More evidence for impossible speed of "UA175"

http://pilotsfor911truth.org/forum/index.php?showtopic=18300

Much controversy has surrounded the speeds reported for the World Trade Center attack aircraft. However, none of the arguments for either side of the debate have been properly based on actual data, until now. Pilots For 9/11 Truth have recently analyzed data provided by the National Transportation Safety Board in terms of a "Radar Data Impact Speed Study" in which the NTSB concludes 510 knots and 430 knots for United 175 (South Tower) and American 11 (North Tower), respectively. A benchmark has been set by the October 1999 crash of Egypt Air 990, a 767 which exceeded it's maximum operating limits causing in-flight structural failure, of which data is available to compare to the WTC Attack Aircraft.

Egypt Air 990 (EA990) is a 767 which was reported to have entered a dive and accelerated to a peak speed of .99 Mach at 22,000 feet. Boeing sets maximum operating speeds for the 767 as 360 Knots and .86 Mach. The reason for two airspeed limitations is due to air density at lower vs. higher altitudes. To understand equivalent dynamic pressures on an airframe of low vs. high altitude, there is an airspeed appropriately titled "Equivalent Airspeed" or EAS<1>. EAS is defined as the airspeed at sea level which produces the same dynamic pressure acting on the airframe as the true airspeed at high altitudes.<2>

Pilots For 9/11 Truth have calculated the Equivalent Airspeed for EA990 peak speed of .99 Mach at 22,000 feet as the equivalent dynamic effects of 425 knots at or near sea level. This airspeed is 65 knots over max operating for a 767, 85 knots less than the alleged United 175, and 5 knots less than the alleged American 11. Although it may be probable for the alleged American 11 to achieve such speed as 430 knots is only 5 knots over that of EA990 peak speed, It is impossible for the alleged United 175 to achieve the speeds reported by the NTSB using EA990 as a benchmark.

Pilots For 9/11 Truth have further studied if a 767 could continue controlled flight at such reported speeds. According to the NTSB, EA990 wreckage was found in two distinct debris fields, indicating in-flight structural failure which has been determined to have occurred a few seconds after recording peak speed. Based on EA990, it is impossible for the alleged United 175 to have continued controlled flight at more than 85 knots over the speed which failed the structure of EA990.

Full detailed analysis, including analysis of a recent simulator experiment performed, and interviews with United and American Airlines 757/767 Pilots can be viewed in the new presentation, "9/11: World Trade Center Attack" available only at http://pilotsfor911truth.org. Although other factors come into play within the transonic ranges, Dynamic pressure is dynamic pressure. Math doesn't lie. Boeing needs to release wind tunnel data for the Boeing 767. Despite the fact that the data can be fabricated, such a release of data may alert more pilots and engineers to the extremely excessive speeds reported near sea level for the Boeing 767 in which they can decide for themselves.

Founded in August 2006, Pilots For 9/11 Truth is a growing organization of aviation professionals from around the globe. The organization has also analyzed Flight Data provided by the National Transportation Safety Board (NTSB) for the Pentagon Attack and the events in Shanksville, PA. The data does not support the government story. The NTSB/FBI refuse to comment. Pilots For 9/11 Truth do not offer theory or point blame at this point in time. However, there is a growing mountain of conflicting information and data in which government agencies and officials refuse to acknowledge. Pilots For 9/11 Truth Core member list continues to grow.

First let me say I believe Pilots For 9/11 Truth on this. I saw the piece they did on the Pentagon, very interesting.

What baffles me is why the NTSB would find it necessary to skew these numbers.

Thanks for the info.

How do they find us?

... if they believe EA990 suffered structural failure for simply exceeding the certified V_D of the aircraft by 5 knots.

Don't they think the safety margin should be much greater than 1%? I certainly do.

- Make7

Mach 1 at Sea Level = 660 knots.

If UA175 was going 510 knots when it hit the tower, that speed was ~ .77 Mach, well below the .86 Mach maximum operating speed.

Edi: http://www.fighter-planes.com/jetmach1.htm
mach speeds at altitudes.

Sid

before reaching their cruising speed. because doing it at or near sea level is simply impossible.

so where did they get the idea for the official story? from a Disney Pixar cartoon? a Hollywood movie? My Pet Goat?

not because it's "simply impossible".

It's entirely possible for an airliner to fly at 500 feet. In fact, an airliner can fly "faster" at 500 feet than it can at 30,000 feet, because sound travels faster through the thicker atmosphere at lower altitudes.

Higher altitude = less friction = higher fuel efficiency = less $ on fuel

Also, with "thinner" air, comes less turbulence, and more passenger comfort.

Sid

for knowing less about aerodynamics and aviation than the dungeon debunker squad.

I was admonishing rollingrock for not knowing anything about aerodynamics and aviation, a fact amply demonstrated in their follow up to my post.

Sid

for not knowing about the English language?

'A 757 flies faster at 500 ft than at 30,000 ft...'

Uh, No. That might be true on the moon or on Mars, but not here on earth where there is something called atmospheric pressure, which is many times denser and thicker at 500 feet than at 30,000 feet.





'....because sound travels faster at lower altitude than higher altitude'

huh? wtf is that supposed to mean? that's like some kind of Bushism, it's so non-sensical.

(1) Neither of your quotations is accurate. Is your use of single quotation marks and italics intended to warn readers that you're about to misquote another poster? I don't really see the point.

(2) Sound travels faster at sea level than at cruising altitude. See, for instance, here. What is it that you find "like some kind of Bushism, it's so non-sensical"?

same way as sound! except in a Bugs Bunny cartoon!

Every time you fail to acknowledge blatant mistakes, in effect you are warning careful readers that they should not take you seriously.

Is that the intended effect?

and ask yourself the same question. consider that as polite advice.

If you're going to excerpt parts of my post, shouldn't you at least take the care to make sure your quotes are accurate?

Second, yes, sound propegates through denser air faster than through thinner air. You really didn't know that? And, since the Mach number is a function of the speed of sound, and Equivalent Air Speed is a function of Mach number and altitude (well, air pressure actually) then the EAS for a plane at cruising speed (.8 Mach) is higher at 500 feet than at 30,000 feet.

Sid

same way as sound does! duh! except in a Bugs Bunny cartoon!

most people learn about it in high school. you must have been absent that day.
heck, your local weather man or woman could explain it to you, if you ask them nicely.

Arrogant ignorance from an anonymous internet poster - it never fails to amuse me.

I might as well try to learn something on this thread.

it talks about Indicated Airspeed, Calibrated Airspeed, Equivalent Airspeed and True Airspeed. More detailed equations are available if you drill down to the main article on each type.

Sorry, not much help :)

Sid

Damn, forgot the link: http://en.wikipedia.org/wiki/Airspeed

is a walk-through of how (if at all) these numbers bear on some of the issues that get... discussed here.

For instance, somewhere around here I have a Google Books link to a book called something like "Aeronautical Performance" (maybe not very much like that) with a chart that indicates that Vmax in true airspeed (but not in EAS) is typically maximized well above sea level. What this means in practical terms, I don't really know. I know just enough about the physics of flight to know how much I don't know. (I try not to be the person who knows just enough to be dangerous....)

The premise that we can use an analysis of 990 to determine how fast the WTC planes could have flown seems facially silly. But thinking about the various constraints on how fast a plane can go is kind of interesting.

It gets into some details that I haven't seen elsewhere.

Egypt Air 990 was in a steep dive when it broke apart. The dynamic pressure alone was not what caused a structural failure but the attitude (i.e. angle) of the aircraft when it operated at these conditions. United 175 was flying straight and level and thus experienced a much different load distribution across the airframe.

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to the rest of us.

Please, never stop.

Sid

It must have been a doozie.

It's been a long time since I read anything about this accident, but if I recall correctly, the first officer fought the captain for control of the aircraft. The timeline was something like: 1) flight departs & reaches cruise altitude 2) captain leaves flight deck to go to the bathroom 3) first office says prayers to allah and starts dive 4) captain reenters flight deck and attempts to pull out of dive 5) crash.

There was something in the report about a initial steep descent, climb and then final descent. I could see airframe failures during such a flight. Obviously, this was a very different flight profile from the WTC airplanes.

maximum rated operating speed for a standard Boeing 767 is 360 knots. but the NTSB says the amateur hijacker pilots flew Flight 11 at 430 knots, 70 knots over the maximum speed? and Flight 175, at 510 knots, was 150 knots over the maximum rated speed? wtf? that's not physically possible, except maybe on Mars or Pluto.

man, this official story stuff is better than a Hollywood movie script! someone should give Steven Spielberg a call.

which, at sea level, essentially where the crashes happened, is 567 knots.

You're not only wrong, you're spectacularly wrong.

Sid

.86 mach is the top speed AT ALTITUDE. the rated Mach speed applies only when the aircraft is at cruising altitude, not at sea level. in aviation, the RATED TOP speed is 360 knots, which applies when the aircraft is at or near sea level.

Please, quit embarrassing yourself with such a pitiful display of ignorance.

Mach number, like Reynolds number, is dimensionless for a reason - similitude.

Boeing provides two max. operating speeds for the 767, for a reason. give them a call and ask them to explain it to you.

Don't project your ignorance on us.

http://en.wikipedia.org/wiki/China_Airlines_Flight_006



What's the maximum speed of the 747SP-09, spooked?

The Scene from "9/11: World Trade Center Attack"

SPEED - Scene from "9/11: WORLD TRADE CENTER ATTACK", is now available to view online. Watch it here...

http://pilotsfor911truth.org/forum/index.php?showtopic=18314

"Analysis of the speeds for the World Trade Center Attack aircraft reportedly used on 9/11. Please visit http://pilotsfor911truth.org/wtc_speed for supplemental press release and sources described in above scene. For full film in DVD High quality which includes Black Box Recovery, Radar and Speed data analysis, Aircraft Control, "Hijacker" Pilot Skill and more interviews with 757/767 Captains from United and American Airlines who have actual Command time in the aircraft reportedly used on 9/11, please visit http://pilotsfor911truth.org. "

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you do realize there's a difference between an aircraft's maximum OPERATING speed near sea level and the speed when it is out of control at high altitude, don't you?

have you contacted Steven Spielberg yet?

This Boeing aircraft exceeded Mach 1 and still landed. Speed is speed. If this out-of-control aircraft survived speeds in excess of Mach 1 and 5g's, then the Pilots for 9/11 Truth's "analysis" is full of bullshit to the very tippy top.

- for one, a 747SP is not the same as the 767s that flew into the twin towers.

- it hit Mach 1 temporarily because it was 30,000 feet in the air. That is not its normal operating speed. The aircraft was out of control for a long period of time, the pilots were very lucky to have regained control at the last minute because, one they were able to SLOW the aircraft down.


- the China Airlines plane was a 747SP, SP standing for Special Performance. The SP is a modified version of the 747 that is even lighter, faster, and SMALLER with a shorter fuselage, making it even more maneuverable and faster than the standard 747. The performance features and high maneuverability is what saved it from crashing.




China Flight 006 damage from excessive speed:

The 747SP is not smaller than the 767-223ER or the 767-222. If you're going to be comparing aircraft maybe you should make sure you get your facts straight first.

how the out-of-control aircraft is expected to survive speeds over Mach 1 and 5 gs, while the under-control aircraft has to break up.

:rofl:

unless this is some sort of game he is playing.

the alleged hijacked aircraft on 9/11 was at sea level.

do you understand the difference?

Please go read up on dimensionless numbers. There are plenty of decent fluid mechanics books out there that you can pick up cheap.

if you knew what you what you were talking about, it shouldn't be a problem should it?

Do your own legwork. You can start with the wikipedia article on similitude.

you can have all the book knowledge and theory in the world, but if you can't even explain how it applies to the real world or the discussion at hand it doesn't do anyone any good.

What is the saying? Those who can, do. Those who can't, teach.

you don't belong in the discussion. I'm not going to be able to give you those two things - you have to obtain them by yourself.

you actually knew what you were talking about. Is that too much to ask?

I'm not just going to take your word for it.

It's obvious from the content of your posts. Please go read the links I provided.

Your statement is factually inaccurate.

747sp Mmo is .92 Mach and typically cruises at .88 according to Wiki.
http://en.wikipedia.org/wiki/Boeing_747SP#Specifications_.28747SP.29

767 Mmo is .86 Mach.

You are correct, its not a valid comparison. The 747sp is actually a much "slicker" aircraft. And still it lost control surfaces. The pilots (highly experienced) were lucky to get it back home safe, with pieces missing. Only those who make excuse for the govt story would compare the two.

...and over and over while it was out of control and didn't break apart in a way that crippled it at all, in fact, allowing it to fly away and land while only losing one engine...

And yet 175 or 77 or 11 is supposed to break apart while being flown under control straight into their targets?

:rofl:

Bolo,

If you want something to compare to a 767, why not use another 767 as did Pilots For 9/11 Truth...?

Here is the link to the detailed analysis video again. Please watch it so you can understand the definition of Equivalent Airspeed and proper comparison.

http://pilotsfor911truth.org/forum/index.php?showtopic=18314

According to the NTSB, Egypt Air 990 broke up at speed equivalent of 425 knots at seal level. These are the facts.

LOL!

Keep blogwhoring your BS PFT "analysis".

ETA: Oh, Jesus fucking Christ, stop with the Egypt 990 BULLSHIT. From your link...

"The flight data recorder reflected that the Captain then commanded the nose up while the First Officer commanded the nose down, at the same time as the engines were shut down."

Are you kidding me here? :rofl:

Please describe this quality and provide backup for your assertion.

http://www.answers.com/topic/slick

Its a slang used by pilots regarding aircraft which are fast aircraft, not much drag, as compared to another aircraft.

The 747SP is known as a "Slick" aircraft. Its Mmo reflects as such since it is .92 Mach, as compared to a 767 which is .86M.

Hope this helps.

If you're still unsure of the term, call a local flight school. Perhaps they'll give you a free lesson.

Considering that I worked at a flight school for years during school, I've scored enough free lessons already. That won't help much - most pilots I've known haven't had a very good understanding of drag and flight near Mach - it takes an engineering degree to understand that. Unfortunately for you, engineering schools don't generally give out free lessons (although MIT has the OpenCourseware).

"Slick" encompasses less drag and more power, ie a "fast aircraft" as compared to another. As illustrated by the 747SP Mmo as compared to the 767.

I apologize if such a term confused you. I tend to speak in pilot terms since we are talking about aircraft here, and I am a pilot.

I'll do my best to put it into more laymen's terms in the future. I'm surprised you never heard such a term working at a flight school. There are a lot of "slick" aircraft in General Aviation. Baron, Bonanza, Mooney as compared to Cessna or Piper... just to name a few.

Have you watched the video yet?

http://pilotsfor911truth.org/forum/index.php?showtopic=18314

Mmo isn't related to drag - it's related to the critical Mach number. Learn some fucking fluid dynamics.

Well, yes and no...


"Mmo... it's related to the critical Mach number"

Yes...

It's good you know that, but you may want to inform Ryan Mackey, NASA Scientist as he thinks Boeing's cruise above Critical Mach all day long...

http://forums.randi.org/showpost.php?p=5239019&postcount=3864

Mackey seems to think 0.80M is above Mcrit for 757/767's. lol


"Mmo isn't related to drag..."

No...

Critical Mach is all about drag and therefore so is Mmo. Look at a Mcrit Chart. The divergence of drag is the Mcrit number.

http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Wings/TH20G3.htm

Try not to get too upset, your language is showing your frustration.

Rob Balsamo is lecturing me about aerodynamics. I'll have to save this exchange.

Really?

Looks like you're confusing cause and effect. The drag coefficient is about the same for all the wings tested when they were below their critical Mach number. The drag shoots up at the critical Mach number because of the shock wave created by the supersonic airflow -- something to do with that compressibility thing Mackey was trying to explain to you. In that experiment, the critical Mach number is not "all about drag" -- it's all about the sweep angle, which delays the onset of supersonic airflow.

Got any more "expertise" to share with us? Which reminds me, I'm still waiting for an explanation for why your "FDR experts" never noticed that extra four seconds of AA77 data and the 4-foot final radar altitude it recorded. Don't you have some DVDs to update, or are you just gonna keep selling what you've got to the unsuspecting rubes?

William,

As soon as the drag divergence occurs is defined as critical mach. Its also the point where supersonic airflow starts to occur over the wing. Both are synonymous. you cant have one without the other. Please click the links provided above.

Do you understand the term "Sound Barrier" and why it is/was called a "barrier"? It's all about drag. Do you know why its call "CRITICAL MACH"? Its all about drag. Since AZCat also realizes Mmo relates to critical mach, he is wrong when he claims Mmo is not related to drag.

Critical Mach is not the same for all aircraft. Hence the term "Slick" for the 747SP and a Mmo of .92 vs a .86M Mmo for a 767.

To compare the two is completely and utterly intellectually dishonest.

As for the extra 4 seconds of data regarding AA77, its thoroughly discussed here. Including exposing multiple logical fallacies offered by Mackey.

http://pilotsfor911truth.org/forum/index.php?showtopic=18239

Although i can understand why you would want to shift a WTC topic you and your cohorts are losing, to AA77.

> As soon as the drag divergence occurs is defined as critical mach.

Anyone who can use Google can look up the actual definition of critical Mach, and I did "click the links provided above." That's exactly how I noticed that the diagram you linked to refuted your claim that "critical mach is all about the drag." "You cant have one without the other" has nothing whatever to do with your confusing cause and effect. Although it's rather entertaining watching you spin when you're caught dead wrong, anyone who still takes you seriously just isn't paying attention.

Although I can understand why you would want to shift to the "impossible speed" of UA175 after the bottom fell out of your AA77 FDR analysis market. But my advice is don't quit your day job.

"With the supercritical wing, a substantial rise in the drag-divergence Mach number is realized and the critical Mach number is delayed even up to 0.99. This delay represents a major increase in commercial airplane performance." - http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Wings/TH20.htm

you can also see this clearly in the diagram i provided for Seger...

http://www.centennialofflight.gov/essay/Theories_of_Flight/Transonic_Wings/TH20G3.htm
(Seger, look on the left side of the above graph, what does it say?)

Clearly Seger never took a course in aerodynamics. But i did. Several. And is another reason why i teach it to students and am certified as a Flight Instructor.. :-)

... the entire concept of cause and effect, and the distinction between them, plays no part in your "reasoning?"

As soon as the drag divergence occurs is defined as critical mach. Its also the point where supersonic airflow starts to occur over the wing. Both are synonymous.

Bolded this time since Seger missed it the last time.


Bottom line, Drag has everything to do with critical mach and therefore Mmo, proving AZCat wrong.

Do you disagree?

If so, this is your new google word for the day,

Wave Drag

Google it.

Its the reason for the behavior of the charts you have seen. Cause and Effect.

You just completely reversed your claim, but nah, you don't have any problem with distinguishing between cause and effect, huh.

Anybody who still takes you seriously just isn't paying attention.

"Critical Mach is all about drag and therefore so is Mmo. Look at a Mcrit Chart. The divergence of drag is the Mcrit number."

I said this in my first post exposing AZCat in which AZCat claimed Mmo isnt related to drag.

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=274087&mesg_id=274216

Seger, are you ok? Seriously... I'm getting a bit worried about you. You used to be sharper.

In your first post, you said critical Mach is all about drag, then when I pointed out to you that your own link shows that critical Mach is all about sweep angle in that experiment, whereas drag coefficient is nearly identical below critical Mach, you switch it 180 degrees around to say drag is all about critical Mach, completely ignoring that I already explained why drag shoots up at critical Mach. Now, you would like to hand-wave away all that stupidity by claiming there are "related."

I wish I could say you used to be sharper, but I really can't recall any time that your arguments weren't absurd.

Critical Mach is the number at which a sharp increase of drag occurs. This is caused by supersonic airflow over the wing which creates Wave drag.

Sweep design delays this drag divergence, as well as other factors already quoted, such as supercritical wing design.

AZCat claimed Mmo is based on critical Mach, This is true.

AZCat also claimed Mmo is not related to drag. This is not true as Critical Mach is defined as stated above. Critical Mach is DIRECTLY related to drag. A sharp increase in drag is what DEFINES the Critical Mach number. Hence the term "CRITICAL"!

AZCat is wrong.

Seger, you are wrong.

Nice try to spin it up though. I admire your attempt to protect your cohort.

Now, do you also believe Ryan Mackey when he says .80M is above Mcrit for the 757/767?

In the long run, that would probably be less embarrassing than insisting that even when you're wrong, you're right. As it is, you've forced yourself back to the ridiculous claim that critical Mach is "defined" as the point at which drag shoots up drastically. It is not, as anyone can verify for themselves with a Google search: It is defined as the point at which airflow exceeds the speed of sound over some part of the airframe. That causes a shock wave, which causes the increased drag, due to compressibility. Cause and effect, Cap'n Bob -- if you can't even get that straight, then pretending to be some kind of aerodynamics expert is pretty silly. Not that it really matters much, of course, since anyone who still takes you seriously hasn't been paying attention for several years, anyway.

Seger,

Read this post carefully, the source, and the chart linked.

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=274087&mesg_id=274248

Note in the chart where the "drag divergence" is located for each wing sweep. This is the Critical Mach Number as it directly relates to Drag.

Critical Mach is all about drag. Drag is all about Critical Mach. The glass is half empty, the glass is half full. TomAto, TomatO.

You are wrong, AZCat is wrong. Mackey is wrong.

Congratulations. :sarcasm:

I didn't realize he was posting here. No wonder his posts are so clueless.

It was a lie told by your cohorts which you believed hook, line and sinker.

personal attack and smears. that's when you know they're getting desperate.

"special ed students" and "special needs students".

You said that yourself. That's not a lie, right?

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Nice victim card you got there. Goes well with the chip on your shoulder.

Its clear you havent a clue how the FAA works, and im tired of attempting to teach you the basics on the internet.

I got my medical back.. yes, not my "license". All i did was pay 70 bucks and went to see a AME.. and passed, despite Reheats claims he said he would have it stopped through people he knew..lol

I didnt get my "license back". you were wrong. My license was never revoked, expired or suspended. Nor did i voluntarily surrender it.

The claim on the PfT website "Pilots For 9/11 Truth do not offer theory or point blame at this point in time" is a lie.

he seems to be of the academic world and used to dealing in theory and formal terms. I don't think he would be very familiar with practical applications and terminology commonly used in the real world.

... such as the proof that it was "dynamic pressure" alone that caused EA990 to break up, rather than say, Mach buffeting and Mach tucking. None of the 9/11 planes experienced any of that, since they never exceeded their critical Mach numbers.

Seger,

Familiarize yourself with a Vg diagram...

here...

A 172 is the same as a 767, huh? And that's your answer to what I actually said, huh? Or are you just hoping nobody read it?

Something else that's missing from your argument, btw, is any explanation for why all those videos show UA175 hitting the WTC at a speed you claim is "impossible." Has your marketing research indicated that "TV fakery" will sell more videos? Maybe I shouldn't underestimate the gullibility of "truthers," but it seems me anyone can get that bullshit by the ton on YouTube for free.

1. Please prove it is "UA175". You can start by providing serial numbers and mx logs for cross check.

2. Are you familiar with the effects of dynamics pressure and the reason Boeing assigns two airspeeds?

3. Have you watched the video yet? (clearly you havent, so here it is again...)

http://pilotsfor911truth.org/forum/index.php?showtopic=18314

Hint, P4T doesnt dispute aircraft hit the WTC. We do dispute the speeds reported by the NTSB, for anyone who takes the 20 mins to watch the above analysis.

Those who make excuse for the govt story would rather not watch and instead spend their days and nights being proven wrong on the "interwebs".

But you are claiming that a 767 can't fly at 510 mph at 700 feet. So, are you claiming that that's not a 767 in the photos and videos?

Here it is again...

http://pilotsfor911truth.org/forum/index.php?showtopic=18314


Seger, the above video is only 20 mins. Why do you elect to spend hours arguing about a topic you have not thoroughly reviewed both sides?

Teach the controversy!

Here describes where i started to wake up....

http://patriotsquestion911.com/pilots

Before that i was more into motocycles, boats, jets, and boobs (not in that order...)

I still am, but now i have a bigger passion, saving our country. You seem to make excuses for it, behind your screen, obsessed with people like me daily, people who you think are nuts.

Hey Bolo, you know how much time i spend thinking about you, vs. the time you spend writing about people like me or even me personally?

I havent been on DU in probably over a year before today. How many times you written about me on here over the past year?

Too funny. Sad actually.

Now, anytime you want to address the topic, feel free. And no, that doesnt include Holocaust denial as im sure that will be your next card since you already admit you're losing with your Creationist card. Perhaps you wish to personally attack my race or sexual preference? lol


Ok, back on topic.

So Bolo, i guess you also agree that .80M is above Mcrit for a 757/767 as does Mackey? lol

Nominated for the most unintentionally creepy post fragment...

You haven't met JohnDoeX before now.

Speaking of which, I just did a search of my own posts back to February 06, 2006. The word "Balsamo" appears in them once. It's the post above.

Sigh.

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smearing people, dude?

BTW, how's that math coming?

what off-topic nonsense are you on now?

dude.

have fun with your arithmetic lessons.

you're the one smearing Bolo. It's really a hoot to claim that math is "off-topic" in a discussion about speed. Also, you've been challenged over and over to provide some real math for your goofy claims. I think you're the one that needs math lessons, dude.

It was the same nonsense as the OP and -- what a surprise -- it didn't answer any of my questions.

So, what we have is a self-proclaimed aerodynamics expert who thinks that "critical Mach is all about drag" and who thinks that the only effect of transonic flight is increased dynamic pressure. And if you buy that, then please buy his new DVD, too -- act fast, and you can also get a special package including the DVDs where the same self-proclaimed FDR expert assures us that the CSV data released by the NTSB ends one second before AA77 "allegedly" hit the Pentagon. (Well, no need to hurry, I guess, since it appears that he intends to keep selling those even though he now knows (and may well have known for some time) that it isn't true and that the last radar altitude reading was 4 feet.) Oh, but they don't "endorse any particular theory" mind you. Not that anyone could put together a coherent theory out of such "reasoning" as: the FDR data found in the Pentagon proves the plane was flying too high to hit the Pentagon; and the 767 that we see in dozens of videos hitting WTC2 was flying at an "impossible" speed. Nope, no theories here, so get our your credit cards and feel free to use THE ULTIMATE INFORMATION PACK ($69 with free shipping) to support whatever 9/11 delusions you prefer.

I thought I was the only one. At least I was doing something else at the same time.

OK, so my impression is that EAS does influence drag, but that critical Mach (with the concomitant shock waves and rapid increase in drag) depends on TAS and the local speed of sound (which is higher near sea level). So the EAS calculation is basically a red herring. What part of that is wrong?

And shhh, don't tell Cap'n Bob, but after spending the last half hour digging around -- it wasn't as easy to determine as one might think -- I'm certain that Ryan Mackey is correct about modern jetliners routinely cruising just over their critical Mach numbers: Their Maximum Range Cruise speeds are just slightly above their Mcrit numbers, and their Long Range Cruise speeds (burning 1% more fuel but getting there faster) is a little above that. Cap'n Bob is gonna be so heartbroken over this, since he's spent much more than half an hour blathering all over the net about how Mackey is wrong.

Of course I would not want to depend on a Wikipedia article (and "routinely" is not a very useful claim). But I would have been pretty astonished if Mackey had flamed out so spectacularly -- not just the claim about critical mach, but all the supporting details.

... and Cap'n Bob is now accusing Mackey of using that Wiki as his source, but as is typical, Cap'n Bob didn't think through the alternate theory that Mackey and the Wiki might be correct. It appears that a lot of people -- pilots included -- share Cap'n Bob's confusion over the difference between critical Mach and something called the drag divergence Mach, which is the actual point at which drag starts increasing exponentially. But in fact the standard cruising speeds (called Maximum Range Cruise, Long Range Cruise, and Econ Cruise) of high-altitude jets all lie between the two values -- "routinely" is exactly the right word. That confusion seems to be because of the term "critical" being used, but that's really just an historical artifact from early experiments. (One funny post I read suggested that the solution to that confusion and frequent questions and debates about it was to rename the value to "M triv" and then forget about it.)

It's actually easy to prove that Mackey is right, but to maximize the entertainment value, I think I'll wait for another of Cap'n Bob's famous "I'm right even when I'm obviously wrong" posts. (No, this post won't scare him off -- he just can't stop himself.)

is what part of the aircraft is experiencing supersonic flow, and what the consequences are. If we're seeing a significant pressure shear it can cause icing even when the shear isn't over control surfaces, but that depends on local environmental conditions.

"With this modification, the critical Mach number (Mach number where drag abruptly increases) could be delayed by about 0.03."

http://oea.larc.nasa.gov/PAIS/Concept2Reality/supercritical.html
(last sentence of 3rd paragraph)

Seger, feel free to post VERIFIED sources for your claims. I've already posted sources from aerospaceweb, NASA, Centennial Of Flight and now Langley research. AZCat agrees, Mcrit relates to Mmo on subsonic aircraft. Although AZCat is wrong with respect to drag, the above verified sources all claim critical Mach is the number where drag increases. As i said, you cant have one without the other (supersonic airflow without drag rise).

(edit: sorry folks, i dont come around here often as Seger is a waste of time since he rarely sources any of his claims, and only believes claims which suit his bias, regardless of source)

Is that your final answer?

And by the way, if that were true, would it mean that these planes don't cruise above Mcrit?

And by the way, if that were true, would it mean that the 9/11 planes couldn't have achieved the reported speeds?

For someone who has apparently spent a lot of time on this subject, you don't seem especially interested in it.

LOL, citing other people who make the same mistake as you doesn't do it, Cap'n Bob, so first, let's get the correct definition of the two terms you're confusing, critical Mach and drag divergence Mach. Just one example (many more can easily be found):

Source: http://www.aerospaceweb.org/question/airfoils/q0003.shtml


Of course, your confusion over terms doesn't necessarily mean that jetliners routinely cruise above their critical Mach, does it. So I did a lot of digging around on that, and read a lot of opinions both ways. Most people who seemed to know what they were talking about (and weren't confusing critical Mach with something else, like you) agree with Mackey (and the Wiki article). The best and most detailed explanation I found was in a thread at Professional Pilots Rumor Network (2nd post, by OldSmokey). Note in particular that he describes precisely how the Maximum Range Cruise is determined, and why it's above critical Mach:

http://www.pprune.org/tech-log/13127...rimmers-2.html

But maybe OldSmokey doesn't know what he's talking about? Sorry, Cap'n Bob, but the proof is that several people on that board and others mentioned that they had actually seen shock waves (by refraction) over wings while on passenger jets, and a few mentioned photographing them. Sure enough, a search of Google images turns up several examples. This one is particularly interesting because it exactly matches the description given by several people:


(Source: http://www.sky-chaser.com/flying.htm)

A picture is worth a thousand words, huh. You can keep claiming that you know more about all this stuff than anyone else, but that shock wave is the proof that you're wrong. So sorry you've made such a fool of yourself, for no particularly good reason, Cap'n Bob, but your attempts to embarrass Ryan Mackey over a trivial point have backfired because (A) you don't know what you're talking about, and (B) you didn't make any effort to find out before shooting off your netmouth. But don't sweat it; anyone who still takes you seriously hasn't been paying attention, anyway, so they aren't likely to start now.

Thats a GREAT source you have there Seger, especially considering your link is broken, (but i found it anyway)...

Heres one of your forum sources who support your theory...

"I don’t fly airliners, and of course I could be wrong." - hawk37

The other, "Old Smokey", claims to fly a 737. Unverified of course. None of his claimed charts are available and the thread is closed! Perhaps for posting misinformation? Seems "Old Smokey" might have chosen the correct name as it appears he may be blowing smoke up your exhaust stack.

Some guy on a forum, that's your source. Why am i not surprised...lol

Now, back to reality.

(Google for source as i dont feel like wasting too much time here...)

"Several methods exist to reduce wave drag, including the use of swept wings, slender or thin bodies, and supercritical airfoils. These airfoils have critical Mach numbers very close to one (hence the term supercritical) thereby delaying and reducing the large increase in drag due to wave drag." - aerospaceweb

"With the supercritical wing, a substantial rise in the drag-divergence Mach number is realized and the critical Mach number is delayed even up to 0.99. This delay represents a major increase in commercial airplane performance." - Centennial Of Flight Commission

"The airfoil has a flattened upper surface which delays the formation and strength of the shocks to a point closer to the trailing edge. Additionally, the shock- induced separation is greatly decreased. The critical Mach number is delayed even up to 0.99. This delay represents a major increase in commercial airplane performance." - SP-367 Introduction to the Aerodynamics of Flight, NASA

"With this modification , the critical Mach number (Mach number where drag abruptly increases) could be delayed..." - Dryden Research

Which is exactly what i said on this thread...

"Critical Mach is the number at which a sharp increase of drag occurs. This is caused by supersonic airflow over the wing which creates Wave drag." - Rob Balsamo, Pilot

And since he wanted to throw his hat in the ring...

"Mmo... it's related to the critical Mach number." - AzCat

Now for Mackey's claims and the response from real, verified pilots with real names (not some anonymous guy on a forum).

"Boeing's typically cruise above their critical mach" - Ryan Mackey

Response.

"Bullshit" - Captain Rusty Aimer - United Airlines 757/767 pilot

"Ahahahahahaha, clearly the guy doesn't have a clue what he is talking about" - Captain Ralph Kolstad - American Airlines 757/767 Pilot

Seger, when a shockwave is present, it means the air over that section of the airframe is above the speed of sound. Yes, this is the technical definition of Critical Mach. However, when a shockwave is present, it creates WAVE drag and drag increases abruptly known as drag divergence. You cannot have one without the other. "Typical Cruise" for any aircraft will not be at a speed where there is added drag. It is counter intuitive to fly in an regime of increased drag added to the already increasing parasitic drag. Air traveling at Speed of Sound = Added Drag. Period. This is why supersonic aircraft fly through transonic ranges as fast as they can. In the olde'n, some aircraft didnt have the power to fly through the transonic range, but were supersonic aircraft. They had to dive almost vertically to transit this range. Once supersonic, life was good...

Now, back to the original argument (which is a bit off topic here, but for clarity). Mackey claimed the static system on the 757 was experiencing "Compressibility issues" and this is the reason the new decode from Warren Stutt for AA77 still shows too high. Mackey goes on to explain that compressibility happens at critical mach. The speed data shows .70 - .72M. Mackey must believe this is above critical mach for the 757 if he believes the static system was experiencing compressibility issues. This is a crock and Mackey perhaps knows it, but knows people like you will buy it hook, line and sinker. This lead to Mackey claiming "Boeing's typically cruise above their critical mach".

Seger, "Old Smokey" and a picture from some website are not sources (although they appear to be good enough for you if it supports the govt story). Please see the verified sources above. Let us know when you will contact all of them and advise them of their "mistakes" to amend their statements. I suppose you should start with aerospaceweb and work your way down through the NASA sources you claim are also mistaken. Be sure to link to "Old Smokey" for your backup... I'm sure they'll get right on it...lol

Speaking of NASA, why isnt Mackey listed here with his credentials?

http://forums.randi.org/showpost.php?p=2572560&postcount=193

You guys tout Mackey as if he is your messiah, but dont list him with the others? I find it ironic those who list their credentials are anonymous, yet those who claim to use their real names dont list their credentials. After reviewing several of Mackeys claims, i can see why.

If anyone would like to follow along with the original debate, it is posted here... we dont expect Seger will register, he has a problem with civil debate.
http://pilotsfor911truth.org/forum/index.php?showtopic=18239

This will probably be obvious to anyone who bothers to Google the terms together -- even to someone who reads your NASA source carefully. It's hard to fathom why you don't concede the point.

As for your "real, verified pilots," there's no indication that they know what Mcrit for a 757 is, so their unsubstantiated assertions don't really cut much ice. Do you have anything relevant?

Ask AZcat. He said it up the thread.

Mmo for the 757/767 is .86M.

This was also verified by Rusty Aimer, United Airlines 757/767 Capt for United and current consultant on the 787 project at Boeing, if you care to click the link to the original debate.

Bottom line; .70M - .72M is not above Mcrit for the 757 as claimed by Mackey with his Compressibility theory.

There is no point to concede. However, if you wish to have some sort of concession of terms, as i said, you may want to start with aerospaceweb, work you way through NASA, Dryden Research and then perhaps every aerodymics syllabus taught in the world. You cannot have Mcrit without an added increase in drag. Its just that simple.

Once you get them to concede, and amend the statements and the way its taught, i'll also amend the way i teach it.

Enjoy your Sunday... :-)

So you admit that drag divergence Mach isn't the same as critical Mach? and you don't know what Mcrit is for a 757? and you'd rather talk about Mmo?

... in the hope that his preferred debating tactics will work better in that venue than they do on the web.

:rofl:

Are you really hoping there's someone around here who is dumb enough to fall for that bullshit song and dance, or are you trying to fool yourself into thinking that you weren't wrong?

Yes, Cowboy Bob, when a shockwave is present, it means the air over that section of the airframe is above the speed of sound. Yes, Cowboy Bob, that is the technical definition of Critical Mach. Yes, Cowboy Bob, that photo and others you can find on the web prove that OldSmokey does indeed know what he's talking about. So yes, you were wrong, Cowboy Bob, and you've made a fool of yourself.

Again.

No, Cowboy Bob, you can't muster enough bluster to change that reality. Not that it makes much difference, though: Not even an 11.2g pull-up could save your pathetic career as a conspiracy huckster from the nosedive it's suffered since Warren Stutt found that extra four seconds in the FDR data. But I do appreciate your extra efforts to entertain us with this professional quality buffoonery.

:rofl:

I was looking through the site sourced with your picture Seger... cool site.... nice pictures..

Was he standing on top of the wing when he took this shot?



You can even see what appears to be the ocean below behind the trailing edge. Now thats a daring photographer!

Too bad he didnt get a picture of the airspeed indicator. Then again, thats kind of hard to do when standing on the wing...

lol.. .too funny.

Seger, are you able to make one post without attacking the other person? You're so predictable.

Let us know when you have influenced NASA, Dryden, aerospaceweb and others to amend their statements. Also let us know when you or Mackey prove .70M - .72M is above Mcrit for the 757 to hold onto your compressibility theory..lol

Have a nice day... Tell your wing-walker friend i said hello.

You have attempted to gain fame and fortune by literally selling bullshit to gullible paranoids, convincing them that your experience as a pilot means that the nonsense you're selling in your DVDs is reliable. So yes, you can comfortable predict that I will attack you every time you show up here. But no thanks for your invitation to bring it over to your forum. I couldn't possibly care less about what goes on there.

Are you trying to say it was not a 767? It looked like one on film.