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MH17 down near Donetsk

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MH17 down near Donetsk

Old 4th Aug 2014, 05:42
  #1101 (permalink)  
 
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777 cockpit window info

http://www.ppg.com/coatings/aerospac...Summer2007.pdf
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Old 4th Aug 2014, 07:36
  #1102 (permalink)  
 
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Apologies if this is a repeat request, is there info on the fusing of the missile available, where both the contact and proximity fuse are located?
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Old 4th Aug 2014, 09:37
  #1103 (permalink)  
 
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Apologies if this is a repeat request, is there info on the fusing of the missile available, where both the contact and proximity fuse are located?
BUK-M1 dont have contact fuse (naval BUK-M1-2 have it) but only proximity fuse (9E241M1) with initiate range 17m or lesser with angle 120 degree or more.


1 - semi-active radar homing
2 - proximity fuse
3- warhead
Checking a fuse
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Old 4th Aug 2014, 09:41
  #1104 (permalink)  
 
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Here better images about how look 9M38M1
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Old 4th Aug 2014, 14:24
  #1105 (permalink)  
I don't own this space under my name. I should have leased it while I still could
 
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GR, why?

As the proximity fuse must initiate the explosive train before the missile reaches the target it follows that it must be in the nose.

Impact fuzing is more problematical.

It will function as a result of a sudden deceleration. It could be behind the warhead but that risks breakup of the warhead before detonation. It follows that it will behind the proximity fuse system but close to it. Best position is as far forward as possible.
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Old 4th Aug 2014, 14:42
  #1106 (permalink)  
 
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it follows that it must be in the nose.
Actually, not true. modern missiles often use a [email protected] prox situated in the body of the missile well back from the nose seeker system - as is the warhead.
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Old 4th Aug 2014, 15:07
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Certainly impact fuzing for some missiles was electrical contact on the fins. These had small warheads though and the idea was to allow the warhead to be inside the target before detonation. Partial destruction of the detonator was allowed for and it would still function for a short time (2-3 msec) after damage.
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Old 4th Aug 2014, 18:21
  #1108 (permalink)  
 
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Originally Posted by Pontius Navigator View Post
GR, why?

As the proximity fuse must initiate the explosive train before the missile reaches the target it follows that it must be in the nose.

Impact fuzing is more problematical.

It will function as a result of a sudden deceleration. It could be behind the warhead but that risks breakup of the warhead before detonation. It follows that it will behind the proximity fuse system but close to it. Best position is as far forward as possible.
Every missile I have known [OK not that many] has the proximity fuse placed to trigger the warhead in the most effective way, usually close to the warhead position itself.

I was asking because of the thermal damage to the cockpit area remains.

The explosion must have been very close indeed.
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Old 4th Aug 2014, 20:45
  #1109 (permalink)  
 
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What is the point of all the Where's Waldo forensic photos with arrows and such?
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Old 4th Aug 2014, 20:54
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I believe it was postulated a few pages back that they would normally Fire two missiles for a higher PK.

I suggested that the damage suggested late functioning and as only one missile was launched it was an lucky hit.
1. Possible 2 missiles was fired (each from different position)
2. Fat target like 777 is very easy target - big radar cross-section, high alt, no speed, no maneurs, no electronic warfare, no chaffs, etc.
Radar equipment of SA-11 produced for kill targets with RCS=1sq.m.


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Old 4th Aug 2014, 22:35
  #1111 (permalink)  
 
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obvious

33M, obviously the point of a detailed forensic analysis, using incomplete information and lots of arrows, is to accomplish two key objectives:

1. To illustrate how knowledgeable the poster is
2. To illustrate flaws in Boeing's design that made this plane (and ostensibly others in its commercial lineup) extremely susceptible to being destroyed by a meager 6m long SAM going Mach 3+

I'm sure once Boeing sees these detailed forensic analyses their future planes will resemble the A-10 and/or Su-25.

I tend to believe theory #1 more

lmao at your post 33M - good one
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Old 5th Aug 2014, 00:42
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Originally Posted by Pontius Navigator View Post
GR, good answer. I believe it was postulated a few pages back that they would normally Fire two missiles for a higher PK.
Buk PK is pretty high anyway for a large a/c target - presuming whoever it was thought they were firing at a transport aircraft. Not sure two at once would be SOP, especially if you only have four. If fired from Schizne then there would be time for a second shot if the first misses.

I suggested that the damage suggested late functioning and as only one missile was launched it was an lucky hit.

Your supposition supports that.
Where it will go off will depend a lot on target radar profile (to the fuse radar), missile and approach angle. There are some combinations of missile/target/approach that result in zero PK (at least in simulation) usually due to the fuse triggering too soon. Note - if I ever knew details of any examples they are long forgotten, not that I could say anyway.

In this case, if the missile was approaching from directly below (or above) and fused at the side of the cockpit, then, yes, that looks a bit late.

On the other hand, if it is approaching from the front, maybe slightly to one side, it could be exactly as designed/expected. Depends on which part of the a/c the fuse will "see". It may be the wing box and/or engine fan that is the biggest return or centre of it. Fuse distance seems most often quoted as 17m, although I have seen other numbers (large radius zone, this is a big warhead). By my reckoning, approaching from front slightly to one side, 17m from wing box / engine on a 777 would put you right about the cockpit window...
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Old 5th Aug 2014, 01:29
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Originally Posted by ThreeThreeMike View Post
What is the point of all the Where's Waldo forensic photos with arrows and such?
I would have thought it was to supply information to the debate as to where the missile hit and what direction it flew, so possibly who fired it.

I also appreciate their aircraft/airframe knowledge and the photoshop skills.

One thing it has certainly confirmed is the crew never knew what hit them it was instant

Last edited by oldoberon; 5th Aug 2014 at 02:53. Reason: typo
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Old 5th Aug 2014, 04:48
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about warhead of missle

Accordingly this
http://www.ctro.hr/universalis/175/d...1606332201.pdf
On the 7th slide there are interesting captured frames of detonation of the projectile. The peculiarity is that detonation generates relatively a narrow stripe of small fragments and this somehow should be portrayed on the fuselage but distance play a key role in that case.
On the 9th slide there is interesting graph about velocities distribution of the fragments.
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Old 5th Aug 2014, 12:20
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One thing it has certainly confirmed is the crew never knew what hit them it was instant
Between the sudden decompression and the blast wave of the warhead detonation, it was instant for everybody.

That recorded rebel speculation that the plane had been carrying corpses is, of course, nonsense. But it was based on observations that the bodies were not bleeding, looked like they were dead before they hit the ground. Without going into morbid details, I can only say that a close look at the available photos confirms this.
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Old 5th Aug 2014, 15:32
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I have trouble believing it was "instant" death for all on board. A couple of seconds at least for some, I feel that a small few would have had only a couple to few seconds of realising something is wrong before death.
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Old 5th Aug 2014, 18:13
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In this case, if the missile was approaching from directly below (or above) and fused at the side of the cockpit, then, yes, that looks a bit late.

On the other hand, if it is approaching from the front, maybe slightly to one side, it could be exactly as designed/expected. Depends on which part of the a/c the fuse will "see". It may be the wing box and/or engine fan that is the biggest return or centre of it. Fuse distance seems most often quoted as 17m, although I have seen other numbers (large radius zone, this is a big warhead). By my reckoning, approaching from front slightly to one side, 17m from wing box / engine on a 777 would put you right about the cockpit window..."
The proximity fuse in a missile like Buk is "side looking" rather, than "front looking" (probably at an angle of about 60deg from missile axis). It is designed to detonate when it passes close to target, there is no point to detonate ahead of a typical aircraft target. The speed of shrapnels from the warhead is much higher than closure speed of the missile/target, so the warhead doesn't work like a "shotgun shot". It just explodes passing close to target and the shrapnels are thrown to the sides fast enough to hit it (shrapnel is several times faster than the missile)

So if the missile was going head-on horizontally or from above with slight side offset, then the warhead detonated as soon as the cockpit came into FOV of side-looking proximity fuse antennas. And looking at the cockpit damage, it was only few meters, so most of the shrapnel was absorbed by front part of the hull with very high fragment density. The spread pattern of warhead shrapnels is not omnidirectional, almost all of the fragments are directed to the sides. Nearly all other plane parts were outside of the shrapnel kill-zone, only one wing and it's engine could get some.

Detonating a bit ahead of target would be good only against really fast target kile ballistic missile or anti-radiation missile, where speed of target/missile is comparable to speed of shrapnels from warhead.

Last edited by amizaur; 5th Aug 2014 at 20:04.
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Old 5th Aug 2014, 20:46
  #1118 (permalink)  
 
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The operating principle of proximity fuse radars is to detonate the warhead at the point of closest approach. Once the measured range stops decreasing and instead increases - kaboom.
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Old 5th Aug 2014, 22:30
  #1119 (permalink)  
 
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The operating principle of proximity fuses is that they detonate the warhead in proximity of the target.

Some proximity fuses measure distance to target and can detect the moment of closest approach. Such method is used in torpedo proximity fuses and especially in naval mines, but is not usually needed or practical in missiles.

The proximity fuse of a a Sidewinder missile project narrow beams of [email protected] light perpendicular to the flight of the missile. If any of the beams strikes the target it is reflected back to the missile where detectors sense it and detonate the warhead. There is no "measuring the range" at all, abd it is not needed - when a target is detected to the side of the missile then it's probably as close as it could be and is is good place to detonate the warhead.

Radar proximity fuses work on similar principle (beams of radio energy projected to the sides, perpendicular to misile or at an angle, to front-side) but they can have a predetermined maximum range at which the fuse can detonate. If the target is let's say closer than 17m the fuse would detonate warhead.

Usually there is no need to determine the "point of closesd approach" because the fuse anyway can detect a target ONLY to the side. So only when it passes by. And then in 95% of cases target is already as close as it can be (passing by) and the warhead (which is also designed to throw shrapnels to the sides) should be detonated NOW.

Radar fuse COULD measure range to target and detect optimal point for detonation, but this would be rarely usefull at all.
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Old 6th Aug 2014, 08:57
  #1120 (permalink)  
 
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Between the sudden decompression and the blast wave of the warhead detonation, it was instant for everybody.
I suspect that a blast wave would instantly be dissipated by opposite explosive decompression and fast moving slip stream. Decompression at FL330 would not kill healthy people instantly. Occupants not directly hit by shrapnel or airframe parts during the in-flight break up would become unconscious from lack of oxygen and the freezing air blast. But when descending through lower altitude and warmer air, (FL100) surviving occupants would likely regain consciousness.
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