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The Kerch Bridge Thread

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The Kerch Bridge Thread

Old 11th Oct 2022, 22:20
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Originally Posted by fdr
If it was the truck, how was it timed for detonation? was this an area on a strategic site with purported high security that didn't jam cell phone signals or disrupt GPS?
Assuming it wasn't triggered manually by the driver, then maybe by detecting that it started to climb, perhaps with some combination of accelerometers and gyros? Nose up attitude, positive rate of climb = detonate.
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Old 11th Oct 2022, 22:24
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Originally Posted by MikeSnow
Assuming it wasn't triggered manually by the driver, then maybe by detecting that it started to climb, perhaps with some combination of accelerometers and gyros? Nose up attitude, positive rate of climb = detonate.
GLONASS instead of GPS?
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Old 12th Oct 2022, 00:08
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Originally Posted by ORAC
Link from the following post.



This page has quickie analysis by engineers https://theconversation.com/crimean-...-damage-192161
.
That page has this link https://archive.org/download/crimean-bridge which has a link to a 242pg PDF of the Kerch design documents and diagrams ... in russian (naturally). It's all engineering geek and russian to me.
Via the link:

“…It appears the girders are continuous over the piers, with expansion joints only every four spans. Just like picking up a table cloth in the middle, the massive vertical force due to the blast would pull in the ends of the continuous steel girders, popping them off their supports…”
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Old 12th Oct 2022, 00:43
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Originally Posted by MikeSnow
Assuming it wasn't triggered manually by the driver, then maybe by detecting that it started to climb, perhaps with some combination of accelerometers and gyros? Nose up attitude, positive rate of climb = detonate.
Seems to me, with a truck load (allegedly) of explosives, KISS might strongly apply.
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Old 12th Oct 2022, 00:59
  #165 (permalink)  
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Revision A

Originally Posted by MikeSnow
Assuming it wasn't triggered manually by the driver, then maybe by detecting that it started to climb, perhaps with some combination of accelerometers and gyros? Nose up attitude, positive rate of climb = detonate.
That would have been pretty dodgy, how many slight rises exist between "Bulgaria" and 100 mtrs west of the rise on the Kerch bridge...?

However, the video gives a pretty good datum point for the truck and timing to the detonation... if the attitude of the truck is looked at, it takes approximately 4 seconds from the change in the vodka level until the detonation, the video down the roadway captures the rear door and roof of the truck, the attitude change is identifiable. From the photos, (still looking for the info in the plans... my Russian is pretty rusty) the change in the road from level to incline happens at the west side of the pier after the large cassion like structure off to the north of the roadway, with the easternmost expansion joint just east of that cassion.

Assuming the truck speed is the national limit of 90Km/Hr (the road limit is 120Km/Hr) as all Russian truckers abide by the law... then the truck is 100mtrs to the west of the point of incline (pier) when the detonation occurs. Unfortunately for the assumption of the blast coming from underneath, that is almost exactly in the center of the scorched area of the bit that was blown downwards... and is the midpoint more or less of the inter-pier distance. That is the gap before the most northerly expansion joint which failed as well. but without obvious scorching.

There are a bunch of unknowns, known, unknown etc... but the main thing is that the truck is going to be around the midpoint of where the explosion was located. If the truck was doing 120, it would be 33mtrs beyond the epicenter... and it would have gone into the drink on the section of road that collapsed from the western expansion joint. There is a possibility that the truck was past the next pier, and went into the water as the bridge collapsed. That arises as there is a difference in the soot that would be around the position that the truck would have got to at the higher speed... and it is of a truck size masking of the sooting... Hmmm. fast truck?

So...

boat or truck?

The truck could be right in the center. The wind was around 16kts steady from the right side... a fireball from below is going to be brought over the same area as is scorched, and as yet we have not seen any of the undersides of the section that collapsed in the V (for Victory).

Either way it is a weak bridge, if the overpressure of the truck delivery method blows the bridge in half between piers, they may want more Meccano next time. If a charge went off between piers from below, the failure, in the end, would still result in a collapse at or near the midpoint; the presence of the truck reasonably at the epicenter points to the truck. That still leaves a lot of questions unanswered, and the FSB is still a high-probability actor. If FSB, the outcome is probably a little more mayhem than desired, have any new FSB dudes gone land diving?



Last edited by fdr; 12th Oct 2022 at 01:26. Reason: fast truck comment
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Old 12th Oct 2022, 01:19
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Old 12th Oct 2022, 03:21
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I think I know the reason so many people claim the explosion occured way behind the suspected truck: the CCTV camera filming from behind the suspected truck has a quite narrow field of view, making the part of the bridge that climbs look much steeper than it actually is (lens compression). For the same reason, the preceding flat segment looks shorter than it actually is. If you then look at other footage of the aftermath, the damaged segment doesn't seem as steep, so it's easy to misidentify it in the explosion video.

Looking at satellite images, the part that climbs towards the top segment is over 1000 meters long and consists of 4 segments, with expansion joints between them. Those 4 climbing segments are preceded by flat and level segments. I labeled 5 relevant segments of the bridge visible in the explosion video over a satellite image (another two preceding segments are actually visible in the explosion video, but I didn't include them to keep things simpler):



A - 260 meters, last flat and level segment before the climb, not damaged; the surviving truck was probably on this segment at the time of the explosion;
B - 260 meters, first climb segment; starts flat then slowly pitches up; this was the segment destroyed by the blast;
C - 260 meters, second climb segment, flat, not damaged;
D - 260 meters, third climb segment, flat, not damaged;
E - 320 meters, fourth climb segment, begins to level off, not damaged;

The CCTV camera is probably at least 500 meters further back behind those 5 segments. To give you an idea of how much the field of view effect can fool you, I'll include a dash-cam video of crossing the bridge:


In this video, at 10:58 we reach the beginning of segment A, on which the surviving truck stopped. At 11:09 we see the beginning of the destroyed segment, B. At around 11:16 we reach the most likely point for the explosion, based on the scorching on the opposite lanes. At 11:20 we can see the beginning of segment C, which survived. At 11:31 segment D begins. At 11:42 the final climb segment, E, begins. That segment slowly starts to level off, and we reach its end and the beginning of the top segment at 11:56.

Last edited by MikeSnow; 12th Oct 2022 at 03:38.
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Old 12th Oct 2022, 04:12
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Originally Posted by MikeSnow
I think I know the reason so many people claim the explosion occured way behind the suspected truck: the CCTV camera filming from behind the suspected truck has a quite narrow field of view, making the part of the bridge that climbs look much steeper than it actually is (lens compression). For the same reason, the preceding flat segment looks shorter than it actually is. If you then look at other footage of the aftermath, the damaged segment doesn't seem as steep, so it's easy to misidentify it in the explosion video.

Looking at satellite images, the part that climbs towards the top segment is over 1000 meters long and consists of 4 segments, with expansion joints between them. Those 4 climbing segments are preceded by flat and level segments. I labeled 5 relevant segments of the bridge visible in the explosion video over a satellite image (another two preceding segments are actually visible in the explosion video, but I didn't include them to keep things simpler)

A - 260 meters, last flat and level segment before the climb, not damaged; the surviving truck was probably on this segment at the time of the explosion;
B - 260 meters, first climb segment; starts flat then slowly pitches up; this was the segment destroyed by the blast;
C - 260 meters, second climb segment, flat, not damaged;
D - 260 meters, third climb segment, flat, not damaged;
E - 320 meters, fourth climb segment, begins to level off, not damaged;

The CCTV camera is probably at least 500 meters further back behind those 5 segments. To give you an idea of how much the field of view effect can fool you, I'll include a dash-cam video of crossing the bridge:

https://youtu.be/rAdPwAT5Ntg?t=635

In this video, at 10:58 we reach the beginning of segment A, on which the surviving truck stopped. At 11:09 we see the beginning of the destroyed segment, B. At around 11:16 we reach the most likely point for the explosion, based on the scorching on the opposite lanes. At 11:20 we can see the beginning of segment C, which survived. At 11:31 segment D begins. At 11:42 the final climb segment, E, begins. That segment slowly starts to level off, and we reach its end and the beginning of the top segment at 11:56.
And the truck driver is claimed to survive?
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Old 12th Oct 2022, 04:22
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Who claims that?
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Old 12th Oct 2022, 04:51
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Originally Posted by MikeSnow
Who claims that?
The truck owner is alive. The driver is the owners uncle, and was last reported missing. Both were Russians.
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Old 12th Oct 2022, 07:35
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Originally Posted by 20driver
I don't think the RU would have done this. Putin hardly needs an excuse to launch missiles......
Exactly this.

Quite apart from the fact I can't see him trying to destroy a powerful symbol of Russian dominance in the region, if he really needed a pretext for 'retaliatory' missile strikes there are plenty of easier targets less crucial to Russian logistics.
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Old 12th Oct 2022, 07:51
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Originally Posted by MikeSnow
Assuming it wasn't triggered manually by the driver, then maybe by detecting that it started to climb, perhaps with some combination of accelerometers and gyros? Nose up attitude, positive rate of climb = detonate.
If it was a truck bomb (not that I personally think it was) you don't need a complicated navigation- or inertial-based trigger system, nor do you need a complicit suicide bomber, you just need someone following behind, at a safe distance, with a remote control.
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Old 12th Oct 2022, 08:08
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Originally Posted by Andy_S
Exactly this.

Quite apart from the fact I can't see him trying to destroy a powerful symbol of Russian dominance in the region, if he really needed a pretext for 'retaliatory' missile strikes there are plenty of easier targets less crucial to Russian logistics.
It does appear paradoxical, however, the guys purportedly wrapped the IED explosive with foil to "make it undetectable"??? Doesn't take much to increase the shock formation (don't put crackers in your hand...) The bridge also appears to be much more tender as a design than one would expect. That is the upside of the exercise there, this bridge can be dropped basically at will with a little bit of planning.

My guess remains that it wasn't the Ukrainians, it was likely the FSB and someone is looking at their shoes while being berated by his superior for being a klutz for being a bit enthusiastic in the amount of pyrotechnics. To make a fashion statement, Ukraine would have been somewhat more pointed literally, if they did this, by simultaneously taking out the primary MSRs out over by Zaporizhia Oblast. How did the FSB find the name of a "Ukrainian" ordering explosives in a NATO country, (one with EU/Shenghen bans against Russia), that are wrapped rat cunningly in tinfoil, and that gets sent undetected to Georgia, North Ossetia, Krasnodar, and onwards towards Crimea. That's... 1,2,3,4,5 security/customs control points... and in the middle of a Special Yada Yada no less. And it gets through the crack troops at the final security checkpoint who have no concern with fertiliser, nitrates etc... And the transit time for this exercise is.... what? 3 hours, 3 months? what is the time to get stuff between Bulgaria and Georgia, how do you get Georgians to play a part? they remember Abkhazia, and South Ossetia, and the Russian Federations part in the obscenities that occurred there. So it is done with a cell phone remote, which has a year long battery life, and good cell reception, (its not with my service providers then).

And to time it, the team follow the truck through Russian territory, and from behind wait until it is on a desirable bit of the roadway, and of course, they have to be behind it, and are going to be caught in the traffic jam from the outcome of their handiwork.

If it involved any other country than Russia, I would be less suspicious, but the truth is the word truth doesn't hold a meaning in Russia, currently or historically.

Spoiler
 

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Old 12th Oct 2022, 08:11
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Various sources like Meduza are reporting that russia has arrested 8 terrorists patsy's 5 russian and 3 ukrainian / armenians

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Old 12th Oct 2022, 08:20
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Originally Posted by rattman
Various sources like Meduza are reporting that russia has arrested 8 terrorists patsy's 5 russian and 3 ukrainian / armenians
that's their haul for conscripts? "Wanted 300,000 able patriots 8 locals in wheelchairs, and with good life insurance (optional), Must have heart beat preferred. Apply 2 Bolshaya Lubyanka Street, Moscow".
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Old 12th Oct 2022, 08:25
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Originally Posted by MechEngr
GLONASS instead of GPS?
Unless I'm missing something (quite likely), GLONASS is GPS.
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Old 12th Oct 2022, 09:01
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Yes, but often referred to differently, GPS is the "Western system" the other is the not so good Russian system, hence a lot of the in Russian cockpit shots you see tend to have Garmins and the like stuck to the panel
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Old 12th Oct 2022, 10:09
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Originally Posted by NutLoose
Yes, but often referred to differently, GPS is the "Western system" the other is the not so good Russian system, hence a lot of the in Russian cockpit shots you see tend to have Garmins and the like stuck to the panel
The global abbreviation for such systems is GNSS - global navigation satellite systems. GPS and GLONASS are examples. There are others including the European system Galileo. See https://en.m.wikipedia.org/wiki/Satellite_navigation for more!
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Old 12th Oct 2022, 16:43
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Old 12th Oct 2022, 16:53
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According to Russian-appointed head of Crimea, waiting at the ferry crossing in Crimea takes about 3-4 days. And there are about 900 trucks in line at the moment.

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