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Post by Kerr on Sept 2, 2017 17:27:03 GMT
what the? What do you need so much electricity for? I don't. However, a fusion rocket is going to impart some of it's heat to the the ship no matter what you do with your magnetic nozzles. Alright. Status update on your ships? |
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Post by Kerr on Sept 2, 2017 18:41:39 GMT
ironclad6I've found 3 direct energy converters with an maximum projected efficiency of 90% 1. Periodic Electrostatic focusig Used for 400-800 kev DT Plasma 2. Travelling-wave DEC An gyrotron build to convert 14.7MeV Protons (D-He3) into electricity. Electrostatic DECs are unable to convert such high energy particles. 3. Inverse Cyclotron An direct upgrade from the traveling-wave DEC. It is much shorter and requires an 15x weaker magnetic field. Designed for D-He3 and p-B11 high energy particles.
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Post by matterbeam on Sept 2, 2017 21:07:11 GMT
Or just use kinetic energy. They should be more practical at 0.01c. Because their blast is directed, meaning nearly 100% go into the target instead of an omnidirectional explosion which has pn impact 50% coupling. 1kT vs. 1.37kT effective yield. And this is if you used an 1kg clump of pure zubrol compared to an 1kg Submunition which could have 100g MH and get 1750m/s Dv to track the target and to perform dodge burns. If your missile's going too fast the whole thing will blast through the enemy ship, leaving a hole, and some, if not most of the kinetic energy will still be on the missile. What do you mean by 'too fast'? |
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Post by Enderminion on Sept 2, 2017 21:07:52 GMT
If your missile's going too fast the whole thing will blast through the enemy ship, leaving a hole, and some, if not most of the kinetic energy will still be on the missile. At these velocities you need an crater excavation equation to find out the impact effect. For my 1kg submunitipn it is a crater 10m deep and 5000m3 in volume. For structural steel. IIRC I thought things going supersonic in the target material left thing shaped holes in the target, correct me if I'm wrong, please. also WTF has 10 METERS of STEEL armour? |
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Post by matterbeam on Sept 2, 2017 21:09:29 GMT
At these velocities you need an crater excavation equation to find out the impact effect. For my 1kg submunitipn it is a crater 10m deep and 5000m3 in volume. For structural steel. IIRC I thought things going supersonic in the target material left thing shaped holes in the target, correct me if I'm wrong, please. also WTF has 10 METERS of STEEL armour? This will put things into perspective: toughsf.blogspot.com/2016/08/space-warship-design-ii-guns-and-shields.html |
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Post by Kerr on Sept 2, 2017 21:18:18 GMT
If your missile's going too fast the whole thing will blast through the enemy ship, leaving a hole, and some, if not most of the kinetic energy will still be on the missile. What do you mean by 'too fast'? He thinks that at extreme velocities a projectile will just leave an hole the area of the projectiles cross section. |
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Post by Kerr on Sept 2, 2017 21:26:00 GMT
matterbeamWhat would be the radiator material with the highest MW/kg ratio? Or atleast a pretty good one.
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Post by Enderminion on Sept 2, 2017 22:02:15 GMT
reading through it, I got to the missile section, "missiles too small to mount nuclear engines" WTF all of my standard missiles save one REALLY tiny one use Nuclear Thermal Rockets, also Casaba Howitzers are mostly bomb, shot and casing, the Casing is a thin (less then 10cm) DU plate, the shot is a lump of something and the bomb is a small nuke. also nothing in the article related to C fractional impacts |
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Post by matterbeam on Sept 2, 2017 22:40:33 GMT
matterbeam What would be the radiator material with the highest MW/kg ratio? Or atleast a pretty good one. What we need is a radiator that has both the highest surface area per kg, and the highest operating temperature. For solid radiators, I know of the wire loop radiator. Wires have the highest possible surface area to mass ratio for continuous objects. You can throw carbon loops into space and maintain their shape through centripetal force, but I think a much saner version for maneuvering spacecraft is the rolling wire loop radiator which I 'invented' for my 'All the radiators' post. (couldn't find anything like it anywhere else). The wire runs between rollers that hold it up through tension and physical structures. Since then, I've realized that super-strong materials such as graphene allow for ultra-thin wires. Something like micrometer thickness wire will look like spider silk. They will be used as millions of parallel wires that will look like sheets of glowing silk going around the spaceship, as if it caught in a spider web. Here's a quick calculation: 4000K operating temperature graphene fibres twisted together to form a wire. 1 micrometer diameter wires allows for roughly 1.8 nanograms per meter length. We get 1739m^2/kg and an astounding power density of 25.24GW/kg. If we tone it down to 3000K, we still get 7.98GW/kg. The mass of the physical structure, heat exchanger and so on will cut into this figure. If you have sufficiently powerful magnetic fields, a dusty plasma radiator allows for extremely hot particles with even better power density. A pure plasma (no dust) radiator, extending like flares out of the spaceships, has practically infinite power density. |
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Post by The Astronomer on Sept 3, 2017 1:09:26 GMT
What do you mean by 'too fast'? He thinks that at extreme velocities a projectile will just leave an hole the area of the projectiles cross section. That pretty much sums up my idea. Yes, not exactly the area of the projectile's cross section, but probably closer and closer the faster the projectile goes. Which means balancing terminal v is important. |
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Post by ironclad6 on Sept 3, 2017 1:45:43 GMT
I don't. However, a fusion rocket is going to impart some of it's heat to the the ship no matter what you do with your magnetic nozzles. Alright. Status update on your ships? As if this morning I threw all my work out and started over. I am starting to think fusion ships just aren't plausible without hand waving too much stuff and making a litany of absurdly optimistic assumptions. |
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Post by ironclad6 on Sept 3, 2017 2:23:52 GMT
Do you guys think things like stranded wire radiators are really plausible?
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Post by The Astronomer on Sept 3, 2017 2:58:22 GMT
Do you guys think things like stranded wire radiators are really plausible? If the wire is strong enough, yes. I don't know about the details though. |
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Post by ironclad6 on Sept 3, 2017 3:03:01 GMT
Do you guys think things like stranded wire radiators are really plausible? If the wire is strong enough, yes. I don't know about the details though. Don't see any reason stranded graphene couldn't be used. I'll do some reading and work it out. While I am at it, if anyone else has any advice on modelling a magnetic confinement nozzle I am all ears. I should not have started serious design work until I had worked these things out. |
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Post by matterbeam on Sept 3, 2017 3:30:17 GMT
Alright. Status update on your ships? As if this morning I threw all my work out and started over. I am starting to think fusion ships just aren't plausible without hand waving too much stuff and making a litany of absurdly optimistic assumptions. I'm sad to hear this. My personal suggestion is that you stop focusing on selecting technologies and making them work, but by starting from the other end and trying to define the needs of your plot or setting. Make a list of requirements, going from strictest to most lenient. THEN try to find technologies which fit and iterate between adapting the requirements to the specificities of the technology, or finding reasons to reject a technology to avoid its unintended side-effects. |
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