[UT] Plasma Torch vs. big metal door on a spaceship?

[Joseph Paul]

Looking at the hvy plasma torch in UT - 4d+1(5) - I think the problem is that you need a real industrial torch or water jet cutter for anything over an inch in steel. And that should have an AD(10) and a much larger damage.

Also are you attacking the whole surface (112 DR/inch) or the Cover DR (~70DR)? I would rule that these tools are continuously piercing the Cover DR in a very small space. RAW doesn't seem to include metals in the semi-ablative/ablative note so move onto a better tool.

[Anthony]

Originally Posted by Joseph Paul

Looking at the hvy plasma torch in UT - 4d+1(5) - I think the problem is that you need a real industrial torch or water jet cutter for anything over an inch in steel. And that should have an AD(10) and a much larger damage.

Not over the course of a single GURPS combat turn.

[Joseph Paul]

Originally Posted by Anthony

Not over the course of a single GURPS combat turn.

I am not sure I understand your objection. Care to expound?

[Fred Brackin]

Originally Posted by Joseph Paul

I am not sure I understand your objection. Care to expound?

You appear to be looking for something that will penetrate very high DRs in a single round i.e. as in normal combat.

We can definitely say that HT torches don't work that way though they can penetrate very high DRs over a longer period of time. Possibly much longer. It took the Mythbusters many minutes to burn into a safe with a TL 8 "plasma" torch. It is to be hoped that UT torches will do at least a little better on that time/DR relationship.

So, modeling TL8 performance we need some kind of cumulative damage paradigm such as making metallic DR ablative or semi-ablative v. Burning damage or treating Burning as Corrosive and that's what has made up the bulk of discussion in this thread.

[GodBeastX]

Originally Posted by vicky_molokh

Greetings, all!

I remember that drills and rotary hammers treat wooden, brick and stone obstacles as [semi-]ablative. However, I do not remember any similar notes about gradually cutting metal obstacles, even for things like the plasma torch (which does burning damage). So my questions are:

• Am I missing a rule about torches doing corrosion damage instead of burning when focusing on a single section of a hull/wall/door/etc.?
• If not, how does one cut down through metal armour and doors, since those tend to have non-ablative DR that increases with thickness.

Thanks in advance!

Ultratech is calling Laser and Plasma Torches tools. Those are the combat stats, not how it affects objects during work. I think that if a GM has you measuring work load by combat damage then something fell apart.

Now if you are looking for how long a plasma torch would take to cut though a bulkhead then that's more math than I can offer =) Maybe someone wants to jump in with physics on this one.

[Joseph Paul]

Originally Posted by Fred Brackin

You appear to be looking for something that will penetrate very high DRs in a single round i.e. as in normal combat.

We can definitely say that HT torches don't work that way though they can penetrate very high DRs over a longer period of time. Possibly much longer. It took the Mythbusters many minutes to burn into a safe with a TL 8 "plasma" torch. It is to be hoped that UT torches will do at least a little better on that time/DR relationship.

So, modeling TL8 performance we need some kind of cumulative damage paradigm such as making metallic DR ablative or semi-ablative v. Burning damage or treating Burning as Corrosive and that's what has made up the bulk of discussion in this thread.

All plasma torches have thickness limits generally tied to the amperage they can put into the arc but the relevant industries seem to like plasma up to the 6 inch range. They find it more economical to use oxy-fuel cutting torches for really thick material – up to 40 inches. With a plasma cutter properly matched to the task at hand you will see very fast initial piercing and high cutting rates – because that makes it profitable to use. Last night I watched an industrial demonstration of cutting a part out of 2 inch thick material. The pierce took all of 2 seconds and the linear run was better than 20 inches in a minute. Every second that torch moved through a third of an inch or more of material completely annihilating it. That is several times the amount of material the initial pierce dealt with and I think that definitely shows that the torch is not only dishing out enough damage to overcome the DR but it is doing it several times a second. I can't speak to Jamie and Adam's experience because my googlefu is failing me (Got a URL?) but it seems we have seen very different examples of plasma torches. I know that hand held torches are designed to cut their max thickness at no slower than 10" per minute and the thinner stock goes much faster. CNC rigs can do 80 or more IPM.

I think the line of thought on having to treat the DR as semi or fully ablative is misguided and based on the relatively weak stats of tools that are light duty and meant to be highly portable. Neither the HT nor UT plasma torches detail how thick of a material they should be used for and that is what should be noted as well as the cutting speed in that thickness. Those stats answer the important story questions “Can we breach it?” and “How long will it take?”.

[Lord Azagthoth]

In GURPS, Maximum Rof is 20. A cutting torch is a continues beam, so it should deal damage at least 20 times the listen damage in HT/UT. Probably you should consider over penetration rules if you don't move the torch, or move it to slow.

[safisher]

Originally Posted by vicky_molokh

That's an effect that applies to wood, stone, brick and concrete. I'm looking for cutting through huge metal obstacles.

I realize that, and I am saying that I would apply that rule to tools (cutting torches, etc.) against metal, armor, etc. The saws, torches, etc. in all the GURPS tech books work that way; it's how metal cutting tools work in the real world. That table you reference is referring to much larger areas (SM 0) rather than very small areas (SM -14 or so), and for non-tool attacks (such as super powers). If you are asking if there is a more canonical opinion, I don't know of one.

[Fred Brackin]

Originally Posted by Joseph Paul

I can't speak to Jamie and Adam's experience because my googlefu is failing me (Got a URL?) .

https://en.wikipedia.org/wiki/MythBu...on)#Water_Safe

Episode "Crimes and Mythdemenors 2", segment "Water Safe. I see that they are referring to the tool used as a "thermal lance" rather than a "plasma torch".

There may be a YouTube video of at least part but I suspect it'd just be the climactic explosion.

[Joseph Paul]

So could vicky_molokh and safisher do worked examples of figuring out how long it takes to cut a 1'x3' hole in a 2" thick airlock door?