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Post by namewithheld on Aug 26, 2018 22:16:46 GMT
Timid hello! I've lurked on this forum since the game came out, utterly terrified of saying anything due to my complete lack of any actual expertise. I managed to beat the campaign, even if that fucking polar orbit intercept mission took me getting my parents (who both are literal rocket scientists with actual PHDs) to come over and help.
But while I love hard science, I also love tabletop RPGs. And one day, after reading Diaspora (a hard SF game that uses the Fate system) and the D&D 5th edition handbook in the same afternoon, a thought struck me.
"What if I was on a rocket...and I had a wand of create water?"
Create Water is a spell in D&D that creates, out of literal nothingness, 10 gallons of water. So, I started doing math using Atomic rocket. And before you know it, I've started creating a setting with two rules in mind: Hard science, hard magic. Hard science is clear enough, but hard magic means "if it cannot be cast by a player character, using the rules as written, it doesn't exist." In a lot of D&D settings, they have magic that breaks the rules that player characters get to use, and I wanted to give myself a similar constraint with magic as you have with technology...if only because if you could just make up any old magical hoozit then I could just say, "Well, someone builds a magical brick that uses magic to fly magically."
And where's the fun in that?
So, I've come to ask a question: What would the capacity to regenerate reaction mass en route do to spaceships? Basically, I figure that all or most rockets would be nuclear thermal, because it's simple enough to boil and accelerate water out of the back of a ship. I did a bit of math with the idea of using electrolysis to split water into oxygen and hydrogen, but you'd end up with a bunch of oxygen and hydrogen and that's potentially explosive and it takes an obscene amount of electricity. Even with a nuclear reactor! Meanwhile, 100 wands of Create Water can makes roughly 4 tons. And each wand has 7 charges and recharges 1d6+1 (so, 2-7) charges per day. So, a single Wand of Water Creation Unit (WOWC Unit for short) can make 4 tons per charge per day. Since 100 wands, even if you assume they're in a housing to make them easily used (since magic items need to be physically touched and then activated with an activation word), isn't that heavy, you can have multiple WOWC-Units.
That'd mean that you'd no longer need to have 80% of the ship be propellant and reaction mass, right?
Are there any things that I'm not thinking about in this equation?
And if anyone knows D&D as much as they know about spaceships, I'd love to hear any suggestions!
I already know that, thanks to the ease of industrially manufacturing gemstones, casting the Clone spell would be a lot easier. Meaning that astros and adventurers could get Clone insurance (for those who haven't played D&D, clone creates a copy of your body, which your soul inhabits when you die. Which does mean that I can make ship combat nice and lethal and not worry about TPKs!)
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Post by apophys on Aug 27, 2018 2:38:56 GMT
Welcome! I'm not knowledgeable in D&D, though there should be people here who are. What would the capacity to regenerate reaction mass en route do to spaceships? Being able to refuel continuously would make exhaust velocity much less of a concern, so yes, I'd expect thermal rockets to be the norm. Nuclear thermal would compete with solar thermal, and possibly with some magic that you can use for creation of heat (fire? lightning?). You'd be able to do brachistochrone transfers at a high average acceleration, making travel to the outer system very easy, and making interstellar travel much simpler. Needless to say, the violation of mass-energy conservation would change a lot of aspects of civilization back on Earth.
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Post by The Astronomer on Aug 27, 2018 4:38:01 GMT
Unlimited mass also means unlimited energy. The future is bright!
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Post by namewithheld on Aug 27, 2018 5:53:02 GMT
Whee! Though, there is not actually un*limited* mass, since there's a choke point in production: You need a cleric to produce the suckers, and the materials to make the wands.
And clerics requires legitimate belief in the gods of the setting - you can't just send someone to cleric school. Which I suppose gives a bit of an edge to theocracies...
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Post by The Astronomer on Aug 27, 2018 5:58:24 GMT
Cleric is the choke point yes, but still potentially unlimited. Broken wands, if they do break, can be recycled.
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Post by coaxjack on Aug 27, 2018 6:06:06 GMT
You end up with Mutually Assured Cleric Destruction, where you can send your arsenal of cleric-powered relativistic suicide missiles at the enemy, which they will detect and fire their own relativistic cleric missiles (RCMs). Or have a cleric summon trillions of tons of water into a sub-Schwarzschild point mass to make a black hole while on a spy mission aboard an enemy space station.
What I'm saying is that the ability to summon matter from nothing, the people with the ability, and the tools to do so will be extremely tightly regulated.
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Post by shiolle on Aug 27, 2018 6:17:20 GMT
I... wasn't expecting this. Regardless, I did some calculations just for fun. Let's take a spaceship with 1000 tons dry mass that can accelerate at 1g when full with "fuel" and 10 km/s of delta-v. Ve is 3.67 km/s, since you mentioned using NTRs. That is an average exhaust velocity of stock water NTRs in the game. The thrust is about 10 MN and thrust power is 18.67 GW. Mass flow of water through the engine is 2.773 tons per second. That is a bit over 16 wands per second emptied, so the ship should still contain some form of tanks where the amount of water for the next maneuver is contained. Those temporary tanks are assumed to be part of the dry mass for simplicity; it should not affect calculations that much. That means that 10 km/s of delta-v requires only 38 tons of wands. You can copy the spreadsheet I made for this from here and play with the numbers if you want. Orange fields are for input, grey for non-magical calculated values and violet are for wand-related stuff. P.S. I can't believe I actually made a spreadsheet for hard magic spaceships!
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Post by gedzilla on Aug 27, 2018 6:29:59 GMT
Timid hello! I've lurked on this forum since the game came out, utterly terrified of saying anything due to my complete lack of any actual expertise. I managed to beat the campaign, even if that fucking polar orbit intercept mission took me getting my parents (who both are literal rocket scientists with actual PHDs) to come over and help. But while I love hard science, I also love tabletop RPGs. And one day, after reading Diaspora (a hard SF game that uses the Fate system) and the D&D 5th edition handbook in the same afternoon, a thought struck me. "What if I was on a rocket...and I had a wand of create water?" Create Water is a spell in D&D that creates, out of literal nothingness, 10 gallons of water. So, I started doing math using Atomic rocket. And before you know it, I've started creating a setting with two rules in mind: Hard science, hard magic. Hard science is clear enough, but hard magic means "if it cannot be cast by a player character, using the rules as written, it doesn't exist." In a lot of D&D settings, they have magic that breaks the rules that player characters get to use, and I wanted to give myself a similar constraint with magic as you have with technology...if only because if you could just make up any old magical hoozit then I could just say, "Well, someone builds a magical brick that uses magic to fly magically." And where's the fun in that? So, I've come to ask a question: What would the capacity to regenerate reaction mass en route do to spaceships? Basically, I figure that all or most rockets would be nuclear thermal, because it's simple enough to boil and accelerate water out of the back of a ship. I did a bit of math with the idea of using electrolysis to split water into oxygen and hydrogen, but you'd end up with a bunch of oxygen and hydrogen and that's potentially explosive and it takes an obscene amount of electricity. Even with a nuclear reactor! Meanwhile, 100 wands of Create Water can makes roughly 4 tons. And each wand has 7 charges and recharges 1d6+1 (so, 2-7) charges per day. So, a single Wand of Water Creation Unit (WOWC Unit for short) can make 4 tons per charge per day. Since 100 wands, even if you assume they're in a housing to make them easily used (since magic items need to be physically touched and then activated with an activation word), isn't that heavy, you can have multiple WOWC-Units. That'd mean that you'd no longer need to have 80% of the ship be propellant and reaction mass, right? Are there any things that I'm not thinking about in this equation? And if anyone knows D&D as much as they know about spaceships, I'd love to hear any suggestions! I already know that, thanks to the ease of industrially manufacturing gemstones, casting the Clone spell would be a lot easier. Meaning that astros and adventurers could get Clone insurance (for those who haven't played D&D, clone creates a copy of your body, which your soul inhabits when you die. Which does mean that I can make ship combat nice and lethal and not worry about TPKs!) Just out of curiosity, what did your rocket scienctist parents think about CoaDE ?
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Post by treptoplax on Aug 27, 2018 12:26:41 GMT
For further fun, consider that this allows both (manned!) Planet-cracking relativistic missiles, and free energy / perpetual motion machines.
The key in both cases is that the newly created mass is presumably at rest with respect to its creator, which could give it considerable kinetic energy with respect to a reference frame in which the creator is moving. Launch a ship, create water on board, and catch it in a giant coilgun generating more energy than it took to launch it!
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Post by treptoplax on Aug 27, 2018 14:32:18 GMT
Also, probably no need for radiators. I haven't done the math, but I expect you could just generate and boil water, then vent the steam.
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ghgh
Full Member
Still trying to make kinetics work.
Posts: 136
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Post by ghgh on Aug 27, 2018 16:51:10 GMT
Also, probably no need for radiators. I haven't done the math, but I expect you could just generate and boil water, then vent the steam. This thread makes my head hurt. Wouldn't it depend on the temperature of the water? The steam would also be an issue especially coming off the reactor. We're not talking about steam from a tea kettle. We're talking about 2500K (assuming apophys style reactor) steam/plasma rapidly disassociating into hydrogen and oxygen which would damage the exhaust vent (pure oxygen does not play well with metal) and propel the ship in directions not intended.
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Post by AtomHeartDragon on Aug 27, 2018 18:34:54 GMT
Also, probably no need for radiators. I haven't done the math, but I expect you could just generate and boil water, then vent the steam. This thread makes my head hurt. Wouldn't it depend on the temperature of the water? The steam would also be an issue especially coming off the reactor. We're not talking about steam from a tea kettle. We're talking about 2500K (assuming apophys style reactor) steam/plasma rapidly disassociating into hydrogen and oxygen which would damage the exhaust vent (pure oxygen does not play well with metal) and propel the ship in directions not intended. With unlimited water there is no need for closed cooling system. All the reactors become continuously burning, water based NTRs. When you don't want to produce net thrust, you simply thrust in opposite directions.
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Post by Kerr on Aug 27, 2018 20:52:11 GMT
Unlimited water? Use it to terraform mars while also turning a wheel for power, power interstellar missions with that amount of energy or something on that order of magnitude. You've now entered the magic of mega(infra)structures.
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Post by thorneel on Aug 27, 2018 22:13:09 GMT
If reaction mass basically stops to be a problem, can you make a wand of create mercury instead? If you're going for thrust only, mercury is the best room-temperature liquid propellant around, being the heaviest (we'll be better ignoring radon) - the downside being of course that it has a pitiful Isp, and its rarity, the very two things we don't care about anymore. (Fun fact: that's why the very first MPD I made with the game was using mercury as propellant for that reason. (And the third one used radon, because why not.)
And then, if your wands produce water or mercury based on volume instead of mass...
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Post by newageofpower on Aug 28, 2018 0:58:48 GMT
Congratulations, you just solved the heat death of the universe. The cost is we transition to a dystopian society where we breed vast legions of Wandcrafters & Clerics, selecting for traits that make one conducive to becoming a cleric or wandcrafter
Quadrillion-Quadrillion-Quadrillion-Quadrillion humans inhabit a vast Birch World orbiting a supermassive black hole, as Seed-class AIs continuously optimize mankind for Faith and Wandcraft, continuously magicking entire solar systems worth of mass in water and feeding the conjured substances into optimized Kugelblitz singularities to generate exponentially increasing power, using the power output to fuel vast transmutation machines for the sake of increasing the infrastructure and supportable population size (and thus conjuration rate).
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