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> Explosive Ratings, What am i missing?
20thCenturyFox
post Nov 25 2003, 09:10 AM
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Why do explosives (like C4) have such large fall-offs with damage?

For instance, 50kg of C4 (rating 6) has a damage rating of 42D, but it falls of 6 power per meter. So it's only going to effect anything that's within 7m of the blast point.

Doesn't that seem a little light on for 50kg worth of explosives, or am i a math-tard and haven't worked it out right (rating x sqare root of Kg used). True enough it'll ruin anything in that space, but standing 9 meters away and being unscathed is a tad strange.

Please correct me if i'm wrong! :)
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RedmondLarry
post Nov 25 2003, 09:30 AM
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I picked up my explosive knowledge from Roadrunner cartoons, and based on that I have to agree with you! :)

While we do read the same chart (SR3 p. 283) you see, and do interpret it the way you describe, we use that reduction in power only for properly-formed and properly-placed charges being used to destroy a barrier where no one is intentionally or accidentally introducing shrapnel into the blast.

When explosives go off amidst vehicles or gear, or when someone deliberately or accidentally introduces shrapnel into the blast, we play as if the falloff in power was 1 per meter. It may not be canon, but it works for us.
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Sahandrian
post Nov 25 2003, 01:05 PM
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Maybe the damage falloff should be tied to the sucesses in a Demolitions test? Better placement means less dangerous shrapnel and more focused force (away from the people nearby)?
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Athenor
post Nov 25 2003, 01:38 PM
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Could it possibly be because industrial-grade explosives (barring TNT and such) are actually highly contained explosions meant for precision work?

Athenor
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Austere Emancipa...
post Nov 25 2003, 02:19 PM
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Has been done before, and everyone who knows anything about explosives agrees that the Blast rating for all explosives, regardless of their Power, should be the same. What exactly the Blast rating should be, we've never really gotten a good answer on.

It should probably be around -2/m (-1/0.5m), perhaps a bit higher. I use whatever I feel like, which generally means -3/m (-1/0.33m) when there is no debris around, like a kilo of C12 sitting on a stone floor, which goes down to -2/m if there's enough debris (small rocks, metal junk, etc).

Using Demolitions to make the Blast rating better is limited to either gathering the debris from the site of explosion to a pile on top of the explosive device (which generally won't help much) or making a fragmentating bomb in the first place (which might help a lot, depending on the size of the charge and vehicle and so on).

I won't use -1/meter even when there's lots of natural debris, because that generally won't be as effective as are the fragments on a hand grenade, mortar round or artillery shell, which are the kinds of explosive devices that do have -1/meter Blast in my games. However, that kind of reasoning won't hold in an otherwise canon game where even an Anti-Vehicle Mine has a -1/meter Blast rating.

So, umm, yeah, if you want explosives to be really, really leathal, just go ahead and use Blasts in the -1/meter through -2/meter range, depending on number and quality of potential shrapnel. For slightly less lethality, use Blasts in the -2/meter through -3/meter range.

It would be great if there were any army engineers around to comment (and I mean people who've been at it for a long time, and who have training for blowing people up and making anti-personnel explosive devices), but that hasn't happened once in the past 13 months and (at least) 3 major explosives/demolitions threads.

QUOTE (Athenor)
Could it possibly be because industrial-grade explosives (barring TNT and such) are actually highly contained explosions meant for precision work?

I don't think it is physically possible to create explosives that are "contained", i.e. explosives that create just as much pressure+heat as regular explosives but simply do not spread that over as large an area as regular explosives do.

I suppose it might be possible to design the charges in such a way that they would be directed ("shaped") in almost any conditions, though, through the use of different layers of explosives with different burn rates, etc. I doubt that'd be the standard though, since a large number (if not a majority) of commercial applications require explosives that are not directed.
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spotlite
post Nov 25 2003, 02:54 PM
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Or perhaps its just 2060 and the plastique is more advanced that we know...?

Its a convenient explanation if you're looking for a plot-flange and aren't a demo expert!
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Austere Emancipa...
post Nov 25 2003, 03:16 PM
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QUOTE (spotlite)
Or perhaps its just 2060 and the plastique is more advanced that we know...?

To paraphrase: Perhaps the rules of physics and chemistry have been abolished and natural sciences have taken an all-around turn for the absurd?

Well sure, that's possible, considering magic and dragons and all. I just like to keep my world as sensible as possible, which means that if the books don't state that some part of the world has changed, then it hasn't. And, AFAIK, it does not state anywhere in canon that they have generated pressure waves that work in ways that are totally incomprehensible to modern scientists.

Maybe if C12 is really just magical nano-bots with quantum powers...
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Kagetenshi
post Nov 25 2003, 03:25 PM
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In one of the runs in Survival of the Fittest there's an explosive in there which is, as far as I can tell, a stock Shadowrun explosive (I don't remember which; CXII?) which falls off at -1/meter. I have no idea why this is different from everything else, though...

~J
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Ol' Scratch
post Nov 25 2003, 03:31 PM
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I'm just baffled that Plastic XII (Power 12) creates exactly the same size boom as the same amount of Plastic IV (Power 6) and Commercial (Power 3) does. One kilo of any of those has no effect outside of one meter, so you can stand three feet away and just feel a slight breeze after detonating that large chunk of explosives -- neat!
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Austere Emancipa...
post Nov 25 2003, 03:32 PM
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And apparently, the Xth corrected printing of the German SR3 has -1/meter for all commercial explosives (I think it was SR3.05D or something like that). That too came up in one of the Old Forum demolition threads. I can't remember which one and I couldn't find a link, but I'm absolutely certain that was in some errata somewhere.
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Austere Emancipa...
post Nov 25 2003, 03:35 PM
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QUOTE (Dr Funk)
I'm just baffled [...]

Oh we all are... Sometimes even a bit more than baffled, which apparently has led me to say that "The blast radii of explosives are fucked up" several times in the old Forums.
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spotlite
post Nov 25 2003, 04:49 PM
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QUOTE (Austere Emancipator)
QUOTE (spotlite)
Or perhaps its just 2060 and the plastique is more advanced that we know...?

Its a convenient explanation if you're looking for a plot-flange and aren't a demo expert!

To paraphrase: Perhaps the rules of physics and chemistry have been abolished and natural sciences have taken an all-around turn for the absurd?


to rephrase: :D

Its a convenient explanation if you're looking for a plot flange and don't know any better.


More acceptable?
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Austere Emancipa...
post Nov 25 2003, 05:01 PM
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Well yeah, if you think ignorance is acceptable. I don't. At least when it comes to ranged combat and explosives etc. :P
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spotlite
post Nov 26 2003, 05:18 PM
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OK. Well, I was just trying to be funny with that last one. I can afford to be funny about ranged combat and explosives because I'm likely to never be involved in either in Real Life ™!
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Austere Emancipa...
post Nov 26 2003, 05:32 PM
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You're absolutely right. I'm sorry, I'm just a very un-funny person.
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Corywn
post Nov 26 2003, 06:37 PM
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Speaking of explosions, does anyone really have an idea what kind of boom different fuels make? Such as:
Diesel
Gasoline
Jet
Methane

I've researched approximate weights (3 kilos per liter Gasoline, 4 for Diesel and Jet), but have no references for what type of explosion (I've been eyeing the FAE rules in M&M, but they give no guidelines.)
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Austere Emancipa...
post Nov 26 2003, 07:08 PM
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QUOTE (Corywn)
[...] 3 kilos per liter Gasoline [...]

Ehh? I'm pretty sure the weight of 1 liter of gasoline is about 0.75kg. I think you got liters confused with gallons there.

You don't want the FAE rules, because with those gasoline won't do shit. The rating certainly shouldn't be as high as actual explosives, maybe 2 or 3 (2-4kg is as effective as 1kg of commercial explosives). And don't allow them to be blown up simply by putting a detonator on a truck's gas tank -- you need a significant amount of explosives to vaporize the fuel so that it will really explode and not just catch fire and slosh around.

This old forum thread has some thoughts about the "nade in a jerry can" trick, go ahead and disregard my first msg in it because I though the gasoline wouldn't vaporize. Still, putting a concussion grenade in a 100l tank or something probably wouldn't cause the same effect but something more akin to what I suggested there at first.
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Corywn
post Nov 26 2003, 08:31 PM
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QUOTE (Austere Emancipator)
QUOTE (Corywn)
[...] 3 kilos per liter Gasoline [...]

Ehh? I'm pretty sure the weight of 1 liter of gasoline is about 0.75kg. I think you got liters confused with gallons there.

You don't want the FAE rules, because with those gasoline won't do shit. The rating certainly shouldn't be as high as actual explosives, maybe 2 or 3 (2-4kg is as effective as 1kg of commercial explosives). And don't allow them to be blown up simply by putting a detonator on a truck's gas tank -- you need a significant amount of explosives to vaporize the fuel so that it will really explode and not just catch fire and slosh around.


I think I did screw up some stuff.
The numbers I found were roughly:
7.~ lbs/gal Diesel
6.~ lbs/gal Gasoline
~Diesel for Jet
(I haven't looked into Methane yet, that's more a density matter, and just recently came to mind.)

I just realized I calculated wrong, which really screws up my hopes. Should be more along the lines of:
.75 kg/L Diesel (as you mentioned)
.675 kg/L Gasoline

As for the "activation" of it, I've been considering either EX Explosive rounds (spark off the tank, but useless traveling through the vehicle) or Incendiary rounds (which I would imagine would work nicely.)
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Austere Emancipa...
post Nov 26 2003, 09:03 PM
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Incendiary or EX-Explosives would both ignite the stuff, sure, but wouldn't make it explode. Unless we're talking about minute amounts of the substance.

In the Composite Explosives thread, we sorta concluded that with 5 gallons of gasoline, you'd need at least the hand grenade (not flash bang) to make it explode. For a vehicle's full fuel tank, it would certainly have to have the charge size of a frag grenade (~80g TNT IRL, AFAIK (abbr hell)).

So if you want to level a few city blocks, use a 5,000 gallon fuel truck + 10kg C12.

If you want to make the FAE rules more sane, change the Radius to something like (Kg x Rating)^0.5 and ignore the change of price in the new errata. [Edit]This would mean that a 5 gallon gasoline tank would do 6D in a 6 meter radius, -1/meter beyond that, + the explosive that set it off (assuming 0.675kg/liter and Rating 3). The 5,000 gallon fuel truck would do 6D in a 240 meter radius, -1/meter beyond that, and 38D from the C12.

And now I'm thinking 5,000 gallons of gasoline probably wouldn't vaporize like FAEs are supposed to, even with 10kg of C12... But it does make FAEs sufficiently mean for many other purposes.[/Edit]

This post has been edited by Austere Emancipator: Nov 26 2003, 09:10 PM
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Corywn
post Nov 27 2003, 05:10 AM
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Actually, I was just going to trash the radius rules, FAEs spread the explosive first, THEN detonate it. Without the spread, I'd think a tank would have an effective radious -1Power/2 or 3 meters.

Since you've apparently considered alternative explosives, do you know anyone who's considered a Sodium/Water load in a Capsule round, or have any idea the kind of micro-bang it might make (specifically, could it set off a gastank, perhaps?)
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Tanka
post Nov 27 2003, 05:15 AM
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Yes, it could. It generates enough heat to do so.

Anything in the first column on the periodic table, when mixed with H2O, makes a nice bang and some heat. The lower it is on the table, the bigger the bang and heat.
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Tiralee
post Nov 27 2003, 03:21 PM
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Okay - chemist/biological/mad scientist background here...

Firstly, go find a few pyro sites, you know, ones with strange people who think making C4 in your garage is a fun and exciting hobby?

Then you go and grab a few MSDS (Material Safety and Data Sheets.) There are thousands of sites online, and it's a good way to be really scared of what is actually able to be bought over the phone with a credit card.


The tradition of "grenade in the fuel-tank" is a long and happy one - It works well with planes because they use Kerosene (no idea of what translation I'd have to do for the Americans...) with a bunch of additives. It's cheap-ish, burns hot and well and gets a lots of energy from it... You can't run a plane on Auto fuel, even Diesel.

(It will make the carb choke and die, big-time There are a few interesting stories of this happening to propeller planes in the USA...)

Ok, with trucks? Unlikely to have the movie-explosive effects all shadowrunners dream of. Diesel needs to be heated and compressed. (I used to know the flame/spark points, and they're high...) for the spark-point, but if you've a few indenderies, you'll have enough remaining heat to warm the rest enough to start a combustion reaction, promoting a more interesting fireball.

Propane! Now, this is great. Most industry has at least one large (20-30 feet?) propane tank, used for various things, mostly for boilers, etc. Now, these babies have a total kill/blast zone of ~roughly~ 75-150 meters. Compressed, explosive flammables...mmmmm....

Now, if there's a tank-farm, well, your day has gotten brighter. Say you have 4-5 of these suckers? Well, during a fire in Oz a couple of years ago in an industrial estate, one of the smarter chiefs grabbed a truck (over the outrage of the owners watching their business burn to the ground) to hose something that wasn't anywhere near the flames. What was it? A propane tank farm.
Estimates by experts worked out that the 4 full tanks would have levelled everything in a quarter-mile radius of the blast site.

Now, that's gonna sting.

Want a cheap FAE? Hijak a propane truck. Hook up a remote rigger/decker virtual cockpit. Or a smart drone. Pack the truck with, say, 5 kg of plastique? And a couple of extra detonators. Rig a dummy, drive truck to location, blow it.

Chances are the shockwave alone will pulp people within a 100-200 m radius.
Cover the truck in refractile shrapnel (Ie: high temp. Drill bits are an excellent example.) and there will be a cloud of death raining down for some time to come.

Methane? A short brief explosion - it burns hot and fast.

Actylene? Same. (I've lost my eyebrows many a time.)

Sugar? Ok, when sugar is heated, it caramelizes (Ie: turns brown.) and changes from a discrete crystal to a amorphous mass. This means that with a drum of say, jam, you can make napalm faster and easier than the old "Gas and OJ concentrate" (BTW, the typical OJ concentrate is, maybe, 40 Brix (~40 % sugar.) but jams are between 66.5 and 68 %, because higher and it will crystalise out. Honey is +80 Brix, but the sugars in honey are shorter and more "fragile" so no handy napalm in the honey-pot gags for Winnie-the-Pooh fans. Phew.)

Basically, to make something flamey, you have to choose a compound that has enough to it (Ie: the compound is large and simple enough) so that the heat input has a lot of fuel to work on, but not small enough so that it will be consumed utterly (Ie: secondry chain compounds needed. Maybe Tertiary, if you're lucky.) without delivering a high degree of heat.

I could go into how tertiary bonding is best as it will generate the mostr heat when the bonds are broken, but the rule of thumb is that if a combound has a lot of hydrogen and carbon, chances are that it will burn and produce heat quite nicely.

If it's a big molecule, it will need a lot more heat input before it starts to break down, but when it does, it will burn longer.

Which is why you can lose your eyebrows to a paint-thinner exposion, but are more likely to kill yourself welding an empty fuel tank than a full one. (It's a vapourised environment, needs only a small amount of heat input before combustion and explosive expansion, the full one needs to vapourise first, so it's slower.


Gods, what a disconnected rant.

L.
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Zazen
post Nov 27 2003, 05:30 PM
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QUOTE (Tiralee)
Propane! Now, this is great. Most industry has at least one large (20-30 feet?) propane tank, used for various things, mostly for boilers, etc. Now, these babies have a total kill/blast zone of ~roughly~ 75-150 meters. Compressed, explosive flammables...mmmmm....

I'd love some more information about propane, if possible. :)

Can you set one off by shooting it with a bullet, provided that you pierce the tank?
How much barrier rating might you give the wall of the tank?
How large is the blast for a smaller propane tank, the ones you find on peoples barbeques?
Can a mostly empty tank still explode, due to the remaining vapors and whatnot?
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spotlite
post Nov 27 2003, 05:50 PM
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All I know about it is there's a Propane 'farm' in the midlands of England which estimates say would outright kill everything within 2 miles and level everything within 15 if it exploded. Now THAT is a big bang. The farm is no more than a hundred metres per side (I think its just a storage area, with underground tanks. I don't know for sure), and you aren't allowed to bring a naked flame or mobile phone within 3/4 of a mile of the gates.
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Diesel
post Nov 27 2003, 05:53 PM
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I remember some RealTV! video of a gas truck exploding in Mexico (City?). It was a huge boom, but worse was when the underground storage went up.

Just wow.

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