06-27-2017, 12:24 PM | #31 | |
Join Date: Sep 2011
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
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As I understand it, lasers initially heat up the surface of a material and as the surface heats, that heat penetrates more deeply as well as spreading laterally. Continuous beam lasers encountered a problem in that the surface continued absorbing heat even after it's transformation into the gaseous state because the laser beam effectively pressurized the gas preventing its escape and thereby degraded the efficiency of the laser. Pulse lasers were developed as a solution to the problem by briefly interrupting the beam to allow the heated surface gas an opportunity to "boil off" before resuming. Assuming that laser and plasma torches have a pulsing interruption feature that allows the surface gas to boil off, it seems reasonable to say that the laser/plasma torch doesn't engage more than 1 mm of depth at any given instant, so it never has to deal with more than DR 1 due to thickness, so most of its burning damage is expended directly in attacking the HP of the wall. Last edited by Curmudgeon; 06-27-2017 at 12:40 PM. |
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06-27-2017, 12:25 PM | #32 | ||
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Join Date: Oct 2007
Location: Indianapolis, IN
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
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As I stated earlier all plasma torches (and lasers, gas-axes, and water jet cutters) have a limit on how thick a material they will cut. Just letting it sit there and arc into the plate doesn't work once you've reached that limit. With plasma torches that limit seems to be closely associated with the amperage the rig can handle. It looks to me (still) like the examples given are pretty light weight ( the Heavy Plasma Torch is all of 40 pounds and works on Dp battery) and the real answer is get a bigger rig with more power. To me this is the equivalent of asking 'Why won't my 37mm AT penetrate the front of that Panther?" As for cutting speeds we may have to do what we do for vehicles - look at actual stats and punt. There are graphs of cutting speed vs material thickness. And yes it may very well be that on a damage per second basis that looks like the torch isn't doing as well as its damage would suggest it should. I would chock that up to the operation needing a certain amount of 'overkill' to maintain the arc or waste in needing to control the motion and not kill the arc etc. Remember what you are getting out of it is a hole right where you want it with out a lot of shrapnel flying around.
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Joseph Paul Last edited by Joseph Paul; 06-27-2017 at 12:44 PM. |
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06-27-2017, 12:50 PM | #33 | ||
Join Date: Jun 2013
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
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Assuming that chunk of steel were RHA (it probably isn't) or similar, that's 3-4 seconds to get through Cover DR 140, which the plasma torch from HT will do at maximum (or just consistently above-average for 4 seconds) damage if we just let things add up from round to round. Beyond that, we're looking at 20 seconds for a 2*pi in linear cut (the circumference of that circle), 50 seconds for 15 in. The first is 3.18 s/in, the second is 2.78 s/in. Considering the circle was done with two rotations - possibly just for added precision - I'd be tempted to go with 3 seconds per inch. That basically works out as something like piercing time per inch, which makes things a bit easier - work out pierce time, and multiply it by the length of the cut (or perimeter, if cutting out a section) +1 for the initial pierce. Realistically, torches have a maximum thickness - or perhaps just maximum DR - that they can reach. Looking at the specs for that particular model, that 2" pierce is actually around the best it can do, so something like a 3-second maximum may be appropriate. I don't know if the laser/plasma torches in UT work the same way, but it may not be horribly inappropriate to assume so. For cutting into a thick metal door, then, a Fusion Torch (8d+2(5), or 50 damage vs 1/5th DR) has a piercing time of 0.2 seconds for a DR 50 door, 1 second for a DR 250 door, and at maximum can pierce through a 750 DR door in 3 seconds. Cutting a 2-yard by 1-yard "doorway" (to get through) takes P*217 seconds (perimeter of 216 inches, +1 for initial pierce), where P is Piercing Time - so around 45 seconds against DR 50, 217 seconds (~3.5 minutes) against DR 250, and 651 seconds (~11 minutes) for DR 750. Cutting a 1-yard diameter circle (to crawl/dive/fall through) takes P*114 seconds instead. Quote:
These are all just rough estimates, but would probably work well enough for a game.
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GURPS Overhaul |
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12-12-2017, 03:49 AM | #34 |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
It has been recently pointed out to me that Thermite (High-Tech 188) does turn metal armour semi-ablative for the purpose of cumulative damage (but only for a direct burn).
So what I'm thinking: should the two categories of TL9 torches be comparable to TL6 thermite for the purposes of cutting through metal? The question applies both to the 'normal' mode of functioning, and to some hypothetical higher-power mode of the devices. |
12-12-2017, 06:03 AM | #35 |
Join Date: May 2013
Location: Ellicott City, MD
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
That sounds reasonable enough for both realism and playability.
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12-13-2017, 06:56 AM | #36 | |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
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(Other source of numbers: the regular Plasma Torch seems to require about ¼ the power compared to some modern plasma torches people tried bringing up.) |
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12-13-2017, 08:50 AM | #37 | |
Join Date: May 2013
Location: Ellicott City, MD
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
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12-13-2017, 11:49 AM | #38 | |
Join Date: Aug 2007
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Re: [UT] Plasma Torch vs. big metal door on a spaceship?
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Molten iron contains an enormous amount of energy by itself but when circumstances are right you get a layer of molten iron between the burning thermite and the surface below. That can transmit heat energy by conduction rather than radiation. Your torch is having to work hard to be better at damaging materials than thermite.
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Fred Brackin |
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Tags |
ablative, ablative dr, corrosive damage, plasma, plasma cutter, plasma torch, spaceships, ultra-tech |
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