tag:blogger.com,1999:blog-8062651468331172034.post1790897387982958835..comments2024-01-03T03:13:36.569-08:00Comments on <center>Atomic Skies</center>: Building a Spaceship in Dungeons & Dragons, Part 2.5Markhttp://www.blogger.com/profile/12523189413175446117noreply@blogger.comBlogger16125tag:blogger.com,1999:blog-8062651468331172034.post-56276101028731187092016-11-26T18:25:57.510-08:002016-11-26T18:25:57.510-08:00Sure!
http://www.dtic.mil/dtic/tr/fulltext/u2/411...Sure!<br /><br />http://www.dtic.mil/dtic/tr/fulltext/u2/411786.pdf<br /><br />I must warn you, though, it is pretty darn boring. Given the timing, I'd hoped it was a followup to the original Manhattan Shelter Study. Unfortunately, it turned out to be a massive compilation of statistics and other information about tunnel excavation in urban areas, with no mention of designs or anything - just how to price the tunnels. It's possible that it was prompted by the MSS, but there's no evidence of it in the paper, and the depths it considers are much shallower (typically about 100 to 200 feet).Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-4274048875011487902016-11-26T17:37:50.371-08:002016-11-26T17:37:50.371-08:00Hi,
Could you provide us a link to that "merc...Hi,<br />Could you provide us a link to that "mercilessly boring" paper? I must admit that I find the Manhattan Shelter Study and related projects so fascinating as to outweigh the boringness, and in any case, having written a fair number of like papers (though on less fascinating matters), I have a soft spot for them :)<br />Thanks in advance!Dareknoreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-18315211321237213052016-11-17T13:36:39.973-08:002016-11-17T13:36:39.973-08:00On alternate means of communications: My e-mail is...On alternate means of communications: My e-mail is in the upper right hand corner; drop me a line. :)<br /><br />On permanency: While our astronaut can cast permanency, he's not high enough level to cast it on a wall of force, so we need to contract it out.<br /><br />On hardness: The problem is that we don't <i>know</i> what the final damage is. The heat can be approximated by just adding up all the blast of flame spells, but the pressure damage can't be calculated in any way I can find.<br /><br />On Initiate of the Seven-Fold Veil: Let me get back to you on this, I'm AFB at the moment.<br /><br />On Walls of Force: One problem here is that we still need the lyres - the wall of force needs to be anchored in something, which will then be exposed to the exhaust gases. The main advantage I see there is that it roughly halves the mass of the vehicle - which is a pretty significant advantage, since it means we can use a weaker, and therefore cheaper, engine.<br /><br />On control currents: sadly, the velocities involved are trivial compared to what we've got now, and what we need.<br /><br />On EFTs and walls of force: To capture the entirety of the blast of flame, we need each of our side walls to be 60' tall and 60' wide, for a total area of 1800 square feet. A wall of force covers CL * (10 foot squares), so we need the wall to be cast by an 18th-level caster. The base cost of the EFT is 5,910, plus 18x50 = 900 gp for the wall, and we'd need four, so that's 27,240 gp total. Plus spell traps and the mithral framework, but that probably won't be a huge amount of money, and even if it takes us over the price of the existing approach, the system will be much lighter. But I feel like I considered this approach in the past and rejected it for some reason, but cannot recall what it was... Let me think about this and see if I can remember.<br /><br />On zone of elemental immunity: only protects against heat, not pressure, and we already have ways to protect the system against heat.<br /><br />Still digging on pumping and prismatic walls, we'll post more later.Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-730007262049994722016-11-15T23:48:18.227-08:002016-11-15T23:48:18.227-08:00Is it cheaper to power 4 walls of force with an en...Is it cheaper to power 4 walls of force with an energy transformation field or 4?Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-65914235951741129222016-11-15T23:43:17.235-08:002016-11-15T23:43:17.235-08:004 walls of force (since we'll need to leave on...4 walls of force (since we'll need to leave one end open and one end with an adamantine cap for our pressure) come to 10,000 xp. 40k GP. (I assume the pressure will be greater than 1,000 pounds per... unit. (Dark way measures these units by creature. so perhaps psi just to be... non-silly?) On the other hand, this does get you a torchship. <br /><br />Hrmm. With control currents (Druid 4) we can induce a remarkable amount of water flow. Can you just show that providing 30ft/round extra movement to a 20 foot radius section of our chamber (assuming that it's evenly filled with decanters) provides less energy than the steam or firetrap boilers? Either way, I suspect it would make an absolutely wonderful first stage or primary pump.Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-67215411886566738632016-11-15T14:16:00.274-08:002016-11-15T14:16:00.274-08:00Argh. threaded convos. Can we take this discussion...Argh. threaded convos. Can we take this discussion to a different medium? <br /><br />Permanency spells cast by *yourself* are much much much much much cheaper. <br /><br />In terms of hardness, let's start by talking about what damage we must withstand to see if it's worth checking. Assume that every part of the wall takes the full damage from your final flame product. (I just don't know what that number is) If it's too far above normal hardness, we can ignore the rest of the exercise. <br /><br />Enchanting a magic item with just one colour of a prismatic wall (at full price plus the cost of all the other negation spells) could... be... a DM ruling? Ew) <br /><br />Another route is to figure out how to get class features into magical items, as the initiate of the sevenfold veil's yellow warding is exactly what's indicated. <br /><br />Bleh. I can't find anything about magical items bypassing (we'll ignore artefacts). Perhaps figure out how to extend metamagic or up caster level? The wall from initate works for 10 min / level, and there are plenty of ways to boost caster level.Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-19962682170380100882016-11-15T13:53:13.068-08:002016-11-15T13:53:13.068-08:00I just looked something up and found one of my ans...I just looked something up and found one of my answers some years ago: http://rpg.stackexchange.com/questions/45474/how-can-we-protect-a-ship-from-magical-rain-of-acid<br /><br />Apparently the stronghold builder's guidebook has a "zone of elemental immunity" that could be quite handy for this sort of thing. And, in the same vein, http://www.giantitp.com/forums/archive/index.php/t-86964.html asserts that the guide has a prismatic screen effect. Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-1276776957401277712016-11-15T13:40:40.888-08:002016-11-15T13:40:40.888-08:00Here's a thing: the SRD says that you need to ...Here's a thing: the SRD says that you need to bring each layer in the prismatic wall down in order, with the last layer being destroy-everything violet, so the <i>spell</i> won't work. But it also says that "certain magic items can create prismatic effects one color at a time" - any idea what it's talking about? I ctrl+F'd the magic items section but didn't spot anything...Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-89745416653441606402016-11-15T13:35:10.455-08:002016-11-15T13:35:10.455-08:00Re: hardness requirements: the problem is that the...Re: hardness requirements: the problem is that there's no way I've found to put numbers on what the actual requirements are. We can make stuff really hard, but there's no way to tell if we've made it hard <i>enough</i>.<br /><br />Re: force and prismatic walls: the rules are self-contradictory on this. At various points force walls are called out as immobile, then at other points there are instructions on how to build them into mobile fortresses. Ultimately I concluded that the most plausible explanation is that they are immobile relative to whatever they're adjacent to, so if we have a rigid framework of some material, then we can anchor the force walls to it. I initially planned for the combustion chamber to be made of force walls, to save weight, but ultimately concluded that the cost was prohibitive - all those permanency spells!<br /><br />But the idea of using yellow-indigo prismatic walls as a one-way membrane, to let the water through but keep the exhaust gas from leaking back, that had not occurred to me, and that's a <i>very</i> good idea. I need to do some math to determine how the costs break down - an animated mithral pump may ultimately be more cost-effective, even if it means a lower chamber pressure - but that's a <i>very</i> good idea.<br /><br />Thank you for your help!Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-47349013228050854782016-11-15T13:23:09.294-08:002016-11-15T13:23:09.294-08:00In terms of pressure and heat, let's see what ...In terms of pressure and heat, let's see what we're looking at in terms of hardness requirements. Since we can make the decanters out of adamantine, if we're over hardness to start with, then we can do magically reinforcing nonsense. I haven't seen any obvious ways to make things one-way, though "skate" (psi1) does impressively reduce friction. Otherwise, (as is the case in reality) it may be time to accept that the chamber pressure is too high due to engineering constraints. <br /><br />Have you found any useful citations for anchoring walls of force or prismatic walls to a ship? For a prismatic wall, it differentiates between gasses and "everything else" If you can figure out how to anchor one to a moving vehicle, then destroy all colours except yellow and indigo, you get a "gas-proof" wall. That blocks the flame and the super-hot steam.Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-36596447840031742282016-11-15T12:13:09.038-08:002016-11-15T12:13:09.038-08:00I've been using an Artificer (main character&#...I've been using an Artificer (main character's cohort) as Chief Project Engineer.<br /><br />I'm going to do some asking around on pumping systems. Between our absurdly high Knowledge (Architecture & Engineering) skill check, D&D super materials, and fabricate spells, we ought to be able to make a pumping system at least as good as what they use in the real world today. If we can physically isolate the decanters from the combustion chamber, that makes everything so much easier; in particular, it lets us use animated objects to control the decanters, rather than antimagic fields. But we're also assuming that the combustion chamber reaches asymptotically high pressure, and I'm not sure if we can actually pump water into that, or how much performance we lose if we limit the chamber pressure to something we can pump into.Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-68922085998610154412016-11-15T12:02:59.068-08:002016-11-15T12:02:59.068-08:00(Sorry, just waking up here, it's 7am) In term...(Sorry, just waking up here, it's 7am) In terms of levels and items and whatnot, it may be wroth going down the artificer or warlock routes, especially considering the artificer gets such wonderful bonuses. (http://alcyius.com/dndtools/classes/artificer/index.html (of especial note is the "item creation" line: "For purposes of meeting item prerequisites, an artificer's effective caster level equals his artificer level +2.") Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-82950944071134722442016-11-15T11:43:07.543-08:002016-11-15T11:43:07.543-08:00On use-activated items: Thanks, I should have thou...On use-activated items: Thanks, I should have thought of that. That's definitely got potential, but I need to think about how to make this work. We're way into DM interpretation territory here - well, we really always have been - but I would personally rule that, for a use-activated item, we would still need to do something to the item to turn it on and off. That could be something as simple as screwing a lid onto the decanters, but we would still need to do something. Unfortunately, the existing methods of keeping the system from blowing apart won't apply to animated objects and other creatures. Fortunately, we could probably arrange some kind of trap door arrangement. Let me cogitate for a bit on the details of this, but I think it will work, and it should at least be cleaner than mucking about with antimagic fields.<br /><br />On erudites: Yeah, StP erudite probably is the optimal way to go, but I really don't like them. <br /><br />On blowback: I can put together a decent estimate of the damage from fire, but not the damage from pressure, since there's no modeling basis for it I can find. In theory, it should be possible to isolate the decanters from the combustion chamber - it's essentially the same as how, in real life, the exhaust flame doesn't back up into the fuel tank. In D&D, though, I don't know of any way to model this. Maybe pumps powered by animated objects? That might work.<br /><br />On Wall of Flame: I did cost using wall of flame as part of a steam rocket. Using the current assumptions for how blast of flame works, the blast approach outperforms any of the steam rocket approaches. However, that's dependent on a number of assumptions about what blast of flame actually does.Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-53761721883113731642016-11-15T11:32:08.081-08:002016-11-15T11:32:08.081-08:00It's here: http://www.d20srd.org/srd/magicItem...It's here: http://www.d20srd.org/srd/magicItems/creatingMagicItems.htm#tableEstimatingMagicItemGoldPieceValues <br /><br />Normally some rather broken stuff can be done with custom magic items, but since we're already into spell-trap territory that doesn't matter. <br /><br />This build actually sounds like it could be productively done by an erudite (with the variant in http://archive.wizards.com/default.asp?x=dnd/psm/20070629a (though that does beg the question of very high level spells.)<br /><br />With regards to blow-back, have you worked out how much damage the chamber is taking? And is there any piping/pressure arrangement which can have the water piped into the chamber?<br /><br />Also, as an aside (since the prior conversation was many years ago) have you costed using wall of flame (with permanency cast on it) as your energy source? (Perhaps with ejecting molten iron (wall of iron)? Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-38020279258498513882016-11-15T08:29:42.737-08:002016-11-15T08:29:42.737-08:00On ventriloquism and its cousins: the problem is t...On ventriloquism and its cousins: the problem is that the decanters are going to be in vacuum much of the time. They're built into the vehicle structure, so theoretically if you shout loud enough they could hear, but I don't see any way to model that in the rules, and I suspect you'd end up blowing out your own eardrums if you managed to yell that loud.<br /><br />On damage: I did consider fyrite, not just for the decanters but also to build the combustion chamber itself out of. But heat isn't the only problem: we also need to worry about the pressure in the combustion chamber, which - since it's an ideal chamber with asymptotically high pressure - is going to be <i>absurdly</i> high. Unfortunately, there's no way I can find to put numbers on that, since D&D - for some reason - doesn't have any rules on pressure damage that I can find.<br /><br />On quintessence: That's an interesting idea. I don't think we can use it to protect the decanters, because there always needs to be a path from the decanters to the combustion chamber when they're in operation, and the exhaust gas could flow back along the path. I do wonder, though, if there might be a way to submerge the decanters in quintessence when not in use, as a throttling mechanism... But that does require a Shaper-7, to make the stuff in bulk. Would need to restat our astronaut to make this work - which I'm not necessarily averse to doing; in the original draft of this, way back when, the astronaut was a named character, Mazin the Maker, and he was a shaper, not a wizard. Let me think about this...<br /><br />On command thoughts: that's also very interesting; I wasn't aware that psionic items used command thoughts instead of command words. I'm not sure we can use it here, but it's something worth knowing, so thank you. I think the argument that a command thought should be able to control the decanters from the cockpit is stronger than the argument that a command word should be able to, but, of course, the SRD doesn't give us any real sense of the <i>range</i> of these things... I dunno, if I was DMing, I would rule that you have to be holding an item for a command thought to work, but that's a very questionable ruling. I'll consult the RAW questions thread at giantitp.com and see if anyone knows.<br /><br />On the portable hole: there are three problems I see here: first, the hole is only 10' deep, and our blast of flame is 60' long. The thrust/cost ratio of these spells drops precipitously as the volume of the combustion chamber declines. Second, you still need to use lyres of building to protect your decanters and spell traps even if they're inside the hole. And third, now you need to worry about control systems that can cross planar boundaries (a lot of divination effects explicitly call out that they can't do that). In particular, I would be very hesitant to say that you could have a spell trap where the trigger is on one side of the hole and the spell is on the other.<br /><br />I just don't think it's worth it, unless we can find a variant portable hole with a bigger volume. The only real advantage - aside from the fact that it would look cooler - is that it would save us the cost of the combustion chamber, about 30,000 gp.<br /><br />Final note: is there an actual listed price somewhere for upgrading a magic item to use-activated? That would make a lot of things much easier.Markhttps://www.blogger.com/profile/12523189413175446117noreply@blogger.comtag:blogger.com,1999:blog-8062651468331172034.post-89141897103774418182016-11-14T23:53:46.190-08:002016-11-14T23:53:46.190-08:00Some notes in no particular order.
For control of...Some notes in no particular order.<br /><br />For control of the decanters, I suspect Ventriloquism (Sor/Wis 1) is better suited. Or pipes. Having the decanters in the cockpit, or surrounded by an Amplify (Bard 1, Magic of Faerun (ew)) effect could be useful. Stormvoice (Champions of Valor (seriously?)) can also be a useful sound control thingo. Or Control Sound (Psi 2) Command words are poorly defined. As a (fairly) bad idea, making them intelligent items with the 10 ranks in listen is not the worst idea ever (but it's quite bad).<br /><br />Do we have a formal amount of damage that the flasks would need to withstand? If you make them (and the combustion chamber) out of "Fyrite (Dragon 347 p49) which is completely immune to heat and is costed at 50gp/lb"<br /><br />If the whole chamber is made out of Fyrite (which does not have a hardness) or adamantium, or has the hardening spell applied (depending on damage), or use a *remarkable* amount of quintessence to isolate the heating chamber from time because physics is cute? <br /><br />A portable hole is 20kGP, a lyre is 13kgp. Since, when spread on a surface, it doesn't exist, the whole "exhaust gasses are hot" problem isn't a problem (Or line the exhaust port with something approprirately durable -- though that makes controlling stuff inside the whole much harder. On the other hand, psionic items are command thought activated. Worst case, you can pay the extra to upgrade them to use-activated and have the "use" be some sort of mechanistic interaction with the environment that's environment-safe.<br />Brian Ballsun-Stantonhttps://www.blogger.com/profile/09506402044183009177noreply@blogger.com