Pedestrian steps on rock, gets foot blown off in Central Park; cops initially called it...

racing_kitty said:
Directional charge, yes. Shaped charge, no. Originally designed as an anti-tank weapon, but more commonly used as a mining charge before OIF made them famous, a shaped charge utilizes a void cut into the explosive. Inside the hollow area of that cone, you will find a liner (typically metal, but glass can work). The main charge is evenly packed around the outside of that cone. When it detonates, assuming the HE is packed properly and the initiator is in the right place, the Munroe Effect occurs. In layman's terms, the cone is evenly compressed, and the liner is forced forward, forming a jet.

It is possible to channel the direction of the blast wave. For example, using IV bags or water bottles on one side of a main charge will tamp the blast on one side, and allow the blast to continue on in the other direction. Another example is when a breaching team utilizes explosive tools in a hallway. Each time the blast wave reflects off of a wall, it grows stronger. That's why a breaching team would be safer staging closer to the charge in that instance.

That said, based on the one photo I've seen, the damage to his foot is indicative of blast injury, but not a shaped charge injury. It would've been (at least somewhat) cleanly severed if it were in line with the jet, as opposed to blown off. While I have ideas for what the main charge could've been, I can't make any guesses without a little more information (color of smoke, etc). It wasn't large, and it could've been anything from TATP to Armstrong's mixture. From what I've gathered, the main charge was placed beneath the rock that he stepped on. The earth below would serve to reflect the blast wave back up towards the more mobile rock. The rock itself would then deflect the blast wave somewhat, which could be why his foot was only mangled all to hell, as opposed to becoming pink mist. This is just from a small charge.

While it's better to not have been blown up to start with, he got lucky. As far as who placed it, I'm going to withhold my speculation for the time being. If it turns out that the main charge was actually a primary charge, then the emplacer was also lucky (not to mention stupid).
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Thanks, you're still teaching me things.
 
Diamondback 2/2 said:
Hummm, college kid make really big firework, places it under rock, light it and stands on rock, bang! Oh shit our buddy is all jacked, lets make a story quick and get help!!!

Would be my guess, but I guess it could be a noob terrorist pissed off at college kids who go climbing. The confetti around the area looks like an actual firework (maybe several put together) I fully agree with RK on the rock and besides I can't see any flash burning and I can see some stupid college kids doing some stupid shit like that.

Not saying that's what happened, but I can see some hipster college dork saying hold my water bottle and watch this, as he lit that bundle of bang and stood on the rock balancing himself into the "oh fuck my foot" award.

$.02

ETA: Don't stand on anvil bombs!:-o
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From what I've read, the victim and his climbing party were cooperative with investigators, and they do not believe that they had anything at all to do with the placement of the explosives. Also, it initially appeared that whatever the explosives were, the item had been there for at least a day. It could've been anyone from some dude with more magnesium sparklers than sense, to a fledgling mujahedeen trying out his version of the Colonel's secret recipe before he goes off and rips one right in the middle of downtown Manhattan.

The expended matchbook could very well be from our Guy Fawkes wanna-be trying to crank it off, but only succeeding in making that baggie of hate even angrier than it was when he first put it there. Depending on what the main charge was, and especially if John Doe poked it with little red phosphorous-tipped twigs, the heightened state of sensitivity would have made any kind of trip wire or pressure plate unnecessary. The simple act of stepping on that rock would've provided enough heat/shock/friction to go ahead and set it off. Even C-4 gets mad enough to bite when you set it on fire, or your shot snots (blasting cap low orders, sending gobs of angry bomb snot all over the place).

TATP is quite squirrelly; I've seen a video of a man detonating a jar of TATP just by lightly scraping a bird feather across the top of it. Remember the house in California back in 2010, the one that local authorities burned to the ground? That guy had whole shelves of TATP and other similar, highly sensitive homemade explosives in that house. None of it was safe to move, especially considering it had been sitting in there for a while. The bomb squad guys said "Fuck that shit. Get fire on line, get us air clearance in case the whole house high orders, and get the neighbors the fuck outta here for a while. We're going to thermite this bitch." As far as I know, that dude was never tied to any kind of terrorist group. He was just some oddball loner with a knack for chemistry, and an astounding lack of consideration for the safety of his neighborhood.

In this case, it's altogether possible that this was a dress rehearsal for something larger and uglier (think: London bus bombings, etc). However, it could very well just be a vindictive lunatic that, just for fun, wanted to fuck up people that were climbing all over the boulders. Without a chance to poke around at the site, or any idea of what the FBI found in their PBI (I'm not putting very much stock in NYPD's report right now), either one of my possibilities has equal opportunity to turn out right or wrong.
 
Ex3 said:
I know zero about explosives, but does the fact that there was no shrapnel or ball bearings indicate that this could have been a dud homemade firework? Maybe this is wishful thinking, but it doesn't make sense to me that an IED would be placed so far off the beaten path.

http://i.imgur.com/xRR3CgA.png
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For a pressure trigger, they'd need soft ground to dig it in. I'm not familiar with Central Park, so I don't know if the trails are paved or not; but I would assume a lot of them are.

Pressure type mines (step on them or drive over them) usually don't have a lot of fragmentation other than the body of the mine itself. They are often made of plastic to help reduce the chance of detection. Since the victim comes in direct contact with the device, the blast itself is plenty to cause injury.

Tripwire type mines usually are of the fragmentation (and sometimes bounding) variety, but require a larger explosive since they are farther from the victim.
 
It wouldn't surprise me if it was a crazy tree hugger that placed it. There's been quite a few cases up here of idiots setting up cables at head height, across trails frequented by mountain bikers.
 
Etype said:
For a pressure trigger, they'd need soft ground to dig it in. I'm not familiar with Central Park, so I don't know if the trails are paved or not; but I would assume a lot of them are.
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Paths in the park are paved, but as I said, this was well off a path. There are tons of rock formations like the one these guys were running down in Central Park; it's called schist and it's the reason we can build such tall building here.
Screen Shot 2016-07-06 at 9.15.33 AM.png
 
Ex3 said:
Paths in the park are paved, but as I said, this was well off a path. There are tons of rock formations like the one these guys were running down in Central Park; it's called schist and it's the reason we can build such tall building here.
View attachment 15997
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Looks pretty well traveled to me.

The emplaced would need to strike a balance between-
- soft ground ground.
- enough traffic to trigger the device (it only takes one).
- secluded enough to bury it unnoticed.
 
Red Flag 1 said:
My son left USMC pilot training to be a Combat Engr. He's a doc now, and when I described the injury to him, the first thing he said was "toe popper".
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I was thinking that same thing, J. Toe poppers were prolific in our AO. Enough HE to blow a few toes or your foot off and eliminate your contribution to the war. And send another maimed dude home to inspire the anti-war movement. :rolleyes: Those and tripwired frags across trails were probably the most common rigged explosives we encountered.

I don't understand blast physics...but this young man in Central Park would've faired much worse if there'd been nails packed around the charge.
 
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Ex3 said:
Central Park blast explosive identified - CNN.com
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I'm not surprised.
RackMaster said:
Let's just hope it wasn't a test run.
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More like product testing. The question now becomes "Who's making it?" One might expect subpoenas for beauty supply and hardware stores' security camera footage to see if anyone made purchases in suspicious quantities, although that might be too much information to sift through, seeing as that's NYC. However, there's no telling how large the first batch was; if this was a product test, it's possible that the quantities purchased were not sufficient to arouse suspicion.
 
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