02-07-2014, 04:33 AM | #21 |
Experimental Subject
Join Date: Jan 2005
Location: saarbrücken, germany
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Re: Steam Bomb
iirc, there was an explanation in the Guardians of the Flame series where the mages guild created guns in a very similiar way. It was a rather convoluted setup where, similiar to the ideas here, water got superheated in a metal casing, and the casing held together with magic. Somehow they ended up with a highly pressurized bullet, which somehow released this energy upon contact with water (which had been defined as breaking the enchantment holding everything together).
As I said, it was a bit convoluted. Also, the mages guild in the books never was able to mass produce these wizard guns. Still, the description in the books might be of interest.
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02-07-2014, 10:10 AM | #22 | |
Join Date: Aug 2007
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Re: Steam Bomb
Quote:
However, if we compare the size/cost relationship of the examples in the Boil Water text t quantities of black powder I have seen used the basic "fist-sized" for 2 energy would do any small cannon such as a swivel gun up to maybe a 6-pounder. For 4 energy it does a cubic foot of water which should handle most Age of Sail guns. With the next size up from that you're giant siege gun size.
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Fred Brackin |
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02-07-2014, 10:23 AM | #23 | |
Join Date: Aug 2007
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Re: Steam Bomb
Quote:
If the water which was displacing an equivalent volume of air at 15 psi expands by a factor of 1600 that appears to me to be having your steam bomb pressurized at 1600 atmospheres or 24,000 psi. That's at the high end of black powder gun barrel pressures and you're trying to contain it for a much longer time i.e multiple seconds instead of thousandths of a second. I won't say you can't make a sphere out of simple iron with Shape Metal that can do it but it's going to be much thicker than a gun barrel and _heavy_. It would probably be very unlikely to hold the steam but then rupture upon hitting the ground or even a stone wall. You could make a Steam Bomb with Boil Water and Delay and make your metal walls no thicker than you want for fragmentation purposes. That would be about 1/2 the whole projectile weight if using the rule of thumb that applies to aircraft bombs and mortar rounds.
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Fred Brackin |
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02-07-2014, 10:26 AM | #24 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Steam Bomb
Problem is that boil water doesn't specify what pressure of steam it produces, and given that it doesn't cause explosive damage, it may simply not produce enough pressure to power a useful gun. Other than that, figure 1 hex of steam is about equivalent to 1 ounce of gunpowder.
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02-07-2014, 10:35 AM | #25 |
Aluminated
Join Date: Feb 2005
Location: East of the moon, west of the stars, close to buses and shopping
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Re: Steam Bomb
Most of them do. That said, the steam cannon has been demonstrated to work. An operational model was constructed a few years back (I think it was a bunch of MIT students) and successfully fired. That's what provided the performance from which FT's steam cannon stats are derived.
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02-07-2014, 11:10 AM | #26 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Steam Bomb
High pressure steam is a perfectly viable working substance for a gun, it's just that you need it at ridiculous temperatures (exceeding the triple point of water) to actually produce cannon-level force.
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02-07-2014, 11:55 AM | #27 | |
Join Date: Oct 2006
Location: Chagrin Falls
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Re: Steam Bomb
Quote:
Is your materials science/metalurgy, dimensional tolerancing, temperature measurement and magical control of heat flux advanced enough that your operators can reliably predict when the casing will fail? If not it seems like you are asking them to risk messy death or ineffectiveness with every launch. If all of those problems are solved then pre-grooving for shrapnel is trivial.
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02-07-2014, 12:09 PM | #28 |
Join Date: Oct 2007
Location: Kentucky, USA
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Re: Steam Bomb
Just make it two enchantment/spells.
The first dramatically increases the pressure the vessel can contain. The second makes the steam. When the first one ends or fails, the pressure is already so far past the vessels ability to contain it just explodes into (pre-grooved?) shrapnel. With linking spells, you could have it reliably air burst, or make it like a landmine that goes of only when people get close. Another option is that instead of making steam, you summon essential steam from where the elemental planes of fire and water meet. |
02-07-2014, 12:10 PM | #29 | |
Join Date: Sep 2004
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Re: Steam Bomb
Quote:
Having said that, I'm guessing that's you're working very hard to duplicate what a fire mage can do with just Create and Shape Fire across enemy lines... Or perhaps even what a small conjured elemental would do. |
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02-07-2014, 01:24 PM | #30 |
Night Watchman
Join Date: Oct 2010
Location: Cambridge, UK
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Re: Steam Bomb
Here's the web page for the MIT steam cannon, which is not explained.
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