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Russian Tu-154 'Disappears From Radar' Near Sochi

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  • Russian Tu-154 'Disappears From Radar' Near Sochi

    A Russian plane has disappeared from radar just minutes after take-off from the Black Sea resort of Sochi, Russian media say.

    They are quoting a source at the emergency ministry as saying the missing aircraft is a Tu-154.

    Between 70 and 100 people are reported to be on board the plane.

    Unconfirmed reports say the aircraft belongs to the defence ministry, flying to Syria's Latakia province. Russian officials have so far made no comment.

    All 92 people on board a Russian military plane are feared dead after it crashed into the Black Sea.

  • #2
    A Russian military jet with 91 people on board has crashed shortly after take-off near Sochi, the Defence ministry said.

    The ministry said the plane was carrying the famous Alexandrov military band for a concert at the Russian air base in Syria.

    (snip)

    Search and rescue groups have now found the crash site, close to the coast, it is being reported.

    The Defence Ministry said that there were 83 passengers and eight crew on board.



    Reported to be RA-85572.

    RA-85572. Tupolev Tu-154B-2. JetPhotos.com is the biggest database of aviation photographs with over 5 million screened photos online!

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    • #3
      Russian information, including photography of the aircraft.

      https://life.ru/t/%D0%BD%D0%BE%D0%B2%D0%BE%D1%81%D1%82%D0%B8/951853/stal_izviestien_spisok_passazhirov_razbivshieghosia_nad_chiornym_moriem_tu-154_mo_rf


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      • #4
        Seems like the debris field is quite large. http://tass.com/defense/922397

        Given the crash occurred relatively close to the shore I am surprised they have not found the main part of the Aircraft yet. There is also a video, supposedly taken near the Airport, which shows an explosion - https://www.youtube.com/watch?v=VE2BRieTgr8.

        The Russian Government may not suspect foul play but I do. Not much evidence available yet but what there is certainly suggests the Aircraft broke up prior to impact. Which could be Structural failure, fuel explosion - or a bomb. Terrorists have got bombs on Russian Liners before by bribing Security Staff (https://aviation-safety.net/database...?id=20040824-0) and I don't think it is impossible they could get a bomb on a Military Aircraft.

        Whatever the cause RIP to the victims.

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        • #5
          The preliminary analysis of a black box from a Russian military plane that crashed Christmas Day suggests a combination of pilot error and mechanical error are to blame, according to Russian media.

          The investigation into the crash has not yet revealed why the plane's wings experienced a problem with the flaps, the moveable panels mounted on the edge of the wings that increase lift, a source familiar with the investigation told news agency Interfax.

          Another source aware of the details in the preliminary crash investigation told Interfax that although a mechanical error could be to blame, "The crew's erroneous actions during takeoff shouldn't be ruled out either."

          The preliminary theory is that the pilots reacted incorrectly to the issue, and the plane crashed as a result, according to Interfax.

          The plane had two black boxes, only one of which has been recovered so far.

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          • #6
            Whatever is a mechanical error??????

            --- 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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            • #7
              I'm putting my money on them failing to fly the plane and entering a stall. Perhaps a deep stall, which would have developed into a flat spin if they didn't hit the water so soon. And maybe the plane was overweight due to some special "humanitarian" cargo on board.

              RIP to all on board.

              Why use a vintage 154-B2?

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              • #8
                Originally posted by BBC News
                A flight data recorder from the Russian airliner that crashed into the Black Sea on Sunday has revealed that faulty flaps were to blame, Russian media say.
                The flaps, panels on the wings that help lift an aircraft, did not open in sync, a source close to the probe told the private Interfax news agency.
                The pro-Kremlin Life news website says this led the pilots to lose control as the plane was at a "critical angle".
                It also quoted the crew's last words, including: "The flaps, hell... !"
                Source: http://www.bbc.co.uk/news/world-europe-38449058

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                • #9
                  Asymmetrical flaps alone do not cause a crash. But I'm wondering how much more difficult it might be to control with an anhedral swept-wing aircraft...

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                  • #10
                    Originally posted by Evan View Post
                    Asymmetrical flaps alone do not cause a crash.
                    Why not?

                    --- 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


                    • #11
                      Originally posted by Gabriel View Post
                      Why not?
                      Well duh, you also have to have a hard surface to crash into, flaps alone won't give you that... and taxiing with asymmetric flaps is probably no big deal either, you really need to be flying with them.

                      Or could it be that Evan wants them to improvise and nose over as AA-191 'could have done'?
                      Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                      • #12
                        Originally posted by Gabriel
                        Why not?
                        Asymmetrical take-off flaps on a conventional (dihedral) a/c are not going to overwhelm aileron authority. Survival lies in quickly recognizing the situation and that pilot input happens before entering a spiral dive. The perception of roll would be almost non-existent aside from the visual horizon or instruments, and whatever indications and alarms the a/c has for split flap conditions. But it is a controllable situation assuming you have enough airspeed for aileron authority. However, the Tu-154 is a rare bird, with low-mounted anhedral wings. I assume it has a split flap indicator and probably an aural warning (there was an alarm on the CVR). But it lacks the spiral stability of a dihedral wing and I'm wondering if that makes it unrecoverable at a sooner point than a conventional aircraft. Is it inherently more vulnerable to split flap conditions?

                        Can you answer that?

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                        • #13
                          Originally posted by Evan View Post
                          Asymmetrical take-off flaps on a conventional (dihedral) a/c are not going to overwhelm aileron authority.
                          Why not? Or how do you know that this is a universal truth? I don't remember any requirement saying that an airplane must be controllable at any given speed with any degree of asymmetric flaps. Yes, the plane must be flyable in any foreseeable and reasonable abnormal condition, which is typically managed by means to either prevent that from happening (like a system to mechanically interconnect all the flaps and to detect immediately any split flap situation and immediately stop any further flap movement), so any asymmetry is kept to minimum.

                          Look at this picture: that's a lot of flap surface, and probably a lot of effectiveness too if they are of the sliding and slotted type. I can perfectly imagine that flaps 15 on one side and zero in the other may be uncontrollable at take-off speeds / AoAs.

                          However, the Tu-154 is a rare bird, with low-mounted anhedral wings. I assume it has a split flap indicator and probably an aural warning (there was an alarm on the CVR). But it lacks the spiral stability of a dihedral wing and I'm wondering if that makes it unrecoverable at a sooner point than a conventional aircraft. Is it inherently more vulnerable to split flap conditions?

                          Can you answer that?
                          Short answer:
                          The dihedral will have no direct effect on how badly the plane will want to roll due to the split flaps, nor in how much you can compensate for that with traditional roll inputs (ailerons / roll spoilers). However, it may play a role if you run out of traditional roll authority and decide to use the rudder to induce do a sidelip and induce a roll.

                          Ok, long answer:

                          So one thing is the geometrical dihedral (which is just the angle between the 2 wings when seen from the front or back), and another the aerodynamic dihedral or dihedral effect, which is the coupling effect that sideslip has on roll. All airplanes (atr least all commercial airplanes AFAIK) have a positive dihedral effect, meaning that a sideslip angle to the right will induce a bank to the right. This effect can be pretty strong (to the point of being more powerful than the ailerons under some circumstances, as we all learned with the 737 hard-over reversals at below cross-over speed). So you can take more or less advantage of using the rudder to control roll for example in an asymmetric flap condition but, no matter if the dihedral effect is positive or negative (and how much at that), it is basically neutral in direct roll control authority (ailerons/flaperons/elevons/roll spoilers).

                          There are 3 main sources of dihedral effect:
                          1- The geometrical dihedral, which if positive provides a higher AoA to the forward wing than to the rear wing (in a sideslip).
                          2- The location of the wing.In a sideslip, the air needs to flow laterally across (in afact around) the fuselage. So it will split, the the upper half would move up, around the top, and down again, and the lower half will move down, around the bottom, and up again. This will induce an AoA in the wing which is equivalent to a positive dihedral if the wing is on top of the fuselage, or to a negative dihedral in a low wing airplane. This is why many high-sing airplanes have negative geometric dihedral (anhedral).
                          3- The roll moment done by the fin when it is generating lift (this is a combo of sideslip and rudder deflection, that tend to cancel each other)
                          4- Last but not least, wing sweep. Imagine the airplane below flying in a sideslip so as the forward wing is perpendicular to the free stream. You can very quickly note how much further this wingtip will be from a line parallel to the freestream and passing through the CG, compared to the other wingtip. With a little bit of imagination you can also see that the AoA will be higher in the forward wing (think only in the sweep effect and forget the geometrical dihedral).

                          This last effect is very significant, and I am pretty confident that this plane will have a clear positive dihedral effect despite the geometric anhedral, and that this slight anhedral was in fact designed to reduce a too strong dihedral effect, which is linked with bad dutch roll manners (which is in turn compensated with a very good yaw damper in western jets, I don't know in this one).

                          All in all, the direct roll effect of the split flaps by themselves is not sensible to dihedral, and the effectiveness of the direct roll controls aren't either. And because I am assuming that this plane has a positive net dihedral effect, rudder would have helped to control roll with sideslip as in a conventional plane, although perhaps not as strongly as in a 737 where the roll induced with rudder/sideslip can overwhelm the ailerons in certain circumstances.

                          Click image for larger version

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                          --- 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


                          • #14
                            Originally posted by Gabriel View Post
                            Why not? Or how do you know that this is a universal truth? I don't remember any requirement saying that an airplane must be controllable at any given speed with any degree of asymmetric flaps. Yes, the plane must be flyable in any foreseeable and reasonable abnormal condition, which is typically managed by means to either prevent that from happening (like a system to mechanically interconnect all the flaps and to detect immediately any split flap situation and immediately stop any further flap movement), so any asymmetry is kept to minimum.
                            Based on the frequency of flap asymmetry incidents and the uneventful landing vs the hull-loss rate and the splits flaps procedures I am familiar with, a flaps 15 asymmetry will not overwhelm aileron authority with sufficient airspeed if dealt with at a reasonable bank angle. In a dihedral aircraft anyway...

                            Look at this picture: that's a lot of flap surface, and probably a lot of effectiveness too if they are of the sliding and slotted type. I can perfectly imagine that flaps 15 on one side and zero in the other may be uncontrollable at take-off speeds / AoAs.
                            Maybe. This was a Tu-154B (older double slotted flaps) vs a 154M (upgraded triple-slotted flaps), if that makes any difference to the actual flap area....


                            Shore answer:
                            The dihedral will have no direct effect on how badly the plane will want to roll due to the split flaps, nor in how much you can compensate for that with traditional roll inputs (ailerons / roll spoilers). However, it may play a role if you run out of traditional roll authority and decide to use the rudder to induce do a sidelip and induce a roll.
                            What about roll-rate? I have the impression that anhedral will have a greater roll-rate and that is why certain fighters use it. If true, the situation might allow less time before it becomes uncontrollable. Check out the terrifying Tu-154 videos on this thread. There's some serious roll-rate going on: http://www.pprune.org/rumours-news/4...her-ua232.html

                            Ok, long answer:
                            Thanks for the short answer.

                            Ha! Kidding, thanks for the long answer. As usual, I will have to study it.

                            I have no idea if the Tu-154 has a yaw damper or even needs one. But I thought the decision to go anhedral was to avoid the drag penalty, and since life in Russia is cheap, the safety factor of spiral stability was of no concern.

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                            • #15
                              Originally posted by Evan View Post
                              ...thanks for the long answer...
                              Did he mention AA-191, or PSA-182, or some other incident with a 727 that lost a flap?...can't seem to remember that third one...something involving a takeoff over run.

                              Those planes didn't do so good with asymmetrical flaps, although I recall hearing that had the AA-191 folks improvised and deviated from procedure and nosed over for more speed, the plane was 'supposedly' controllable.
                              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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