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[1.12.x] Kerbal Atomics: fancy nuclear engines! (January 22, 2022)


Nertea
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  • 2 weeks later...

Could someone elaborate why some of the engines offer the possibility to switch between pure LH2 and LOX consumption? I assumed the former provides less thrust but higher efficiency thus more Delta V. In reality the LOX mode provides more thrust AND almost twice as much Delta V than the LH2 mode (with the corresponding fuel tank configured that it only stores LH2). Is it supposed to work like that? If so, why? If not, how could I fix this?

UPDATE: I totally get it now, lol. The tank variant with embedded Oxidizer weighs about 50t more!

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Edited by pckbls
found the answer myself
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18 hours ago, Brigadier said:

Radiators, active and/or passive, and stop thrusting :P

Didn't work for me for some reason. Probably because all the radiators are on the station and not the vessel itself. Spent months moored to the station waiting to extract the nuclear waste and it doesn't seem cool down when station is not loaded. I installed System Heat and problem was solved. Just need to retrofit the station with heat pumps.

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6 hours ago, DichromaticLotus said:

Didn't work for me for some reason. Probably because all the radiators are on the station and not the vessel itself. Spent months moored to the station waiting to extract the nuclear waste and it doesn't seem cool down when station is not loaded. I installed System Heat and problem was solved. Just need to retrofit the station with heat pumps.

Yeah... I am probably going to drop support for the NFE NTR patch shortly. It's too much work to maintain and the SH stuff is at this point undeniably better. 

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Hello.

Thank you for all the work you've put into this. I have  question about how to manage my nuclear engines. I am running a test with the Neptune Trimodal and I am having trouble when shutting the engine down.  I have plenty of cooling attached, but when I shutdown the engine when it is at full heat all cooling stops and heat climbs until the reactor melts down.

The only way I can safely shut it down is to manually throttle the Fission Reactor down to minimum, wait until it cools, and then shutdown the engine. Is this intended?

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On 4/3/2021 at 6:45 AM, Bursoma said:

Hello.

Thank you for all the work you've put into this. I have  question about how to manage my nuclear engines. I am running a test with the Neptune Trimodal and I am having trouble when shutting the engine down.  I have plenty of cooling attached, but when I shutdown the engine when it is at full heat all cooling stops and heat climbs until the reactor melts down.

The only way I can safely shut it down is to manually throttle the Fission Reactor down to minimum, wait until it cools, and then shutdown the engine. Is this intended?

You should shut down the reactor vs shutting down the engine. 

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2 hours ago, Nertea said:

You should shut down the reactor vs shutting down the engine. 

I'm having an issue where activating the engine also activates the reactor and I cant independently shut down the reactor without turning off the engine as well leading to meltdowns.  I tested a few of the engines as well as the stock NERV and they all seem to do it.  I have system heat and all its extras installed.

I recently had the NFElectrical Extra installed but removed it at as it was causing an issue with reactors overheating per your recommendation.  

Edited by KSPNoob
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11 minutes ago, KSPNoob said:

Im having an issue where activating the engine also activates the reactor and I cant independently shut down the reactor without turning off the engine as well leading to meltdowns.  

Yes you can. Click shutdown reactor in the panel. That will turn off the engine too, but that's fine. If the engine is powerful, you may need some radiators to handle the decay heat until it shuts down. 

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8 minutes ago, Nertea said:

Yes you can. Click shutdown reactor in the panel. That will turn off the engine too, but that's fine. If the engine is powerful, you may need some radiators to handle the decay heat until it shuts down. 

I have three of the large thermal control systems and whenever I shutdown the engine it still overheats and melts down.  I remember I use to just shut down the reactor and let the engine discharge some of the heat via thrust towards the end of my burns or shortly after, is this not possible anymore?  Sorry I like the new system heat mod but Im having a terrible time with the atomic engines/reactors.
 
So it's not a bug that the actual atomic engine and reactor are tied together?  

Edited by KSPNoob
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7 minutes ago, KSPNoob said:

three of the large thermal control systems

Stock or Heat Control? The latter cools much better. If you don’t have it, you should get it. 

7 minutes ago, KSPNoob said:

So it's not a bug that the actual atomic engine and reactor are tied together?  

Yes. In an IRL NTR, the reactor is used to heat the working fluid(usually hydrogen). 

The engine only produces thrust because of the reactor. 

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8 minutes ago, KSPNoob said:

I have three of the large thermal control systems and whenever I shutdown the engine it still overheats and melts down.  I remember I use to just shut down the reactor and let the engine discharge some of the heat via thrust towards the end of my burns or shortly after, is this not possible anymore?  Sorry I like the new system heat mod but Im having a terrible time with the atomic engines/reactors.
 
So it's not a bug that the actual atomic engine and reactor are tied together?  

I would really prefer system heat stuff to be in the system heat thread, by the way.

You need to get used to the new concept that nuclear reactors take time to heat up and cool down. The old mod implementation had no cool down period. You need a way to get rid of the heat during that time span, there are several ways to do this. You can just turn off the engine which will work fine with weaker engines like the LV-N, there will be a temperature spike but it will cool town in time. The higher energy engines need you to either slowly reduce thrust to some extent or provide some additional radiator capacity. 

 

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9 minutes ago, Nertea said:

I would really prefer system heat stuff to be in the system heat thread, by the way.

You need to get used to the new concept that nuclear reactors take time to heat up and cool down. The old mod implementation had no cool down period. You need a way to get rid of the heat during that time span, there are several ways to do this. You can just turn off the engine which will work fine with weaker engines like the LV-N, there will be a temperature spike but it will cool town in time. The higher energy engines need you to either slowly reduce thrust to some extent or provide some additional radiator capacity. 

 

Ok sorry I know the System Heat stuff is separate but I wasn't sure if it was a bug with Atomics mod.  Basically the engines and reactors are now tied together as a single unit instead of being separate with the old NFElectrical Extra. 

I was just really confused on why activating the engine suddenly now was activating the reactor and deactivating the reactor also deactivated the engine.

Edited by KSPNoob
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38 minutes ago, KSPNoob said:

I was just really confused on why activating the engine suddenly now was activating the reactor and deactivating the reactor also deactivated the engine.

I thought this was better? If you activated the engine, you probably wanted the reactor, and if you deactivated the reactor, the engine was no longer relevant. Maybe the second use case does make sense if all you want to do is exhaust propellant for cooling.

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3 minutes ago, Nertea said:

I thought this was better? If you activated the engine, you probably wanted the reactor, and if you deactivated the reactor, the engine was no longer relevant. Maybe the second use case does make sense if all you want to do is exhaust propellant for cooling.

I personally like that it automatically ramps up when the engine is activated. 

I also think that running the engine sans reactor to cool it off is helpful as well. 

Maybe a “cool down” option could use some propellant in exchange for providing a temporary powerful cooling source. 

or

Add and exhaust cooling mode which allows the user to run the engine to cool it off. 
 

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4 minutes ago, Nertea said:

I thought this was better? If you activated the engine, you probably wanted the reactor, and if you deactivated the reactor, the engine was no longer relevant. Maybe the second use case does make sense if all you want to do is exhaust propellant for cooling.

Not better or worse just different from what I was use to, as you said I use to just shut down the reactors and vent heat via some LH2. It'll just take some getting use to and require having more rads then I usually went with, but itll be far less micro managing so thats a plus.

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6 hours ago, Nertea said:

Maybe the second use case does make sense if all you want to do is exhaust propellant for cooling.

 

6 hours ago, Spaceman.Spiff said:

Maybe a “cool down” option could use some propellant in exchange for providing a temporary powerful cooling source. 

You're both talking to how real, non-bimodal NTRs are supposed to work.  When there aren't a plethora of radiators, the brute force solution is to run propellant through the shutdown reactor.  Many non-bimodal NTR mission profiles include a propellant fraction that's just for cooling.

Unless propellant is being vented symmetrically, those same profiles probably also assume that useful thrusting is still happening during cool down (at rapidly degrading Isp).   Unless you know exactly when to hit the shutdown button, you're either going to need another thruster to finish/correct the burn, or risk core damage, because you didn't finish cooling before the maneuver was finished.

One approach could probably be like Spiff's proposal and add a cool down "flush" button that just consumes propellant - without thrusting - and can automatically and/or manually be turned off once safe temperatures are reached.  LH2 tank propellant density is already a bit "gamed", so this arbitrary inefficiency would spice things up a little bit and encourage the use of radiators, while providing an escape option from the head-banging frustration of watching your core melt down in the middle of a mission.

A more elegant solution would probably be a "cool down helper" indicator that predicts how much time would be needed to cool the reactor down to safe levels, so you could shut it down at the right moment, while still thrusting*.  Even more elegant would be an "auto-shutdown in current maneuver node" toggle (MJ compatible, of course).

Thinking out loud, I assume propellant turbo-pumps are optimized for max thrust under full reactor power, so propellant flow rate would likely be limited to that maximum - but Isp is going down with temperature, and if flow rate stays the same, thrust would also drop, right?  So the maneuver burn would actually go a bit longer.  A hypothetical "cool down helper" should probably account for that....

EDIT: * There probably should be a cut-off on thrusting availability once the reactor is below a certain temperature, so your Isp doesn't get horrific, and you're just dumping cold Hydrogen into space....

Edited by KSPrynk
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  • 4 weeks later...

Something tells me I'm not quite understanding how to use this mod properly. When operating the Liberator rocket motor, here's what happens:

  1. I extend my radiators, and wait until they are fully extended.
  2. I activate the motor's nuclear reactor, and wait for the heat to reach the max system temperature. (1300 K)
  3. I activate the engine, and turn it up to full throttle.
  4. From this point, the engine is providing much less thrust and ISP than listed. 
  5. I cut the throttle, and the waste heat suddenly rises up, causing a meltdown.

I don't think it's a glitch, but these atomic motors are kind of confusing for me. If anyone can provide any tips on my problem, it'd be much appreciated.

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2 hours ago, intelliCom said:

Something tells me I'm not quite understanding how to use this mod properly. When operating the Liberator rocket motor, here's what happens:

  1. I extend my radiators, and wait until they are fully extended.
  2. I activate the motor's nuclear reactor, and wait for the heat to reach the max system temperature. (1300 K)
  3. I activate the engine, and turn it up to full throttle.
  4. From this point, the engine is providing much less thrust and ISP than listed. 
  5. I cut the throttle, and the waste heat suddenly rises up, causing a meltdown.

I don't think it's a glitch, but these atomic motors are kind of confusing for me. If anyone can provide any tips on my problem, it'd be much appreciated.

These nuclear engines very much dabble in how real NTRs operate (as you can see in the posts above). Their main source of cooling is actually the cryogenic liquid hydrogen flowing over the reactor vanes! Mode of operation seems funky at first but makes sense if you think about it. Here is a quick rundown:

1. Deploy radiators. Make sure they are powered and cooling.
2. Right click engine and manually set Reactor Throttle to roughly 10%.. Any higher and the reactor will rapidly try to melt.
3. Activate Reactor. Notice heat values will steadily start to climb, your radiators are providing a modest heat sink for now but before long they will be saturated.
4. Set your main engine throttle to 100% . Right click the engine, Activate Engine (or activate via staging). Now you can see your reactor starts to quickly cool down thanks to the superchilled propellant coursing through it.
5. Isp and thrust are currently crummy, because the reactor is throttled way down and not generating much heat. Slowly throttle the reactor up to 100%. 
6. You are now NTR-ing.

To safely shutdown, deactivate the reactor before you cut engine throttle. This will automatically shut down your engine and therefore stop propellant flow. This is where your radiators come back in - they will gradually whick away the remaining heat in the reactor core. Coast to destination.

OH, also make sure you are in space during all this, NTRs don't do much in the atmosphere.

Edited by lemon cup
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11 hours ago, lemon cup said:

These nuclear engines very much dabble in how real NTRs operate (as you can see in the posts above). Their main source of cooling is actually the cryogenic liquid hydrogen flowing over the reactor vanes! Mode of operation seems funky at first but makes sense if you think about it. Here is a quick rundown:

1. Deploy radiators. Make sure they are powered and cooling.
2. Right click engine and manually set Reactor Throttle to roughly 10%.. Any higher and the reactor will rapidly try to melt.
3. Activate Reactor. Notice heat values will steadily start to climb, your radiators are providing a modest heat sink for now but before long they will be saturated.
4. Set your main engine throttle to 100% . Right click the engine, Activate Engine (or activate via staging). Now you can see your reactor starts to quickly cool down thanks to the superchilled propellant coursing through it.
5. Isp and thrust are currently crummy, because the reactor is throttled way down and not generating much heat. Slowly throttle the reactor up to 100%. 
6. You are now NTR-ing.

To safely shutdown, deactivate the reactor before you cut engine throttle. This will automatically shut down your engine and therefore stop propellant flow. This is where your radiators come back in - they will gradually whick away the remaining heat in the reactor core. Coast to destination.

OH, also make sure you are in space during all this, NTRs don't do much in the atmosphere.

Thank you. The ISP and thrust being crummy is a little painful, but at least I can use them now. It makes sense as to why it does this, but it does seem like a lot to consider compared to other engines in stock and NF. Would it be safe to let the reactor sit on automatic control?

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5 minutes ago, intelliCom said:

Thank you. The ISP and thrust being crummy is a little painful, but at least I can use them now. It makes sense as to why it does this, but it does seem like a lot to consider compared to other engines in stock and NF. Would it be safe to let the reactor sit on automatic control?

Good question.  I followed @lemon cup's directions (that was SO needed) and successfully conducted an NTR burn with an Eel and four YF-15 radiators.  I was then trying it out with a MechJeb-controlled burn and realized I'd have to control reactor power ramp-up and ramp-down within a few seconds of the burn starting and finishing, respectfully, to avoid a core meltdown.  I haven't tried out automatic control yet.  Let us know what you learn!  I'm liking this approach to propellant-based core cooling so far, but I need to check out other engines.

P.S. - I also learned the hard way that updating to the latest System Heat (from 0.4.0  to 0.4.1) solved a lot of problems....

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  • 2 weeks later...

Kerbal atomics with community tech tree question

Hi, today I noticed that even the most powerful and most efficient engines are unlockable in just one and only tech tree node...

Everytime I research that node I feel like i'm cheating since I have access to overly good engines early in the game.

So: Can I ask you to move some of the better engines in a more advanced tech tree node? Like for example in the "Improved nuclear propulsion" and "High efficiency nuclear propulsion"

Thank you

 

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