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"Was 9/11 an 'Inside Job'?"


Guest James H. Fetzer

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THE 9/11 COMMISSION REPORT cites a pancake collapse in 10 seconds as a result of the

plane's hitting the buildings and the resulting fires. But that is ridiculous.

The 911 Commission report makes a single reference to a pancake collapse.

While they were doing so, the North tower began its pancake collapse

But the purpose of the 911 Commission wasn't to investigate the probable causes of the collapses of any of the buildings, that was NIST. From the 911 Commission preface:-

The law directed us to investigate “facts and circumstances relating to the terrorist attacks of September 11, 2001,” including those relating to intelligence agencies, law enforcement agencies, diplomacy, immigration issues and border control, the flow of assets to terrorist organizations, commercial aviation, the role of congressional oversight and resource allocation, and other areas determined relevant by the Commission.

Do you agree that it makes more sense to refer to the NIST report when characterising the nature of the "official position" of the collapses, rather than a single line in the 9/11 Commission report?

UL had certified the

steel to 2,000 degrees F for as long as four hours without weakening or melting, while NIST

examined 236 pieces of steel from the towers and found that 233 had not been exposed to heat

higher than 500 degrees F and the other three no higher than 1200 degrees F. Fires could have

burned forever at those temperatures and not affected the steel. Plus the fires in the South

Tower only burned around an hour and in the North about an hour and a half. The buildings were

enormous heat sinks, of course, so there was never any chance the steel could have weakened or

melted. In fact, there was an intense fire in the North Tower in 1975 that burned around 2,000

degrees F for four hours, but the steel did not weaken and the floor did not collapse, although

it was on the 11th floor and had the force of 99 floors pressing down, vastly more than in the

case of the North Tower (with 16 floors pressing down), much less the South (none pressing down).

I hope you have better arguments than this.

I'm not presenting arguments. I'm pointing out areas where I believe you've incorrectly represented the "offical position". You can only attack the "official position" if it is correctly represented, rather than a strawman.

In the meanwhile, since the buildings were destroyed below ground level, where did all those pancakes go? If not whole floors, then massive debris? Perhaps you will understand me better if you would view http://twilightpines.com/JF-BuenosAires/Buenos-Aires.html

Much of it collapsed into the basement levels, some of it was clearly visible above "ground floor".

I digress. The main thrust of my post was to try and point out where I think you've mis-represented the "offical position", in the hope that you will do so more accurately.

Take the claim that Flight 93 crashed into a mine-shaft. I've shown that the official position is that it crashed into a field (on the edge of a reclaimed strip mine). Do you agree that you haven't correctly stated the official position? If not, do you have a source for Flight 93 crashing into a mine-shaft? (I realise that probably isn't one of your main arguments, but it's useful to illustrate what I'm getting at).

Thanks.

Edited by Dave Greer
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So your site claims that the collapse of the Twin Towers took 13-14 seconds? And it also admits,

Despite the availability of video evidence establishing lower bounds of total collapse times of

over 13 seconds for each of the towers, assertions that they collapsed in under ten seconds are

widespread. Collapse times of eight to ten seconds are common not only in literature of the skeptics,

but also in publications promoting the official explanation. A Scientific American article about a

2001 public meeting of engineers on the MIT campus in Cambridge, MA gives a figure of nine seconds.

And as David Greer has explained, even NIST set the figures at 9 and 11 seconds, for an average of

10. But far more important than this attempt to read events beneath a cloud of dust is that neither

of the buildings "collapsed", from which it follows that none of those times represent the time that

it took for them to collapse. They were converted into millions of cubic yards of very fine dust,

as "New 9/11 Photos Released", http://jamesfetzer.blogspot.com/2010/02/new-911-photos-released.html, so dramatically displays.

No, there is a lot of misinformation out there. Notice I said the towers were destroyed in about

10 seconds, while he corrects me to say one fell in 9 and the other in 11 (9 + 11 + 20/2 = 10)!

Talk about splitting hairs! And I explicitly discuss the frames from the Pentagon cameras in my

Powerpoint presentation at http://twilightpines.com/JF-BuenosAires/Buenos-Aires.html It's hard to show what you are

talking about in written words when so much of the evidence is photographic, as I also explain.

A truther site that shows the towers took considerably LONGER than 10 seconds each to collapse

http://911review.com/errors/wtc/times.html

How is that site misinformation?

First, not "my site". A site. I happen to agree with that conclusion but I am in no way affiliated with the site, nor do I agree with everything presented.

How does that answer my question? How is the site I posted which breaks the collapse down into half second intervals and clearly shows that they each took at least 13 seconds misinformation? I didn't ask about what other sites and sources may say.

And Dave Greer did NOT say that NIST said the collapses were 9 and 11 seconds, nor did NIST. They said the first exterior panels hit the ground in that time. That says NOTHING about how long the total collapse took.

Still wondering why YOU would claim the collapses took 10 seconds when the available evidence shows otherwise.

Edited by Matthew Lewis
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Guest James H. Fetzer

Well, the official account has the plane just barely skimming the grass as it approaches the Pentagon, even

taking out lampposts on its trajectory. This is quite absurd, of course, since the effects of a plane flying at

500 mph hitting a stationary lamppost would be the same as a lamppost flying at 500 mph hitting a stationary

plane. If you know the damage that can be inflicted on a plane by a tiny bird, you may begin to appreciate

this point. The wing, loaded with fuel, would have exploded in flames and the plane's trajectory would have

been affected. Plus at the speed of 500 mph, it could not have come closer than about 60 feet to the ground,

so the trajectory was not even aerodynamically possible. Check with pilots and aeronautical engineers, with

whom I have discussed all of this. In fact, Pilots obtained data from the NTSB that it insisted came from the

recorder for Flight 77, which had the plane on a different approach and far too high to hit any lampposts and

did not even impact the building. Check out Pilots for 9/11 Truth for their study of the government's own data.

In "What Didn't Happen at the Pentagon", I make many points that I did not make in the summary overview.

Just want to clarify something here

does this

The aerodynamics of flight would have made the official trajectory—flying at high speed barely above ground level—physically impossible, because a Boeing 757 flying over 500 mph could not have come closer than about 60 feet of the ground, which means that the official account is not even aerodynamically possible.

refer to ground effect? If so, it was pointed out in another thread that ground effect decreases with speed. It also decreases as the angle of attack decreases (or vice versa) and the impact would have been at a negative angle of attack. Both of these mean that ground effect would have been negligible. What do you think about those facts?

Edited by James H. Fetzer
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Well, the official account has the plane just barely skimming the grass as it approaches the Pentagon, even

taking out lampposts on its trajectory. This is quite absurd, of course, since the effects of a plane flying at

500 mph hitting a stationary lamppost would be the same as a lamppost flying at 500 mph hitting a stationary

plane. If you know the damage that can be inflicted on a plane by a tiny bird, you may being to appreciate

this point. The wing, loaded with fuel, would have exploded in flames and the plane's trajectory would have

been affected. Plus at the speed of 500 mph, it could not have come closer than about 60 feet to the ground,

so the trajectory was not even aerodynamically possible. Check with pilots and aeronautical engineers, with

whom I have discussed all of this. In fact, Pilots obtained data from the NTSB that it insisted came from the

recorder for Flight 77, which had the plane on a different approach and far too high to hit any lampposts and

did not even impact the building. Check out Pilots for 9/11 Truth for their study of the government's own data.

In "What Didn't Happen at the Pentagon", I make many points that I did not make in the summary overview.

Just want to clarify something here

does this

The aerodynamics of flight would have made the official trajectory—flying at high speed barely above ground level—physically impossible, because a Boeing 757 flying over 500 mph could not have come closer than about 60 feet of the ground, which means that the official account is not even aerodynamically possible.

refer to ground effect? If so, it was pointed out in another thread that ground effect decreases with speed. It also decreases as the angle of attack decreases (or vice versa) and the impact would have been at a negative angle of attack. Both of these mean that ground effect would have been negligible. What do you think about those facts?

You didn't even answer my questions. I don't CARE about light posts, trajectory, or the data recorder. I didn't mention them. Please try to stay on topic. I asked if YOUR STATEMENT was referring to ground effect and stated that if so then according to rules of aerodynamics that ground effect would be negligible. So again, does your statement refer to ground effect? What do you think about the FACTS that show that ground effect would be negligible at high speed and a low angles of attack?

Ground effect is caused by induced drag which is highest at low speeds and high angles of attack. At high speeds and low angles of attack, induced drag and therefore ground effect, is negligible.

http://www.aerospaceweb.org/question/conspiracy/q0274.shtml

http://www.faatest.com/books/FLT/Chapter17/GroundEffect.htm

http://www.allstar.fiu.edu/aero/airflylvl3.htm

http://en.wikipedia.org/wiki/Ground_effect_in_aircraft

Edited by Matthew Lewis
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Guest James H. Fetzer

THE 9/11 COMMISSION REPORT states (on page 305), "At 9:58:59, the South Tower collapsed

in ten seconds, killing all civilians and emergency personnel inside, as well as [others] . . . ." Now,

why do you suppose anyone would believe that the buildings collapsed in about ten second each?

But, of course, and far more importantly, THEY DID NOT COLLAPSE AT ALL but were converted

into millions of cubic yards of very fine dust, as I have already explained and also demonstrated.

So your site claims that the collapse of the Twin Towers took 13-14 seconds? And it also admits,

Despite the availability of video evidence establishing lower bounds of total collapse times of

over 13 seconds for each of the towers, assertions that they collapsed in under ten seconds are

widespread. Collapse times of eight to ten seconds are common not only in literature of the skeptics,

but also in publications promoting the official explanation. A Scientific American article about a

2001 public meeting of engineers on the MIT campus in Cambridge, MA gives a figure of nine seconds.

And as David Greer has explained, even NIST set the figures at 9 and 11 seconds, for an average of

10. But far more important than this attempt to read events beneath a cloud of dust is that neither

of the buildings "collapsed", from which it follows that none of those times represent the time that

it took for them to collapse. They were converted into millions of cubic yards of very fine dust,

as "New 9/11 Photos Released", http://jamesfetzer.blogspot.com/2010/02/new-911-photos-released.html, so dramatically displays.

No, there is a lot of misinformation out there. Notice I said the towers were destroyed in about

10 seconds, while he corrects me to say one fell in 9 and the other in 11 (9 + 11 + 20/2 = 10)!

Talk about splitting hairs! And I explicitly discuss the frames from the Pentagon cameras in my

Powerpoint presentation at http://twilightpines.com/JF-BuenosAires/Buenos-Aires.html It's hard to show what you are

talking about in written words when so much of the evidence is photographic, as I also explain.

A truther site that shows the towers took considerably LONGER than 10 seconds each to collapse

http://911review.com/errors/wtc/times.html

How is that site misinformation?

First, not "my site". A site. I happen to agree with that conclusion but I am in no way affiliated with the site, nor do I agree with everything presented.

How does that answer my question? How is the site I posted which breaks the collapse down into half second intervals and clearly shows that they each took at least 13 seconds misinformation? I didn't ask about what other sites and sources may say.

And Dave Greer did NOT say that NIST said the collapses were 9 and 11 seconds, nor did NIST. They said the first exterior panels hit the ground in that time. That says NOTHING about how long the total collapse took.

Still wondering why YOU would claim the collapses took 10 seconds when the available evidence shows otherwise.

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Guest James H. Fetzer

The plane was just skimming the ground as the purported trajectory, which included hitting a series of

lampposts--are you unaware of the official trajectory?--and at 500 mph would have had sufficient ground

effect that it could not have come closer than about one wing length (about 60 feet for a 757 with a wing

span of 125 feet) to the ground. Among those with whom I have discussed this is a pilot and aeronautical

engineer, Nila Sagadevan, where additional confirmation can be found on the site of Pilots for 9/11 Truth.

Without understanding that the plane was purportedly flying just above ground level for a considerable

horizontal distance, of course, you could argue about "angles of attack". But it was on a flat trajectory.

Indeed, if you check it, Pilots concluded the whole Pentagon attack scenario is ridiculous aerodynamically.

Well, the official account has the plane just barely skimming the grass as it approaches the Pentagon, even

taking out lampposts on its trajectory. This is quite absurd, of course, since the effects of a plane flying at

500 mph hitting a stationary lamppost would be the same as a lamppost flying at 500 mph hitting a stationary

plane. If you know the damage that can be inflicted on a plane by a tiny bird, you may being to appreciate

this point. The wing, loaded with fuel, would have exploded in flames and the plane's trajectory would have

been affected. Plus at the speed of 500 mph, it could not have come closer than about 60 feet to the ground,

so the trajectory was not even aerodynamically possible. Check with pilots and aeronautical engineers, with

whom I have discussed all of this. In fact, Pilots obtained data from the NTSB that it insisted came from the

recorder for Flight 77, which had the plane on a different approach and far too high to hit any lampposts and

did not even impact the building. Check out Pilots for 9/11 Truth for their study of the government's own data.

In "What Didn't Happen at the Pentagon", I make many points that I did not make in the summary overview.

Just want to clarify something here

does this

The aerodynamics of flight would have made the official trajectory—flying at high speed barely above ground level—physically impossible, because a Boeing 757 flying over 500 mph could not have come closer than about 60 feet of the ground, which means that the official account is not even aerodynamically possible.

refer to ground effect? If so, it was pointed out in another thread that ground effect decreases with speed. It also decreases as the angle of attack decreases (or vice versa) and the impact would have been at a negative angle of attack. Both of these mean that ground effect would have been negligible. What do you think about those facts?

You didn't even answer my questions. I don't CARE about light posts, trajectory, or the data recorder. I didn't mention them. Please try to stay on topic. I asked if YOUR STATEMENT was referring to ground effect and stated that if so then according to rules of aerodynamics that ground effect would be negligible. So again, does your statement refer to ground effect? What do you think about the FACTS that show that ground effect would be negligible at high speed and a low angles of attack?

Edited by James H. Fetzer
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All I asked for is where it says it collapsed in 10 seconds. The rest is superfluous. 10 seconds is OBVIOUSLY wrong. So why accept it? Especially when it is in the official report and you reject the official report?

THE 9/11 COMMISSION REPORT states (on page 305), "At 9:58:59, the South Tower collapsed

in ten seconds, killing all civilians and emergency personnel inside, as well as [others] . . . ." Now,

why do you suppose anyone would believe that the buildings collapsed in about ten second each?

But, of course, and far more importantly, THEY DID NOT COLLAPSE AT ALL but were converted

into millions of cubic yards of very fine dust, as I have already explained and also demonstrated.

So your site claims that the collapse of the Twin Towers took 13-14 seconds? And it also admits,

Despite the availability of video evidence establishing lower bounds of total collapse times of

over 13 seconds for each of the towers, assertions that they collapsed in under ten seconds are

widespread. Collapse times of eight to ten seconds are common not only in literature of the skeptics,

but also in publications promoting the official explanation. A Scientific American article about a

2001 public meeting of engineers on the MIT campus in Cambridge, MA gives a figure of nine seconds.

And as David Greer has explained, even NIST set the figures at 9 and 11 seconds, for an average of

10. But far more important than this attempt to read events beneath a cloud of dust is that neither

of the buildings "collapsed", from which it follows that none of those times represent the time that

it took for them to collapse. They were converted into millions of cubic yards of very fine dust,

as "New 9/11 Photos Released", http://jamesfetzer.blogspot.com/2010/02/new-911-photos-released.html, so dramatically displays.

No, there is a lot of misinformation out there. Notice I said the towers were destroyed in about

10 seconds, while he corrects me to say one fell in 9 and the other in 11 (9 + 11 + 20/2 = 10)!

Talk about splitting hairs! And I explicitly discuss the frames from the Pentagon cameras in my

Powerpoint presentation at http://twilightpines.com/JF-BuenosAires/Buenos-Aires.html It's hard to show what you are

talking about in written words when so much of the evidence is photographic, as I also explain.

A truther site that shows the towers took considerably LONGER than 10 seconds each to collapse

http://911review.com/errors/wtc/times.html

How is that site misinformation?

First, not "my site". A site. I happen to agree with that conclusion but I am in no way affiliated with the site, nor do I agree with everything presented.

How does that answer my question? How is the site I posted which breaks the collapse down into half second intervals and clearly shows that they each took at least 13 seconds misinformation? I didn't ask about what other sites and sources may say.

And Dave Greer did NOT say that NIST said the collapses were 9 and 11 seconds, nor did NIST. They said the first exterior panels hit the ground in that time. That says NOTHING about how long the total collapse took.

Still wondering why YOU would claim the collapses took 10 seconds when the available evidence shows otherwise.

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Come on, Dave! The claim is that Flight 93 "disappeared" because it crashed into an abandoned mine shaft (or, if you

prefer, a close facsimile)! I don't mind your asking, if you are serious in your intent.

Your initial claim was that they should have carried on digging to look for survivors because the official government position was that it crashed into a mine shaft. But that isn't the official position. The official position is that it crashed, nose first, at 580mph, into a field. That field was at the edge of a reclaimed strip-mine. The plane did not crash into a mine shaft. If someone takes issue with the "official position", do you agree that it is incumbent upon that person to state the "official position" correctly, rather than ambiguously (at best), or completely incorrectly (at worst)?

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Guest James H. Fetzer

If you know the score, you know that NIST had to exaggerate the sag in the trusses ten times

more than their data supported to create the conditions for any kind of "collapse". Even then,

it did not model the collapse sequence. And the fires did not burn hot enough or long enough

to cause the trusses to sag in the first place. Either you are serious about all this or you are

not. Either you know enough to make serious arguments or you are not. I think I know which.

THE 9/11 COMMISSION REPORT cites a pancake collapse in 10 seconds as a result of the

plane's hitting the buildings and the resulting fires. But that is ridiculous.

The 911 Commission report makes a single reference to a pancake collapse.

While they were doing so, the North tower began its pancake collapse

But the purpose of the 911 Commission wasn't to investigate the probable causes of the collapses of any of the buildings, that was NIST. From the 911 Commission preface:-

The law directed us to investigate “facts and circumstances relating to the terrorist attacks of September 11, 2001,” including those relating to intelligence agencies, law enforcement agencies, diplomacy, immigration issues and border control, the flow of assets to terrorist organizations, commercial aviation, the role of congressional oversight and resource allocation, and other areas determined relevant by the Commission.

Do you agree that it makes more sense to refer to the NIST report when characterising the nature of the "official position" of the collapses, rather than a single line in the 9/11 Commission report?

UL had certified the

steel to 2,000 degrees F for as long as four hours without weakening or melting, while NIST

examined 236 pieces of steel from the towers and found that 233 had not been exposed to heat

higher than 500 degrees F and the other three no higher than 1200 degrees F. Fires could have

burned forever at those temperatures and not affected the steel. Plus the fires in the South

Tower only burned around an hour and in the North about an hour and a half. The buildings were

enormous heat sinks, of course, so there was never any chance the steel could have weakened or

melted. In fact, there was an intense fire in the North Tower in 1975 that burned around 2,000

degrees F for four hours, but the steel did not weaken and the floor did not collapse, although

it was on the 11th floor and had the force of 99 floors pressing down, vastly more than in the

case of the North Tower (with 16 floors pressing down), much less the South (none pressing down).

I hope you have better arguments than this.

I'm not presenting arguments. I'm pointing out areas where I believe you've incorrectly represented the "offical position". You can only attack the "official position" if it is correctly represented, rather than a strawman.

In the meanwhile, since the buildings were destroyed below ground level, where did all those pancakes go? If not whole floors, then massive debris? Perhaps you will understand me better if you would view http://twilightpines.com/JF-BuenosAires/Buenos-Aires.html

Much of it collapsed into the basement levels, some of it was clearly visible above "ground floor".

I digress. The main thrust of my post was to try and point out where I think you've mis-represented the "offical position", in the hope that you will do so more accurately.

Take the claim that Flight 93 crashed into a mine-shaft. I've shown that the official position is that it crashed into a field (on the edge of a reclaimed strip mine). Do you agree that you haven't correctly stated the official position? If not, do you have a source for Flight 93 crashing into a mine-shaft? (I realise that probably isn't one of your main arguments, but it's useful to illustrate what I'm getting at).

Thanks.

Edited by James H. Fetzer
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The plane was just skimming the ground as the purported trajectory, which included hitting a series of

lampposts--are you unaware of the official trajectory?--and at 500 mph would have had sufficient ground

effect that it could not have come closer than about one wing length (about 60 feet for a 757 with a wing

span of 125 feet) to the ground. Among those with whom I have discussed this is a pilot and aeronautical

engineer, Nila Sagadevan, where additional confirmation can be found on the site of Pilots for 9/11 Truth.

Without understanding that the plane was purportedly flying just above ground level for a considerable

horizontal distance, of course, you could argue about "angles of attack". But it was on a flat trajectory.

Indeed, if you check it, Pilots concluded the whole Pentagon attack scenario is ridiculous aerodynamically.

You didn't even answer my questions. I don't CARE about light posts, trajectory, or the data recorder. I didn't mention them. Please try to stay on topic. I asked if YOUR STATEMENT was referring to ground effect and stated that if so then according to rules of aerodynamics that ground effect would be negligible. So again, does your statement refer to ground effect? What do you think about the FACTS that show that ground effect would be negligible at high speed and a low angles of attack?

I am a pilot. I have experienced ground effect for myself and know when it does and does not occur. I also have a degree in aviation. Another pilot on this board has also weighed in. I am aware of the trajectory and the lamp posts but that is NOT what I am talking about. I have asked twice if your statement is specifically referring to ground effect and you have until now failed to give a clear answer. I say that it is WRONG that ground effect would cause the trajectory to be impossible for the reasons that I have already stated. Aeronautical science shows this.

A flat trajectory would NOT be a high angle of attack. It would be low or more likely zero. Yet again showing that ground effect would be reduced and NOT a factor.

Edited by Matthew Lewis
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But, of course, and far more importantly, THEY DID NOT COLLAPSE AT ALL but were converted

into millions of cubic yards of very fine dust, as I have already explained and also demonstrated.

Jim, with respect, I'm going to find it very hard to maintain any kind of reasoned debate with someone who holds an opinion like that. The towers didn't collapse, but turned to dust? I'm going to withdraw from this debate there is clearly nothing further left for me to say.

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Guest James H. Fetzer

Come on, Dave! If it didn't crash into an abandoned mine shaft, THEN WHERE IT IS? Crashing

into a field won't cut it. Haven't you looked at videos of the purported "crash site", Dave? You

are grasping after straws. When did they bring out the bright lights and heavy equipment,

Dave? You are making yourself look silly by trying to make something out of trivial points.

In fact, if it didn't disappear into a mine shaft, then the official position is that much worse off.

Come on, Dave! The claim is that Flight 93 "disappeared" because it crashed into an abandoned mine shaft (or, if you

prefer, a close facsimile)! I don't mind your asking, if you are serious in your intent.

Your initial claim was that they should have carried on digging to look for survivors because the official government position was that it crashed into a mine shaft. But that isn't the official position. The official position is that it crashed, nose first, at 580mph, into a field. That field was at the edge of a reclaimed strip-mine. The plane did not crash into a mine shaft. If someone takes issue with the "official position", do you agree that it is incumbent upon that person to state the "official position" correctly, rather than ambiguously (at best), or completely incorrectly (at worst)?

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Guest James H. Fetzer

Well, that's probably wise of you. If you are that unfamiliar with the gross observable evidence,

which I have cited several times, then you are obviously incompetent to discuss the Twin Towers:

http://jamesfetzer.blogspot.com/2010/02/new-911-photos-released.html I thought that you were ignorant, but just not this massively.

You really should watch my Buenos Aires Powerpoint to get yourself up-to-speed about all of this.

But, of course, and far more importantly, THEY DID NOT COLLAPSE AT ALL but were converted

into millions of cubic yards of very fine dust, as I have already explained and also demonstrated.

Jim, with respect, I'm going to find it very hard to maintain any kind of reasoned debate with someone who holds an opinion like that. The towers didn't collapse, but turned to dust? I'm going to withdraw from this debate there is clearly nothing further left for me to say.

Edited by James H. Fetzer
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Guest James H. Fetzer

Matt, I could tell you thought you had some special competence in this area. But as I understand it--

with which you are of course in disagreement--the compressed gas beneath the fuselage and wings of a

commercial carrier flying near the ground at high speed would make it impossible to get closer to the

ground than about a wing's length. Planes are only able to land because they decrease their airspeed

and the packet of compressed gas diminishes, which of course is what happens in normal fight. Now if

Nila was wrong in his explanation to me at LAX in June 2006, then I may be mistaken. But he is very

competent and I have no reason to suppose that I am wrong, with due respect to you and your buddy.

Of course, it a plane were not flying on the horizontal, the situation would be different, which was

why you wanted to disregard the horizontal flight trajectory. Pilots has also observed the alleged

flight path in coming down out of the spectacular turn attributed to the plane before it made its "final

approach" would also have been impossible because of the g-forces involved, but that's another matter.

I think my understanding is consistent with http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml, but no doubt there are

more complex ways to explain it. That is how I have understood "ground effect" to function from Nila.

It would have been impossible to fly just skimming the ground on a horizontal approach at 500 mph.

The plane was just skimming the ground as the purported trajectory, which included hitting a series of

lampposts--are you unaware of the official trajectory?--and at 500 mph would have had sufficient ground

effect that it could not have come closer than about one wing length (about 60 feet for a 757 with a wing

span of 125 feet) to the ground. Among those with whom I have discussed this is a pilot and aeronautical

engineer, Nila Sagadevan, where additional confirmation can be found on the site of Pilots for 9/11 Truth.

Without understanding that the plane was purportedly flying just above ground level for a considerable

horizontal distance, of course, you could argue about "angles of attack". But it was on a flat trajectory.

Indeed, if you check it, Pilots concluded the whole Pentagon attack scenario is ridiculous aerodynamically.

You didn't even answer my questions. I don't CARE about light posts, trajectory, or the data recorder. I didn't mention them. Please try to stay on topic. I asked if YOUR STATEMENT was referring to ground effect and stated that if so then according to rules of aerodynamics that ground effect would be negligible. So again, does your statement refer to ground effect? What do you think about the FACTS that show that ground effect would be negligible at high speed and a low angles of attack?

I am a pilot. I have experienced ground effect for myself and know when it does and does not occur. I also have a degree in aviation. Another pilot on this board has also weighed in. I am aware of the trajectory and the lamp posts but that is NOT what I am talking about. I have asked twice if your statement is specifically referring to ground effect and you have until now failed to give a clear answer. I say that it is WRONG that ground effect would cause the trajectory to be impossible for the reasons that I have already stated. Aeronautical science shows this.

A flat trajectory would NOT be a high angle of attack. It would be low or more likely zero. Yet again showing that ground effect would be reduced and NOT a factor.

Edited by James H. Fetzer
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Matt, I could tell you thought you had some special competence in this area. But as I understand it--

with which you are of course in disagreement--the compressed gas beneath the fuselage and wings of a

commercial carrier flying near the ground at high speed would make it impossible to get closer to the

ground than about a wing's length. Planes are only able to land because they decrease their airspeed

and the packet of compressed gas diminishes, which of course is what happens in normal fight. Now if

Nila was wrong in his explanation to me at LAX in June 2006, then I may be mistaken. But he is very

competent and I have no reason to suppose that I am wrong, with due respect to you and your buddy.

The compressed air explanation of ground effect is wrong as shown on the references I previously posted. Even if it wasn't, it still wouldn't change the FACT that ground effect DECREASES as speed INCREASES

These quotes specifically

First of all, there is no bubble of air that pushes an aircraft away from the ground. The true cause of ground effect is the influence of the ground on the wing's angle of attack as described above. Ground effect does nothing to force an aircraft upward from the ground, it only changes the relative amount of lift and drag that a wing will generate at a given speed and angle of attack. Second, we have seen that this effect actually decreases with speed since induced drag has increasingly less influence on an aircraft the faster it flies.
This dependency is rather simple to remember--if speed is high, angle of attack is low. If speed is low, angle of attack must be high. Furthermore, when angle of attack is low, we have seen that induced drag is also low. If induced drag is low, the downwash generated by the wing must be small. If downwash is small, then the trailing vortices must be relatively narrow in diameter. If the trailing vortices are narrow, then the proximity of the ground can have little effect on their formation and ground effect will be minimal by definition.

And this quote which explains Nila

Another common phenomenon that is misunderstood is that of ground effect. That is the increased efficiency of a wing when flying within a wing length of the ground. A low-wing airplane will experience a reduction in drag by 50% just before it touches down. There is a great deal of confusion about ground effect. Many pilots (and the FAA VFR Exam-O-Gram No. 47) mistakenly believe that ground effect is the result of air being compressed between the wing and the ground.

And this graphic

lift-curve.gif

Notice specifically how ground effect (and lift itself) is less with lower angles of attack

Of course, it a plane were not flying on the horizontal, the situation would be different, which was

why you wanted to disregard the horizontal flight trajectory.

No, if you had noticed I said a horizontal trajectory would mean a LOW or ZERO angle of attack which supports me.

I think my understanding is consistent with http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml, but no doubt there are

more complex ways to explain it. That is how I have understood "ground effect" to function from Nila.

It would have been impossible to fly just skimming the ground on a horizontal approach at 500 mph.

Even though that site says this?

"there is no "cushion of air" holding the plane up and making it "float." "

It in no way indicates that it would impossible to fly horizontal at high speeds.

Edited by Matthew Lewis
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