If you get someone that's really skilled with explosives, how concentrated a blast could you get using something like plastic explosives? I read in a newspaper about an assassination that used a remote control car-bomb that the police described as 'super professional'. It was placed under the car beaneath the drivers seat, and when activated basically mangled the guy and ripped the steering wheel off. The other passengers though escaped with only minor injuries. Is this kind of precision possible or were the newsies either mistaken or playing it up a bit for a better story? Thanks.

In terms of SR... If the Barrier Rating is high enough to protect the other people, it could happen. Just put the right strength of material in strategic points and the explosion will have nowhere else to go.

At least, that's how I read it. I'm not Explosives Expert, but that's about as close as I can see it.

Shaped charges work by focusing the blast by using the shape of the explosive and some fairly complex planning.

The effect is the opposite of the shape of the explosive. Most anti-tank rounds are basically inverted cones. When they hit the tank, the force of the expolsion blasts a cone into the tank, injecting super hot metal.

The same thing would work for yoru car bomb- the charge was shaped in an inverse of the area the man was sitting on, so that the explosion was directed towards him and no one else. Any injuries were a reult of the secondary effects of the blast (fragmentation and whatnot).

moosegod is right

The shape of the charge does matter, i read an article on it once, about how not only the shape of the explosive matters but where the detonator is placed is also key.

Watch a movie called "Blown Away" if you have a thing for explosives, some cool stuff.

To put it simply, demolitions and the use of shaped charges is definately a fine art, and a very precise science at the same time. It's entirely possible to use a shaped charge to do something like that.

A short and simple explanation: The "shaping" of a charge is merely placing a cavity within the explosive to cause a balancing of forces to achieve a desired effect. Many armor piercing charges use a cone-shaped cavity lined with metal. When it explodes, the force of the explosion will squeeze the metal into a semi-liquid stream to do the penetration for you. The same effect can be achieved, though not as powerfully, without using a projectile.

The other part of shaping is called "tamping". Using materials around the explosive to channel force. The explosive force will tend to follow the path of least resistance. Water is one of the best tamping agents, due to it's incompressability, but earth is very good too.

Just as a reference, fill a coffee can with C4, and remove enough to form a geometric right cone with a top angle of 45 degrees, and a base the same as a coffee can. With the proper standoff distance (distance of the explosive from the target), this can easily penetrate more than a foot of solid steel, with little damage to surroundings.

I guess it's worth saying explicitly and clearly (before arm chair generals begin sharing too much wisdom about HEAT munitions and the Monroe effect)...

"Shaped Charges" and "HEAT" are often used synonomously (sp?) but HEAT munitions are just specialized sub-type of shaped charges.

Shaped explosives covers a wide range of explosive applications. Some resemble HEAT (like the linear shaped charge), but others involve any re-direction of explosive effects. For example, the famous claymore mine, or getting a bomb in a car to wipe out the driver but no one else.

"Blown Away," if that's the Stallone movie I'm thinking of, is an excellent demonstration of shaped charges. I like the one with the coffee cup and saucer.

Unfortunately, I'm not sure how to pull this off with canon rules. What I would suggest attempting is an application of barrier rating rules: wrap an explosive in a high barrier material, leaving one or more sides open. While the explosives are wasted against the barrier in most directions, the explosion is free to travel and have normal effects in the open directions. I'd recommend some kind of ballistic plastic as the barrier - it will make poor shrapnel but a good barrier.

Doubly unfortunately, you'd have to do some number crunching to determine the effect of reflected blasts bouncing of the container. That'll jack up the power of the blast inside the container and might require a very high barrier. (Or do you have to calculate that power increase for determining the chance of breaching a barrier?)

"Blown Away" has Tommy Lee Jones as the IRA terrorist out for revenge.

It took the whole "watching the fuse burn and detonate" schtick way, way too far.

-Siege

If you leave an opening, I don't believe there's any reflected power accumulated. It all just gets directed one way.

Now, if you wanted to make it extra spicey, make it a full surrounding Barrier, but have one side weaker than the rest. It reflects for a while until it overcomes the weak barrier side, correct?

Directional Chunky Salsa, anyone?

The Plastic Warriors supplemental has some rules for shaped charges. I'll try to dig up a link for you, we've used that supplemental a lot in my playing group.

Edit: Here we go, Plastic Warriors Downloads You want the "Running Gear" link on the left side, it's about 100 pages of .pdf. Shaped charges are on p. 27.

Ruleswise, I'm sure it would rebound at least once even if the one side is completely open. It'll bounce of the wall opposite to the open.

As for breaking the Barrier... Personally, I think I'd use something like half the Power of the first reflected shock wave, to represent that most of the pressure will just escape out through the open area. Stricly abiding the Blast Against Barriers rule, you'd end up having a pretty large Power against the side walls, as the explosion would just keep bouncing back and forth.

So, for 2kg of C12 in a 0.5 x 0.5 x 0.5 meter heavy metal box with one side open (Barrier 12), using a few house rules (half-reflected vs Barriers, -3/m blast): 16D -3/m.
Reflected distance for breaching the box walls: 0.5m = -1.5 Power.
Total Power for breaching the box walls: 16 + (16 - 0.5 x 3)/2 = 23
Area of effect outside the box: 90 - 135 (or more, depending on a lot of things) degree cone extending from the center of the box
Power of the explosion in the AoE: 16 + (16 - 0.5 x 3) = 30

30D -3/m in a 90+ degree cone. The metal box walls will be damaged (-1 Barrier Rating) but they'll hold. Don't try using the same box repeatedly, though...

Strictly by the rules, the situation won't be that bad, since the reflection distance is 0.5 meters and the Blast is -12/m.
Power against the box walls: 16 + (16 - 0.5 x 12) + (16 - 1 x 12) = 30
Ie don't try it without a Barrier Rating 16 box.
The damage in the AoE is: 16 + (16 - 0.5 x 12) = 26D, -12/m

However, the same thing with a 0.25 x 0.25 x 0.25 box would result in whacky numbers:
Power against the box walls: 16 + 13 + 10 + 7 + 4 + 1 = 51, so anything less than a Barrier Rating 25 box will blow into bits.

no expert here, but I am pretty sure reactive armor (for tanks) works the same way as well - little inverted cones (or whatever hollow shape works best, i guess) on an inner layer of armor pop off at the place where the outer layer armor is hit and push back against the impact force and help keep the nasties out

-3Threes

A box of heavy structural material?

~J

20cm/8" of hardened armor-grade steel should do the trick.

Don't ask me how the hell you'd manage a Barrier Rating of 196, though. Maybe a few dozen meters of hardened armor...

remember one thing here guys, a car seat isnt exactly reinforced concrete or hardened steel, its some springs, some foam and maybe some leather.

if the cutting charge was angled slightly forward and slightly towards the drivers door, it would detonate, the primary blast would rip upwards tearing him a new asshole, the secondary blast would go outwards but meet the steel rails and support structure built into the chair, some power wuld be lost throught the lining but the majority would bounce back and go ou the now easiest path, where the springs, seat and driver used to be. of course all passengers would be very deaf and very unhappy.

Another instance of the use of this sort of metallic penetrator explosives was used to assassinate someone in a passing car (i don't remember the exact circumstances). A satchel was filled with explosives and hung over the handlebars of a bicycle. A copper plate was affixed inside the satchel. The bike was chained to a street sign at a street corner, the plate facing the street. When the target's car passed the bike, the explosive was detonated. The projectile killed both men in the back seat of the car, blowing the remains out the opposite door. The men in the front seat were fine.

As for how to deal with it in-game, one of my players has years of experience IRL as a demolitions specialist in the Army Corps of Engineers. My system is to ask him what it would take him to achieve the desired result. I place that on one end of the scale, take what the SR rules say and put it on the other. ~4-5 successes gets what the expert says, 1 gets what the book says, and I fudge anything that falls between the two. I usually set the TN to between 4 and 6, modified for environment and such. I'm going to see if I can get the player in question to make a post with some suggestions for how to deal with it.

As a side note, some good info on shaped charges, and some more here.

And before I forget about it, another common use of shaping charges is used by police and government SWAT teams. It's a v-shaped channel on a frame, easily portable, about the size of a window or door. Hold it against the portal in question, push the button, and a nice knife-shaped shockwave cuts a hole into wherever you want to go. It's a one-shot deal, but good for dealing with boarded windows and such.

Actually, it's not chunky salsa. It's referred to as the pinball effect, or something similar (I may be forgetting the actual name, at the moment). In simplest terms, anything in the car that is not nailed down (as well as a fair amount of whatever was) gets turned into shrapnel and bounces all over the place, effectively punching tons of holes through everything and everyone possible. The AT4 works like this, if I recall correctly.

Ooh! Ooh! So, we've got 25.46875kg of C-12 instead! That gives us 60D.

The highest Power it can accumulate is then 60 + 57 + 54 + ... + 6 + 3 = 630
So we'll want a box with a Barrier Rating of 316, 314 on the weak side. The Damage Code in the AoE will be 316D, -12/m. Not too shabby.

Now, where to get that Bar 314/316 box...

Chunky salsa is a term used to describe the effect of a blast in an enclosed space purely in relation to amplification of the blast's effect due to reflection off of sufficiently strong barriers.

In contrast, the pinball effect specifically refers to the use of explosive force in a confined space to hurl small objects around as shrapnel in the confines of that space.

These two effects compound eachother to create the killing potential for a weapon like the AT4, in which overpressure from the chunky salsa effect does only a portion of the killing. Bits of armor that have exploded through the outside of the vehicle, unsecured (and often, by the point, fragmented) equipment, and lighter portions of the internals of the vehicle get hurled around at significant speeds due to the blast, all but guaranteeing a 100% casualty rate.

Hence, a description of the blast turning everything inside into shrapnel is not, in fact,t he chunky salsa effect.

Oh, pfft. Meanie.

Anyway, I was replying to Camouflage's post that called cykotek's mention of HEAT induced shrapnel the chunky salsa effect.

And yes, the AT4 pretty much has a well designed but largely basic HEAT warhead, and most HEAT munitions will pretty much work along those lines, though it's worth noting that the AT4 is one of the more effective designs at present, to my knowledge.

I haven't read the book, but from what I hear one of the "heroes" is a convicted pedophile. They changed his name for the movie, apparently. I think that's hilarious.

Oh well, there's my extremely-off-topic post for the day.

Hey, as far as I'm concerned the guy who brought us Chinatown can dope up all the 13 year olds he wants.

My point exactly...