big part of this threads wildness. And not only this thread.

In general we do not have mathematical proof for stuff we know that we know. Neither do we always have an reference handy (not even with the help of google). Be it engineering or the access to firewood in Sweden. And getting challenged on stuff we know that we know, that are basic, does not prompt eagerness to prove it, for what proofs would be acceptable for those that does not share our knowledge? And then a "you prove it - no you prove it" is quickly started.

Therefore I am not sure this debate over Pentagon will lead anywhere. On the other hand I would be interested in a diary on what plane crashes into objects usually look like. I know formulating it would probably mean some work for you (it is that way with knowledge we normally use rather then describe) but I think it would be interesting. If you like to compare it with 911 is up to you.

Sweden's finest (and perhaps only) collaborative, leftist e-newspaper Synapze.se

by A swedish kind of death on Fri Sep 15th, 2006 at 09:38:53 PM EST
[ Parent ]
Great suggestion. And may I add a diary on how buildings collapse. I'm thinking about the "pancake" theory which explains the collapse of the twin towers.
Note: very important for that matter would be to know the actual structure of the centre of those towers (or an estimation of it), and an estimation of the temperature inside after the attack (as a function of time). these "parameters" could be given as an appendix or as a separate thread.

that would be extremely nice. I know nothing about structural mechanics.

by findmeaDoorIntoSummer on Sat Sep 16th, 2006 at 06:28:48 AM EST
[ Parent ]
The "basic" report is here....(quite a lot of pdf files)!

An important point would be the "B.4.3 Floor Truss Seated End Connections at Spandrel Beam and Core" chapter... As it would seem that some of those connectors were supple (as design) and couldn't be fireproofed very well... ?

An audio-slide show shows for the layman the whole story !

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Sat Sep 16th, 2006 at 08:56:17 AM EST
[ Parent ]
Hey, you gave me a 4! If I get a 2 from you as well I'll have comment properly rated as a 2. I haven't had one of those in absolutely ages.
by Colman (colman at eurotrib.com) on Fri Sep 15th, 2006 at 04:24:49 PM EST
[ Parent ]
No, it's ok, I found the 2. I'll treasure it.
by Colman (colman at eurotrib.com) on Fri Sep 15th, 2006 at 04:25:54 PM EST
[ Parent ]
I think we should be harsher on our grading, but we'd need to all synchronize our watches to do it (so that no one stops giving 4s systematically if the others don't follow).
And as grades push comments up (or down), they really should not be used lightly, no?
Would it be difficult to rewrite the grading system to have something along the lines of:

"Acknowledged"
"Funny"
and then "0-9" for an actual grading of instructiveness/pertinence/whatever of the comment

The first two would not count in the grading average.

by Alex in Toulouse on Fri Sep 15th, 2006 at 04:30:16 PM EST
[ Parent ]
My own preferred grading system:

  1. outstanding [implies nothing on agreement/disagreement]
  2. agree strongly
  3. uncivil
  4. troll
  5. disgraceful

I have never actually applied it except for occasional 2's that I am always recriminated about.

We have been warned on at least one occasion not to deviate from the binary unrated/4 rating system, as people get really sensitive really quick.

Those whom the Gods wish to destroy They first make mad. — Euripides

by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:36:55 PM EST
[ Parent ]
Actually that system's not bad at all, so perhaps we could just add text labels next to the number for a reminder (inside the scroll list, in the same format you used above). This could help people lighten up about grading.
by Alex in Toulouse on Fri Sep 15th, 2006 at 04:39:37 PM EST
[ Parent ]
And now, after saying this, I just notice (or remember for the firs time, habit being what it is) that there already are text labels next to the values.
Pffffou, can't wait to go out tonight. Will be called for a few whiskey shots when some friends leave a restaurant.
by Alex in Toulouse on Fri Sep 15th, 2006 at 04:43:20 PM EST
[ Parent ]
Aha, the phone rang! Need to go in a hurry, we'll also be watching the film rushes (I mentioned doing a suit & tie company ultralight role in a university movie, this week).
Love to all.
by Alex in Toulouse on Fri Sep 15th, 2006 at 04:45:14 PM EST
[ Parent ]
Trouble is, nobody uses the 3's for quality and people (including myself) tend to use 4s for endorsement. I do a conscious effort of giving 4 to insightful posts I am inclined to disagree with, but it's hard.

Those whom the Gods wish to destroy They first make mad. — Euripides
by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:47:32 PM EST
[ Parent ]
I'm sceptical, but if manon has techical arguments, I'm interested too.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Fri Sep 15th, 2006 at 04:24:55 PM EST
[ Parent ]
What I mean is that I'm actually more sympathetic than you are to the conspiracy theories. Which will make it really amusing when I present and ridicule the conspiracy theories about March 11.

Those whom the Gods wish to destroy They first make mad. — Euripides
by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:29:06 PM EST
[ Parent ]
What I meant was that I am more sympathetic to the conspiracy theories than you are. On the other hand, you have obviously done more reading on the technical details than I've had the patience for.

Those whom the Gods wish to destroy They first make mad. — Euripides
by Migeru (migeru at eurotrib dot com) on Fri Sep 15th, 2006 at 04:42:29 PM EST
[ Parent ]
I fail to see how examining physical evidence scientifically can be extrapolated into being the conspiracy theory that J so objects to.

There are some things that appear to be anomalies - unexpected phenomena to scientists. Some things that need explaining.

Now if we have knowledgeable people here at ET, on the possible explanations for these phenomena, then I think we are entitled to discuss them.

Of course, we may find that the answer is in ourselves - according to the theory of a very respected and senior medical researcher friend of mine. He told me three months ago about it, and I heard more at a meeting today. Clinical tests are confirming his theory.

The answer is a panic disorder caused by changes in CO2 levels. This is a cousin of the panic of suffocation or drowning. Apparently we have two 'sensors' - one is in the medulla at the back of the brain, the other in a main aorta leaving the heart. The brain monitors the levels of CO2 in the blood in a kind of steroscopic way. A differential in the two signals causes a reaction of seeking to avoid the situation (like lifting the head or going outside) on up in severity to a full blown panic attack. Jogging for instance does not cause the panic, because oxygen going down is not a trigger. There also seems to be an element of pattern recognition in which, if the cause of of the CO2 rise is 'logical' - such as swimming underwater holding your breath, the reaction can easily be suppressed.

The real feeling of panic is when your brain detects a differential but 'sees' no cause for it.

Perhaps therefore, our tendency to see conspiracy in 9/11 is related very much to one of the constant interests of this forum. The existence, origin and consequences of changes in CO2 levels in our urban environments.

Now there's a conundrum...

Somewhat like a brain surgeon performing surgery on his own brain - perhaps the ultimate feedback system.

You can't be me, I'm taken

by Sven Triloqvist on Fri Sep 15th, 2006 at 04:54:26 PM EST
[ Parent ]
Panic attacks and CO2 increase.

Could you elaborate a bit more.

Verrry interesting.

"When the abyss stares at me, it wets its pants." Brian Hopkins

by EricC on Fri Sep 15th, 2006 at 06:27:49 PM EST
[ Parent ]
I don't know much more at the moment, other than that a handheld scrubber is under development - like an asthma inhaler except it works like a scuba rebreather.

In limited trials it has proved very effective, bigger trials coming up. Main problem has been the caustic chemical used for scrubbing - but now solved.

Original observation of reaction is quite old and well documented. What is new is the understanding of how it works.

You can't be me, I'm taken

by Sven Triloqvist on Sat Sep 16th, 2006 at 03:37:01 AM EST
[ Parent ]
The importance of the angle of impact comes from the effects of gravity and the distance that can be travelled across surface structures before hitting the ground. I don't see where you mentioned the impacted medium. Which medium you had professional experience with compares to a building with a dozen lines of parallel support columns and various walls?

This discussion is frustating because it's like shadow boxing. You make claims without going specific about them. As Migeru pointed out, I have a level of physics education to at least follow your technical arguments if made explicit.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Sep 15th, 2006 at 04:02:49 PM EST
[ Parent ]
now you're clutching at straws.  gravity is a minor matter in this type of event - with forward velocity equaling 520 mph?  it affects lift and drag, but we're not looking at aeronautical effects, we're talking about destructive effects of impact

and we're not talking about the molecular level either

this is the FIRST incident of a plane "vaporising" due to an impact and you can't even see any metal vapour coating on the buildings or on the cable spools in front of the building, about 15 feet from the impact point.  amazing!  a plasma effect from Jet-A1 fuel (which has about the same properties as diesel fuel)

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 04:09:57 PM EST
[ Parent ]
now you're clutching at straws.  gravity is a minor matter

Gravity was just a small part of what I wrote, picking it out of context, and as the only bit to respond to, more fits your charge.

with forward velocity equaling 520 mph?

For a falling plane, gravity adds to speed before impact and adds 1G to impact force. For a plane flying into a building more or less level, the speed you name is initial speed. This was of course an academic point making part of my argument countering your dismissal of impact angle as a factor, not a specific Pentagon impact argument.

this is the FIRST incident of a plane "vaporising"

Vaporising??? Are you now taking figurative speech literally? I again refer you to the photographs of wreckage from the wings.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Sep 15th, 2006 at 04:20:58 PM EST
[ Parent ]
there is no wreckage from the wings.  

there is a burn pattern on the building but nothing that would indicate the geometry of the object that caused it.

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 04:37:32 PM EST
[ Parent ]
By now its pretty obvious that you haven't really looked at the photos in my link, or just scrolled across them without reading even the captions, not to mention the explanatory text.

No wreckage? I must be hallucinating:

Here I must be seeing paper clips and the piece of the Global Hawk:

Bur damages? These aren't burn damages:



*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Sep 15th, 2006 at 04:52:07 PM EST
[ Parent ]
no, sorry, I see a part of a nose cone that should have been the first thing to strike the building, but it doesn't seem to be discoloured in any way

I don't see anything except some soot on a building that was hit by something which some people tell me was an airplane.  I can't see anything on the building that convinces me of that.  There is some debris, but very little for such a large object such as a 757.  

Sorry but that's what I see

by manon (m@gmail.com) on Fri Sep 15th, 2006 at 05:20:35 PM EST
[ Parent ]
Okay but - have you considered what's involved in crashing an airliner into a building * exactly * at ground level?

This may have been debunked already, in which case I'm happy to see links explaining how it was done.

But otherwise, this one has me baffled.

Normal airport landings use a system called ILS which guides the pilot to the runway, and optionally autolands if visibility is poor, or the pilot is feeling lazy.

The Pentagon obviously had no ILS. So we're talking about aiming something with the handling characteristics of a very, very large and unwieldy object, travelling at a very high speed.

I'd estimate the target corridor subtends an angle of a couple of degrees. Too high and you overshoot. Too low and you crash into the ground well ahead of the target, spraying the facade with debris, but not doing any structural damage.

You have to get this angle right while flying at between 300 and 500mph. This doesn't give you a lot of time to make pitch and altitude corrections during the final approach.

You can't use the altimeter to improvise a glideslope because there are no clear horizontal cues outside of the windows that you can check against - and everything is happening too fast to run a checklist anyway.

So you're:

Not using instruments or other aids

Approaching at a rate at which everything is happening between 2 and 4 times faster than for a typical landing.

Hitting a target corridor, which has to be accurate to (let's be generous) a few degrees

In something with the handling characteristics of an airborne express train

This may be exactly what happened. But if so, it's extremely impressive flying.

by ThatBritGuy (thatbritguy (at) googlemail.com) on Fri Sep 15th, 2006 at 06:15:48 PM EST
[ Parent ]
If the target was the Pentagon (you know, the largest building on earth), it's not that impressive, unless you say that the pilot actually targetted the part where he actually hit.

The fact that he hit so low suggests that he almost missed the target, which is not surprising, as you point out.

In the long run, we're all dead. John Maynard Keynes

by Jerome a Paris (etg@eurotrib.com) on Fri Sep 15th, 2006 at 06:23:23 PM EST
[ Parent ]
It's not that simple. Come on - think this through.

The Pentagon may cover the biggest surface area of any building, but it's not particularly tall. In fact it only has four storeys, at maybe fifty feet. There's a scale photo from a recent study here. For comparison the tail fin on the 757 is just over 44ft.

Let's be conservative and say the approach speed is 300mph, or five miles a minute.

Let's say you're a minute away from your target at an altitude of a couple of thousand feet. How tall does a four storey building look five miles away at a shallow angle?

Fifteen seconds from impact, that four storey building is still more than a mile away.

Because I'm in a pedantic mood, I've worked out the visible width of the target corridor from a mile away. It's a little more than half a degree. And that's just to hit the damn thing at all, never mind score a bullseye on the ground floor.

Let's call it a degree if you assume that some overshoot into the body of the building still counts as a success. (And that's generous considering the actual shallow angle of approach.)

Unlike a car, which is fairly responsive, any altitude and pitch correction is going to take at least a few seconds to work itself through your brain, the avionics, the engines and flaps. Mostly likely you'll overshoot any correction and have to compensate in the other direction, which will eat further into your time allowance. What you certainly can't do is throw a 757 around the sky like a sports car.

Still, being even more generous, the reality is that if you're more than a few degrees out a mile away, you've already missed - by a long way.

As I said - impressive flying.

by ThatBritGuy (thatbritguy (at) googlemail.com) on Fri Sep 15th, 2006 at 07:25:08 PM EST
[ Parent ]
I doubt it's much harder to hit than a runway.

In the long run, we're all dead. John Maynard Keynes
by Jerome a Paris (etg@eurotrib.com) on Fri Sep 15th, 2006 at 07:27:32 PM EST
[ Parent ]
Hitting the ground floor is impressive only if the pilot was aiming at the ground floor.  

Do you if the pilot was aiming for the ground floor?

And if so ... how?

(Just being my usual amiable self  ;-)

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre

by ATinNM on Sat Sep 16th, 2006 at 12:33:40 AM EST
[ Parent ]
extremely good argument.  
by manon (m@gmail.com) on Fri Sep 15th, 2006 at 06:47:59 PM EST
[ Parent ]

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