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Post by TheStrodeman on Oct 14, 2016 22:43:58 GMT
Would including heat sinks be a possibility in the future? So you can retract radiators so they don't get shot off?
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Post by beta on Nov 13, 2016 14:31:46 GMT
I did some napkin math on how much water you would need to sink the heat of 10 people in an ISS size crew compartment. Turns out its not very much (efficiencies of actually transferring the heat not withstanding). Also found out you got about 1 hour to go from 21C to 50C in an ISS sized crew compartment based off just body heat alone. Kind of terrifying.
Heat sinks for low-level waste heat would be awesome. I would be totally willing to spend 10-100 tons on heat sinks for crew compartments or low heat output RTGs so a ship can "button up" and still have power/control.
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Post by thorneel on Nov 13, 2016 15:35:12 GMT
Yes, water is a great heat sink. So is hydrogen. Are there other great materials? What I would love to see (in addition to reusable heat sinks) is expendable heat sinks, where the vaporised propellant at thousands of kelvins is then dumped overboard. Note that this would also give decent propulsion, as if we are dumping it, let's dump it through nozzles. So we would effectively have a radiator/thruster bimodal system.
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Post by beta on Nov 13, 2016 15:44:02 GMT
For many heatsink designs, heat pumps will be required to effectively cool your sink material. Otherwise, you are stuck with venting the coolant. With a heat pump and hydrogen/water/methane as propellant, you can have the benefit of your reaction mass doubling as a heat sink.
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Post by apophys on Nov 13, 2016 16:12:44 GMT
Decane is also quite excellent, since it has a large temperature span from melting to boiling in addition to nice specific heat.
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Post by n2maniac on Nov 13, 2016 22:43:47 GMT
Would including heat sinks be a possibility in the future? So you can retract radiators so they don't get shot off? Heatsink is a bit too vague of a term. I think there is something to a specific one that is not modelled: sublimators, such as those used in manned spacecraft. Doing some math on this, it would take ~800 tons of water to cool my 3GW (thermal) reactor on my 8kt frigate for 10 minutes (main assumption: 2250 kJ/kg enthalpy of vaporization does all of the cooling). My 15cm thick SiC radiators on the ship (which also weigh about 800 tons total) could be replaced with very thin ones (~1.5cm or less) and just be retracted as combat begins. This gets even easier on the stock ships (1 has 1GW, 2 have 500MW, and the rest are under 300MW). This seems a worthwhile option. Methane (~20% as mass effective but common on ships as a propellant) and sodium (common on ships as a coolant and ~2x as mass effective as water) would also be good candidates. This seems even more valuable for running lasers that don't work very effectively above 1200K whose radiators 1) outweigh the 2400K reactor radiators and 2) only operate during combat. Flushed coolant would be "ammo". Both resistojets and nuclear thermal rockets are big heat exchangers to vented gasses and could be modelled as the heat exchangers (indeed, they are essentially focused heat sinks). Would be interested in qswitched 's thoughts on this. It feels like it could be a game changer on radiator armoring for the exceptionally high-powered warships.
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Post by subunit on Nov 14, 2016 20:20:58 GMT
An ability to "button up" rads would add a large array of tactical options. Maybe you could eject the sinks in an emergency as an ersatz flare?
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Post by shiolle on Nov 15, 2016 12:11:58 GMT
An ability to "button up" rads would add a large array of tactical options. Maybe you could eject the sinks in an emergency as an ersatz flare? Or vent them. "Button up" would be a great strategy against nuclear missiles, but I also would like to include here an optional component that would close the engines with armored plates and bind all of it to a button.
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Post by subunit on Nov 15, 2016 19:11:01 GMT
An ability to "button up" rads would add a large array of tactical options. Maybe you could eject the sinks in an emergency as an ersatz flare? Or vent them. "Button up" would be a great strategy against nuclear missiles, but I also would like to include here an optional component that would close the engines with armored plates and bind all of it to a button. An armored bell around the rockets would be super useful. I'd throw one on my boom&zoom craft so if they screw up the merge, they stop getting lasers up the unprotected butt on egress.
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Post by dragonkid11 on Nov 16, 2016 12:26:31 GMT
Armored bell would be nice to just be put on any warship as they could be used to protect engine.
But at the same time, you have to wonder if it's worth it.
Since you could either fire up the thrusters to dodge the nuke and risk getting your thruster ruined, or you used armored bell but you ended up taking the full hit of a nuke barrage.
The reason why I'm asking that is because armored bell that weight several dozens ton or more would probably require sometimes to close and open, thus opening both options for risk and reward.
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acatalepsy
Junior Member
Not Currently In Space
Posts: 97
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Post by acatalepsy on Nov 16, 2016 16:36:57 GMT
Armored bell would be nice to just be put on any warship as they could be used to protect engine. But at the same time, you have to wonder if it's worth it. Since you could either fire up the thrusters to dodge the nuke and risk getting your thruster ruined, or you used armored bell but you ended up taking the full hit of a nuke barrage. The reason why I'm asking that is because armored bell that weight several dozens ton or more would probably require sometimes to close and open, thus opening both options for risk and reward. I think the armored bell for the nuclear rocket is more important for avoiding laser fire than nuclear bombardment, especially after a high speed pass at odd angles.
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Post by shiolle on Nov 16, 2016 18:12:38 GMT
Armored bell would be nice to just be put on any warship as they could be used to protect engine. But at the same time, you have to wonder if it's worth it. Since you could either fire up the thrusters to dodge the nuke and risk getting your thruster ruined, or you used armored bell but you ended up taking the full hit of a nuke barrage. The reason why I'm asking that is because armored bell that weight several dozens ton or more would probably require sometimes to close and open, thus opening both options for risk and reward. Of course closing and opening the bell will take time (and power). In a very unlikely case it is actually added, there probably will be sliders that influence that speed. I think it is reasonable to make an assumption that this time can be made comparable to the time it takes to retract and extend radiators. As to your question whether it's worth it - it is another design decision with its pros and cons. You say that the time needed to close the bell is the time the ship is not dodging, but I would argue that after the patch to missile guidance if you need to dodge for the last few seconds before detonation, you won't be able to dodge enough, at least if the missile guidance is properly tuned. After all, we are talking about missiles pulling multiple gees and carrying nuclear payloads. Currently I found that your engines are fried after the first of second detonation anyway and that means you are not dodging anything afterwards. On the other hand, consider the following scenario. You are intercepted by a flight of nuclear missiles; there are no enemy ships in combat. You dodge and try to shoot them down with lasers/flare missiles, but some get through. In my experience even when you turn your ships to face the missiles before impact (which also takes time that could be spent for dodging), some of the missiles will still detonate behind your ship. That chance increases with increase in closing velocity. Also, when you have multiple ships in your fleet, at least some of them will be disabled most of the time. This is true both with stock missile designs and my own. If anything, detonators can be tuned to increase this chance, and it is very effective. After that some of your ships can no longer intercept the enemy and are likely helpless wrecks on their way out of the combat zone.
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