1. TWCobra

    TWCobra Senior Member

    The claim:

    Pilots for 9/11 truth have published several videos claiming that airliners travelling slightly above the Design Dive Speed; known as Vd, are subject to structural failure. This assertion, amongst others, forms the basis of this video;



    The video itself takes numerous licences with what it states; which will be addressed later, but for now let us concentrate on their claims about the ramifications of flying faster than Vd.

    The specific claim at 5.00 is that Egypt Air 990 suffered structural failure at 425 KEAS. (Vd+5).

    (EAS is Equivalent Air Speed, is a value mainly used by test pilots to equate the aerodynamic loads on an aircraft at different altitudes and speeds to a speed at sea level, where the air is thickest.)

    This claim is completely without merit and contradicts the NTSB report into the incident as discussed in this post. Analysis of the FDR data shows that the 767 suffered no structural failure at Vd+23 knots or 443 KEAS whilst pulling 2.1G, with split elevators.

    Research has uncovered another incident of a Easyjet 737-700, G-EZJK^ which pitched down during a test flight whilst flying at 15,000 ft. The aircraft had its hydraulic flight controls turned off as part of the test. The AAIB investigation into the incident finds that the aircraft, which has a Vd of 380 KEAS, recovered slightly below 6000 feet after achieving 429 KCAS which converts to 424 KEAS, or Vd+44 knots.

    The aircraft, according to the report, landed undamaged and continues to fly in Brazil for GOL airlines^ as PR-VBI. During the recovery this aircraft pulled ~1.7G at ~420KEAS.

    Another 737 did go much further past Vd before it unfortunately broke up. The report of the Adam Air Flight 574 crash on New Years Day 2007 in Indonesia shows that whilst descending in a tight spiral dive after the pilots mishandled problems with the aircraft's navigational equipment and lost spatial awareness, the aircraft broke up whilst pulling 3.5G (max G limit 2.5) whilst flying at 495 KCAS at 12,000ft.

    This aircraft was a 737-400 which has a Vd of 400 knots. The KEAS value at the point of breakup is 480 or Vd+80.

    Pilots for 9/11 truth make these videos in an attempt to push their claim that UA 175, a United Airlines 767-200 was in some way modified to achieve the highest speed reported by the several studies that were done into UA175, that of ~508 KEAS or VD+88. They claim it is not possible for an unmodified 767 to survive at these speeds.

    EA990, a 767-300 was undamaged @Vd +23/2.1G and split elevators (Which caused massive twisting loads on the tailplane).

    G-EZJK, a 737-700 was undamaged @Vd +44/1.7G and recoverable with hydraulic controls switched off.

    Adam Air 574, a 737-400 did not break up till reaching Vd+80 and pulling 3.5G. There is no indication of structural failure before that point.

    None of this data proves that UA175 could get to Vd+88 and survive. However UA175 did not reach Vd+80 until about 5 seconds before impact with the South Tower of the WTC. It was in a slight descent and rolling towards 38 degrees of bank. The G force in that scenario would be slightly over 1G.

    I have gone through this research because UA175 has interested me since I learned of the speeds it reached. It should be noted that the range of speeds obtained from the various studies is 437-510 kts Groundspeed.

    All of the best case studies indicate the aircraft should have easily survived, some are below the Vd+23 of EA 990. The highest speed is right on the limits of believability, however none of the alternate theories; modified, guided, holographic; are credible.

    One thing that has been proved however is that Boeing build damn strong aeroplanes.
     
    Last edited: Feb 23, 2014
    • Informative x 6
    • Like x 3
    • Winner x 3
    • Agree x 1
    • Useful x 1
  2. George B

    George B Extinct but not forgotten Staff Member

    TWCobra . . . Thanks for your analysis . . . I realize there is a range of professional judgement, aeronautical theoretical understanding, and practical sophistication within the ranks of commercial pilots; however, to the layman it is difficult for us to understand the existence of such a contradictory group, all be it tiny , making these assertions . . . could you address what you feel are the causes or reasons behind this groups efforts ? Why are they risking their professional reputation on such issues . . . any thoughts?
     
  3. TWCobra

    TWCobra Senior Member

    George, my personal opinion is that, particularly with regards to UA175 and AA 77 they argue from incredulity. There is some basis for that as UA175 did fly very fast according to the NTSB, faster than any 767 had ever gone before and much faster than what Boeing was legally required to demonstrate via test flying to get the aircraft certified.

    As a group P4T demonstrate the typical intense distrust of government that we find in most CT groups. IMHO they also show contempt for the abilities of the hijackers and have large cultural bias that I believe is the basis for forming the conspiracy theory.

    I don't think they were aware of the Easyjet aircraft though. The incident happened on a test flight with only a two man crew and so was not heavily publicised outside of the UK. I wasn't aware of it either till I saw a reference on PPRUNE.

    All these examples, and others, show however the Boeing build aircraft to a standard much higher than that required by the regulations.
     
    • Like Like x 2
    • Agree Agree x 1
    • Useful Useful x 1
  4. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    TWCobra,

    Your post is misleading.

    1. You misinterpret the information provided by Pilots For 9/11 Truth. They have never claimed "that airliners travelling slightly above the Design Dive Speed; known as Vd, are subject to structural failure.". It is the Illustrated Guide To Aerodynamics who makes such claims. If you actually view the video, the underlying VG Diagram is based on the Illustrated Guide To Aerodynamics. And if you know anything about VG Diagrams, VD is the end of the flight envelope and the start of the Structural Failure Zone. So, in short, yes, any aircraft which exceeds VD is now traveling in what as known as a Structural Failure Zone.

    "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/

    2. You fail to provide FDR CSV files of the EasyJet incident. You have previously misread many reports including the reports of EA990 until you were corrected by P4T and given the actual CSV files. Let us know when you actually provide actual sources for your claims.
     
    • Disagree Disagree x 2
    • Like Like x 1
  5. TWCobra

    TWCobra Senior Member

    The AAIB report was referenced in the original post. Included in the report was the FDR data. May I suggest you read it? It states that the max speed attained was 429 KCAS at approx 6000 feet. KEAS 424. Vd +44. Undamaged.

    I don't misinterpret what P4T state. The video above clearly makes the statement @5.09 that EA990 suffered structural failure at Vd plus 5 knots when both the NTSB report and the CSV data supplied by P4T clearly show that there was no structural failure at VD+23.

    That is an error pointed out to Robert Balsamo that he has not corrected.

    Your Vd reference is someone's blog? FAR 25.35 gives all the details about the requirements for Vd. May I suggest you read that as well?
     
    • Like Like x 1
    • Agree Agree x 1
  6. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    Here, maybe this will help the readers as your argument compares to the aircraft on 9/11?
    [​IMG]
     
  7. TWCobra

    TWCobra Senior Member

    Once again, EA990 is incorrect.

    The Easy jet aircraft did not lose control at Vd+44; it recovered at that speed. The initial loss of control was caused by an out of trim condition after the hydraulics were turned off for test flight purposes.

    The Adam Air aircraft needs to be put at 3G with an annotation that the G experienced was rolling G due to the fact that the pilot were in a spiral dive and attempting to pull out of the dive by simply pulling back on the stick instead of the correct recovery technique.

    Other annotation should include the fact that you reference only the fastest speed attained by UA175 from the various studies and have omitted the range of the other studies. ( 437 knots-510 knots).

    You should also include the annotation that the terminal speed of UA175 was achieved only in the last few seconds of the flight and was not maintained throughout.
     
    • Agree Agree x 5
  8. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    No one is stopping you from creating your own VG diagram proving the above incorrect. In fact, the amount of time you spend attempting to discredit P4T might be better spent creating your own illustration of exactly what you are trying to say? I would almost bet it would actually take you less time than all the chest thumping you attempt through text. Especially given the fact you have not provided any source for your claims, and have proven in the past you are unable to accurately read an FDR graph, until I had to make this for you..

    [​IMG]
     
    • Dislike Dislike x 1
  9. WeedWhacker

    WeedWhacker Senior Member

    Yes. Indeed. And, that seems to be a relevant fact that is often lost, in oh these many years of the tedious 'back-and-forth' on this subject.
     
  10. WeedWhacker

    WeedWhacker Senior Member

    Oh, I see that an originally poor argument has now been "enhanced". I once knew a girl in LA {"Tiff"...we called her "Tiff"}, and she had a much poorer example....but in either case, they are both equally false. Now, I need to chat with my friend "turbofan". We may decide to meet up with our "friends" at the C.I.T. Bar.

    Later, everyone!
     
  11. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    [​IMG]

    Do you "767 Pilots" ever get tired of being wrong?
     
    • Dislike Dislike x 1
    • Disagree Disagree x 1
  12. WeedWhacker

    WeedWhacker Senior Member


    I am assuming that a layperson is not aware of the inherent flaws in the estimates of groundspeeds provided by SSR radar?
     
    • Agree Agree x 1
  13. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    You think that Daniel R. Bower is a "layperson"? What exactly is "SSR" radar"?
     
  14. TWCobra

    TWCobra Senior Member

    Ok, so we have established who you are.

    That report references GROUNDSPEED Robert. Do the EAS calculations.

    Your graph you produced is a classic strawman tactic. I acknowledged the 20 knot error as you well know, yet you bring it here as some attempt to discredit me? Please stick to the subject.

    Acknowledge YOUR error with EA990. You constant refusal to do so leads me to suspect that you do not wish to publicly acknowledge that information on a video you charge people money for is incorrect, perhaps calling into question the entire premise of the video with loss of associated earnings for yourself?

    Would that be fair?
     
    • Agree Agree x 4
    • Like Like x 1
  15. WeedWhacker

    WeedWhacker Senior Member

    No, obviously not. Perhaps you misinterpreted my comment. I consider you to be a layperson, and am addressing you (and the audience at large) as such (NO disrespect intended for any of the readers), and also for the benefit of others who read this thread, so they will not be lost in obscure details....if I wanted to switch into "pilot speak", then I would defeat the purpose of enlightening the audience.

    K.I.S.S. is the axiom, here.
     
    • Agree Agree x 2
    • Like Like x 1
  16. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    Your constant refusal to admit that EA990 suffered in flight structural failure prior to ocean impact as told by the NTSB, the fact that you refuse to acknowledge potentially large errors in RADES data as told by the NTSB, the fact you ran from me on the reddit pages, the fact you have refused to plot your own VG diagram proving our VG diagram as false, and the fact you refuse to acknowledge the fact you still have yet to come up with one aircraft which exceeded Vd by more than 80-90 knots, remained stable and in control, speaks volumes.

    Yes, I am Rob Balsamo, Founder of Pilots For 9/11 Truth.

    Who are you, "TWCobra"?

    Are you allowing me to post the images you sent me?
     
    • Dislike Dislike x 1
    • Disagree Disagree x 1
  17. Keith Beachy

    Keith Beachy Active Member

    Poor video doomed by previewing fake speeds, and a fake Vg diagram.
     
    • Like Like x 1
    • Agree Agree x 1
  18. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    • Dislike Dislike x 4
  19. George B

    George B Extinct but not forgotten Staff Member

    Rob Balsamo, I am glad you came to participate. For the non pilot types here trying to follow the debate would really like to know why you feel the aircraft that were involved in 911 are suspect? They did hit their targets. What are we missing? Were they modified or piloted by someone or thing other than the hijackers? We know you want a new investigation we get that, but why?
     
    • Like Like x 1
  20. MikeC

    MikeC Closed Account

    • Agree Agree x 2
    • Like Like x 1
  21. JRBids

    JRBids Senior Member


    I wonder what the answer is also. Assuming you are correct, what does that mean, Robert?
     
    • Like Like x 2
  22. TWCobra

    TWCobra Senior Member

    For those not familiar with EA 990, the narrative from the NTSB report states that the aircraft dived twice before it hit the ocean. The first dive was recorded on the Flight Data Recorder (FDR); the second was not due to the recorders no longer being powered because the engines had been shut down.

    The report unequivocally states that there is no evidence that EA990 suffered any structural failure in the first dive; where it reached an EAS of 443 Knots. This come directly from the CSV data supplied directly to me from Robert Balsamo which I include below. The relevant data point is at Cell number 15774 and clearly shows the aircraft at 17152 feet flying at 463 K Calibrated airspeed and pulling 2.17G.

    Using this aviation calculator you can derive the figure yourself.

    At some point in the second dive, the left engine fell off with some other bits. The resultant debris field was only 400 metres long, indicating it was close to the ocean surface. The speed that this happened is not known or recorded, but clearly the aircraft survived 443 EAS or Vd+23, unscathed.

    This clearly refutes Roberts video, even though it uses his own evidence. I have brought this up with Robert countless times and he refuses to acknowledge his error. He merely introduces random spurious arguments to deflect away from the core issue debated here.

    Robert, rather quixotically, claims that the radar data that saw the aircraft climbing to 25,000 feet after the first dive could have an altitude error and that they were tracking "wreckage". I conceded the possible altitude error, however the four radar stations tracked the "wreckage" record the primary radar trace altering course by 60 degrees before commencing the second terminal dive. This course changed lead directly to the position of the debris field.

    Robert has never addressed this either.

    Robert, I went through all this with you on Reddit and left once it became clear that your argument style is based on deflection, strawmen, ad hominem attacks and appeals to authority. We see it here again in this thread. You claim on that thread that the RAT (Ram Air turbine) powers the electrical system on the 767. It doesn't. You claimed that windmilling engines on a 767 can power the bleed air system. They cannot.

    As a "Pilot for truth" I would have thought that the path towards truth includes admitting errors and correcting them. Once you do that I will know you are serious and are not conflicted for commercial gain.

    Your VG diagram has been debunked elsewhere. I won't embarrass you any further.

    As to your request to find a aircraft that exceeded Vd by 80-90 knots and remained stable; until proven otherwise, United Airlines Flight 175.
     

    Attached Files:

    • Like Like x 4
    • Winner Winner x 4
  23. WeedWhacker

    WeedWhacker Senior Member


    I wish to "reply" to this most excellent post...and at the same time mention...that the person being replied to is not currently capable of responding. I hope that the "history" of my replies, in this thread, will also be taken into account....for those that choose to review them. Meanwhile, I do not wish to distract from what I've already described as an "excellent post". A post that I, as an airline pilot of 24 years, and with other flying experience that goes back even further....cannot find fault with.

    Good job to "TWCobra"!!
     
    • Like Like x 1
  24. WeedWhacker

    WeedWhacker Senior Member

    Oh, dear. If these are actual quotes that can be attributed to Rob Balsamo, the owner and "manager"...or, "Forum Manager" of the "PilotsFor9/11Truth" website? If he can make THAT kind of mistake? Well (full disclosure)....there are many other examples of mistakes by the "PilotsFor9/11Truth". And these mistakes, numerous as they are, can be revealed...but of course for FREE!!! Just ask!

    Dear readers...."RAT" is an acronym for "Ram Air Turbine". On the B757 this is a device that will deploy automatically after the N2 (that is the speed of the N2 turbine sensors) diminishes below a certain point...which in NORMAL powered flight will not happen, but IF there is a power loss in BOTH engines simultaneously, then the RAT...this applies only to those airplanes certified for ETOPS....( I will add that SOME B767s have a RAT too. However, for ETOPS certification there were other considerations on the B767 fleet, and this was an option for the airline customers who purchased them).

    THEN the RAT will deploy. What does the RAT do? Glad you asked....the Ram Air Turbine is designed to provide sufficient hydraulic pressure to the Fight Controls, so that the pilots will retain control as they attempt to restart one, or both engines, and at the same time, begin to start the APU (if it is not already running) as an additional electrical and pressurization source. I should mention, also, that Flight Controls that are hydraulically powered require electrical power, for the pumps that are electrically powered...hence the desire to get AT LEAST one generator back online...either via an engine, and its CSD, or from the APU.

    I took WAY too many words to explain what ALL airline pilots already understand. But, this is an attempt, to help explain, in maybe not so simple a way, for the average layperson, and non-pilot who may read this. Trust, there is a LOT more to it, and it would take many, many pages to cover it all.

    Hope this "snippet" helps, even if only a little bit.
     
    Last edited: Mar 6, 2014
    • Like Like x 2
    • Agree Agree x 2
  25. TWCobra

    TWCobra Senior Member


    Robert, deliberately or otherwise posted the above attempting to paint a picture that UA 175 maintained Vd+80/100 during it final descent. Being a pilot he is of course aware of the relationships between the various types of airspeeds, to whit, a groundspeed of 510 knots at 10000 feet does not mean the same thing as the same groundspeed at 1000 feet.

    The EAS (Equivalent air speed) is the key speed to focus on with regards to structural failure. The EAS can be inferred from the NTSB radar trace by converting the groundspeed to a nil wind True airspeed (TAS), and from there an approximate EAS can be derived.

    The following table has been derived from this graph that recorded the approximate groundspeed of UA 175 during its terminal dive. I have only used readings below 10,000 feet as the EAS from above 10,000 is incrementally slower. Mach Number is included in the first three calculations, the aircraft never exceeded MMO of M0.86 so lower altitude readings are not really germane to the discussion. There will be small errors because the TAS only describes the speed through still air. There was a small headwind in the lower levels and I do not have the winds below 10,000 feet.


    UA 175 final speed profile.


    It can be seen in the light of the experience of the Easyjet 737 which survived Vd+44 without damage, that this aircraft did not exceed that benchmark till 13 seconds before impact. It should also be noted that applying this techniques to most of the visual speed studies of this aircraft would result in the aircraft never exceeding the Easyjet benchmark.

    IMHO however, this aircraft would have been on the verge of structural failure as it hit the tower.
     
    Last edited: May 31, 2016
    • Like Like x 2
    • Agree Agree x 1
  26. WeedWhacker

    WeedWhacker Senior Member

    Yes indeed, and this was an extremely thorough analysis, not only using facts, but also exposing quite a few untruths...the sorts of deceptive methods that some in this discussion have used, throughout.

    I realize that some might have a little difficulty comprehending, but I trust that the majority of the audience will not.

    It is an unfortunate fact that in matters of some technical complexity, there are ways for unscrupulous people to take advantage, and attempt to sway those less cognizant of arcane details.

    This could well be true. But, Boeing builds a very robust product. At the airspeeds involved (speaking of UAL 175), yes any abrupt or excessive control surface movements would no doubt have resulted in additional structural stresses, perhaps to the point of failures...but, certainly not a "catastrophic" failure as is seen in an animation produced, and published, by a group calling themselves the "Pilots for 9/11 Truth".

    The animation I refer to has likely been seen, by all reading this...I have little desire to link it and allow it more "views", as a YouTube metric. However, if asked (or searched), it can be found, as I'm sure it still exists....for free. Online.
     
    Last edited: Mar 12, 2014
    • Like Like x 1
  27. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    I won't bother to waste my time exposing all the false statements made by "TWCobra" above.... as I will probably be "banned" for it once again... but the above quote stands out. And is one of the reason people like "TWCobra" and "Weedwhckier" will never confront us directly....

    People should be asking "TWCobra" to provide part numbers and serial numbers of the parts recovered matched to maintenance logs in order to determine the performance of "United Airline Flight 175".

    In short, a Flight number can never determine aircraft performance. In fact, many different types of aircraft can be dispatched under the same flight number. And if "TWCobra" were a real pilot, he would know this and never try to mislead the readers on this forum using a flight number.
     
  28. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    Hi George,

    Thank you for your questions. I wish I had a chance to reply sooner.

    But to answer your question, it is all covered on our website. I wish I could give you a simple one sentence answer, but 9/11 is a bit more complicated than that.

    Should you have any further questions after reviewing our work, feel free to contact me personally through our website or at our forum.
     
  29. WeedWhacker

    WeedWhacker Senior Member

    And this is an untruth.
     
  30. Soulfly

    Soulfly Banned Banned

    • Agree Agree x 1
  31. TWCobra

    TWCobra Senior Member

    What are my "false statements" Robert? List them one at a time and lets go through them.
     
    • Like Like x 1
  32. jaydeehess

    jaydeehess Senior Member

    What reason is there to suspect that the aircraft that hit the towers, or the Pentagon, or crashed near Shankesville, were not the aircraft that took off as flts 11, 175, 77, and 93? I mean besides the outlandish claims of PFT and CIT?
     
    • Like Like x 1
    • Agree Agree x 1
  33. jaydeehess

    jaydeehess Senior Member

    What does the serial numbers of any aircraft parts have to do with whether or not the aircraft incident described in the OP, the 737, exceeded Vd by the same margin as the UA175 up to within ten seconds of the later aircraft's existence?
     
    • Like Like x 1
    • Agree Agree x 1
  34. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    No FDR data, no radar data.... and based on pure speculation.

    Who are you trying to fool?
     
  35. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned


    Because it didn't?
     
    • Dislike Dislike x 1
  36. jaydeehess

    jaydeehess Senior Member

    What didn't do what? And what does this serial number business have to do with the OP?
     
    • Like Like x 1
  37. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    As pointed out by "TWCobra", his data is an "estimate" based on data I gave him, not cross checked by anyone... and in fact is wrong.

    But you believe him.. .right?

    :)
     
  38. jaydeehess

    jaydeehess Senior Member

    The data you gave him is wrong?
    How about the data provided by the AAIB for the Easyjet? That's wrong too?

    ,,, and again, what does the serial numbers on the UA 767 have to do with whether or not there are other examples of aircraft exceeding limits and surviving?

    ,, and again, what didn't do what? You did not answer either question I posed, despite quoting my post.
     
    • Agree Agree x 2
  39. jaydeehess

    jaydeehess Senior Member

    Oh, and I have no reason to disbelieve TW. You OTOH, I do.
     
    • Like Like x 1
    • Agree Agree x 1
  40. SpaceCowboy

    SpaceCowboy Rob Balsamo of P4T Banned

    Would you trust information you were given from P4T? How many times have the JREF come up with really good April Fools jokes? :)


    I don't know. Have you checked into it? Have you gotten your own copy? Or do you just believe it since it was posted on this forum by some anonymous person....?

    Surviving with a crew which has thousands of hours in flight and time in type is very different than those with zero time in type. Or perhaps you disagree?

    How much flight time do you have?