My First Ever Banning

[KoihimeNakamura]

[SIZE=-1]United Airline Flight 175 struck the south face of WTC 2 near the 80th floor with an estimated speed of. 545 mph ± 18 mph. Intense fireballs then formed on ...
www.fire.nist.gov/bfrlpubs/fire05/PDF/f05173.pdf

I don't see 570. Am I blind or someting?
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[rwguinn]

I don't see 570. Am I blind or someting?
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Well, he didn't mean that Literally

 

[Hokulele]

The Boeing 767-200 is rated for a cruising speed of 530 mph and maximum speed of 568 mph (at 35,000 ft.)

568 mph is the maximum cruising speed at that altitude. The max specification speed for a 767-200 is 592 mph.

 

[jaydeehess]

568 mph is the maximum cruising speed at that altitude. The max specification speed for a 767-200 is 592 mph.

Oddly enough it seems that the guys at the controls were quite the scoff-laws concerning the safe operation of the aircraft they had commandeered and were pushing them to the limits of their velocity without regard as to what effect this might have on the engines or airframe................

 

[jaydeehess]

Currently I'm interested in the more important issue of how NIST tweaks model parameters to achieve predetermined results ie. collapse initiation.

Wow, I never saw any of that in the NIST report and I did read quite a bit of it.

They did run their simulations several times, changing parameters of the aircraft impacts and compared the sim results against what could be determined to have actually occurred as per the photographic and video record of the damage inflicted on the buildings.

 

[PhantomWolf]

Oddly enough it seems that the guys at the controls were quite the scoff-laws concerning the safe operation of the aircraft they had commandeered and were pushing them to the limits of their velocity without regard as to what effect this might have on the engines or airframe................

Most aerospace engineers I have heard discussing it think that the airframe of 175 would have been seriously damaged by the turn it did to hit WTC 2 and that had it missed, they would have been in an unrecoverable stall so would have crashed anyways. Very safe flying that.

 

[R.Mackey]

Well when I get time I'll take a look at how you explain your belief that the unspent fuel had sufficient kinetic energy to wreak havoc on core columns.

Still refusing to answer my question, eh? Disappointing, but not surprising.

Tell you what: If I show you again how you don't have the foggiest idea what you're talking about, will you go away? Or at least ask for help, rather than stamping your feet and calling attention to your mistakes?

I'll give this one last try.

The supposed justification for this disparity is because in the computer modeled severe case simulation, NIST gave the 767-200 a speed of 570 mph which gave it greater momentum and kinetic energy. They also said they tweaked their models but stayed within reality.

If NIST is being so honest and scientifically realistic in the numbers they use, how can you condone their extreme, and I do mean extreme use of aircraft speed to create the necessary damage to make their collapse initiation hypothesis work?

Fine, let's talk about honesty.

For starters, NIST states their estimate of Flight 175's impact speed, given in Table 6-3 of NIST NCSTAR1-2, as 542 MPH +/- 24. Table 6-2 gives the individual results from single videos, seen to span from 523 +/- 31 to 573 +/- 55 MPH, and this overlaps Dr. Kausel's result. However, 546 MPH appears as the baseline figure in the actual model, for reasons given explicitly by NIST on page 158:

Initial results from the simplified motion analysis produced a mean speed for UAL 175 of 546 mph. This speed was therefore used in the global impact analysis, discussed in Chapter 7. Subsequent refinement of the analysis and associated uncertainties produced the slightly lower mean value of 542 mph as discussed above. Since this difference in speed was less than 1 percent and well within the uncertainty range, the speed used for the impact analysis was not modified.

What does this mean? It means that their "extreme" case wasn't extreme at all, but within the bounds of uncertainty, as supported by the evidence. Your comment is nothing but hyperbole.

NIST further comments directly on Dr. Kausel's results, same report, page 165, and explains not only that the report you happen to have cherry-picked is an outlier, but further identifies a likely cause of the discrepancy:

Table 6–7 compares the results of the various motion analyses for the UAL 175 impact. The Hart-Weidlinger and the analyses presented here were consistent with the exception of the lateral approach angle. The MIT estimates of impact speed were low compared to the other analyses. However, assuming a lateral approach angle of 20 degrees would have increased the MIT estimate of the UAL 175 impact speed to about 524 mph. The simplified analysis (NIST NCSTAR 1-5A) yielded a speed that was very close to that obtained in this study.

Now on to your other amateur, misleading, and inaccurate points:

A few facts which I'm sure you are well aware of;

The Boeing 767-200 is rated for a cruising speed of 530 mph and maximum speed of 568 mph (at 35,000 ft.).

I am aware. I am also aware that the design speed is not the true upper limit the vehicle is capable of. My automobile is designed for a cruising speed of 100 kph, but will easily do more than double that.

In their less severe case NIST used 521 mph and in their baseline they used 546 mph. NIST was still using numbers that exceeded the careful analysis of MIT's Professor Kausel. Unfortunately for NIST, those numbers failed to create a collapse initiation so they tweaked the speed upwards until they found a number that would achieve their desired expectations. The magic number turned out to be 570 mph to achieve collapse initiation success.

Multiple fallacies here.

First, NIST's numbers are consistent with Dr. Kausel's, albeit slightly higher. Both numbers contain large uncertainties. Dr. Kausel was unable to adequately estimate experimental error, as he did not know the locations of observers, was unable to obtain original videos, and could not always account for speedups or format changes of his inputs. Parallax, frame-per-second differences in videos, and motion of the camera as it tracked the aircraft are all large contributors to his error, as NIST noted and I have demonstrated above. Dr. Kausel, who unlike you is a responsible scientist, even identifies this in his paper:

Pitfalls in determining the speed from videos
The velocity of the two Boeing 767-200 planes that were crashed onto the Twin Towers is not precisely known, especially the speed of the North Tower plane. The speed calculations are made more complicated by the following facts:

• The original format in which the videos were recorded is not only unknown to me, but they were also converted back and forth (once or twice) between the American NTSC format and the British PAL system. These two video standards differ in various aspects, which include the number of frames displayed each second and the screen resolution. ...
• Some of the videos include running time counters or indices.
• Many of the videos have clearly been slowed down by a factor of perhaps two or three, in order to show in more impressive detail the incoming planes immediately before collision. ...
• The filming position was generally not known to me, a situation that introduced an unknown degree of geometric perspective or parallax effect. However, in most cases these recording positions appeared to have been sufficiently distant from the target that the parallax effect could safely be disregarded.
• In many videos, the camera either panned or zoomed into the target (or both), a situation that greatly complicates the determination of flight distances.

Second, NIST did not run cases until they achieved collapse initiation. The "more severe" case, which included the 570 MPH initial condition, was selected on the basis of impact model results which most closely matched observation just after impact. I've corrected this bald-faced lie of yours endlessly in the other thread.

Third, the NIST number wasn't "tweaked" at all. It represents the reasonable "one-sigma" upper bound given uncertainties in the measurements. It is an entirely reasonable choice of input.

Fourth, as NIST explained before, the dominant factor in damage assessment is the angle of impact, not the speed. This is partly why WTC 1 collapsed in a manner similar to WTC 2, even though Flight 11 impacted at a mere 443 MPH +/- 30, which is well below even the lower number you argue for here. This fact also demonstrates that, unlike your claims, the lower impact speeds might very well have led to a collapse.

NIST says this was within reality, even though their computer model now is being made to simulate a 767 at 1,000 ft in heavy air, tweaked to fly 12 mph faster than the 767-200's maximum speed at 35,000 feet where air is extremely thin and offers little air speed resistance.

767's are not drag-limited. They are control-limited.

Care to comment?

At this point, I am not sure any further conversation with you is warranted, given that you clearly lack all of the requisite technical background to even cite papers adequately.

And you still haven't answered my question. I don't understand what you're afraid of.

 

[aggle-rithm]

Still refusing to answer my question, eh? Disappointing, but not surprising.

Tell you what: If I show you again how you don't have the foggiest idea what you're talking about, will you go away? Or at least ask for help, rather than stamping your feet and calling attention to your mistakes?

I'll give this one last try.



Fine, let's talk about honesty.

For starters, NIST states their estimate of Flight 175's impact speed, given in Table 6-3 of NIST NCSTAR1-2, as 542 MPH +/- 24. Table 6-2 gives the individual results from single videos, seen to span from 523 +/- 31 to 573 +/- 55 MPH, and this overlaps Dr. Kausel's result. However, 546 MPH appears as the baseline figure in the actual model, for reasons given explicitly by NIST on page 158:



What does this mean? It means that their "extreme" case wasn't extreme at all, but within the bounds of uncertainty, as supported by the evidence. Your comment is nothing but hyperbole.

NIST further comments directly on Dr. Kausel's results, same report, page 165, and explains not only that the report you happen to have cherry-picked is an outlier, but further identifies a likely cause of the discrepancy:



Now on to your other amateur, misleading, and inaccurate points:


I am aware. I am also aware that the design speed is not the true upper limit the vehicle is capable of. My automobile is designed for a cruising speed of 100 kph, but will easily do more than double that.



Multiple fallacies here.

First, NIST's numbers are consistent with Dr. Kausel's, albeit slightly higher. Both numbers contain large uncertainties. Dr. Kausel was unable to adequately estimate experimental error, as he did not know the locations of observers, was unable to obtain original videos, and could not always account for speedups or format changes of his inputs. Parallax, frame-per-second differences in videos, and motion of the camera as it tracked the aircraft are all large contributors to his error, as NIST noted and I have demonstrated above. Dr. Kausel, who unlike you is a responsible scientist, even identifies this in his paper:



Second, NIST did not run cases until they achieved collapse initiation. The "more severe" case, which included the 570 MPH initial condition, was selected on the basis of impact model results which most closely matched observation just after impact. I've corrected this bald-faced lie of yours endlessly in the other thread.

Third, the NIST number wasn't "tweaked" at all. It represents the reasonable "one-sigma" upper bound given uncertainties in the measurements. It is an entirely reasonable choice of input.

Fourth, as NIST explained before, the dominant factor in damage assessment is the angle of impact, not the speed. This is partly why WTC 1 collapsed in a manner similar to WTC 2, even though Flight 11 impacted at a mere 443 MPH +/- 30, which is well below even the lower number you argue for here. This fact also demonstrates that, unlike your claims, the lower impact speeds might very well have led to a collapse.



767's are not drag-limited. They are control-limited.



At this point, I am not sure any further conversation with you is warranted, given that you clearly lack all of the requisite technical background to even cite papers adequately.

And you still haven't answered my question. I don't understand what you're afraid of.

It's exactly this type of reckless fact-wielding that gets people banned at CT forums!

(Like how I got us back on topic?)

 

[Miragememories]

Fine, let's talk about honesty.

For starters, NIST states their estimate of Flight 175's impact speed, given in Table 6-3 of NIST NCSTAR1-2, as 542 MPH +/- 24. Table 6-2 gives the individual results from single videos, seen to span from 523 +/- 31 to 573 +/- 55 MPH, and this overlaps Dr. Kausel's result. However, 546 MPH appears as the baseline figure in the actual model, for reasons given explicitly by NIST on page 158:

The numbers NIST decided to use, are what is really important.

These are the numbers that NIST used;

NIST's Table9-10. Input parameters for additional WTC 2 global impact analyses.
Base Case 546 mph plain and simple.
Less Severe 521 mph
More Severe 570 mph

I'm most concerned with the 570 mph used for obvious reasons.
Not only does it well exceed Dr. Kausel's meticulous calculations which arrive at a figure of 503 mph, but he found this calculation to be in "excellent agreement with information from air traffic controllers".

Given the importance of a large projectile's mass and speed, NIST heavily relied on their 570 mph Flight Parameter to achieve collapse initiation.

Originally Posted by NIST NCSTAR1-2, page 158
Initial results from the simplified motion analysis produced a mean speed for UAL 175 of 546 mph. This speed was therefore used in the global impact analysis, discussed in Chapter 7. Subsequent refinement of the analysis and associated uncertainties produced the slightly lower mean value of 542 mph as discussed above. Since this difference in speed was less than 1 percent and well within the uncertainty range, the speed used for the impact analysis was not modified.

What does this mean? It means that their "extreme" case wasn't extreme at all, but within the bounds of uncertainty, as supported by the evidence. Your comment is nothing but hyperbole.

NIST further comments directly on Dr. Kausel's results, same report, page 165, and explains not only that the report you happen to have cherry-picked is an outlier, but further identifies a likely cause of the discrepancy:

In the bounds of NIST's chosen uncertainty!

"Bounds of uncertainty", is a convenient engineering means of saying "realm of possibility". They are using the "+" side of a +/- error factor to validate the credibility of an upper number. They are using the "-" side of a +/- error factor to validate the credibility of their number of with more accurate estimates, like Dr. Kausel's.

My statement was not hyperbole! NIST used 570 mph as stated in Table 9-10. It WAS extreme because it not only ignores Dr. Kausel's carefully determined results, but the design specifications for UAL 175. A Boeing 767-200 has a maximum rated speed of 568 mph at it's normal cruising altitude of 35,000 feet in thinner atmosphere!

At UAL 175's impact altitude of approximately 1,000 feet, it would have a maximum speed significantly reduced due to far greater air resistance.

Page 165 basically gives a rambling explanation for a table of possible speeds based on the videos it used for reference. Regardless of NIST's uncertainty range, based on those video calculations, NIST has to acknowledge the actual speeds possible for that plane and reference their calculations to a design reality and not a video based error factor range of possibilities.

Keep in mind that Dr. Kausel's statement "The velocities listed in this table for the two WTC planes are in excellent agreement with flight data based on radar provided by the NTSC"

Now on to your other amateur, misleading, and inaccurate points:

Arrogantly saying it is so does not make it so.

Originally Posted by Miragememories
A few facts which I'm sure you are well aware of;

The Boeing 767-200 is rated for a cruising speed of 530 mph and maximum speed of 568 mph (at 35,000 ft.).

I am aware. I am also aware that the design speed is not the true upper limit the vehicle is capable of. My automobile is designed for a cruising speed of 100 kph, but will easily do more than double that.

That's it? Your earthbound car's cruising speed? Based on that logic, you are suggesting a 767-200 could attain 1136 mph. We aren't talking about cars which perform better at low altitude. At 35,000 feet, there are no speed limits, no traffic cops, minimal air resistance and few restrictions to place on maximum cruising speed. Time is money.

Flying at 1,000 feet, maximum cruising speed and aircraft stability are greatly effected.

Originally Posted by Miragememories
In their less severe case NIST used 521 mph and in their baseline they used 546 mph. NIST was still using numbers that exceeded the careful analysis of MIT's Professor Kausel. Unfortunately for NIST, those numbers failed to create a collapse initiation so they tweaked the speed upwards until they found a number that would achieve their desired expectations. The magic number turned out to be 570 mph to achieve collapse initiation success.

Multiple fallacies here.

First, NIST's numbers are consistent with Dr. Kausel's, albeit slightly higher. Both numbers contain large uncertainties. Dr. Kausel was unable to adequately estimate experimental error, as he did not know the locations of observers, was unable to obtain original videos, and could not always account for speedups or format changes of his inputs. Parallax, frame-per-second differences in videos, and motion of the camera as it tracked the aircraft are all large contributors to his error, as NIST noted and I have demonstrated above. Dr. Kausel, who unlike you is a responsible scientist, even identifies this in his paper:

The number NIST had success with was significantly higher!.

I am aware of the challenges Dr. Kausel encountered and I confined my post to the WTC2 impact for that very reason. Now you are conveniently "cherry picking" to distort things in your favor! The statement you quote was specifically introductory to his WTC1 estimates which as we all know had very poor video coverage.

Regarding WTC2 which is the focus of my posting, Dr. Kausel, as you well know, had this to say;

"Velocity of South Tower plane

The speed of the plane that crashed onto the South Tower can be determined with greater confidence than that of the North Tower. This is because there are several videos taken from different angles available which show the last few seconds prior to the collision."

After all his careful effort in calculating the impact speed for UA-175 which struck WTC 2, Dr. Kausel had this to say: "This speed is in excellent agreement with information from air traffic controllers, who reported that “Flight 175 had screamed south over the Hudson Valley at about 500 miles per hour, more than double the legal speed."

Second, NIST did not run cases until they achieved collapse initiation. The "more severe" case, which included the 570 MPH initial condition, was selected on the basis of impact model results which most closely matched observation just after impact. I've corrected this bald-faced lie of yours endlessly in the other thread.

Obviously, based on the fact that only the more severe case model lead to collapse initiation, NIST needed a big number to achieved that desired result. Obviously I have no whistle blower to state that NIST was aware in advance that if they interpreted impact model results for an arrived figure of 570 mph that they would achieve a successful collapse initiation.

That does not change the fact that the unrealistic 570 mph parameter caused a simulated collapse initiation where as the NIST baseline 546 mph parameter was unsuccessful, and that Dr. Kausel was quite confident in his calculations of 503 mph.

Regarding NIST's objectivity and lack of bias;

Ronald Hamburger, one of the structural engineers who contributed to the NIST report, was in conversation with Michael Green following a lecture he (Hamburger) had just given. Green asked: "Was your group given the task of explaining how the Towers collapsed, based on the assumption that the collapse was caused solely by the damage from the impact of the planes and the subsequent fire?" Hamburger replied, simply, "yes."

Third, the NIST number wasn't "tweaked" at all. It represents the reasonable "one-sigma" upper bound given uncertainties in the measurements. It is an entirely reasonable choice of input.

And it's just a mere coincidence that this questionable "reasonable" choice of input was the parameter that lead to a successful collapse initiation.

Considering NIST themselves chose the baseline speed of 546 mph to be the most accurate and that this speed failed to achieve collapse initiation, and especially considering Dr. Kausel's confident belief that his calculations of a real speed of 503 mph were accurate, I find it preposterous that you can confidently state that a successful choice of 570 mph was "entirely reasonable."

Fourth, as NIST explained before, the dominant factor in damage assessment is the angle of impact, not the speed. This is partly why WTC 1 collapsed in a manner similar to WTC 2, even though Flight 11 impacted at a mere 443 MPH +/- 30, which is well below even the lower number you argue for here. This fact also demonstrates that, unlike your claims, the lower impact speeds might very well have led to a collapse.

That sounds like a "slight of hand" argument. "Forget about speed, it's the penetration angle that's really important." kind of reasoning.

Increasing the weight, material strength and particularly the air speed of the 767 for the worst case scenario certainly was a major factor in the total momentum and kinetic energy component delivered in the impact, especially considering the impact angle was only adjusted by 1 degree from the baseline impact angle parameter.

I don't see the validity of your comparison of impact angles with WTC1.

WTC1 More Severe Trajectory Pitch of 7.6 degrees was used.
WTC1 Base Case Trajectory Pitch of 10.6 degrees was used.
WTC1 More Severe Orientation Pitch of 5.6 degrees was used.
WTC1 Base Case Orientation Pitch of 8.6 degrees was used.

WTC2 More Severe Trajectory Pitch of 5.0 degrees was used.
WTC2 Base Case Trajectory Pitch of 6.0 degrees was used.
WTC2 More Severe Orientation Pitch of 4.0 degrees was used.
WTC2 Base Case Orientation Pitch of 5.0 degrees was used.

Also, Flight AA-11 struck the North Tower 15 stories higher (95th floor) where the columns would be expected to be lighter and weaker than those at the South Tower's 80th floor which were supporting 15 stories of additional load. Yet the North Tower was estimated by NIST to have only 6 core columns severed and they estimated the South Tower with it's corner hit, to have had 10 core columns severed.

Originally Posted by Miragememories
NIST says this was within reality, even though their computer model now is being made to simulate a 767 at 1,000 ft in heavy air, tweaked to fly 12 mph faster than the 767-200's maximum speed at 35,000 feet where air is extremely thin and offers little air speed resistance.

767's are not drag-limited. They are control-limited.

So I guess when pilots at 35,000 feet talk about ETA being effected by head winds or tail winds, they're not referring to the effects of air resistance on the speed of the plane?

Since I do believe they are indeed referring to the fact that air movement, and thus it's density both must effect the achievable air speed, and considering the Boeing 767-200's maximum cruising speed is 568 mph @35,000 feet; at 1,000 feet, I would expect the effects of heavier air to be even more dramatic.

At this point, I am not sure any further conversation with you is warranted, given that you clearly lack all of the requisite technical background to even cite papers adequately.

And you still haven't answered my question. I don't understand what you're afraid of.

You are entitled to inflate your self opinion as much you like.

Believe me I'm not in fear of your questions. I may be bored by dogmatic NIST rhetoric, but I'm hardly afraid of responses that rely on mockery and ridicule to bolster weak arguments.

MM

 

[Corsair 115]

A Boeing 767-200 has a maximum rated speed of 568 mph at it's normal cruising altitude of 35,000 feet in thinner atmosphere!

"Rated maximum speed" does not mean that's the maximum speed the aircraft is actually physically capable of, it's just the speed that the manufacturer advises not be exceeded in normal operation.

Your earthbound car's cruising speed? Based on that logic, you are suggesting a 767-200 could attain 1136 mph.

Actually, he suggested no such thing. What he was saying was exactly what I've said above - that the maximum rated speed does not necessarily equal the maximum speed the vehicle is physically capable of achieving.

Flying at 1,000 feet, maximum cruising speed and aircraft stability are greatly effected.

I suggest you think about what that all-important word "cruising" means.

So I guess when pilots at 35,000 feet talk about ETA being effected by head winds or tail winds, they're not referring to the effects of air resistance on the speed of the plane?

No, they are referring to winds. You know, the thing which makes clouds move across the sky. Flying into the jetstream is quite significant since it is a very fast-moving stream of air.

...and considering the Boeing 767-200's maximum cruising speed is 568 mph @35,000 feet; at 1,000 feet, I would expect the effects of heavier air to be even more dramatic.

I suggest you think about what that all-important word "cruising" means.

Oh, okay, I'll tell you: cruising speed means the speed at which the aircraft travels the furthest distance per unit of fuel consumed. In other words, its fuel efficiency. The best cruising speed depends on a variety of factors, such as the aircraft's weight, altitude, weather conditions, and so forth, but this commonly will fall within a certain range of speeds. Thus, a 568 MPH maximum cruising speed means that's the fastest the aircraft can go and still be fuel efficient.

The maximum speed physically possible by the aircraft is something else entirely.

That maximum physically possible speed is not something that's going to be mentioned much by a manufacturer simply because it's not something that the aircraft would ever come close to in normal day-to-day operation. Commerical pilots are not going to be out there flying their aircraft to the edge of its flight envelope.

 

[R.Mackey]

Thank you, Corsair 115. I was reasonably certain that every single person other than Miragememories understood my points.

To Miragememories, as usual, you are completely out to lunch. I will demonstrate this one last time, and then you are on your own.

I'm most concerned with the 570 mph used for obvious reasons.
Not only does it well exceed Dr. Kausel's meticulous calculations which arrive at a figure of 503 mph, but he found this calculation to be in "excellent agreement with information from air traffic controllers".

I explained where the 570 MPH came from. It was the one-sigma upper bound of their measurements, offset by 4 MPH from an early calculation error.

The air traffic controller comment "about 500 MPH" contains only one significant digit. It is therefore reasonable to assume that 550 MPH would be "in excellent agreement," and even 600 MPH is "in agreement." Take some science classes.

Given the importance of a large projectile's mass and speed, NIST heavily relied on their 570 mph Flight Parameter to achieve collapse initiation.

This is a lie.

In the bounds of NIST's chosen uncertainty!

"Bounds of uncertainty", is a convenient engineering means of saying "realm of possibility". They are using the "+" side of a +/- error factor to validate the credibility of an upper number. They are using the "-" side of a +/- error factor to validate the credibility of their number of with more accurate estimates, like Dr. Kausel's.

This is a pack of lies. The +/- reflects the standard deviation of their measurements, plus their estimated experimental error which is assumed to be uncorrelated. It is not "convenient" and it was not chosen strictly to create a veneer of credibility. Take some statistics classes.

My statement was not hyperbole! NIST used 570 mph as stated in Table 9-10. It WAS extreme because it not only ignores Dr. Kausel's carefully determined results, but the design specifications for UAL 175. A Boeing 767-200 has a maximum rated speed of 568 mph at it's normal cruising altitude of 35,000 feet in thinner atmosphere!

Your statement is hyperbolic. The one-sigma upper bound is never "extreme," and the rated speed is in no way the maximum speed possible. I'll illustrate with examples below.

At UAL 175's impact altitude of approximately 1,000 feet, it would have a maximum speed significantly reduced due to far greater air resistance.

You are clearly not an aeronautical engineer. I am. Listen up: The flat and level top speed increases with altitude for most aircraft, due to engine inlet performance and maximum permitted stress. But the maximum speed actually decreases with altitude for a 767, because as you climb, the sound speed decreases, and it is primarily compressibility effects that limit control. There is nothing incredible whatsoever about a 767 going 570 MPH on the deck, given that it was dived towards the target.

Honestly, do you think NIST would propose such a thing if it was impossible? You think you're the only genius smart enough to see this, and everybody else is either duped or in on it? Guess again.

Page 165 basically gives a rambling explanation for a table of possible speeds based on the videos it used for reference. Regardless of NIST's uncertainty range, based on those video calculations, NIST has to acknowledge the actual speeds possible for that plane and reference their calculations to a design reality and not a video based error factor range of possibilities.

570 MPH on the deck is a design reality. End of story.

Keep in mind that Dr. Kausel's statement "The velocities listed in this table for the two WTC planes are in excellent agreement with flight data based on radar provided by the NTSC"

Actually Dr. Kausel says the radar results were 10% higher than his calculation (which is close enough to be considered "excellent agreement"). How interesting.

That's it? Your earthbound car's cruising speed? Based on that logic, you are suggesting a 767-200 could attain 1136 mph. We aren't talking about cars which perform better at low altitude. At 35,000 feet, there are no speed limits, no traffic cops, minimal air resistance and few restrictions to place on maximum cruising speed. Time is money.

Except the Mach limit.

Flying at 1,000 feet, maximum cruising speed and aircraft stability are greatly effected.

The aircraft was not cruising. Non sequitur.

The number NIST had success with was significantly higher!.

Another lie. After correcting Dr. Kausel's number for experimental error, it was only one sigma away from the NIST best-guess. One sigma is not "significant" except at artificially low confidence levels. Again, take a statistics class.

I am aware of the challenges Dr. Kausel encountered and I confined my post to the WTC2 impact for that very reason. Now you are conveniently "cherry picking" to distort things in your favor! The statement you quote was specifically introductory to his WTC1 estimates which as we all know had very poor video coverage.

(ahem)

The velocity of the two Boeing 767-200 planes that were crashed onto the Twin Towers is not precisely known, especially the speed of the North Tower plane. The speed calculations are made more complicated by the following facts:

(emphasis added)

Nothing about his reservations was restricted to WTC 1. Another lie. I'm losing count.

Regarding WTC2 which is the focus of my posting, Dr. Kausel, as you well know, had this to say [...]

After all his careful effort in calculating the impact speed for UA-175 which struck WTC 2, Dr. Kausel had this to say: "This speed is in excellent agreement with information from air traffic controllers, who reported that “Flight 175 had screamed south over the Hudson Valley at about 500 miles per hour, more than double the legal speed."

Yes, "about 500 miles per hour." That also agrees well with the NIST result, and even agrees with the NIST high estimate.

Obviously, based on the fact that only the more severe case model lead to collapse initiation, NIST needed a big number to achieved that desired result. Obviously I have no whistle blower to state that NIST was aware in advance that if they interpreted impact model results for an arrived figure of 570 mph that they would achieve a successful collapse initiation.

Obviously, you're lying. You have no evidence that the lower speed models wouldn't lead to collapse initiation. The higher speed was the best fit to what we saw, even if we leave the collapse out of it entirely. I've explained this to you at least seven times.

That does not change the fact that the unrealistic 570 mph parameter caused a simulated collapse initiation where as the NIST baseline 546 mph parameter was unsuccessful, and that Dr. Kausel was quite confident in his calculations of 503 mph.

570 MPH is not unrealistic. And I note that Dr. Kausel is not complaining long and loud that he is right while NIST is wrong. Why is this, do you suppose?

Regarding NIST's objectivity and lack of bias;

Ronald Hamburger, one of the structural engineers who contributed to the NIST report, was in conversation with Michael Green following a lecture he (Hamburger) had just given. Green asked: "Was your group given the task of explaining how the Towers collapsed, based on the assumption that the collapse was caused solely by the damage from the impact of the planes and the subsequent fire?" Hamburger replied, simply, "yes."

Seeing as even you cannot challenge the assumption, I don't understand why you think it's in any way unreasonable.

And it's just a mere coincidence that this questionable "reasonable" choice of input was the parameter that lead to a successful collapse initiation.

Another lie.

Considering NIST themselves chose the baseline speed of 546 mph to be the most accurate and that this speed failed to achieve collapse initiation, and especially considering Dr. Kausel's confident belief that his calculations of a real speed of 503 mph were accurate, I find it preposterous that you can confidently state that a successful choice of 570 mph was "entirely reasonable."

That's because you don't understand statistics.

That sounds like a "slight of hand" argument. "Forget about speed, it's the penetration angle that's really important." kind of reasoning.

It's "sleight," and how it sounds to you is not my problem. It happens to be the truth. A steeper impact angle dissipates more impact energy against the floor slabs, whereas a flatter one destroys more of the core. It's all in NIST NCSTAR1-2.

Increasing the weight, material strength and particularly the air speed of the 767 for the worst case scenario certainly was a major factor in the total momentum and kinetic energy component delivered in the impact, especially considering the impact angle was only adjusted by 1 degree from the baseline impact angle parameter.

The impact angle was only adjusted by 1 degree because it could be measured with a relatively high degree of certainty. The choices were based on observational accuracy, not a conscious attempt to scale the damage, and that goes for the speed as well.

I don't see the validity of your comparison of impact angles with WTC1.

The comparison is to speeds. WTC 1 was hit with a "significantly" slower aircraft (about 4 sigma lower), yet still collapsed.

Also, Flight AA-11 struck the North Tower 15 stories higher (95th floor) where the columns would be expected to be lighter and weaker than those at the South Tower's 80th floor which were supporting 15 stories of additional load. Yet the North Tower was estimated by NIST to have only 6 core columns severed and they estimated the South Tower with it's corner hit, to have had 10 core columns severed.

Yes. That's primarily because of the shallower dive angle in WTC 2, secondarily because of the oblique yaw angle that sawed off the edge of the core rather than burrowing straight through it, and tertially due to the higher impact speed.

So I guess when pilots at 35,000 feet talk about ETA being effected by head winds or tail winds, they're not referring to the effects of air resistance on the speed of the plane?

Absolutely not. Apparently you don't understand the difference between airspeed and groundspeed.

Since I do believe they are indeed referring to the fact that air movement, and thus it's density both must effect the achievable air speed, and considering the Boeing 767-200's maximum cruising speed is 568 mph @35,000 feet; at 1,000 feet, I would expect the effects of heavier air to be even more dramatic.

Your beliefs, as seen numerous times, are unreliable at best.

I promised you some examples. Here they are:

First, China Airlines 006, a Boeing 747, is thought to have exceeded Mach 1 by accident... with one of its four engines flamed out, and the other three at ordinary power. It exceeded 650 MPH, well above its "rated" speed.

Second, Egpyt Air 990 nearly reached Mach 1 at sea level as it dived to its destruction. And this was even a fellow Boeing 767, similar to Flight 175. Its final speed was nearly 750 miles per hour. At sea level.

As I have demonstrated, and everyone else here knows, the speeds NIST cites are entirely credible for a 767 in a power dive. Flight 175 was at full power and diving from 28,000 feet at over 10,000 feet per minute when it struck WTC 2.

You are entitled to inflate your self opinion as much you like.

Believe me I'm not in fear of your questions. I may be bored by dogmatic NIST rhetoric, but I'm hardly afraid of responses that rely on mockery and ridicule to bolster weak arguments.

I asked you a question that had nothing to do with NIST, and you still didn't answer. Your excuse is, to put it mildly, absurd.

This is going nowhere. Miragememories, you have repeatedly demonstrated your lack of expertise and your willingness to lie in order to retain your beliefs. My repeated, uninterrupted corrections and explanations have had no effect. Therefore, effective immediately, you warrant no further conversation until you show an ability to learn. Otherwise, there can be no progress.

Until you acknowledge the many errors you made in your last post, and correct them as I have shown above, you will receive no further attention. I cannot help you learn unless we start somewhere. It might as well be here.

 

[beachnut]

The numbers NIST decided to use, are what is really important.

These are the numbers that NIST used;

NIST's Table9-10. Input parameters for additional WTC 2 global impact analyses.
Base Case 546 mph plain and simple.
Less Severe 521 mph
More Severe 570 mph

I'm most concerned with the 570 mph used for obvious reasons.
Not only does it well exceed Dr. Kausel's meticulous calculations which arrive at a figure of 503 mph, but he found this calculation to be in "excellent agreement with information from air traffic controllers".

Given the importance of a large projectile's mass and speed, NIST heavily relied on their 570 mph Flight Parameter to achieve collapse initiation.



In the bounds of NIST's chosen uncertainty!

"Bounds of uncertainty", is a convenient engineering means of saying "realm of possibility". They are using the "+" side of a +/- error factor to validate the credibility of an upper number. They are using the "-" side of a +/- error factor to validate the credibility of their number of with more accurate estimates, like Dr. Kausel's.

My statement was not hyperbole! NIST used 570 mph as stated in Table 9-10. It WAS extreme because it not only ignores Dr. Kausel's carefully determined results, but the design specifications for UAL 175. A Boeing 767-200 has a maximum rated speed of 568 mph at it's normal cruising altitude of 35,000 feet in thinner atmosphere!

At UAL 175's impact altitude of approximately 1,000 feet, it would have a maximum speed significantly reduced due to far greater air resistance.

Keep in mind that Dr. Kausel's statement "The velocities listed in this table for the two WTC planes are in excellent agreement with flight data based on radar provided by the NTSC"


That's it? Your earthbound car's cruising speed? Based on that logic, you are suggesting a 767-200 could attain 1136 mph. We aren't talking about cars which perform better at low altitude. At 35,000 feet, there are no speed limits, no traffic cops, minimal air resistance and few restrictions to place on maximum cruising speed. Time is money.

Flying at 1,000 feet, maximum cruising speed and aircraft stability are greatly effected.

I am aware of the challenges Dr. Kausel encountered and I confined my post to the WTC2 impact for that very reason. Now you are conveniently "cherry picking" to distort things in your favor! The statement you quote was specifically introductory to his WTC1 estimates which as we all know had very poor video coverage.

Regarding WTC2 which is the focus of my posting, Dr. Kausel, as you well know, had this to say;

"Velocity of South Tower plane

The speed of the plane that crashed onto the South Tower can be determined with greater confidence than that of the North Tower. This is because there are several videos taken from different angles available which show the last few seconds prior to the collision."

After all his careful effort in calculating the impact speed for UA-175 which struck WTC 2, Dr. Kausel had this to say: "This speed is in excellent agreement with information from air traffic controllers, who reported that “Flight 175 had screamed south over the Hudson Valley at about 500 miles per hour, more than double the legal speed."

Obviously, based on the fact that only the more severe case model lead to collapse initiation, NIST needed a big number to achieved that desired result. Obviously I have no whistle blower to state that NIST was aware in advance that if they interpreted impact model results for an arrived figure of 570 mph that they would achieve a successful collapse initiation.

That does not change the fact that the unrealistic 570 mph parameter caused a simulated collapse initiation where as the NIST baseline 546 mph parameter was unsuccessful, and that Dr. Kausel was quite confident in his calculations of 503 mph.

Considering NIST themselves chose the baseline speed of 546 mph to be the most accurate and that this speed failed to achieve collapse initiation, and especially considering Dr. Kausel's confident belief that his calculations of a real speed of 503 mph were accurate, I find it preposterous that you can confidently state that a successful choice of 570 mph was "entirely reasonable."

Increasing the weight, material strength and particularly the air speed of the 767 for the worst case scenario certainly was a major factor in the total momentum and kinetic energy component delivered in the impact, especially considering the impact angle was only adjusted by 1 degree from the baseline impact angle parameter.

Since I do believe they are indeed referring to the fact that air movement, and thus it's density both must effect the achievable air speed, and considering the Boeing 767-200's maximum cruising speed is 568 mph @35,000 feet; at 1,000 feet, I would expect the effects of heavier air to be even more dramatic.

You are entitled to inflate your self opinion as much you like.

Believe me I'm not in fear of your questions. I may be bored by dogmatic NIST rhetoric, but I'm hardly afraid of responses that rely on mockery and ridicule to bolster weak arguments.

MM

The reason flight 175 was able to speed up to 590 mph is due to thrust from the engines.

The top speed of the plane is 350 KCAS, period. You have zero knowledge on this topic. You make up stuff as you go. You have no idea on the plane and why the top speed is just one number, 350KCAS. Just one number. But the darn plane does not know it is not to exceed 350 KCAS. It just keeps working until things happen.

The facts are you can get a very good estimate of the speed at impact from the video. It is near 590 mph, you can do it yourself and stop guessing. End of story!

The plane would have no problems speeding at 1000 feet to 590 mph, it would have problems doing anything but going straight and hitting a building. The terrorist would have been in trouble if they had "floored" their jets too early, the damn thing would have problems going fast for any extended period. The engines would not do very well going supersonic. The controls will not do well near supersonic speeds. But we were not that close to supersonic flight at 1000 feet. The time the aircraft were over-speed was only seconds. The engines are very effective at gaining the speeds in the last 20 seconds.

350 KCAS covers the speed, good luck at figuring out what it means. There is also a MACH number that goes with that figure, that you can use around 27,500 feet.

You can not use the ATC figure, it is not accurate, and ATC uses KIAS. What is 503 KIAS in mph? AHHHHHHHHHHHHHH 503 KIAS = 570 mph

OMG! Maybe that is why I slowed to 200 KIAS when ATC told me to slow to 200. Do you think?

Problem with truthers, they believe what ever they hear and read. I usually check the damn numbers myself. Do not trust anyone, trust truthers less; with a name like "truther" you know they are telling big lies.

Remember 503KIAS = 570 mph (really 571.5909) . You should have asked a pilot! The 767/757 could exceed max speed in level flight with just engines, no dive required. But a 3 degree dive gives you a constant speed of 300 KIAS with engines at idle, clean aircraft (about, tlar).

All jets used in the attacks, on 9/11, exceeded max speed of 350 KCAS for short periods prior to impacts. (about 398 mph at 1000 feet) The "thick" air at 1000 feet would not stop the planes from going fast, but the high Q (thick air) could do things to parts on the plane. But who cares, their mission was done and the pilots were not doing much of anything before the impacts except pointing the planes, no significant turns, not massive pull ups, not much of anything except full throttles, which makes the planes go fast.

 

[aggle-rithm]

The numbers NIST decided to use, are what is really important.

These are the numbers that NIST used;

NIST's Table9-10. Input parameters for additional WTC 2 global impact analyses.
Base Case 546 mph plain and simple.
Less Severe 521 mph
More Severe 570 mph

I'm most concerned with the 570 mph used for obvious reasons.
Not only does it well exceed Dr. Kausel's meticulous calculations which arrive at a figure of 503 mph, but he found this calculation to be in "excellent agreement with information from air traffic controllers".

Given the importance of a large projectile's mass and speed, NIST heavily relied on their 570 mph Flight Parameter to achieve collapse initiation.



In the bounds of NIST's chosen uncertainty!

"Bounds of uncertainty", is a convenient engineering means of saying "realm of possibility". They are using the "+" side of a +/- error factor to validate the credibility of an upper number. They are using the "-" side of a +/- error factor to validate the credibility of their number of with more accurate estimates, like Dr. Kausel's.

My statement was not hyperbole! NIST used 570 mph as stated in Table 9-10. It WAS extreme because it not only ignores Dr. Kausel's carefully determined results, but the design specifications for UAL 175. A Boeing 767-200 has a maximum rated speed of 568 mph at it's normal cruising altitude of 35,000 feet in thinner atmosphere!

At UAL 175's impact altitude of approximately 1,000 feet, it would have a maximum speed significantly reduced due to far greater air resistance.

Page 165 basically gives a rambling explanation for a table of possible speeds based on the videos it used for reference. Regardless of NIST's uncertainty range, based on those video calculations, NIST has to acknowledge the actual speeds possible for that plane and reference their calculations to a design reality and not a video based error factor range of possibilities.

Keep in mind that Dr. Kausel's statement "The velocities listed in this table for the two WTC planes are in excellent agreement with flight data based on radar provided by the NTSC"



Arrogantly saying it is so does not make it so.



That's it? Your earthbound car's cruising speed? Based on that logic, you are suggesting a 767-200 could attain 1136 mph. We aren't talking about cars which perform better at low altitude. At 35,000 feet, there are no speed limits, no traffic cops, minimal air resistance and few restrictions to place on maximum cruising speed. Time is money.

Flying at 1,000 feet, maximum cruising speed and aircraft stability are greatly effected.




The number NIST had success with was significantly higher!.

I am aware of the challenges Dr. Kausel encountered and I confined my post to the WTC2 impact for that very reason. Now you are conveniently "cherry picking" to distort things in your favor! The statement you quote was specifically introductory to his WTC1 estimates which as we all know had very poor video coverage.

Regarding WTC2 which is the focus of my posting, Dr. Kausel, as you well know, had this to say;

"Velocity of South Tower plane

The speed of the plane that crashed onto the South Tower can be determined with greater confidence than that of the North Tower. This is because there are several videos taken from different angles available which show the last few seconds prior to the collision."

After all his careful effort in calculating the impact speed for UA-175 which struck WTC 2, Dr. Kausel had this to say: "This speed is in excellent agreement with information from air traffic controllers, who reported that “Flight 175 had screamed south over the Hudson Valley at about 500 miles per hour, more than double the legal speed."



Obviously, based on the fact that only the more severe case model lead to collapse initiation, NIST needed a big number to achieved that desired result. Obviously I have no whistle blower to state that NIST was aware in advance that if they interpreted impact model results for an arrived figure of 570 mph that they would achieve a successful collapse initiation.

That does not change the fact that the unrealistic 570 mph parameter caused a simulated collapse initiation where as the NIST baseline 546 mph parameter was unsuccessful, and that Dr. Kausel was quite confident in his calculations of 503 mph.

Regarding NIST's objectivity and lack of bias;

Ronald Hamburger, one of the structural engineers who contributed to the NIST report, was in conversation with Michael Green following a lecture he (Hamburger) had just given. Green asked: "Was your group given the task of explaining how the Towers collapsed, based on the assumption that the collapse was caused solely by the damage from the impact of the planes and the subsequent fire?" Hamburger replied, simply, "yes."



And it's just a mere coincidence that this questionable "reasonable" choice of input was the parameter that lead to a successful collapse initiation.

Considering NIST themselves chose the baseline speed of 546 mph to be the most accurate and that this speed failed to achieve collapse initiation, and especially considering Dr. Kausel's confident belief that his calculations of a real speed of 503 mph were accurate, I find it preposterous that you can confidently state that a successful choice of 570 mph was "entirely reasonable."



That sounds like a "slight of hand" argument. "Forget about speed, it's the penetration angle that's really important." kind of reasoning.

Increasing the weight, material strength and particularly the air speed of the 767 for the worst case scenario certainly was a major factor in the total momentum and kinetic energy component delivered in the impact, especially considering the impact angle was only adjusted by 1 degree from the baseline impact angle parameter.

I don't see the validity of your comparison of impact angles with WTC1.

WTC1 More Severe Trajectory Pitch of 7.6 degrees was used.
WTC1 Base Case Trajectory Pitch of 10.6 degrees was used.
WTC1 More Severe Orientation Pitch of 5.6 degrees was used.
WTC1 Base Case Orientation Pitch of 8.6 degrees was used.

WTC2 More Severe Trajectory Pitch of 5.0 degrees was used.
WTC2 Base Case Trajectory Pitch of 6.0 degrees was used.
WTC2 More Severe Orientation Pitch of 4.0 degrees was used.
WTC2 Base Case Orientation Pitch of 5.0 degrees was used.

Also, Flight AA-11 struck the North Tower 15 stories higher (95th floor) where the columns would be expected to be lighter and weaker than those at the South Tower's 80th floor which were supporting 15 stories of additional load. Yet the North Tower was estimated by NIST to have only 6 core columns severed and they estimated the South Tower with it's corner hit, to have had 10 core columns severed.



So I guess when pilots at 35,000 feet talk about ETA being effected by head winds or tail winds, they're not referring to the effects of air resistance on the speed of the plane?

Since I do believe they are indeed referring to the fact that air movement, and thus it's density both must effect the achievable air speed, and considering the Boeing 767-200's maximum cruising speed is 568 mph @35,000 feet; at 1,000 feet, I would expect the effects of heavier air to be even more dramatic.



You are entitled to inflate your self opinion as much you like.

Believe me I'm not in fear of your questions. I may be bored by dogmatic NIST rhetoric, but I'm hardly afraid of responses that rely on mockery and ridicule to bolster weak arguments.

MM

Perhaps you should start a new thread to discuss your paranoid fantasies. Or, you could post in one of the many existing threads where this particular dead horse has already been pummeled into submission.

 

[Corsair 115]

But the maximum speed actually decreases with altitude for a 767, because as you climb, the sound speed decreases, and it is primarily compressibility effects that limit control.

I'm willing to bet you're going to have to explain to Miragememories what compressibility means.

Except the Mach limit.

I expect you may have to explain the difference between Indicated Air Speed (IAS) and True Air Speed (TAS) as well.


And lastly, as beachnut excellently observed, there's the conversion from knots to miles per hour. I'm so used to thinking in MPH I completely forgot that knots and nautical miles are the measurement systems traditionally used in the aviation industry.

 

[jhunter1163]

MM clearly doesn't understand the difference between a manufacturer's recommendation and a physical limit. It is quite likely possible to fly a 767 supersonic in a dive at max thrust. As Beachnut correctly pointed out, though, the control surfaces and airframe aren't designed to withstand those stresses for any length of time, so the best plan was to push the throttle to the firewall in level (or near-level) flight and hope they hit the target. Which they did, to tragic effect.

 

[aggle-rithm]

MM clearly doesn't understand the difference between a manufacturer's recommendation and a physical limit. It is quite likely possible to fly a 767 supersonic in a dive at max thrust. As Beachnut correctly pointed out, though, the control surfaces and airframe aren't designed to withstand those stresses for any length of time, so the best plan was to push the throttle to the firewall in level (or near-level) flight and hope they hit the target. Which they did, to tragic effect.

Possibly one of the factors taken into consideration when devising the maximum recommended cruise speeds at certain altitudes is the comfort of the passengers. These planes WERE designed specifically to carry passengers, after all, and it wouldn't do to make the experience so unpleasant that they would never want to board a plane again.

One of the passengers on 175 related how the plane was moving "jerkily" and many of the passengers were throwing up. Doesn't sound like a very smooth flight.

 

[Miragememories]

"Rated maximum speed" does not mean that's the maximum speed the aircraft is actually physically capable of, it's just the speed that the manufacturer advises not be exceeded in normal operation.

Actually, he suggested no such thing. What he was saying was exactly what I've said above - that the maximum rated speed does not necessarily equal the maximum speed the vehicle is physically capable of achieving.

I suggest you think about what that all-important word "cruising" means.

No, they are referring to winds. You know, the thing which makes clouds move across the sky. Flying into the jetstream is quite significant since it is a very fast-moving stream of air.

I suggest you think about what that all-important word "cruising" means.

Oh, okay, I'll tell you: cruising speed means the speed at which the aircraft travels the furthest distance per unit of fuel consumed. In other words, its fuel efficiency. The best cruising speed depends on a variety of factors, such as the aircraft's weight, altitude, weather conditions, and so forth, but this commonly will fall within a certain range of speeds. Thus, a 568 MPH maximum cruising speed means that's the fastest the aircraft can go and still be fuel efficient.

The maximum speed physically possible by the aircraft is something else entirely.

That maximum physically possible speed is not something that's going to be mentioned much by a manufacturer simply because it's not something that the aircraft would ever come close to in normal day-to-day operation. Commerical pilots are not going to be out there flying their aircraft to the edge of its flight envelope.

Trying comprehending what you read before you launch into response mode!

MM

 

[beachnut]

Trying comprehending what you read before you launch into response mode!

MM

See you in 6 years, you need a degree and some experience in aviation. Hurry back.

 

[Miragememories]

Thank you, Corsair 115. I was reasonably certain that every single person other than Miragememories understood my points.

To Miragememories, as usual, you are completely out to lunch. I will demonstrate this one last time, and then you are on your own.

Sorry I'm not in awe of your self-proclaimed brilliance unlike most of the groupies here.

I explained where the 570 MPH came from. It was the one-sigma upper bound of their measurements, offset by 4 MPH from an early calculation error.

The air traffic controller comment "about 500 MPH" contains only one significant digit. It is therefore reasonable to assume that 550 MPH would be "in excellent agreement," and even 600 MPH is "in agreement." Take some science classes.

Combined with Dr.Kausel's belief in his accuracy of his calculations, something less than 500 mph would be a better interpretation.

This is a lie.

It's only a lie if I knowingly misstate the truth. NIST believed in only one explanation for the collapses and the baseline speed of 546 mph wouldn't achieve collapse..570 mph did..hence 570 mph was "a good fit" in their opinion.

This is a pack of lies. The +/- reflects the standard deviation of their measurements, plus their estimated experimental error which is assumed to be uncorrelated. It is not "convenient" and it was not chosen strictly to create a veneer of credibility. Take some statistics classes.

I have taken statistics. You like calling people liars apparently. Standard deviation combined with experimental error is a convenient way to have a big enough swing in possible parameter choice that inevitably it hits a number (570 mph) that achieves a predetermined result.

Your statement is hyperbolic. The one-sigma upper bound is never "extreme," and the rated speed is in no way the maximum speed possible. I'll illustrate with examples below.

You are clearly not an aeronautical engineer. I am. Listen up: The flat and level top speed increases with altitude for most aircraft, due to engine inlet performance and maximum permitted stress. But the maximum speed actually decreases with altitude for a 767, because as you climb, the sound speed decreases, and it is primarily compressibility effects that limit control. There is nothing incredible whatsoever about a 767 going 570 MPH on the deck, given that it was dived towards the target.

Yes yes NASA I'm so impressed..golly gee. The 767 that struck WTC2 was not diving, another lie! It was flying level for a good distance as was shown in a couple of videos with a moderate descent close to impact.

Honestly, do you think NIST would propose such a thing if it was impossible? You think you're the only genius smart enough to see this, and everybody else is either duped or in on it? Guess again.

I know from your posts that you have too much invested in a single belief to ever consider there might be another valid point of view. NIST would propose anything that suited their purposes if they could present sufficient obfuscating data and calculations to mask the fact.

570 MPH on the deck is a design reality. End of story.

End of story because your whole defence lies with an unwaivering belief that NIST would never do anything to satisfy a political agenda over a scientific one.

Actually Dr. Kausel says the radar results were 10% higher than his calculation (which is close enough to be considered "excellent agreement"). How interesting.

How interesting that you choose again to take his paper out of context. I believe that's called "cherry picking" or "lying".

The complete text from that portion of Dr. Kausel's paper was:

"The radar speeds are basically 10% larger, a difference that could easily be explained by the higher altitude at which the aircraft may have remained visible to radar and the probable speedup caused by the descent. Indeed, during their final approach, the airplanes whose transponders had been disabled were flying as low as some 300m (1000 ft) above the ground (i.e. the height of impact), an altitude that is barely above the rooftops of the skyscrapers in lower Manhattan, so radar is likely to have been blind to them. By contrast, the estimates given herein are based on the last mile of flight prior to collision.

The aircraft was not cruising.

At 35,000 feet, they are cruising at the best atainable speed while facing less air resistance than at 1,000 feet.

Another lie. After correcting Dr. Kausel's number for experimental error, it was only one sigma away from the NIST best-guess. One sigma is not "significant" except at artificially low confidence levels. Again, take a statistics class.

There you go with the cheap acusations of lying again. Dr. Kausel is quite capable of explaining his meticulous calculations. He never felt compelled in his lengthy paper to qualify his determination of 503 mph with a +/- error factor. Since his qualifications exceed yours and are not based on a blind faith in what NIST asks everyone to swallow, I think Dr. Kausel's paper stands without needing your distorting re-interpretations.

Nothing about his reservations was restricted to WTC 1. Another lie. I'm losing count.

The lies are yours my friend!

I never said exclusively WTC1. WTC2 was the subject of my post and WTC2 was the one Dr. Kausel said he could do his calculations with greater confidence. He had no issues with video standards (no PAL or SECAM video) as it was shot with the North American standard, NTSC. Virtually all of his issues were with SECAM or PAL which would have been referring to the Naudet video. His only issue that he referred to about the WTC 2 flight was some of the video shot in slow motion, hardly a major hindrance since most of the available footage was normal speed NTSC.

To quote Dr. Kausel yet again:

"The velocity of the two Boeing 767-200 planes that were crashed onto the Twin Towers is not precisely known, especially the speed of the North Tower plane."

"The speed of the plane that crashed onto the South Tower can be determined with greater confidence than that of the North Tower. This is because there are several videos taken from different angles available which show the last few seconds prior to the collision.

Yes, "about 500 miles per hour." That also agrees well with the NIST result, and even agrees with the NIST high estimate.

500 mph agrees with 570 mph? What are you putting in your coffee?

Obviously, you're lying. You have no evidence that the lower speed models wouldn't lead to collapse initiation. The higher speed was the best fit to what we saw, even if we leave the collapse out of it entirely. I've explained this to you at least seven times.

Lying? Maybe the fact that the NIST baseline and less severe scenarios which were both higher than 503 mph, and failed to create a collapse initiation, explains why the severe case 570 mph parameter, which did lead to a collapse initiation, is so significant!

570 MPH is not unrealistic. And I note that Dr. Kausel is not complaining long and loud that he is right while NIST is wrong. Why is this, do you suppose?

Have you asked him? How do you know what he thinks? Again the NISTian interpretation of apparent silence to mean "agreement".

Seeing as even you cannot challenge the assumption, I don't understand why you think it's in any way unreasonable.

So you aren't bothered that a NIST structural engineer who worked on the report and gave a speech about it admitted that his group was given the task of explaining how the towers collapsed "based on the assumption that it was solely due to aircraft impact and fire damage"?

Another lie.

Constantly calling me a person a liar is just a lame excuse for your inability to defend your dogmatic position.

That's because you don't understand statistics.

You mean because I question statistical deviations that provide a conveniently chosen "high swing" for a model's speed parameter that achieves a predetermined result.

It's "sleight," and how it sounds to you is not my problem. It happens to be the truth. A steeper impact angle dissipates more impact energy against the floor slabs, whereas a flatter one destroys more of the core. It's all in NIST NCSTAR1-2.

Yes I know that. But a 67 mph speed increase combined with increased weight and strength to a 767 makes for a far greater effect on damage than just a 1 degree change in angle.

The impact angle was only adjusted by 1 degree because it could be measured with a relatively high degree of certainty. The choices were based on observational accuracy, not a conscious attempt to scale the damage, and that goes for the speed as well.

They admitted as I said pointed out earlier, why they figured WTC 2 collapse. Once you decide it was airplane impacr and fire damage it's just a matter of selecting airplane and fire parameter large enough to make your belief come true.

The comparison is to speeds. WTC 1 was hit with a "significantly" slower aircraft (about 4 sigma lower), yet still collapsed.

Again, if the WTC 2 parameters were intentionally flawed, there's no reason to accept the WTC 1 parameters as being any better.

Yes. That's primarily because of the shallower dive angle in WTC 2, secondarily because of the oblique yaw angle that sawed off the edge of the core rather than burrowing straight through it, and tertially due to the higher impact speed.

Hardly a dive and not a dramatic angle change from the failed baseline scenario. The main core of WTC2 was not as impacted (NIST says 10 core columns severed) compared to the dead center hit on WTC1 (only 6 columns severed). The higher impact speed I'm in strong disagreement with.

Absolutely not. Apparently you don't understand the difference between airspeed and groundspeed.

I understand that tail winds and head winds at 35,000 feet do effect arrival times which means they have a push or drag effect and since I'm sure airlines try to keep to schedule, if they had reserve speed that could overcome opposing winds, they would utilize this speed instead of stating the delay was unavoidable!

AS an interesting footnote, your friends at NASA had this to say:

"As an aircraft moves through the air, the air molecules near the aircraft are disturbed and move around the aircraft. If the aircraft passes at a low speed, typically less than 250 mph, the density of the air remains constant. But for higher speeds, some of the energy of the aircraft goes into compressing the air and locally changing the density of the air. This compressibility effect alters the amount of resulting force on the aircraft. The effect becomes more important as speed increases."

Your beliefs, as seen numerous times, are unreliable at best.

And your beliefs are are dogmatic and expressed with arrogant disbelief that they should be challenged.

I promised you some examples. Here they are:

First, China Airlines 006, a Boeing 747, is thought to have exceeded Mach 1 by accident... with one of its four engines flamed out, and the other three at ordinary power. It exceeded 650 MPH, well above its "rated" speed.

Different jet, 3 of 4 engines. I checked. The 747 has a cruising speed rating of 640 mph. 650 mph hardly qualifies for what you like to call "well above its 'rated' speed", especially considering it was in an uncontrolled descent!

Again you misrepresent the truth:

"The flight from Taipei to about 300 nmi northwest of San Francisco was uneventful and the airplane was flying at about 41,000 feet mean sea level when the No. 4 engine lost power. During the attempt to recover and restore normal power on the No. 4 engine, the airplane rolled to the right, nosed over, and entered an uncontrollable descent. The captain was unable to restore the airplane to stable flight until it had descended to 9,500 feet."

Whose the liar?

Second, Egpyt Air 990 nearly reached Mach 1 at sea level as it dived to its destruction. And this was even a fellow Boeing 767, similar to Flight 175. Its final speed was nearly 750 miles per hour. At sea level.

That speed achieved while diving to it's destruction, nose down in a deliberate gravity-assisted crash initiated by the relief officer, hardly compares the relatively level flight of the 767 that struck WTC 2.

As I have demonstrated, and everyone else here knows, the speeds NIST cites are entirely credible for a 767 in a power dive. Flight 175 was at full power and diving from 28,000 feet at over 10,000 feet per minute when it struck WTC 2.

What a big lie that is! As the long shot video clearly shows, UA-175 was fying relatively level in the last mile as it closed in on WTC2. It was not in a power dive and 10,000 feet per minute is 113 mph.

I asked you a question that had nothing to do with NIST, and you still didn't answer. Your excuse is, to put it mildly, absurd.

Restate your oh so important question since it's evident you'll only continue lying in your feeble defence of NIST while having the uncalled for nerve of acusing me of using mistruths.

This is going nowhere. Miragememories, you have repeatedly demonstrated your lack of expertise and your willingness to lie in order to retain your beliefs. My repeated, uninterrupted corrections and explanations have had no effect. Therefore, effective immediately, you warrant no further conversation until you show an ability to learn. Otherwise, there can be no progress.

Until you acknowledge the many errors you made in your last post, and correct them as I have shown above, you will receive no further attention. I cannot help you learn unless we start somewhere. It might as well be here.

You've seen my responses. I suggest you clean up your act before you tell me what's wrong with mine.

MM

 

[Corsair 115]

Trying comprehending what you read before you launch into response mode!

I'm afraid your response is not all that helpful if you don't cite what exactly I got wrong in the statement of mine you quoted.

Now, if you were to list your objections point-by-point to what I wrote, this would be of considerably more use in understanding your disagreement.