 C4 detonation, what will or will not |
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 Feb 14 2005, 05:23 AM
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#1
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Free Spirit  Group: Dumpshocked Posts: 3,944 Joined: 26-February 02 From: Bloomington, IN UCAS Member No.: 1,920  |
What will set it off? What won't?
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Feb 14 2005, 05:28 AM
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#2
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
A combination of heat and pressure will. Heat alone, pressure alone, or electric current will not. Neither will insulting it, though there are indications that exceptionally harsh language may cause detonation.
~J |
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Feb 14 2005, 05:31 AM
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#3
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Target Group: Members Posts: 30 Joined: 12-December 04 From: Grand Rapids, MI Member No.: 6,881 |
Just as with other explosives, you need to apply some energy to C-4 to kick off the chemical reaction. Because of the stabilizer elements, it takes a considerable shock to set off this reaction; lighting the C-4 with a match will just make it burn slowly, like a piece of wood (in Vietnam, soldiers actually burned C-4 as an improvised cooking fire). Even shooting the explosive with a rifle won't trigger the reaction. Only a detonator, or blasting cap will do the job properly.
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Feb 14 2005, 05:32 AM
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#4
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Runner Group: Members Posts: 3,066 Joined: 5-February 03 Member No.: 4,017 |
Of course, SR explicitly states that plastic explosives in the 2050's and 2060's can be triggered by direct application of electricity. Probably a diffused lower intensity detonator compound mixed with the primary explosive.
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Feb 14 2005, 05:36 AM
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#5
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Target Group: Members Posts: 30 Joined: 12-December 04 From: Grand Rapids, MI Member No.: 6,881 |
Well, it's pretty easy to make a blasting cap that'll work on C-4 (having done it my self). You really don't need much but a way to get a 9V to discharge on the C-4 it's self. It'd say an electrons test of 4 would make it. A failed test would mean a faulty detonator that either discharged soon as it was attached or didn't discharge at all.
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Feb 14 2005, 05:43 AM
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#6
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Runner Group: Members Posts: 2,901 Joined: 19-June 03 Member No.: 4,775 |
It's not impossible now to stabilize a plastique compound that will go off purely with electrical current. It's more a matter of practicality and safety. Semtex'll go off if you look at it funny, but that doesn't really make it attractive...
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Feb 14 2005, 05:52 AM
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#7
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Free Spirit Group: Dumpshocked Posts: 3,944 Joined: 26-February 02 From: Bloomington, IN UCAS Member No.: 1,920 |
Ok, the basics are out of the way.
Say a bit of C4 detonates, How far away could another chunk be without detonating? Or, what (Rating)D damage can it withstand? |
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Feb 14 2005, 06:21 AM
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#8
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Great Dragon Group: Members Posts: 5,889 Joined: 3-August 03 From: A CPI rank 1 country Member No.: 5,222 |
Thinking about it in those terms will get you really funny results, because of the unreasonably high variance of Blast ratings and Power/kgs of SR explosives. With just Commercial Explosives, though, it kind of works out, because the actual blast radii of all types are equal. I seem to remember from my explosives training that a series of 0.25kg TNT charges will only go off if the explosives are within ~20cm of each other. That'd make it ~40cm for a 1kg TNT charge. As a quick rule of thumb, then, you might use (explosive charge weight)^0.5 x (0.5 meters); 1kg = 0.5m, 4kg = 1m, ~15kg = 2m, ~60kg = 3m, etc. A Hand or Minigrenade would probably have to go off in contact with or right next to the explosive to detonate it. This post has been edited by Austere Emancipator: Feb 14 2005, 06:23 AM |
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Feb 14 2005, 06:35 AM
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#9
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Target Group: Members Posts: 30 Joined: 12-December 04 From: Grand Rapids, MI Member No.: 6,881 |
If you had C4 detonate right next to but not touching another lump of C4, the second wouldn't detonate. Without the current it would just get blasted apart and not blow up it's self. Unless it was shoddy C4 wannabe stuff. In that case it's up to the GM. The higher the quality, the close it can be to the point where it's just incinerated without explosion. |
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Feb 14 2005, 08:01 AM
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#10
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Free Spirit Group: Dumpshocked Posts: 3,944 Joined: 26-February 02 From: Bloomington, IN UCAS Member No.: 1,920 |
I was wondering if the heat and pressure from the initial explosion would be enough to detonate it.
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Feb 14 2005, 09:32 AM
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#11
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Resident Legionnaire Group: Dumpshocked Posts: 2,136 Joined: 8-August 04 From: Usually Work Member No.: 6,550 |
When I was overseas, I had to treat a dude who blew his leg off doing this. His buddies said he was using a piece of lit C4 on a stick to heat some food from a field ration and when he finished he threw the thing on the ground and stomped on it to put out the flame. <BOOM> There is plastique that will ignite from just an electrical current but really, nobody really wants to risk using something that unstable. Well, maybe there are some that would, but nobody I know at least. |
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Feb 14 2005, 10:58 AM
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#12
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Great Dragon Group: Members Posts: 5,889 Joined: 3-August 03 From: A CPI rank 1 country Member No.: 5,222 |
Well, it really does depend on the explosive in question, as KaOs said, and a bunch of other factors. I personally haven't got any experience with C-4, just a few other explosives like TNT, RDX, and some others the exact type of which I'm not sure, but most of those can certainly be set off by another major explosion happening very close. On the other hand, I did witness some type of plastic explosive where some moron had rammed the blasting cap through the charge itself, the result of which was that the 300g block of explosive had a 5cm/2" diameter hole through the middle but had not detonated. You can believe we nearly shit outselves when we noticed that lying on a smoking tree stump in the training area. |
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Feb 14 2005, 02:43 PM
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#13
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panda! Group: Members Posts: 10,331 Joined: 8-March 02 From: north of central europe Member No.: 2,242 |
i think the exact statements is that you can get compounds that detonate on anything from a simple battery spark to something that needs more brute force to have it detonate. the stuff in the books are not so much diffrent brands and blends but diffrent detonation classes, you dont want to bring out the C12 if all you need is the comersial stuff, control is the most important thing in demolitions. if you dont have a general idea of how far stuff will fly then you may well be useing to much... still, this have no real effect in SR rules as the damage rating dont take shrapnel into account, if so then the power reduction pr meter may have been much lower... whatever you do, dont compare grenades and other explosives in SR. they work under diffrent laws of physics :P |
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Feb 14 2005, 02:49 PM
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#14
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Target Group: Members Posts: 30 Joined: 12-December 04 From: Grand Rapids, MI Member No.: 6,881 |
This makes me laugh. If it was C4 there is no way that happened. Unless it was homemade. Military grade C4 is stable unless it came from a really really bad batch. Hell, I doubt that would explode either. |
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Feb 14 2005, 03:08 PM
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#15
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Great Dragon Group: Members Posts: 5,889 Joined: 3-August 03 From: A CPI rank 1 country Member No.: 5,222 |
The Blast ratings of commercial explosives don't take sense into account. They are, how can I put this gently, fucking bullshit. |
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Feb 14 2005, 03:15 PM
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#16
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panda! Group: Members Posts: 10,331 Joined: 8-March 02 From: north of central europe Member No.: 2,242 |
well so i have noticed, they cant even blow a hole in a window (but that can have something to do with the industrial strength windows that sr seems to define as avarage). im guessing it have something to do with game balance (why use grenades when you can buy explosives by the kilo and make your own?)
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Feb 14 2005, 04:33 PM
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#17
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Neophyte Runner Group: Members Posts: 2,453 Joined: 17-September 04 From: St. Paul Member No.: 6,675 |
I have access to a chart/equation that calculates the equivalent distance from source based on an amount of explosive/equivalent weight of explosive based on a set distance from the source to all compared to a set amount of TNT for various types of explosive materials. I am not going to share it because I don't want the feds to come a knockin', but the inverse square law holds true for pressure waves.
That being said, the difference between SR rules and RL are astronomical. Remember kids, don't try this at home. Or at least don't tell anyone where you heard of it... |
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Feb 14 2005, 06:07 PM
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#18
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
Yep. Very stable unless exposed to, you know, both heat and pressure. The current is irrelevant to the C4, so your other statement is entirely wrong as well. ~J |
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Feb 14 2005, 06:12 PM
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#19
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Immortal Elf Group: Members Posts: 11,410 Joined: 1-October 03 From: Pittsburgh Member No.: 5,670 |
indeed. C4, contrary to popular belief, is not detonated with electricity. the blasting cap that you wrap the C4 around is detonated with electricity. the C4 itself is detonated by the heat and pressure provided by the blasting cap. blowing yourself up by stomping on a C4 fire is not only possible, it's the most likely result.
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Feb 14 2005, 06:15 PM
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#20
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Chicago Survivor Group: Dumpshocked Posts: 5,079 Joined: 28-January 04 From: Canton, GA Member No.: 6,033 |
That explains using det-cord to set off C-4
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Feb 14 2005, 06:23 PM
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#21
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Great Dragon Group: Members Posts: 5,889 Joined: 3-August 03 From: A CPI rank 1 country Member No.: 5,222 |
With detcord, you should still either stick the end of the cord into the main explosive charge or, better yet, wrap the detcord around the explosive charge. I would not be surprised if a detcord just laying on or next to a plastic explosive charge failed to set it off.
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Feb 14 2005, 06:29 PM
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#22
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Chicago Survivor Group: Dumpshocked Posts: 5,079 Joined: 28-January 04 From: Canton, GA Member No.: 6,033 |
well, yeah. I wasn't thinking of incidental discharge, but it does explain why det-cord can set off C-4.
Though I'm still trying to figure out how det-cord can transmit a detonation faster than a wire. |
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Feb 14 2005, 06:36 PM
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#23
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Manus Celer Dei Group: Dumpshocked Posts: 17,006 Joined: 30-December 02 From: Boston Member No.: 3,802 |
I'm not certain. I'm getting a value of ~200,000,000 meters/second for electrical signal propagation through copper wire, and ~7,500 meters/ second for detcord. Maybe it's just that it transmits it more uniformly?
~J |
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Feb 14 2005, 06:40 PM
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#24
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Chicago Survivor Group: Dumpshocked Posts: 5,079 Joined: 28-January 04 From: Canton, GA Member No.: 6,033 |
well, like most guys I love watching stuff get blown up, and every documentary I have seen on Discovery, TLC, PBS, etc. that talks about explosives says that det-cord is faster than wire for transmitting the signal. Might have something to do with the blasting caps.
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Feb 14 2005, 06:41 PM
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#25
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Chicago Survivor Group: Dumpshocked Posts: 5,079 Joined: 28-January 04 From: Canton, GA Member No.: 6,033 |
Might have to turn to Mythbusters for this one.
Ditto on the stepping on Burning C-4. (mainly cause who doesn't want to watch the dummy go boom?) |
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