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Post by treptoplax on Sept 4, 2017 13:12:36 GMT
Ran across this on G+, thought might be of interest. plus.google.com/+IanMallett/posts/Qrq5xg9ztMjGood discussion of droplet radiators and a link to a calculator. One of the interesting things he found was that most of a droplets' heat is lost in the first millisecond; short flight times are optimal.
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Post by Kerr on Sept 4, 2017 13:19:11 GMT
If the most heat really is radiated in the first few milliseconds, then liquid droplet radiators could be useable spacecraft with acceleration measured in earth gravities of acceleration.
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Post by treptoplax on Sept 4, 2017 14:49:43 GMT
Yeah, it looks like a really good droplet radiator would have similar performance to the physically dubious solid panel radiators we have now. Could be a lot more damage-resistant, too, so maybe we can't depend on an upcoming radiator nerf to overthrow the laserstar meta
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Post by Kerr on Sept 4, 2017 14:57:00 GMT
Yeah, it looks like a really good droplet radiator would have similar performance to the physically dubious solid panel radiators we have now. Could be a lot more damage-resistant, too, so maybe we can't depend on an upcoming radiator nerf to overthrow the laserstar meta They are already "superior", they can be up to 7x lighter than solid panel radiators. The only thing I can imagine being better than a droplet radiator would be a nanowire radiator.
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Post by princesskibble on Sept 4, 2017 15:58:29 GMT
Yeah, it looks like a really good droplet radiator would have similar performance to the physically dubious solid panel radiators we have now. Could be a lot more damage-resistant, too, so maybe we can't depend on an upcoming radiator nerf to overthrow the laserstar meta isn't the laserstar meta already overthrown? Anyway to get short droplet flight times in order to increase acceleration tolerance you need a smaller sheet area. Decreasing the droplet sheet area doesn't decrease the mass of the generator or collector so the system is going to be much more massive, because you need more radiators to make up for less individual area.
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Post by matterbeam on Sept 4, 2017 16:57:26 GMT
Yeah, it looks like a really good droplet radiator would have similar performance to the physically dubious solid panel radiators we have now. Could be a lot more damage-resistant, too, so maybe we can't depend on an upcoming radiator nerf to overthrow the laserstar meta isn't the laserstar meta already overthrown? Anyway to get short droplet flight times in order to increase acceleration tolerance you need a smaller sheet area. Decreasing the droplet sheet area doesn't decrease the mass of the generator or collector so the system is going to be much more massive, because you need more radiators to make up for less individual area. You can make the radiators extend very far yet remain very thin to keep the same total area but shorten droplet flight time. Very narrow radiators and short flight times make the idea of membranes enclosed tubes for the droplet clouds more attractive.
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Post by n2maniac on Sept 4, 2017 18:55:24 GMT
How bad is mass loss over time on these?
(specifically by evaporation)
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Post by matterbeam on Sept 4, 2017 21:24:10 GMT
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Post by Enderminion on Sept 5, 2017 1:48:58 GMT
*when not being shot at/vapourized
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Post by jtyotjotjipaefvj on Sept 5, 2017 9:30:39 GMT
*when not being shot at/vapourized Well mass loss on regular radiators is pretty catastrophic in those cases too.
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Post by n2maniac on Sept 5, 2017 17:13:45 GMT
Huh, didn't realize tin did so well. They say 30 year for tin at only 900K based on the plot, but had trouble finding the reservoir mass to radiator area ratio.
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Post by apophys on Sept 5, 2017 22:52:23 GMT
~1050 K at best? Those temperatures are too low for powerplant radiators. Should be great for laser radiators though.
I'm curious about cobalt, for a Curie point LDR. Vapor pressure limits may be less strict when all solids are pulled back and recovered.
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Post by Enderminion on Sept 5, 2017 23:44:22 GMT
*when not being shot at/vapourized Well mass loss on regular radiators is pretty catastrophic in those cases too. LDRs on warships would have more then what was needed so that a radiator hit would do nothing (unless it hit the sprayer or catcher)
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Post by treptoplax on Sept 6, 2017 3:04:41 GMT
~1050 K at best? Those temperatures are too low for powerplant radiators. Should be great for laser radiators though. I'm curious about cobalt, for a Curie point LDR. Vapor pressure limits may be less strict when all solids are pulled back and recovered. Well, I think the original post was mostly targeting plausible near-future tech, not the more ambitious materials and manufacturing available in CoaDE. As I noted over there, a liquid boron LDR would have crazy heat output... Although I admit handling liquid boron, and recirculating partially refrozon boron slush (with those diamond-hard crystals in it) is more than a little ambitious.
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Post by matterbeam on Sept 6, 2017 7:34:47 GMT
~1050 K at best? Those temperatures are too low for powerplant radiators. Should be great for laser radiators though. I'm curious about cobalt, for a Curie point LDR. Vapor pressure limits may be less strict when all solids are pulled back and recovered. That's a NASA study for droplet radiators supposed to last decades, with only low temperature components to cool down. If we want to prioritize radiator performance over endurance, we could operate at much higher temperatures and just accept the vapor pressure losses.
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