Thoughts on the Boeing tragedies. technically.

Discussion in 'Free Thoughts' started by nebel, Mar 20, 2019.

  1. nebel

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    2,469
    au contraire. the central thrust line of the Comet engines would not have allowed the DC 10 crew to steer the nose up and down (elevator), but yaw (rudder)only.
    Low engines, or inclined thrust line give you attitude control by throttle only. admit it, mid thrust is neutral.
     
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  3. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Except that the Tiger Moth wasn't unstable (in fact, barring massive design errors) no aircraft were unstable until the advent of fly by wire.
    The Tiger Moth simply had a lower stability than (some) other aircraft.
    And, given that the Tiger Moth was designed as an ab initio trainer then unstable definitely wasn't desirable.
    (And your wording is strange: aerobatic aircraft need to make unexpected moves against an enemy?)

    Inane drivel.
    Thousands of hours of computer time and flight testing were put in to ensure no instability was introduced by the placement of the engine pods.

    And wrong again. The thrust line of the Comet's engines was not on the centre line (with regard to pitch CG) - I suggest you learn what the Comet looked like: the engines were effectively fitted to the bottom of the aircraft (i.e. below the CG, therefore essentially underslung).

    Nope. Engine position merely dictates the response to thrust variation with regard to attitude: e.g. low-slung engines give nose down with reduced thrust, high ones give nose up. (This refers to thrust line versus CG, not geometric placing). In other words you're still wrong.
     
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  5. nebel

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    Comet/ Nimrod Engines were inside the wings aligned with the cord. not absolutely coinciding with the center of drag, but nothing compared to A DC 1o. which, with all engines working could be manipulated along the 3 axis, (the tail one did not in the wreck). Engine power on one side engine would make for reasonable aileron action, giving lift and outside speed inducing a turn.
    Switching from 737 to max was a major change. aerodynamically. add new computer works,and you needed all on board really ready for the unforeseen.
     
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  7. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Which doesn't alter the fact that attitude control would still be possible using engine thrust.
     
  8. nebel

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    You are right, but with a crippled craft, you might need more leverage given by the other, low engines, now prevalent designs.
    Boeing 737 was edging closer to the center of cord situation compared to it's predecessors. airflow over the top being the most changed.
     
  9. nebel

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    I have met a few of the Boeing people in Seattle, and even the maintenance staff is passionate about aeronautics.
    Could it be that the line is inspired by Boeing history, where the first projects were sea planes? the front curve symbolizes a bow wave? as long as they did not paint the bottom with an anti - foul coat.
    The instructor I flew Tiger Moth with, trained not just beginners, that could have been done in gliders, but aerobatics. and he weeded out the the reluctant (loop spin and roll) debutantes to bomber command. Some planes are so stable by design, they will not do any of that . Alaska Air flying inverted off the California Coast, an anomaly notwithstanding.
     
  10. nebel

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    2,469
    I did not say enemy, I said opponent.
    All fighter airplanes with deadly opponents are aerobatic, but not all Aerobatic-able planes are fighters, yet often they try to outmanoeuvre their opponents, the other contest competitors.
    One common feature shared by the two doomed planes,( and condolences to the victim's, families s left behind)* is the missing stall indicators. The kind of stall the Mx's wing could experience is one starting in the middle, not at the tips. Middle, where at 13+ degrees angle of attack the engines blanked the leading edge, and the with the new, efficient wing tips, (an upscaled version of the prior puny Airbus offering) the stall could be more total, sudden. imho. The crashes happened during the climbs, where not only the angle of incidence is high versus the horizontal, but also against the airflow.
    If the wings were indeed stalled, ( which the crews would not know, because their planes did not have the optional instruments), the computer would have been right to lower the angle of incidence. Fighting that by trying to pull up, would have worsened the stall. If the computer or sensors were wrong, but the crew not trained to override them quickly, made certain that there was no escape.
    * passengers would be very resistant to being led into more 737 maxes, or book flights were they have no control over which type would be awaiting them at the gate and what fate,
    sad for the victims, sad for a great company.
     
  11. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    False. Many fighters (a number of British jet fighters in the 1950s were, to my knowledge, not cleared for nor capable of aerobatics due to aerodynamic problems).

    Also false: the Comet had stick shake as a stall warning measure, the B 737 has this.
     
  12. nebel

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    The 737 is a ver well build airplane, withstanding years of salt air exposure, flexing in takeoffs, landings, and it will get you home, witness this 1988, picture (cant credit copyright holder where credit is due from Wikipedia) at the moment passengers are not so sure, and airlines are reacting. Note, the wing fairing is still the same, but engine hangs way lower even below the deployed slats. The Arrow is in the original Wiki picture pointing to that, for some reason. 737 will get you home again. no questions. soon, hopefully.

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  13. sideshowbob Sorry, wrong number. Valued Senior Member

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    Try to get your story straight. A bow wave is fundamentally different from airflow over a wing.

    Sometimes a line is just a line.
     
  14. nebel

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    well, are we not glad that the battle of Britain was not fought again in the 50s/ with spitfires then out turning the Mes? and yes I get you see the Starfighter saga.
    I was referring to the anti-stall upgrade that is offered by Being on the max. Lion and Ethiopean did not equip those 2 planes with that option.
     
  15. nebel

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    2,469
    As you might have noticed, I like a good humorous line. one liners. Yes, her in the Pacific northwest are many airplane and boating Enthusiasts., William Boeing was one of them. To me the line actually looked like that of a killer whale surfacing.
    Lines, and even arrows have a funny way to appear and acquire meanings.
     
  16. sideshowbob Sorry, wrong number. Valued Senior Member

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    I'm not sure that's appropriate in a thread about airplane crashes.
     
  17. nebel

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    agreed, and I have yet to see a condolence message from you. It is not about specific crashes, but as the OP states technical, I believe aerodynamic issues.
     
  18. sideshowbob Sorry, wrong number. Valued Senior Member

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    7,057
    Since when is speculating about the "meaning' of aircraft paint schemes an aerodynamic issue?

    Anyway, I don't think the crashes are an aerodynamic issue as much as a computer versus human control issue.
     
  19. nebel

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    2,469
    Lines on wings, fuselages, windscreens were created by tuffs of thread, very meaningful. stick in mind, and I am sure the viewing of different line options bythe Boeing team evoked mental images., of the flow kind.
    hope you are right on the fix.
     
  20. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    So what?
    Aerobatics is not air combat manoeuvring and vice verse. The fact is that your claim was - and remains - erroneous.

    Then that's what you should have said, as opposed to the completely false statement that you did make.
    Although I will admit that the Comet was not fitted - ever - with the B737's anti-stall upgrades (surprisingly...

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  21. nebel

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    ever heard about an Immelmann?
     
  22. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Of course.
    But it doesn't support your contention.
    An Immelman may be used aerobatics or ACM, but that doesn't make the one the same as the other.
     
  23. nebel

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    2,469
    when I was young after 1930, [dog] fighter air combat was all aerobatics. now, with vector thrust, cobras, standstill in air it has reached new heights, so, where is the 737 connection? uninterrupted airflow at the leading edge?
     

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