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  1. jonnyH

    jonnyH Active Member

    A picture is worth a thousand words, you are going to have to draw me a diagram.

    I thought I understood you, but when I put some numbers into excel to calculate the path of the fragments, I got a couple of graphs which seem to indicate that factoring acceleration into the mix has little to no effect on spread.

    with acceleration. Without Acceleration.


    Figures are displacement in meters (m). The interval between data points is 0.00001 seconds, the three series represent the centre and the front and rear limits of the 56 degree spread from a missile travelling at 750m/s along the x axis from left to right, detonating at the origin.
     

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    Last edited: Nov 3, 2015
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  2. ad_2015

    ad_2015 Member

    1. Different size. What size you found different? How much it? Be specific.
    2. What wrong with proportion? Do you understand difference between static test and dynamic explosion?
    3. What is straight edge? Do you seen shape of strike elements recovered by DSB and varied shape of strike elements from A-A test? What edge will leave mishapen, erroded fragment which lose speed after penetration of a few layers?
    4. What probability to met a two close holes (from which strike elements you think it happen?) on surface penentrated with so low fragment density?
    Tricks and magic of voodoo detected.
     
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  3. gsobjc

    gsobjc New Member

    They are all of size/proportion not fit to 13x13x8.2 by visual comparison with details nearby.
    I am sure you have found inventory of damage in the report where those holes are measured.
    Otherwise how did you decide that all those holes are from bow-ties?

    There is no huge difference (in regards to penetration process) between static and dynamic because
    fragments fly mainly perpendicular to the missile velocity (relatively to the plane) due to warhead
    design with the detonator shifted forward. So the test was correct just by turning the missile on
    adjusted angles.

    The skin is the first layer. No distortion on skin's holes is expected.
    They have to have two straight almost parallel opposite edges not rounded like
    those you presented.

    You are free to spend YOUR time as you want calculating theoretical probability
    but it wouldn't change the fact that your examples are not from bow-ties.

    For those who likes probability calculation I have funny "voodoo":

    2781e8708387a78e450319b4fc9b0068.
     
    Last edited: Nov 4, 2015
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  4. ad_2015

    ad_2015 Member

    What size have such holes and what source can leave it? You trying to avoid my questions with pathetic phrases which bring zero knowledge. Be specific - describe what leave bow-tie holes and how happen we seen it in B777 but in Il-86 we see same bow-tie but already from legal source - strike elements.
    Of course there is HUGE dufferences between static and dynamic warhead detonation.
    1. Disclosure angles of warhead dramatically changed. This is reason why cabin with curved shape receive pellets which flying from different angles.
    2. Pellets have not only speed and angle distribution from explosion force but also vector adding of missile and target speed. Its dramatically change ORIENTATION of pellets even in same place.
    3. Pellets gain alot speed (see #2) and penetrate multi-layered target with much more deformation and erroding. Its affect on hole shape.
    4. Static test show only pellets which have BEST MEETING ANGLE because all others just miss skin. How change hole shape with raised meeting angle you can see on their slide.
    Do you talking about Il-86 skin? Different speed - different holes and shape on skin. Read about protection screens against high-speed fragments.
    So you dont know how to calculate probability for met 2 holes all together with certain density? But you proclaim these holes from that effects?
    Very nice tables which clearly show presence of bow-tie fragments.
    What wrong with size of fragments and holes from it?
     
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  5. BombDr

    BombDr Senior Member

    There is a difference as both vehicles will add respective velocity to the effects of the fragmentation.

    Sorry to sound like a stuck record, but no-one has yet to determine the exact attitude, range to target or velocity at the point of function, which means that all following assertions and calculations are flawed by a huge dose of 'unknown'.
     
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  6. gsobjc

    gsobjc New Member

    Here is the example of homework the entomologist failed to do:

    b137bcc02151400f9ea1e5436a24a9f0.


    The hole is more than 20mm in size, unlikely from a bow-tie
     
  7. gsobjc

    gsobjc New Member

    >50% of fragments have velocity backward in the static state. That means that they have velocity projection that countervails the relative velocity in flight. So only orthogonal velocity projection affects penetration. The static test simulates that by adjusted angles to direct that would-be-orthogonal-in-flight part of the spray towards the cockpit.
     
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  8. Antidyatel

    Antidyatel New Member


    Thank you for the effort. However, your calculations are strange. It was easier just to redo. Plus Excel processes trigonometric functions in radians. Hence, your cos(62) is rubbish. See the recalculated version and snapshots of the trajectories with accounting for acceleration and without. I hope that Lancet is now more clear for you.
    upload_2015-11-6_0-32-44.
    upload_2015-11-6_0-33-12.
     

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  9. BombDr

    BombDr Senior Member

    Again, it is not known what range or attitude the weapon functioned relative to the aircraft.
     
  10. MikeC

    MikeC Closed Account

    Not at all - your conclusion is only valid is the bow tie hits the surface at a 90 degree angle - the hole can be much larger for other angles.
     
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  11. jonnyH

    jonnyH Active Member

    Yes, thank you, that helped a lot.

    I took the liberty of correcting some of the errors you made (I highlighted my changes in yellow in the spreadsheet so you can see where you went wrong), and I've re-scaled your charts so that they are easier to compare:
    With. Without.
     

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    Last edited: Nov 5, 2015
  12. Antidyatel

    Antidyatel New Member

    I see. I missed acceleration for the front shrapnel. Thanks. The difference for front and center shrapnel distribution is not so large for accelerated and constant speed options, although still measurable. (I went back to 750 m/s, ignoring the relative speed of the plane for now in order to simplify and I also extended the time to reach roughly 3 meters in Y direction - supposed distance to the cockpit). The larger is the angle in relation to the front shrapnel the larger is the difference in solution for accelerated and non-accelerated models. But we need to take note that it is a wrong assumption that acceleration is same and constant for all shrapnel. So in reality the picture is even more complex. But the overall idea is clear, constant speed solution will lead to wrong interpretation of the results.
    ONE more parameter to take note is the drag force that is proportional to square of speed. Meaning that front shrapnel will also experience highest deceleration along propagation direction leading to additional banding backwards of trajectory. Assuming how high are speeds in question this might not be a minor component that can be ignored.
    upload_2015-11-6_13-6-56.
     

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    Last edited: Nov 5, 2015
  13. Antidyatel

    Antidyatel New Member

    Ups. I made two more mistakes in excel, which caused wrong turn of the curves. Now corrected 9 I also reintroduced the relative speed of rocket and plane 1000 m/s, so that the impact locations can be estimated. The conclusion towards DSB report is not as damning as was originally implied in OP. Apologies. But still a measurable effect.

    And again I repeat that this is calculation in assumption that all shrapnel gets same and constant magnitude of acceleration with only direction of acceleration different. Different shape and location of shrapnel in the warhead will make this assumption invalid. But one can consider that the explosive has a cylindrical shape and thus center shrapnel will get higher acceleration. The dual layer of shrapnel and variation in shape and mass would also be strong parameters. And finally the drag force, that will affect front going shrapnel to much higher extend than center and back shrapnel. All these factors should definitely bend the front shrapnel trajectory backward. I wonder how much. Need sophisticated simulation software. Hard/impossible to handle in Excel.
    upload_2015-11-6_14-27-53.
     

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  14. william wiley

    william wiley Member

    If such a piece entered on an angle far larger than 90 degrees it will give us information about the direction of the missile too.
    A missile coming from side on is likely to leave entry holes on larger angles in more places. This was one of AA's main points. A Z missile sprays pre formed fragments down the length of the plane. Do we know where that piece was from?
     
    Last edited: Nov 5, 2015
  15. RB2

    RB2 New Member

    View attachment 16025
    Interesting single still from Almaz-Antey test detonation to disprove Snizhne launch location,am under the impression they expected more damage as they had claimed previously all starboard panes and cockpit side should show multiple frag exits IL 86 right side-.
     
  16. BombDr

    BombDr Senior Member

    Not an exact direction, as the frag fans out and bumps into each other, and as its for tearing and shredding and ballistic penetration, it will likely change direction on contact with the aircraft skin and tumble.
     
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  17. jonnyH

    jonnyH Active Member

    Hmm, that sounds like a challenge, and I simply can't resist one more spreadsheet. It may not be a very accurate model but I've set it up so you can change the size, mass and drag coefficient and the graph will update accordingly. Do let me know if I've made any obvious blunders.

    The answer to the question of how much effect drag has on the path of the fragments?, is apparently "not much", even less effect than the initial acceleration does. Its really not worth taking into account for all the effort it takes. You have to change the variables by an order of magnitude or two to discern any effect.

    Anyway, I was hoping this exercise would shed light on the lancet, it doesn't. If (as you seem to believe) lancet formation is entirely reliant on the missile being in motion, then a static test would seem pretty redundant.
     

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    Last edited: Nov 6, 2015
  18. gsobjc

    gsobjc New Member

    The exit holes, broken glass and fragment marks on the glass:

    dc34ac576e9a948ef7573b27d533b8a7.
     
  19. gsobjc

    gsobjc New Member

    About AA's credibility. There is important Russia's objection in the appendix V regarding to the fuse algorithm:

    It was the starting point of Russian approach to the analysis of Buk hypothesis.
    The 9M38-series missiles could blast in front of the cockpit only from crossing
    direction (Zaroschenskoe).

    You can independently check their claim by watching the tests of American SAMs

    MIM-104 Patriot
    5f33db07aa3ea61f01dc184b82ccc2c7.

    MEADS

    017965ad0e85ee7a8f2d817cc5849f80.

    It seems it is a general principle of many SAMs not only Russian ones.
     
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  20. Antidyatel

    Antidyatel New Member

    Thanks for the effort. Will look into your calculations when time permits. But just to clarify, my statement included multiple factors that has to be accounted for, not only the drag force. Just look at the origin of acceleration, it is caused by the force created from over-pressure during explosion. This force is a function of surface area to be pushed, explosion non-uniformity and position of each shrapnel in the war-head. Hence accelerations will be different, plus it will actually be time variant.

    In any case. Our combined effort is already much more than DSB done to dig the truth in a year.
     
  21. Antidyatel

    Antidyatel New Member

    Assuming the area and weight of X-shaped shrapnel vs cubes we get different spread through just adjusting acceleration, assuming that explosion pressure is the same.

    And, yes, my OP that suggests lancet due to acceleration effect is debunked. But linear approximation is still erroneous tO use for spread estimation and explosion position with specific rocket orientation.

    Most probable reason for us not to see lancet is assumption that shrapnel density is uniform over the considered initial spread
     

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    Last edited: Nov 7, 2015
  22. RB2

    RB2 New Member

    About AA's credibility. There is You can independently check their claim by watching the tests of American SAMs


    MEADS is PAC-3 with kinetic HTK strike as i recall so be wary of that