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  • #76
    Originally posted by ErwinS View Post
    I fail to see what the Polish Tu-154 crash has annything related to TWA 800....
    1) Plane
    2) Crash
    3) Death

    Oh, yes, I forgot:
    4) Airplane shot down
    5) Evidence tampered with
    6) Government conspiracy

    EDIT TO ADD:

    And yet another one:

    7) Airplane doing things despite that they are physically impossible (Polish: Climbing while rolling inverted. TWA: Climbing after loosing its nose).

    This one will never quit amazing me: Things that insist and succeed in doing things that are impossible.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

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    • #77
      Originally posted by 3WE View Post
      So, your basic streamlining is something blunt on the front and tapered in the back
      Right, but Blunt does not mean WIDE OPEN.

      Would it have stopped instantly? Probably not, but to me it seems even less likely it would have climbed. How about falling apart?

      There are a few simulations for Pan Am 103. I don't feel like digging right now, but on Youtube they have one unidentified from some documentary, and one from ACI/Mayday. Neither of them show a climb. Quick look on Wiki says this about the moments after the nose falling off:

      "The fuselage continued moving forward and down until it reached 19,000 ft (5,800 m), at which point its dive became nearly vertical.[15] As it descended, the fuselage broke into smaller pieces, with the section attached to the wings landing first".

      Again, I'm not seriously researching this right now, though they do site the NTSB report.

      As for the ultra-realistic CIA animation for TWA 800, and some saying it's been "dumbed down" - I don't see a reason for the CIA to get involved in an NTSB investigation in such a way. I understand they, as well as the FBI had to get involved to find out if it was a crime, an act of terrorism, an accidental missile launch. But it's not the CIA that should be making those simulations, pretty much telling us "this is what the eye witnesses could have seen that looked like a missile launch, but wasn't".

      Comment


      • #78
        Thanks for the discussion- your points are valid.

        And I also hear you on the "tone" of the video. Instead of "here's the data and why we have this conclusion", it's "you did not see a missle, you saw a climbing plane, repeating, you did not see a missle"

        Now, I will stand by this one point- I seem to recall a HUGE arcing smoke trail. The hugeness says "flaming airplane" to me and not a missle trail. The trail seems to show something of a climb- but you know what- it could just be the plane slowing and arcing down...

        Do I belive that the plane could have climbed a little (YES!!!!!). And if I hear the words "a climb was impossible" I'm very suspicious (even the use of absolute terms makes me suspicious). Now- do you want to debate 5000 ft vs 500 ft...yeah, bring on an engineer, because I'm not able to go there- and you and I can disagree on just how much it could climb- but don't tell me it's ZERO/IMPOSSIBLE/only a descent is possible...only.

        Back on smoke trails- show me a tiny thin smoking trail that joins the big one (at the exact point that the big one starts) and I'll be more convinced.

        I do not want to invalidate your argument- but would bet that some (many?) eyewitnesses (who are generally innacurate) saw a big smoking arc-which was the plane- and blurted out "missle."
        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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        • #79
          I went and found the CIA animation (and I assume the info therein is also in the NTSB report I just haven't taken time to look for it).

          Explosion happens.
          4 seconds later front 1/3 of the plane falls off. FL138
          Plane pitches up and climbs to FL170 16 seconds later (20s after explosion)
          2nd explosion happens and then dives.

          Seems to me it is at least plausible that said plane with CG that screwed up and at that speed could climb 3200 ft.

          Hmmm... where's the dead horse emoticon when you need it?

          Comment


          • #80
            Originally posted by UncleFire View Post
            I went and found the CIA animation (and I assume the info therein is also in the NTSB report I just haven't taken time to look for it).

            Explosion happens.
            4 seconds later front 1/3 of the plane falls off. FL138
            Plane pitches up and climbs to FL170 16 seconds later (20s after explosion)
            2nd explosion happens and then dives.

            Seems to me it is at least plausible that said plane with CG that screwed up and at that speed could climb 3200 ft.

            Hmmm... where's the dead horse emoticon when you need it?
            I envision in my head that the resulting pitch up is so vertical that it can't climb because the wings are now big speed brakes.

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            • #81
              so i'm assuming that the FDR recorded nothing after the nose separated. either that or they never released the true data

              Comment


              • #82
                Originally posted by Deadstick View Post
                I envision in my head that the resulting pitch up is so vertical that it can't climb because the wings are now big speed brakes.
                Why?
                There are several things to take into account:
                - Pitch is not equal to AoA.
                - Stall is not equal to fall, or even inability to climb. The wing keeps producing lift after stall.
                - We are used to the typical slow speed stall, but it is very different from a high speed stall. In a slow speed stall, the lift was already close to max lift and equal to weight before the stall, so the drop (not disappearance) of lift means that the lift goes below the wight. But at high speed, the lift is equal to weight at a very low AoA. So, before stalling, the wing has to increase a lot of degrees of AoA and increase the lift a lot, several times the wight. The plane will be necessarily climbing strongly even before reaching the stall AoA. Then, the lift will drop but it could still be well above the wight, so not only it can keep climbing but it can keep increasing its climb.
                - Before anyone says that the wings would have broken with such a lift, maybe. But bear this in mind: The required limit load factor is 2.5. Because of the safety margin, the ultimate load factor is 3.75. That is calculated with the MZFW (maximum zero fuel weight). If the plane had, not considering the fuel, a bit less of MZFW, and if there was some fuel in the wings (that surely was quite a bit), then the failure load factor would increase even more, it could for example reach 4.5. Now, a load factor of 4.5 can be achieved at max-lift AoA if the speed is 2.12. The IAS stall speed of a 747 in clean config and with a somehow heavy weight is about 200kts, which times 2.12 is 424kts. But that's IAS. At FL140 the TAS will be about 25% higher, or 530 kts, or if you prefer that would make for M 0.92. Do you think that this 747 was climbing at such a speed? No? Then the wings would not have broken from an aerodynamic overload (of course, this assumes an intact wing structure, I don't know how much the explosion of the CWT affected the structural condition). And before anyone says that the maneuver speed of the 747 is not that high, that's right, but that's because it's calculated with N=2.5, not 4.5.
                - Then we have the CG-shift / stability issue. If the airplane starts from trim and the CG shifts back, then the plane pitches up (something that weight-shift pilots know very well). But that it shifts back, doesn't mean that it shifts beyond the aft CG limit. And if it shifts beyond the CG limit, that doesn't mean that it shifts beyond the neutral point (the point of indifferent stability, or where the plane is neither stable nor unstable). And if it shifts beyond the neutral point, it doesn't mean that the AoA will reach 90° in 5 seconds (especially being something of the size and inertia of a 747).
                - But there is more: The plane lost a big part of the fuselage, all ahead of the original point of the CG. All that fuselage had an unstabilizing effect, and now that effect is gone. And, perhaps the most important and not understood part. The stability behavior of the plane changes radically between fully unstalled to fully stalled. The lateral stability is destroyed by stall, but the longitudinal stability increases a lot, because of two reasons. First, the wing stalls much earlier than the tail, so there is a point where, with the increase of AoA, the lift of the wing (ahead of the CG) is diminishing (because it's starting to stall) and the lift on the tail (behind the CG) keeps increasing. Those two effects are strongly stabilizing. And second, the center of lift of the ing moves from about 25% of the chord when fully unstalled to about 50% of the chord when fully stalled. That means that the transition from fully unstalled to fully stalled is more or less equivalent to a shift of the CG of 25% of the chord FORWARD. Again, strongly stabilizing.

                So, how much did the CH shifted with the lose of the nose? It must have surely been strong enough to create a strong nose-up pitch moment. But was it enough to make the plane unstable? And to make it unstable even beyond the fully-stalled condition? And to make the AoA reach something like 90° in a few seconds? I highly doubt it.

                Another question is that the plane had enough speed energy to climb 3000 ft after fighting for 20 seconds against the gravity, against a highly increased drag, and after having lost thrust (if it was the case). I don't know.

                So, did the plane climb 3000ft? Did it climb at all?
                I don't know.

                But, as 3WE said, things like "it stupid to believe that the plane could have climbed after loosing the nose" are absolutely off-base. It is certainly rational to think that it might have climbed quite a bit, or at least not to discard it with no further information than "it lost the nose".

                --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                --- Defend what you say with arguments, not by imposing your credentials ---

                Comment


                • #83
                  Originally posted by TeeVee View Post
                  so i'm assuming that the FDR recorded nothing after the nose separated. either that or they never released the true data
                  The last thing recorded by the CVR was a fraction of second of a noise that was the onset of the explosion, and which was subject to extensive sound analysis.

                  The FDR stopped at about the same time. The the power and sensor wires were severed together with the nose.

                  --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                  --- Defend what you say with arguments, not by imposing your credentials ---

                  Comment


                  • #84
                    Gabriel, I do enjoy your posts even if they take me awhile to read and digest. Here's my thought process.

                    If 1/3 of the (forward) fuselage detaches from the airframe, there's going to be more than a pitch up due to CG shift. There's going to be a radical pitch up, perhaps approaching 60-90 degrees and the wings are no longer providing lift, rather they are a huge speed brake. The aircraft will make an amazingly fast "stop" in the air and immediately begin falling. I don't see any way any aircraft in that broken configuration climbs 3000 feet. I'm not an aviation engineer, so I could be totally wrong. I do believe the CIA animation is laughable and there was more going on there than what they presented.

                    Comment


                    • #85
                      Originally posted by Deadstick View Post
                      Gabriel, I do enjoy your posts even if they take me awhile to read and digest. Here's my thought process.

                      If 1/3 of the (forward) fuselage detaches from the airframe, there's going to be more than a pitch up due to CG shift. There's going to be a radical pitch up, perhaps approaching 60-90 degrees and the wings are no longer providing lift, rather they are a huge speed brake. The aircraft will make an amazingly fast "stop" in the air and immediately begin falling. I don't see any way any aircraft in that broken configuration climbs 3000 feet. I'm not an aviation engineer, so I could be totally wrong. I do believe the CIA animation is laughable and there was more going on there than what they presented.
                      It's interesting to note that the nose section that separated weighed 80000lbs. Also the 3 pilots that observed the explosion in the air said the plane did not climb.

                      Comment


                      • #86
                        Originally posted by Deadstick View Post
                        If 1/3 of the (forward) fuselage detaches from the airframe, there's going to be more than a pitch up due to CG shift. There's going to be a radical pitch up, perhaps approaching 60-90 degrees...
                        What's the basis for your estimation? And "radical" it's rather ambiguous because it could mean a high pitch angle (as you've said) or a high pitch rate or both. So how fast do you guesstimate that it would have reached the pitch?

                        ... and the wings are no longer providing lift, rather they are a huge speed brake.
                        Again, pitch and AoA are two different things. A plane climbing at 60° of pitch and 55° of slope has an AoA of 5 degrees, which means a good bunch of lift and very low drag. I am not saying that this is what happened to TWA, but let me explain one thing again:

                        First, if the plane will quickly pitch up, it will be making a huge load factor (and hence a huge increase in climb rate) even before achieving the stall AoA. Then, after the critical AoA, the lift will drop a good bunch but if just before the stall you were at say 4G it's quite likely that after the stall the lift will still be more than the wight (more than 1G), hence the plane will keep increasing its climb rate, and if the AoA keeps increasing after that the lift will start increasing again. Any fully stalled airfoil has a lift curve that closely matches that of a fully stalled flat board, which gets its max AoA at about 45° of AoA, and that max lift is about the same than the max lift of an unstalled airfoil (just beofre the stall), so if the speed was the same as before (it will not be, you would have lost speed in the process, but just to fix the idea) you'll be again at about 4G when you are past 45° of AoA, so you've never stopped climbing at an increasing rate. That means that by now your trajectory will be far from horizontal (it will have a steep slope) and hence the 45° of AoA can mean for example 75° of pitch (if the trajectory's slope is 30°, as an example)

                        The aircraft will make an amazingly fast "stop" in the air and immediately begin falling
                        Again, please explain me how the lift will star making a lot of drag without making a lot of lift first.

                        I don't see any way any aircraft in that broken configuration climbs 3000 feet. I'm not an aviation engineer, so I could be totally wrong. I do believe the CIA animation is laughable and there was more going on there than what they presented.
                        I am not saying that it will, not even that it can, but that it is reasonable to think that a good climb is not an impossible outcome.

                        Again, I offer the video of the recent stall accident due to cargo shift as evidence (not of what the TWA did, but of what an airplane with a huge shift in the CG can do). The shift of both CGs could have been similar. While the Afghanistan accident didn't loose the nose, the TWA plane was going 2 times faster, and that means 4 times more kinetic energy with the potential of being transformed in 4 times the altitude gain. Plus, the TWA also lost a lot of weight which the Afghanistan plane didn't.

                        --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                        --- Defend what you say with arguments, not by imposing your credentials ---

                        Comment


                        • #87
                          Originally posted by phoneman View Post
                          It's interesting to note that the nose section that separated weighed 80000lbs.
                          And it's interesting to note that the 3 armored vehicles that shifted in the National Air Cargo crash weighted about twice that much.

                          Also the 3 pilots that observed the explosion in the air said the plane did not climb.
                          So maybe it didn't. That's more convincing than saying that it could have never climbed after loosing the nose.

                          --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                          --- Defend what you say with arguments, not by imposing your credentials ---

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                          • #88
                            Two things that the incidents had in common, both were set for take off regarding power and trim.

                            Pan Am was already in cruise and probably had the power pulled back and was neatly trimmed for cruise.

                            Could that be a cause for 800 to ascend?

                            I also usually wonder about even the observations of a highly trained and proficient air crew when it comes to witnessing a sudden event. By the time something happens and you can sort out "the event", it's probably over. True, when it comes to "run of the mill" incidents where a plane goes in, in proximity to the airport in daylight, I'll take a pilots observations any day for instance in a departure stall; but for those brief seconds where there is nothing but a flash of light in the dark sky while you were concentrating on your own ship? Even that is subject to question. Have you ever witnessed a auto accident? How many times did you "play the tape back" to visualize it? Ask the crew of the other ac what they were doing when there was a sudden flash in the black of night. How much could they objectively observe?
                            Live, from a grassy knoll somewhere near you.

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                            • #89

                              The green rectangle is the debris field of the wing and rear fusealge, the yellow one, of the forward fuselage, and the red one, of the ring of fuselage in the fracture zone.

                              This is highly incompatible with the plane suddenly stopping in flight. The distance from the tip of the green rectangle to the opposite tip of the red rectangle (which is likely close to the point of the explosion) is 5 NM. That's quite a bit considering that the plane was flying just 2 NM high.

                              --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                              --- Defend what you say with arguments, not by imposing your credentials ---

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                              • #90
                                Gabriel, pieces of the airplane moving forward at 300+ knots could easily cover 5 miles as they fell. And what happened to the pieces once they impacted the water? Did currents cause them to drift as they sunk? Clearly none of us know what really happened, it's just speculation on all of our parts mostly. How much altitude did the Afghanistan 747 gain before it fell out of the sky? Granted it was moving more slowly but my guess would be "not much." I think TWA 800, as wounded as it was probably didn't gain more than a couple of hundred feet, not 3000. I hope they revisit the investigation and we get the facts of this crash, but I'm not holding my breath. I don't trust the FBI much less the CIA. They're in the business of hiding the truth.

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