Detonating Cord question

[Anthony]

The DR of the PVC is not particularly relevant, though being plastic I doubt it makes particularly effective shrapnel. GURPS explosives aren't super well correlated with reality (direct effects of blast on humans are fairly unimpressive, it's mostly the indirect effects that kill people) and I'm not sure det cord will give you a proper blast wave. I wouldn't want to be walking over a line of det cord at the time it was exploding, but I also wouldn't be confident in its ability to disable an enemy. Bangalore torpedos have a lot more explosive in them than det cord.

[Anaraxes]

Originally Posted by Donny Brook

The use-case here is that my players want to make an impromptu bangalore with det cord and PVC.

If you double the det cord back and forth through the pipe, you'd wind up with a lot more explosive per hex than a single strand of cord. (Wrapping through the pipe and back down the outside, would get close to having the pipe fully filled, times two for the cord on the outside of the pipe. Leaving an end free so you can attach more non-exploding pipe to push the bomb forward, it'd probably be simplest just to pack the business end full.)

[Donny Brook]

Originally Posted by Anaraxes

If you double the det cord back and forth through the pipe, you'd wind up with a lot more explosive per hex than a single strand of cord. (Wrapping through the pipe and back down the outside, would get close to having the pipe fully filled, times two for the cord on the outside of the pipe. Leaving an end free so you can attach more non-exploding pipe to push the bomb forward, it'd probably be simplest just to pack the business end full.)

Good ideas, but I will let them figure that out ;)

[RyanW]

Originally Posted by Anthony

The DR of the PVC is not particularly relevant, though being plastic I doubt it makes particularly effective shrapnel. GURPS explosives aren't super well correlated with reality (direct effects of blast on humans are fairly unimpressive, it's mostly the indirect effects that kill people) and I'm not sure det cord will give you a proper blast wave. I wouldn't want to be walking over a line of det cord at the time it was exploding, but I also wouldn't be confident in its ability to disable an enemy. Bangalore torpedos have a lot more explosive in them than det cord.

If you bury it in gravel, it might generate enough fragmentation to cause some problems, especially given the area of the body those fragments will likely be focused on.

[Willy]

What about cutting the detcord open, pulling out the explosive and filling it into the PVC tube? Should be posssible for trained soldiers, if the have enough time to prepare. Than just calculate the volume of the tube multiple it with the weight of the explosive per cm3; and you can calculate the damage of the explosion from that point on.

Of course winding the cord around the tube is easier and safer, you just need the outer diameter and can than estimate how much cord you have per hex.

If you want damage to people and stuff and not use it to clear mines / a path etc, than the better way damage wise is making your own claymore, which again a soldier should be able to, you don´t need much skill for it.

To cut heavier or sturdier material like a steel double T beam, you can improve via a angle iron, a standard trick shown every soldier with a specialisation to explosives.

[acrosome]

A single strand of detcord probably shouldn't do much damage if it isn't in actual contact with the target, so I think the 1d-3 may be correct. Yes, it can be used to cut things like trees or girders, but that's because of the high brisance of PETN, not it's sheer power.

Remember that REF isn't a terribly scientific value. It's just meant to let engineers convert the blasting formulas that were originally developed with TNT in mind to other explosives. It actually doesn't tell you much about the explosive's properties. IIRC REF values even vary by the exact usage, IRL.

[Anthony]

The alternative is to have the PC roll demolitions or traps. On a success, they come up with something effective, on a failure they get something noisy and not particularly effective (there's no question you could do something dangerous with detcord).

[Donny Brook]

Well, they'll certainly have to roll regardless.

[Pursuivant]

Originally Posted by Anthony

The DR of the PVC is not particularly relevant, though being plastic I doubt it makes particularly effective shrapnel.

That's a dangerous assumption. Thick-walled PVC is pretty tough stuff and even if it doesn't shatter into fragments the heat of the explosion might be sufficient to melt it. In the latter case, substitute burning fragments for cutting ones. Obviously, explosive force will be lower, though, since PVC will deform or rupture before metal of equivalent thickness.

[Anthony]

Originally Posted by Pursuivant

That's a dangerous assumption.

It being a poor choice doesn't make it harmless. Just significantly worse than alternatives.

Originally Posted by Pursuivant

Thick-walled PVC is pretty tough stuff and even if it doesn't shatter into fragments the heat of the explosion might be sufficient to melt it. In the latter case, substitute burning fragments for cutting ones. Obviously, explosive force will be lower, though, since PVC will deform or rupture before metal of equivalent thickness.

The problem is that PVC is low density (thus poor ballistic and terminal properties). I doubt it would melt, but if it did, that would just make it less effective, burning effects are horribly inefficient, the only reason they're used in warfare is because heat is really easy to produce.