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Post by wafflestoo on Nov 8, 2016 16:51:58 GMT
Hey, just curious to see if anybody has done much work with RTG design in game. I know the current meta is for multi-megawhattt laser ships and kilometer-long, "OMG, how did you get the taxpayers to pay for that thing" dreadnoughts but sometimes, you just need a few kilowatts.
Case-in-point; I've got this little missile boat. It has three 25kw launchers and a modest array of 12- and 25kw railguns for last-ditch defense. The launchers are considered operational artillery; not for use in tactical combat so they're safety'd anytime close-quarters is inevitable so it operates on a power budget of only about 75kw total provided by a trio of 25.9kw RTGs. Seriously, the crew quarters put a noticeable drain on the power system.
These RTG's mass about 165kg each so I get to thinking, "Heck, I can do better than that with a nuclear plant" and I get to work. All said and done with I settled on a 238kw plant that is smaller and cheaper than one of the RTG's and I figure, "done"
Then I install it... uh-oh, not enough crew.
Long story short, (too late) by the time I increase the crew can and pay for the extra armor volume the ship is actually slightly heavier and more expensive than the version powered by the nuclear batteries. I guess ships are systems and focusing on one part while missing others can lead to a more efficient part of the system being less efficient overall.
So, yeah, back to my original point. Has anyone experimented with RTG design? And what tips would you give on how to make them more efficient?
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Post by goduranus on Nov 8, 2016 17:00:05 GMT
they are not worth it, fission generators get the same job done for cheaper using cheap u233 dioxide, but usable fuels for rtgs are very expensive.
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Post by jonen on Nov 8, 2016 17:14:51 GMT
... Pretty sure there are some stock "operational" style missile launchers out there who have only enough power to run one launcher at a time, they work fine (even halfway decent in combat). Launchers - more so than guns or especially launchers - seem to be able to cope fairly well with being occasionally unpowered.
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Post by wafflestoo on Nov 8, 2016 19:15:14 GMT
... Pretty sure there are some stock "operational" style missile launchers out there who have only enough power to run one launcher at a time, they work fine (even halfway decent in combat). Launchers - more so than guns or especially launchers - seem to be able to cope fairly well with being occasionally unpowered. Yeah, I figured that already. I wasn't trying to squeeze more power, just trying to make it a little lighter and a little cheaper (240-ish kW was just where I stopped monkeying with it as I wasn't saving much mass nor dollars by reducing the power much further). I was a little surprised that even though the reactor was less than a third the combined cost and mass of the RTGs it actually made the ship heavier and more expensive. Unexpected consequences of looking at just one part and not the whole I guess
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Post by wafflestoo on Nov 8, 2016 19:48:31 GMT
they are not worth it, fission generators get the same job done for cheaper using cheap u233 dioxide, but usable fuels for rtgs are very expensive. I had a scout-master once who maintained that, "It is far better to stand there and look like you don't have a clue than it is to open your mouth and remove all doubt." Read more than the first half of the first sentence of the post plz
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Post by dragonkid11 on Nov 9, 2016 4:45:00 GMT
Yeah, RTG is made to basically run forever in satellite with barely any maintenance.
Nuclear reactor? They need to get check often to make sure they don't fail or leak deadly radiation.
Of course, it really depends on how much power you want for your ship.
Low power and RTG works fine.
Higher power...and RTG is worth a lot less than nuclear reactor now.
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Post by goduranus on Nov 9, 2016 6:34:58 GMT
they are not worth it, fission generators get the same job done for cheaper using cheap u233 dioxide, but usable fuels for rtgs are very expensive. I had a scout-master once who maintained that, "It is far better to stand there and look like you don't have a clue than it is to open your mouth and remove all doubt." Read more than the first half of the first sentence of the post plz Huh? I read your post and you were asking for a power source that could power 3x25kw launchers and some 25kw railguns plus a crew module. So you need about 100kw. At that kind of power levels Fission reactor is much more cost effective than RTG. If you run into crew size problems, get rid of the crew module and make your ship a drone. Then launch it from a station.
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Post by dragonkid11 on Nov 9, 2016 6:44:58 GMT
Erm...
If you turn into a drone, then RTG is not worth it because a nuclear reactor of same power could be cheaper and lighter and smaller.
What he mean is that he want a RTG powered manned warship.
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Post by goduranus on Nov 9, 2016 7:01:43 GMT
RTGs fuels are very expensive, so 100kW of power seems to cost 1MC. Also, they melt at such low temperatures that radiators for them would cost 1MC. At that kind of cost, it's much cheaper to just use fission(600c) and extend the crew module to add room for 5 people(~500kc).
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Post by someusername6 on Nov 9, 2016 7:03:33 GMT
There might be a small window where you would rather use a RTG than a fission reactor to save up on some 5 people on a crew module, but that is not a lot of design space -- you need to save up more mass and cost on the crew modules than you would spend on extra radiators at a lower temperature. You can build a minimal station / living capsule with not a lot of heat signature, though.
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Post by someusername6 on Nov 9, 2016 7:06:00 GMT
Sorry for the double post, but still on the RTG topic:
1. Did anyone manage to use Tritium? I figure it would need to be cooled with something that is non-solid at temperatures where it is solid; Helium seems like the obvious candidate but the coolant temperature range doesn't go that far down. 2. Did anyone manage to build a thing out of Constantan / Nickel Alloy? Power production seems to shoot up at lower temperatures, but I can never radiate enough heat within the RTG design to make it work.
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Post by leerooooooy on Nov 9, 2016 10:05:39 GMT
Hey, just curious to see if anybody has done much work with RTG design in game. I know the current meta is for multi-megawhattt laser ships and kilometer-long, "OMG, how did you get the taxpayers to pay for that thing" dreadnoughts but sometimes, you just need a few kilowatts. Case-in-point; I've got this little missile boat. It has three 25kw launchers and a modest array of 12- and 25kw railguns for last-ditch defense. The launchers are considered operational artillery; not for use in tactical combat so they're safety'd anytime close-quarters is inevitable so it operates on a power budget of only about 75kw total provided by a trio of 25.9kw RTGs. Seriously, the crew quarters put a noticeable drain on the power system. These RTG's mass about 165kg each so I get to thinking, "Heck, I can do better than that with a nuclear plant" and I get to work. All said and done with I settled on a 238kw plant that is smaller and cheaper than one of the RTG's and I figure, "done" Then I install it... uh-oh, not enough crew. Long story short, (too late) by the time I increase the crew can and pay for the extra armor volume the ship is actually slightly heavier and more expensive than the version powered by the nuclear batteries. I guess ships are systems and focusing on one part while missing others can lead to a more efficient part of the system being less efficient overall. So, yeah, back to my original point. Has anyone experimented with RTG design? And what tips would you give on how to make them more efficient? Use custom crew modules to shave off weight and volume. RTGs are not worth it as the radiator cost alone is obscene
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Post by wafflestoo on Nov 9, 2016 14:17:56 GMT
I had a scout-master once who maintained that, "It is far better to stand there and look like you don't have a clue than it is to open your mouth and remove all doubt." Read more than the first half of the first sentence of the post plz Huh? I read your post and you were asking for a power source that could power 3x25kw launchers and some 25kw railguns plus a crew module. So you need about 100kw. At that kind of power levels Fission reactor is much more cost effective than RTG. If you run into crew size problems, get rid of the crew module and make your ship a drone. Then launch it from a station. No, what I said is I had a ship with a rough power requirement of 100kw and as an experiment I replaced the RTGs with a vastly cheaper, lighter reactor and what I found was the added crew needed to babysit the thing made the ship heavier and more expensive overall. Here's the girl now, post update. She lost a bit of dV because of the NTR changes so I'll have to do some fine-tuning to the engine to bring it up again. I'm sure some of you will nit-pick her to death but for the campaign setting I'm very happy with it. (you can see how "obscene" the radiator costs are)
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Post by goduranus on Nov 9, 2016 15:40:20 GMT
Right.... your 100kW of RTGs cost a combined 2.5MC. Either you use expensive fuel and your RTG is costly, or you use cheap fuel and your radiators are costly.
If you used a 100kW fission instead, you could have gotten away with 600c for the reactor, 5kc for some tiny radiators, and 300kc to extend your crew can by 5.
So, 2.5MC vs 305.5kc, which one is better?
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Post by apophys on Nov 9, 2016 16:01:55 GMT
Expanding a crew can by 5 is actually less than 100kc if you use minimum-thickness boron like I do (and the lithium-6 rad shield you will need is only ~1.5kc, so no biggie).
But more to the point, it weighs ~10 tons more (which is quite a lot of dead weight at smaller scales). You have to consider propellant, and armor for the propellant, for which the effects are less obvious.
I still think it's worth it to switch to fission, but it definitely isn't a no-brainer for some design styles.
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