Debunked: Pilots for 9/11 truth WTC speeds

[TWCobra]

Pilots for 9/11 truth published the following article claiming that it is impossible for a 767 to achieve the claimed speeds of the WTC attacks, based on the data obtained from the investigation into the Egypt Air 767 Flt 990 crash in November 1999.

The article appears here: http://pilotsfor911truth.org/wtc_speed

The NTSB report into the crash can be downloaded here: http://www.ntsb.gov/doclib/reports/2002/aab0201.pdf

The claim from Pilots for 9/11 truth is that the Egypt Air 767 broke up at 22,000 feet whilst descending at Mach 0.99, an EAS (Equivalent Air Speed) significantly less than the EAS postulated for, particularly UA FL175 as it approached the South Tower.

(PilotsFor911Truth.org) - 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.

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The NTSB report however does not state that the aircraft broke up at 22,000 feet. As the aircraft was descending both engines were shut down by the Relief First Officer, the person suspected of deliberately crashing the 767 (disputed by the Egyptians but not germane to the discussion), and the aircraft was still intact as it went through 17000 feet when both the FDR and CVR lost power due to the engine shutdown. Radar returns then have the aircraft climbing to 25,000 feet where it began another descent, apparently intact till it crashed into the ocean.

At no point in the NTSB report is it suggested that the aircraft broke up in flight.

Furthermore, the so called analysis of the loads on the aircraft neglects to mention that analysis of the FDR has the aircraft at just below 17000 feet, at 485 knots and crucially, experiencing 2.5 G as the Captain fought to regain control.

Furthermore, the aircrafts dual elevators were at opposite ends of their travel as the Captain pulled the control wheel back, and the First Officer was pushing it forward, introducing a large torsion moment on the tail assembly.

Furthermore, from the FDR the maximum Mach of 0.99 was actually experienced at 29500 feet, not 22,000 feet giving an EAS of 361 knots, 1 knot over VMO.

Here is the FDR data.



Two facts emerge from this.

1. This 767 airframe underwent a EAS of 462 knots whilst pulling 2.5G and with both elevators at opposite ends of their travel and survived. To say it could survive that and not survive the 1G flight at the speeds of the WTC attacks is not credible.

2. Pilots for 911/truth either did not read the report; couldn't interpret it correctly; or deliberately concocted the breakup/M.99 at 22,000 feet story, to further their own agenda. Take your pick.

For those interested, The NTSB report also contains this paragraph regarding simulations:

The Safety Board also conducted simulations in which pilots from Boeing, EgyptAir, the Federal Aviation Administration (FAA), and the Board evaluated the controllability of the airplane following an initial upset that might have been caused by any of these failure scenarios. During these simulations, the pilots were consistently able to regain control of the airplane and return it to straight and level flight using normal piloting techniques, and the airplane could be trimmed to hands-off level flight. In fact, the 767ís redundant actuation system is designed to allow pilots to overcome dual failures such as these.

Even though increased control forces were necessary, recovery could be accomplished by a single pilot using either the left or right control column.102 Further, the simulations also demonstrated that the airplane could climb to about 25,000 feet msl with the engines shut down, even with the speedbrakes extended. The simulation also documented that the engines could have been promptly restarted and (assuming there were no opposing pilot inputs) that the airplane could have been recovered during the climb after the recorders stopped recording. Although the Safety Board recognizes that the simulator did not duplicate the accident airplaneís actual flight conditions in every way,103 such limitations are not uncommon in simulations, and the Board takes those limitations into account when evaluating simulator results. In this case, the Board determined that the differences were not significant and did not affect the validity of the results of the simulations.

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[Totaro17]

You are reading the FDR graph incorrectly. It clearly shows .99 Mach in line with alt at 22,000ft and air speed around 430knts. This graph is a linear graph which must be read with the horizontal plot points. In other words draw a vertical line that intersects mach,altitude and airspeed and that's what they are given moment. Furthermore this report is only on the FDR and CVR, The NTSB went on to say they had sufficient evidence that the left engine and small piece of the plane did dislodge around 20,000 feet. As far as the simulations they have nothing to do with forces at sea level. Pilots for 9/11 truth are correct this is not debunked

 

[TWCobra]

The NTSB went on to say they had sufficient evidence that the left engine and small piece of the plane did dislodge around 20,000 feet.

Please supply the quote that supports that statement.

 

[jonnyH]

The NTSB went on to say they had sufficient evidence that the left engine and small piece of the plane did dislodge around 20,000 feet

If the engine fell off at 20,000ft how is it that both the lines on the FDR graph that relate engine oil pressure remain reading "normal"?

 

[TWCobra]

The NTSB never said any such thing.

In the NTSB report, on page 150, the Egyptian authorities attempt at rebuttal of the report makes an unsubstantiated claim that the left engine separated in the climb.

Vis:

Precisely what happened after Flight 990 recovered is unknown because both the CVR and FDR stopped recording. It does appear, however, from the location and condition of the left engine, that pieces of the airplane, including the left engine, departed the airplane prior to the beginning of the second, fatal dive toward the ocean. The loss of the left engine -- likely due to an overstress of the airplane during the ascent back to 24,000 feet

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This is neither the official NTSB explanation, nor supported by any evidence. If P4T can explain how an engine separating from an aircraft climbing in excess of 400 knots at 24000 feet, can be found within 400 yards of the main wreckage, without perverting the laws of physics, I'd be very surprised.

Maybe P4T should read up on Toss Bombing

 

[Totaro17]

You do see your mistake, right?? "From the presence of a western debris field about 1,200 feet (370 m) from the eastern debris field, the NTSB concluded that the left engine and some small pieces of wreckage separated from the aircraft at some point before water impact.[1] this was from Wikipedia but I do see where in the NTSB report says that was said from the Egyptian authorities. So I stand corrected on that! But it's actually irrelevant the point they made and I agree with is that 510kts at sea level and level fight is the same 1.32 Mac at 22,000 feet and impossible!!

 

[Chew]

You're using 510 kt EAS at 22,000 ft to get mach??? Nooooo. You're working from the wrong end. 510 kt at sea level is mach .77.

 

[Hevach]

And if I'm understanding the math right it's .82 at 20,000 feet. It's not even mach 1 at 60,000 feet (.89), which is way above anything this plane can reach. 1.32 is just crazypants.

 

[Totaro17]

You're using 510 kt EAS at 22,000 ft to get mach??? Nooooo. You're working from the wrong end. 510 kt at sea level is mach .77.

Please read it again. I said it would be the same as 1.32 Mach at 22,000 ft. Your right at sea level it's .77 . In other words if the aircraft could reach 510knt (586mph) sea level it could reach 1.32 Mach(1004.8mph) at 22,000 feet or higher, which is impossible!

 

[Landru]

Please read it again. I said it would be the same as 1.32 Mach at 22,000 ft. Your right at sea level it's .77 . In other words if the aircraft could reach 510knt (586mph) sea level it could reach 1.32 Mach(1004.8mph) at 22,000 feet or higher, which is impossible!

What do you base this on? Mach .77 at sea level is the same as mach .77 at 22,000. It's the speed over ground that changes.

 

[Totaro17]

What do you base this on? Mach .77 at sea level is the same as mach .77 at 22,000. It's the speed over ground that changes.

Yes I understand Mach speed is Mach speed but see when you're flying an airplane you use knots at sea level and you use Mach at cruising altitude. Reason being is the air density you cannot get the correct air speed if you don't due this and will exceeded vmo(Max velocity operating speed)and eventually exceed VD(design divine speed). 510 kn at sea level and 510 kn cruising altitude are actually two different speeds so you cannot measure the same. And engine that can push and airplane 510 kn at sea level can push the same airplane at 1.32 Mac at cruising altitude. I hope this helps!! Thank you everybody for having and adult discussion here I've brought this up in other places and people just belittling.

 

[Landru]

Yes I understand Mach speed is Mach speed but see when you're flying an airplane you use knots at sea level and you use Mach at cruising altitude. Reason being is the air density you cannot get the correct air speed if you don't due this and will exceeded vmo(Max velocity operating speed)and eventually exceed VD(design divine speed). 510 kn at sea level and 510 kn cruising altitude are actually two different speeds so you cannot measure the same. And engine that can push and airplane 510 kn at sea level can push the same airplane at 1.32 Mac at cruising altitude. I hope this helps!! Thank you everybody for having and adult discussion here I've brought this up in other places and people just belittling.

Sorry, not going to take your word for it. Please provide information that supports your assertions.

 

[Chew]

Please read it again. I said it would be the same as 1.32 Mach at 22,000 ft. Your right at sea level it's .77 . In other words if the aircraft could reach 510knt (586mph) sea level it could reach 1.32 Mach(1004.8mph) at 22,000 feet or higher, which is impossible!

No, it can't reach that mach number for the simple reason drag rapidly increases as the sound barrier is approached. From about mach .9 to mach 1 the drag triples.

You are confusing CAS with EAS.

 

[Landru]

No, it can't reach that mach number for the simple reason drag rapidly increases as the sound barrier is approached. From about mach .9 to mach 1 the drag triples.

You are confusing CAS with EAS.

Calibrated Air Speed and Equivalent Air Speed.

 

[Pete Tar]

Can you back up a little - what claim are you disputing by pointing out that

the point they made and I agree with is that 510kts at sea level and level fight is the same 1.32 Mac at 22,000 feet and impossible!!

And engine that can push and airplane 510 kn at sea level can push the same airplane at 1.32 Mac at cruising altitude.

Are you still talking about flight 990, can you set out your argument again in one post?

 

[Totaro17]

Pilots speak of several types of air speed. When read directly off the air speed indicator, the value is called indicated air speed (IAS). Indicated air speed has several factors that must be corrected in order to determine the actual speed of an aircraft over the ground. To determine the aircraft’s indicated air speed, two pressures are measured. A pitot tube is positioned on the exterior of the aircraft so that the air molecules of the atmosphere “ram” into it. The faster the aircraft is traveling, the greater the ram pressure. As an aircraft climbs, the atmospheric air pressure decreases, as does the ram pressure. To account for this, the aircraft has a static air pressure port that is also connected to the air speed indicator. The greater the difference between the ram and static pressures, the greater the indicated air speed.

As an aircraft changes its air speed and configuration, such as occurs when slowing down and lowering flaps and landing gear, the airflow pattern over the fuselage changes. This change of airflow affects the pressure in the pitot tube and static port. To account for this, the pilot refers to an air speed calibration chart to read the calibrated air speed (CAS). Each type of aircraft has its own calibration chart because the airflow pattern depends on the aircraft itself.

With some aircraft, such as the TB-9 Tampico, the IAS is approximately equal to CAS at all air speeds. This is true for relatively slow-moving aircraft because they have an air speed envelope (the difference between the maximum and minimum speeds) of less than 50 knots. This small envelope means that the airflow pattern does not significantly change from slow to fast air speeds. A jet transport aircraft has a speed envelope of more than several hundred knots.
The airflow pattern over a Boeing 737 cruising at 400 knots with flaps and gear up is significantly different than when the aircraft is landing at 150 knots with gear and flaps down.

When flying faster than 200 knots, the air ahead of the aircraft becomes compressed. This air compression increases the air density and the pressure in the pitot tube. To account for compressibility, the pilot refers to an air speed compressibility chart. The greater the CAS and the higher the altitude, the more the pilot must subtract to attain the equivalent air speed (EAS).

As an illustration, imagine being in a speedboat and sticking your hand out into the wind. The wind pushes your hand back with a particular dynamic force. Now imagine sticking your hand into the rushing water. The dynamic pressure exerted on your hand by the water is greater than that of the air because of the higher density of water. As air is compressed into a pitot tube, the increased density of compression increases the dynamic pressure and therefore the air speed that is read on the air speed indicator. The more the air is compressed, the greater the error.

The air will be more compressed the faster the aircraft is traveling and the higher the pressure altitude. Think of the air at lower pressure altitudes as being pre-compressed by the force of the air pressure. Think of this air as pre-compressed concrete block. Think of the air at higher pressure altitudes as not being compressed, and therefore like a sponge. When the same force is applied to a concrete block and a sponge, the sponge will be more compressed, as is the case with air. So for the same CAS as the pressure altitude increases, so does the amount that must be subtracted from the CAS to determine the EAS. Equivalency charts are used to make this correction. The pilot enters the CAS and pressure altitude into the chart and determines how much to subtract. Equivalency charts are not airplane-specific.

It is the EAS that the aircraft feels. EAS is a measure of the dynamic pressure exerted on the aircraft. This dynamic pressure plays a key role in the lift and drag created by the aircraft. For a given EAS the aircraft feels the same dynamic pressure, and therefore lift and drag, regardless of altitude. The higher the density altitude, the thinner the air, and the faster an aircraft must travel through the air mass to obtain the same EAS. The actual speed of the aircraft through the air mass is called the true air speed (TAS).

A pilot flying at high altitudes must account for reduced air density. Imagine the space shuttle in orbit - even though the orbital speed is more than 17,000 knots, there is virtually no atmosphere to ram into a pitot tube. The EAS would be nearly zero. By knowing the air density, the pilot can calculate the actual speed through the air mass, or true air speed. The only time that EAS is equal to true air speed is when an aircraft is flying at standard sea level (SSL) conditions. It is to the TAS that the velocity of the wind is applied, to determine the speed over the ground. The presence of a tailwind or headwind will increase or decrease the ground speed.

 

[Totaro17]

Pilots speak of several types of air speed. When read directly off the air speed indicator, the value is called indicated air speed (IAS). Indicated air speed has several factors that must be corrected in order to determine the actual speed of an aircraft over the ground. To determine the aircraft’s indicated air speed, two pressures are measured. A pitot tube is positioned on the exterior of the aircraft so that the air molecules of the atmosphere “ram” into it. The faster the aircraft is traveling, the greater the ram pressure. As an aircraft climbs, the atmospheric air pressure decreases, as does the ram pressure. To account for this, the aircraft has a static air pressure port that is also connected to the air speed indicator. The greater the difference between the ram and static pressures, the greater the indicated air speed.

As an aircraft changes its air speed and configuration, such as occurs when slowing down and lowering flaps and landing gear, the airflow pattern over the fuselage changes. This change of airflow affects the pressure in the pitot tube and static port. To account for this, the pilot refers to an air speed calibration chart to read the calibrated air speed (CAS). Each type of aircraft has its own calibration chart because the airflow pattern depends on the aircraft itself.

With some aircraft, such as the TB-9 Tampico, the IAS is approximately equal to CAS at all air speeds. This is true for relatively slow-moving aircraft because they have an air speed envelope (the difference between the maximum and minimum speeds) of less than 50 knots. This small envelope means that the airflow pattern does not significantly change from slow to fast air speeds. A jet transport aircraft has a speed envelope of more than several hundred knots.
The airflow pattern over a Boeing 737 cruising at 400 knots with flaps and gear up is significantly different than when the aircraft is landing at 150 knots with gear and flaps down.

When flying faster than 200 knots, the air ahead of the aircraft becomes compressed. This air compression increases the air density and the pressure in the pitot tube. To account for compressibility, the pilot refers to an air speed compressibility chart. The greater the CAS and the higher the altitude, the more the pilot must subtract to attain the equivalent air speed (EAS).

As an illustration, imagine being in a speedboat and sticking your hand out into the wind. The wind pushes your hand back with a particular dynamic force. Now imagine sticking your hand into the rushing water. The dynamic pressure exerted on your hand by the water is greater than that of the air because of the higher density of water. As air is compressed into a pitot tube, the increased density of compression increases the dynamic pressure and therefore the air speed that is read on the air speed indicator. The more the air is compressed, the greater the error.

The air will be more compressed the faster the aircraft is traveling and the higher the pressure altitude. Think of the air at lower pressure altitudes as being pre-compressed by the force of the air pressure. Think of this air as pre-compressed concrete block. Think of the air at higher pressure altitudes as not being compressed, and therefore like a sponge. When the same force is applied to a concrete block and a sponge, the sponge will be more compressed, as is the case with air. So for the same CAS as the pressure altitude increases, so does the amount that must be subtracted from the CAS to determine the EAS. Equivalency charts are used to make this correction. The pilot enters the CAS and pressure altitude into the chart and determines how much to subtract. Equivalency charts are not airplane-specific.

It is the EAS that the aircraft feels. EAS is a measure of the dynamic pressure exerted on the aircraft. This dynamic pressure plays a key role in the lift and drag created by the aircraft. For a given EAS the aircraft feels the same dynamic pressure, and therefore lift and drag, regardless of altitude. The higher the density altitude, the thinner the air, and the faster an aircraft must travel through the air mass to obtain the same EAS. The actual speed of the aircraft through the air mass is called the true air speed (TAS).

A pilot flying at high altitudes must account for reduced air density. Imagine the space shuttle in orbit - even though the orbital speed is more than 17,000 knots, there is virtually no atmosphere to ram into a pitot tube. The EAS would be nearly zero. By knowing the air density, the pilot can calculate the actual speed through the air mass, or true air speed. The only time that EAS is equal to true air speed is when an aircraft is flying at standard sea level (SSL) conditions. It is to the TAS that the velocity of the wind is applied, to determine the speed over the ground. The presence of a tailwind or headwind will increase or decrease the ground speed.

There are Calculators you can find on the web to convert knots to mock for different altitudes

 

[Landru]

There are Calculators you can find on the web to convert knots to mock for different altitudes

And they don't support your assertions.

 

[Totaro17]

Calibrated Air Speed and Equivalent Air Speed.

It is theoretical you are right if it started to approach that speed of 1.32 mach you would never get to it. You would break up and fall out of the sky that's the whole point to this

 

[Totaro17]

And they don't support your assertions.

I have used a few of them and they have.!!!

 

[Landru]

It is theoretical you are right if it started to approach that speed of 1.32 mach you would never get to it. You would break up and fall out of the sky that's the whole point to this

You claimed .77 mach at sea level is the same as 1.32 mach at 22,000. Support that or you are in violation of the posting guidelines.

 

[Svartbjørn]

Pilots speak of several types of air speed. When read directly off the air speed indicator, the value is called indicated air speed (IAS). Indicated air speed has several factors that must be corrected in order to determine the actual speed of an aircraft over the ground. To determine the aircraft’s indicated air speed, two pressures are measured. A pitot tube is positioned on the exterior of the aircraft so that the air molecules of the atmosphere “ram” into it. The faster the aircraft is traveling, the greater the ram pressure. As an aircraft climbs, the atmospheric air pressure decreases, as does the ram pressure. To account for this, the aircraft has a static air pressure port that is also connected to the air speed indicator. The greater the difference between the ram and static pressures, the greater the indicated air speed.

http://womanpilot.com/?p=61

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.

Are there any other sites youd like to plagiarize while we're at it? That ENTIRE post (I just copied part of it) came word for word from the website I cited above. If you cite sources, thats one thing.. but dont sit there and try to pass something off as yours when you rip it right off a website word for word. The information might be accurate but it brings into question your motives and ability to think critically when you try to speak about things way outside your personal understanding or try to pass off someone else's work as your own.

 

[Landru]

I have used a few of them and they have.!!!

http://www.globalaircraft.org/converter.htm
510 at sea level is .77 mach
.77 mach at 20,000 is 473 knots

 

[TWCobra]

Can I ask what the purpose of defending P4T is? Are they saying that certain airspeed/alt/Mach number combinations are impossible, therefore the FDR data can be ignored?

 

[Chew]

Totaro17's original point was the dynamic pressure would be too high to fly 510 kt at sea level but he was laboring under the mistaken belief that Eygpt 990 broke up at altitude. Now his point is the 767 cannot reach 510 kt at sea level because it cannot reach mach 1.32 at 22,000 ft. He is ignoring the increased drag near the sound barrier.

If you plugged in the airspeed as seen on the graphs of the NTSB report on Egypt 990 into an airspeed calculator it is obvious the speeds are CAS.

This one allows any altitude to be entered and will compute CAS, Mach number, TAS, and/or EAS if a value is entered for any one of them.

http://www.hochwarth.com/misc/AviationCalculator.html

 

[Landru]

I entered this:



Anything wrong here?

 

[Chew]

Nope.

 

[Chew]

It looks like Totaro17 is also using the sea level speed of sound to compute the mach number for 22,000 ft. The speed of sound decreases with altitude.

 

[Landru]

I think he might be trying to say that if the plane used the same power settings then the speed at 22,000 ft would be mach 1.32 ignoring the increase in drag approaching mach that Chew pointed out.

 

[TWCobra]

Totaro, can you clarify your claim please using the Hochwarth calculator? We need to know exactly what you are claiming.

 

[MikeC]

I think he might be trying to say that if the plane used the same power settings then the speed at 22,000 ft would be mach 1.32 ignoring the increase in drag approaching mach that Chew pointed out.

And also ignoring the decrease in thrust due to altitude?

 

[Totaro17]

No, it can't reach that mach number for the simple reason drag rapidly increases as the sound barrier is approached. From about mach .9 to mach 1 the drag triples.

You are confusing CAS with EAS.

It's theoretical of course it would never actually reach that mach speed it would break up and fall out of the sky!! The math says it would but it would not actually reach it that's the whole point here. It would become controllable he would have to tell Wendall when flutter .ru roll

What do you base this on? Mach .77 at sea level is the same as mach .77 at 22,000. It's the speed over ground that changes.

Mach 1.0 is the speed of sound in air, so a plane flying Mach 2.0 is flying twice as fast as the speed of sound. The speed of sound is not a constant, but depends on altitude (or actually the temperature at that altitude). A plane flying Mach 1.0 at sea level is flying about 1225 km/h (661 Knots, 761 mph), a plane flying Mach 1.0 at 30000 ft is flying 1091 km/h (589 knots, 678 mph) etc. Speeds below Mach 1 are called subsonic, between Mach 0.8-1.2 Transonic and above Mach 1.2 Supersonic. Fighter-planes.com. Mach is speed over sound and it changes with altitude. It's NOT "speed over ground that changes" not sure what this quote even means???
As your altitude rises your TAS will change. You then must adjust to bring the aircraft to the EAS.This is why you use knots/mach.

 

[Totaro17]

Ok, can some explain to me how a standard 767/200 can reach speeds of 510knots(586mph) at sea level. When the vmo is 360knots and the vd is 420knots

 

[Gridlock]

The short answer is, by driving it like you stole it.

The longer answer is well documented;

https://www.metabunk.org/threads/ea...-pilot-for-9-11-truth-v-g-diagram-video.3160/
https://www.metabunk.org/threads/de...roelastic-flutter-in-the-events-of-9-11.3359/

 

[TWCobra]

T

Ok, can some explain to me how a standard 767/200 can reach speeds of 510knots(586mph) at sea level. When the vmo is 360knots and the vd is 420knots

To give you a précis: Vd is the fastest speed that an airliners V-N envelope is certified to. The aircraft is guaranteed to not suffer structural failure at Vd at 2.5g/0.0g; which are the limit loads.

The airframes ultimate load is 1.5 times the limit loads.

In addition, the 767 was certified to a requirement that it be free of aeroelastic flutter at Vd+20% or Mach one, whichever comes first. At low altitude that is 504 knots EAS. UA 175 never exceeded that EAS till about 5 seconds before impact. Video shown on this site appears to show the beginnings of aeroelastic flutter from the left wing tip just prior to impact.

 

[Totaro17]

T


To give you a précis: Vd is the fastest speed that an airliners V-N envelope is certified to. The aircraft is guaranteed to not suffer structural failure at Vd at 2.5g/0.0g; which are the limit loads.

The airframes ultimate load is 1.5 times the limit loads.

In addition, the 767 was certified to a requirement that it be free of aeroelastic flutter at Vd+20% or Mach one, whichever comes first. At low altitude that is 504 knots EAS. UA 175 never exceeded that EAS till about 5 seconds before impact. Video shown on this site appears to show the beginnings of aeroelastic flutter from the left wing tip just prior to impact.

I now understand that the 767 can structurally withstand those speeds at sea level. Cobra yet to admit your mistake on 990s FDR graph that I pointed out but that's ok.and landru is correct to say .77 mach is the same at sea level and at cruising altitude. I am not a pilot, but I have 2 high school friends that are. I keep in touch with them and they have agreed with a lot of p4t and disagree with on some. They have told that the 767 can withstand the speeds of UA175 at altitude. But at sea level they do question it. But what they have a big problem with is the ability of the engines to have enough thrust to Propell the plane ( at near level flight) as you say and we see,a slight decent. They have said to me- that kind of speed is impossible at sea level The engines were not designed to produce enough thrust in that dense of air and it's was a warm day making the air more dense and wet(humid). To even come close to the VD it would have to be in a dive that's the definition of VD. I quote-"The dive speed [Vd} is the absolute maximum speed above which the aircraft must not fly. Typically, to achieve this speed, the aircraft must enter a dive (steep descent), as the engines cannot produce sufficient thrust to overcome aerodynamic drag in level flight. At the dive speed, excessive aircraft vibrations develop which put the aircraft structural integrity at stake." - Source -http://theflyingengineer.com/tag/vdmd/ . So can you explain to me how the engines had enough thrust to propel the plane 90 knots past it's VD(DIVE) at sea level at almost level flight. So, is it not true that 90knots past VD at near level flight at sea level is impossible to achieve, do to lack of thrust the engines are capable of. not so much because of structural Ability?

 

[Chew]

The engines were not designed to produce enough thrust in that dense of air and it's was a warm day making the air more dense and wet(humid).

Warm air is less dense than cold air and moist air is less dense than dry air. Geez man.

http://www.denysschen.com/catalogue/density.aspx

 

[Chew]

Vd is the speed that must not be exceeded in a dive or the aircraft may suffer structural damage or failure. It is not the maximum speed an aircraft can achieve in a dive.

 

[Totaro17]

Vd is the speed that must not be exceeded in a dive or the aircraft may suffer structural damage or failure. It is not the maximum speed an aircraft can achieve in a dive.

That's not answering my question. The question is can a 767s engines produce enough thrust to propel it at sea level at near level flight to 586mph?? Please !!! Again I quote- The dive speed [Vd} is the absolute maximum speed above which the aircraft must not fly. Typically, to achieve this speed, the aircraft must enter a dive (steep descent), as the engines cannot produce sufficient thrust to overcome aerodynamic drag in level flight. At the dive speed, excessive aircraft vibrations develop which put the aircraft structural integrity at stake." - Source -http://theflyingengineer.com/tag/
You guys are debunking pilots for 9/11 truth and you're not doing a bad job at it at all I do agree that the aircraft could withstand The structural Loads. My question is about the engines being able to produce the thrust to push the plane that fast at sea level. pilot friends of mine think it's impossible and I Refer you to this video.

[fixed tags]

 

[Totaro17]

Warm air is less dense than cold air and moist air is less dense than dry air. Geez man.

http://www.denysschen.com/catalogue/density.aspx

Obviously that's grammar school education! I was trying to see if anybody's paying attention instead of just trying to pick out things that may be incorrect. Out of everything I asked and said you picked out one thing, why not just answer the question and then correct me