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Post by The Astronomer on Oct 2, 2017 6:34:44 GMT
Why don't you recycle that poop back to food? Also, vacuum energy propulsion sounds weird as it seems. There are chances that the vacuum energy is crazy powerful or awfully weak. Choose one. One farm for food, one for biofuel. Not sure, but it may be a key factor into the vague workings of a warp core in Kemono. bye
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Post by Kerr on Oct 2, 2017 7:37:47 GMT
Yep. Or on large orbital colonies. Then stuffed into a docked ship's remass tanks by the ton. Or as I previously mentioned, have a hydrocarbon-rich algae that's able to thrive on astronaut poop onboard. Another solution could be the use of "vacuum energy" propulsion like in Clarke's novel Songs of Distant Earth. Although that sounds like it dips its toes a little too deeply into Killing Star territory. Why don't you recycle that poop back to food? Also, vacuum energy propulsion sounds weird as it seems. There are chances that the vacuum energy is crazy powerful or awfully weak. Choose one. I think he meant a Quantum vacuum thruster, aka Q-thrusters. A specific kind of Q-Thruster is the RF resonant cavity thruster, also known as the EM Drive.
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Post by Kerr on Oct 2, 2017 7:41:10 GMT
One farm for food, one for biofuel. Not sure, but it may be a key factor into the vague workings of a warp core in Kemono. bye Is a warp core so different from a Void bubble? Displacement, Halo, Void Drives, all sublight warp drives.
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Post by Kerr on Oct 2, 2017 7:45:09 GMT
You mean, biofuel production stations on planets? That doesn't help the ship at all. Zero efficiency improvement. Yep. Or on large orbital colonies. Then stuffed into a docked ship's remass tanks by the ton. Or as I previously mentioned, have a hydrocarbon-rich algae that's able to thrive on astronaut poop onboard. Another solution could be the use of "vacuum energy" propulsion like in Clarke's novel Songs of Distant Earth. Although that sounds like it dips its toes a little too deeply into Killing Star territory. Vacuum Energy is technobabble, there is something close to "vacuum energy" in real life, called virtual particles. But they pop into existence and annihilate shortly after, total Net Power is 0. Again the only solution is to use scoops to get fuel from the vacuum around you, interstellar space has a density of 1e-21kg/m³ Hydrogen. You can't escape with tyranny of the Rocket Equation.
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Post by The Astronomer on Oct 2, 2017 8:11:01 GMT
Is a warp core so different from a Void bubble? Displacement, Halo, Void Drives, all sublight warp drives. Orion's Arm Universe Project fuck yeah!!! Void bubble, displacement drive, halo drive, void drive. According to Wikipedia's article on Warp drive, a warp drive is a faster-than-light (FTL) spacecraft propulsion system in many science fiction works. If the definition of srbrant 's warp drive is the same as this, then, bye. However, if said 'warp drive' is actually a reactionless drive, we can have some talk. For me, the term 'warp drive' refers to FTL version of the reactionless drives, which is, well, not possible.
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Post by Kerr on Oct 2, 2017 8:19:23 GMT
Is a warp core so different from a Void bubble? Displacement, Halo, Void Drives, all sublight warp drives. Orion's Arm Universe Project fuck yeah!!! Void bubble, displacement drive, halo drive, void drive. According to Wikipedia's article on Warp drive, a warp drive is a faster-than-light (FTL) spacecraft propulsion system in many science fiction works. If the definition of srbrant 's warp drive is the same as this, then, bye. However, if said 'warp drive' is actually a reactionless drive, we can have some talk. For me, the term 'warp drive' refers to FTL version of the reactionless drives, which is, well, not possible. A warp drive just means it CAN achieve super-luminal speeds, because nothing can move faster inside spacetime than light, other than spacetime itself (Expanding Universe etc.). The Halo seems very wasteful to me while only having slightly better stats, but the G-Compensation seems nice.
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Post by shiolle on Oct 2, 2017 8:32:50 GMT
srbrant What kind of efficiency do you need for your story? Could you give us a few example missions, like "Earth to Mars in 5 days, fuel fraction below 2" or "Earth to Pluto in three months, fuel fraction is 1.3"? If you want to never worry about fuel at all, like in the Expanse, there is nothing that can help you short of including something like sub-light warp drive or some purely fictional device with the giant can of worms it opens. If you want some 100 km/s of delta-v with hundreds of mg of acceleration, there are many choices of different degrees of viability, like others mentioned. You can't escape with tyranny of the Rocket Equation. Technically you can, but you have to be really careful about that. While I applaud srbrant 's dedication to getting the physics right, 99.9% of his readers won't appreciate clever propulsion ideas in and off themselves. They are only relevant in the context of what kind of world they allow you to build. If Arthur Clark needed a reactionless (still sublight) drive for his Rama stories to work, so be it. The problem is many authors and readers are so subscribed to the cozy standard space opera universe they want to get it no matter what laws of physics they need to bend in the process. That's the canon they are familiar with, they know which stories can work there and they have a few favorite twists of their own they want to add. And they need not do any tiring research of their own since it was done before them during fifties and sixties. Heinlein said he and his wife had to do two weeks of research that went into a single line of text in the book. Many of their followers did nothing like that, but since space opera setting became so convincing, it needs not adhere to reality any longer. As science and space opera conventions diverged, the genre started to mix with fantasy more and more. А story will work (i.e. captivate the reader) whether your plot devices are well grounded in science or not. When I played Mass Effect so much technology there sounded like pure magic (even more so in Andromeda), and so many themes of classic fantasy were integrated into SF, you can barely make the two genres apart anymore. Expanse, for example is riddled with artistic license in physics and biology. Later books added FTL into the mix too, but at the same time it updated many other elements (no artificial gravity at first, some more realistic weapons) to modern day standards and lo and behold, it is praised as hard science fiction. I'm writing all of this to say: do not try to select the laws of physics to fit your imagined world. If you have a picture of the world you want, it is too late to justify any of the technology required for it. Instead look at all those ideas for plausible future technologies and try to imagine what kind of world they would enable.
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Post by srbrant on Oct 2, 2017 16:31:32 GMT
srbrant What kind of efficiency do you need for your story? Could you give us a few example missions, like "Earth to Mars in 5 days, fuel fraction below 2" or "Earth to Pluto in three months, fuel fraction is 1.3"? If you want to never worry about fuel at all, like in the Expanse, there is nothing that can help you short of including something like sub-light warp drive or some purely fictional device with the giant can of worms it opens. If you want some 100 km/s of delta-v with hundreds of mg of acceleration, there are many choices of different degrees of viability, like others mentioned. You can't escape with tyranny of the Rocket Equation. Technically you can, but you have to be really careful about that. While I applaud srbrant 's dedication to getting the physics right, 99.9% of his readers won't appreciate clever propulsion ideas in and off themselves. They are only relevant in the context of what kind of world they allow you to build. If Arthur Clark needed a reactionless (still sublight) drive for his Rama stories to work, so be it. The problem is many authors and readers are so subscribed to the cozy standard space opera universe they want to get it no matter what laws of physics they need to bend in the process. That's the canon they are familiar with, they know which stories can work there and they have a few favorite twists of their own they want to add. And they need not do any tiring research of their own since it was done before them during fifties and sixties. Heinlein said he and his wife had to do two weeks of research that went into a single line of text in the book. Many of their followers did nothing like that, but since space opera setting became so convincing, it needs not adhere to reality any longer. As science and space opera conventions diverged, the genre started to mix with fantasy more and more. А story will work (i.e. captivate the reader) whether your plot devices are well grounded in science or not. When I played Mass Effect so much technology there sounded like pure magic (even more so in Andromeda), and so many themes of classic fantasy were integrated into SF, you can barely make the two genres apart anymore. Expanse, for example is riddled with artistic license in physics and biology. Later books added FTL into the mix too, but at the same time it updated many other elements (no artificial gravity at first, some more realistic weapons) to modern day standards and lo and behold, it is praised as hard science fiction. I'm writing all of this to say: do not try to select the laws of physics to fit your imagined world. If you have a picture of the world you want, it is too late to justify any of the technology required for it. Instead look at all those ideas for plausible future technologies and try to imagine what kind of world they would enable. (Sincerest applause) I like your style.
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Post by srbrant on Oct 2, 2017 19:21:23 GMT
srbrant What kind of efficiency do you need for your story? Could you give us a few example missions, like "Earth to Mars in 5 days, fuel fraction below 2" or "Earth to Pluto in three months, fuel fraction is 1.3"? If you want to never worry about fuel at all, like in the Expanse, there is nothing that can help you short of including something like sub-light warp drive or some purely fictional device with the giant can of worms it opens. If you want some 100 km/s of delta-v with hundreds of mg of acceleration, there are many choices of different degrees of viability, like others mentioned. You can't escape with tyranny of the Rocket Equation. Technically you can, but you have to be really careful about that. While I applaud srbrant 's dedication to getting the physics right, 99.9% of his readers won't appreciate clever propulsion ideas in and off themselves. They are only relevant in the context of what kind of world they allow you to build. If Arthur Clark needed a reactionless (still sublight) drive for his Rama stories to work, so be it. The problem is many authors and readers are so subscribed to the cozy standard space opera universe they want to get it no matter what laws of physics they need to bend in the process. That's the canon they are familiar with, they know which stories can work there and they have a few favorite twists of their own they want to add. And they need not do any tiring research of their own since it was done before them during fifties and sixties. Heinlein said he and his wife had to do two weeks of research that went into a single line of text in the book. Many of their followers did nothing like that, but since space opera setting became so convincing, it needs not adhere to reality any longer. As science and space opera conventions diverged, the genre started to mix with fantasy more and more. А story will work (i.e. captivate the reader) whether your plot devices are well grounded in science or not. When I played Mass Effect so much technology there sounded like pure magic (even more so in Andromeda), and so many themes of classic fantasy were integrated into SF, you can barely make the two genres apart anymore. Expanse, for example is riddled with artistic license in physics and biology. Later books added FTL into the mix too, but at the same time it updated many other elements (no artificial gravity at first, some more realistic weapons) to modern day standards and lo and behold, it is praised as hard science fiction. I'm writing all of this to say: do not try to select the laws of physics to fit your imagined world. If you have a picture of the world you want, it is too late to justify any of the technology required for it. Instead look at all those ideas for plausible future technologies and try to imagine what kind of world they would enable. That's what I'm doing, actually: choosing different technologies to be used and understanding their implications while keeping physics relatively unharmed. Many races are wary of nanorobotics to varying degrees due to the events of the Technocaust and the absolute havoc they wrought during that dark time. Reactionless drives are possible, but they are _very_ illegal and firing one up is the moral and political equivalent of launching an ICBM. As for travel efficiency it's more like "burn to Lagrange point, wait several days, reach Lagrange point, activate warp drive, wait a few days, then get spat out at the Lagrange point of your final destination." Each core and drive is designed so that the amount of travel time that passes is the same as the amount of time passed in normal space. As for what things will look like during transit... The trick, to me at least, is to show the kind of possibilities that ACTUAL astrodynamics provide as opposed to the _Star Wars_ school of space combat and physics. Not showing people what can't happen, but what CAN happen.
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Post by overloaderdave on Oct 2, 2017 20:18:26 GMT
ok so seriously, just look at something which releases huge energy which is not antimatter (seriously don't do it) OR make up something which can be used for such or to enable such to be easy similar to how SPAZ's universe does it (rez) that is in some location we can't easily access currently (planet cores & other areas of extreme pressure) alternatively just have them go dyson swarm -> laser network -> beaming power to ships with gigantic sets of lenses since lasersails can be scaled basically forever. That combined with an unobtainium or just having them use bigger sails for more range could give you your dV you want
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Post by thorneel on Oct 2, 2017 22:49:19 GMT
I would still avoid reactionless drives completely if I were you. You only need one lone crazy getting their hands on a reactionless drive and bye Earth. However iron-fisted your government is, one day or another, it will happen. Unless you want The Martian-level hardness, you can settle for The Expanse-level hardness (which is both very successful and liked by most hard-SF fans, mind you) with their "runs on efficiency" Epstein drive. Basically, the Epstein drive is an absurdly efficient but not-quite-physically-impossible black box fusion drive with both extremely high exhaust velocity and thrust. As such, it gives continuous multi-g thrust for interplanetary travels and ships don't even need to be 95% propellant. Note that at short range, the exhaust has the same effect as a continuous nuclear explosion, which is why they don't use it near planets, stations, rocks and ships they like. They keep it in mind, that can even be useful in a pinch. Space being vast and exhaust widening very fast, it is generally not a problem in most circumstances, though. If you want to go slightly harder, stick giant cerise-red radiators and big tanks that make half the volume of the ship, that should do the trick. If you want cool-looking engines, make them giant bird cages made of inward-facing sharp blades (so they deflect most neutrons) and giant spikes for radiators (to keep the magnetic field-generating mesh cool enough so superconductors keep working) - see Attack Vector:Tactical for good illustrations: (To nitpick, the radiator spikes shouldn't be aligned, it is slightly more efficient to have them shifted out of alignment instead, in order to minimize their inter-reflection) In AV:T, those ships also have classical flat radiators, but retract them for combat, relying on heat-sinks. You may or may not want to do the same, depending on the details of the story you want to tell.
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Post by Kerr on Oct 2, 2017 23:47:14 GMT
One of the best ways to travel inside a planetary system at decent speeds with realistic tech requirements would be an Fusion Pellet Drive. This system has good Isp ranging from 60,000s to 200,000s (can be higher or lower depending on the design), good Thrust, and it is relatively compact. An 10TW Deuterium Pellet Drive providing 35MN thrust at 570km/s is only 3-4m in diameter. Any high-Z element can be used as remass (pellet shells). Pretty much an Fusion Orion.
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Post by shiolle on Oct 3, 2017 12:59:33 GMT
Reactionless drives are possible, but they are _very_ illegal and firing one up is the moral and political equivalent of launching an ICBM. I assume this reactionless drive is going to be used in the story or there is no point in having it at all. If you use it as a weapon, so that an individual or a small group can threaten a planet, a freighter, fully loaded with fuel instead of cargo, can probably achieve the same goal from the story perspective if it has a few hundred km/s of delta-v. If you need it for one-of-a-kind ship that heroes will use to cut on travel times, then perhaps think again whether you really need it. As for travel efficiency it's more like "burn to Lagrange point, wait several days, reach Lagrange point, activate warp drive, wait a few days, then get spat out at the Lagrange point of your final destination." Each core and drive is designed so that the amount of travel time that passes is the same as the amount of time passed in normal space. As for what things will look like during transit... I like the Lagrange point idea, however there are interesting considerations: - Can you jump directly to, say, Moon L1 from Alpha Centauri?
- What happens to conservation of momentum when you jump between solar systems? Nearby stars are usually moving at 20 - 100 km/s relative to each other. Theoretically for most types of jump-like FTL this velocity shouldn't magically cancel out (conservation of momentum).
If you can do the former and momentum is conserved, you can use this speed to your advantage. Just select your destination so that your velocity after the jump points into the general direction of your target. That means there are certain windows of opportunity where you can gain the most advantage out of your relative speed. That also means all interstellar ships in this universe need to have at least a few dozen km/s of delta-v to be of any use. That also means that certain systems, like Barnard's star would be harder to get to even if they are closer to home. Still, could you please clarify how efficient you want your drives to be? see Attack Vector:Tactical for good illustrations Ah, Attack Vector! I love this game. Ken Burnside (the author) has cleverly selected his (mostly very plausible) technologies for tactical maneuvers to matter. When you understand the rules, it is a really fun game to play. Unfortunately, I am one of the two people who has the game in my entire country, and convincing people to actually try to learn the rules proved difficult: too little interest in the theme of the game for a 150 page rulebook. More to the topic, as I said the technology is carefully selected to make tactical maneuvers matter, but I am still not convinced that is the most probable situation. It requires a fusion drive that is 90+% efficient, so that the radiators that cool that magnetic nozzle in thorneel 's picture are small enough. You see, in AV:T weapons and other systems are powered by fission reactors, and their radiators retract in combat. Heatsinks are used to store the heat produced by the reactors while the ship is 'buttoned up'. The drive is cooled by spikes or blades you see on the magnetic nozzle, and these are not retractable, but operate at much higher temperature and loosing a few of them to enemy fire isn't a problem. Even more useful to you may be another detail: the drive supports two modes, like VASMIR: a combat mode with much higher thrust and an economy mode that has a much lower thrust much higher specific impulse. Thanks to that, a ship may have around 120 km/s delta-v for maneuvers, but only around 14 km/s in combat. Thrust power is in 1-4 TW range in combat and an order of magnitude lower in cruise mode.
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elukka
Junior Member
Posts: 73
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Post by elukka on Oct 3, 2017 23:21:16 GMT
If you want to go slightly harder, stick giant cerise-red radiators and big tanks that make half the volume of the ship, that should do the trick. If you want cool-looking engines, make them giant bird cages made of inward-facing sharp blades (so they deflect most neutrons) and giant spikes for radiators (to keep the magnetic field-generating mesh cool enough so superconductors keep working) - see Attack Vector:Tactical for good illustrations: (To nitpick, the radiator spikes shouldn't be aligned, it is slightly more efficient to have them shifted out of alignment instead, in order to minimize their inter-reflection) I noticed from one of the schematic pictures that the spikes are aligned with and set directly behind the beam guns that confine the fusion reaction. I imagine the point is to have them behind whatever shielding the guns have to survive the drive's flame so the spikes don't need separate shielding.
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Post by srbrant on Oct 4, 2017 5:21:07 GMT
"I like the Lagrange point idea, however there are interesting considerations: Can you jump directly to, say, Moon L1 from Alpha Centauri? What happens to conservation of momentum when you jump between solar systems? Nearby stars are usually moving at 20 - 100 km/s relative to each other. Theoretically for most types of jump-like FTL this velocity shouldn't magically cancel out (conservation of momentum).
If you can do the former and momentum is conserved, you can use this speed to your advantage. Just select your destination so that your velocity after the jump points into the general direction of your target. That means there are certain windows of opportunity where you can gain the most advantage out of your relative speed. That also means all interstellar ships in this universe need to have at least a few dozen km/s of delta-v to be of any use. That also means that certain systems, like Barnard's star would be harder to get to even if they are closer to home.
Still, could you please clarify how efficient you want your drives to be?"
Yep. Jump from L1 to Alpha Centauri with a travel time of two or three days. Not sure about the momentum thing. The ship might not be "shot out" of "hyperspace" due to the drive folding space around it. As for efficiency, I'm looking for a ship that can get some decent (14.5?) Delta-V with only 50 or even 20 percent of its mass being reaction mass. Ridiculous, I know...
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