FreeThinker

[1.7.2/1.6.1/1.5.1/1.4.5/1.3.1] KSP Interstellar Extended 1.21.11 Support Thread

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I might be dumb and missing some very basic (and essential) part, because in tutorial/guides I have checked this thing is never explained (or rather, treated as a trival detail that should already be known).

I want to build a HTP refinery for my Niven mission in GPP. I slapped the 2.5m reactor from USI, Thermal Power Generator on top of that. Then I basically covered it with radiators (wrap-up ones plastered all along the reactor and generator + 6 deploable radiator panels). When I turn the thing on, it has like 20% power efficiency and all is fine and dandy.

But the moment I power up the refinery (universal drill + ISRU Processor + Electrolyzer + Refridgerator), the thing just dies. Power output drops to 0, radiators no longer have power to work, so it falls into a vicious circle. I tried tweaking it one way or another, but I am just unable to sustain operations at any rate. What can I do to fix this and what am I doing wrong?

Some notes for clarity:

  • True, in Therman Control window in VAB all values are red - but even if I literally plaster the whole thing with radiators, things barely go into yellow areas.
  • I am trying to use vacuum-optimized radiators exclusively; I am using launch pad as test bed, then launch prototypes to Iota for vacuum tests. My thinking is that if it works in vacuum, it should also work in Niven's thin atmosphere
  • Here's a screenshot of the prototype setup; please note the variant I am describing above has a Thermal Generator added on top of the reactor (between reactor and the reaction wheel); it has also slightly different configuration (Ore processors instead of Karbonite module), but it should not change the thermal situation, right?

front_Apex_Cygnus_1.png

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2 hours ago, Dollehz said:

Found the problem, the ISRU refrigerator consumes power even though it's not doing anything.

Forgot to turn of my lqd methane -> methane conversion (user error). Setting the slider to 0 fixed the problem.
Weird part is there was no lqd methane left but the ISRU kept draining power, don't know if it's suppose to do so.

Good point, it should not have drained power after it has nothing left to convert

1 hour ago, Astraph said:

I might be dumb and missing some very basic (and essential) part, because in tutorial/guides I have checked this thing is never explained (or rather, treated as a trival detail that should already be known).

I want to build a HTP refinery for my Niven mission in GPP. I slapped the 2.5m reactor from USI, Thermal Power Generator on top of that. Then I basically covered it with radiators (wrap-up ones plastered all along the reactor and generator + 6 deploable radiator panels). When I turn the thing on, it has like 20% power efficiency and all is fine and dandy.

But the moment I power up the refinery (universal drill + ISRU Processor + Electrolyzer + Refridgerator), the thing just dies. Power output drops to 0, radiators no longer have power to work, so it falls into a vicious circle. I tried tweaking it one way or another, but I am just unable to sustain operations at any rate. What can I do to fix this and what am I doing wrong?

Some notes for clarity:

  • True, in Therman Control window in VAB all values are red - but even if I literally plaster the whole thing with radiators, things barely go into yellow areas.
  • I am trying to use vacuum-optimized radiators exclusively; I am using launch pad as test bed, then launch prototypes to Iota for vacuum tests. My thinking is that if it works in vacuum, it should also work in Niven's thin atmosphere
  • Here's a screenshot of the prototype setup; please note the variant I am describing above has a Thermal Generator added on top of the reactor (between reactor and the reaction wheel); it has also slightly different configuration (Ore processors instead of Karbonite module), but it should not change the thermal situation, right?

front_Apex_Cygnus_1.png

Have you verified the Reactor works at all?

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Yeah, when I click on Reactor Control window, things seem working - I have actinides being produced, temperature goes up and heat is produced. If I fire up only less power-hungry modules (like the Ore processor) or just the drill, they work indefinitely. Issues begin when I fire up all converters and the drill at the same time.

As I mentioned, I know I used too little radiators to have 100% efficiency - but I see no way to add more without making majority of lander's parts radiators... If anyone could share their reactor setups, I would happily try to reverse-engineer them.

Oh, and one last detail, though I am not sure how relevant is that - since I'm playing GPP, I am using the older version of the mod (though I can't provide the exact version number right now, as I am at work)

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Posted (edited)

Need some help with some numbers here.

So, i't trying to figure out my thrust and ISP for a reactor with a thermal nozzle. I know these values are displayed in the VAB but i'm trying to fully understand this mod and I came across a lot of values that didn't make any sense.

So in my example we combine a pebble bed with a thermal rocket nozzle; look up the numbers; make some calculations and identify some bugs.

Reading the parts info I get

  • Pebble bed: Thermal nozzle Performance: 797.6kN @ 1150s. Great found what i was looking for!
    Spoiler

    EuFEgMr.jpg


     
  • Thermal nozzle: Thrust 138.889 kN - 500.0 kN @ 200s - 720s. Now wait these are completely different numbers..
    Spoiler

    aEKNbW4.jpg


     
  • Let's right click the engine: 
    Spoiler

    uRKwEkb.jpg

    Again different numbers


     
  • But wait there is that whole list of formulas
    Spoiler

    EdAJMPy.jpg

    So according to this for Hydrogen: 1 x 22.136 x Sqrt(3000K) => 1212.438
    Aha! that's the same max ISP as from the right click menu

    Note: these formulas are missing for most fuels on the thermal ramjet/turbojet

    Note 2: here it becomes apparent that the ISP is proportional to the Core temperature, some engines like the nuclear lightbulb have a core temp of 8839K thus a higher ISP (2081.1s)

     

 

  • Lets try another fuel type, let's take Hydrazine
    Spoiler

    From the above formula we should get a max ISP of 0.744 x 22.136 x sqrt(3000K) => 902.054

    zJXHfgQ.jpg

    So... errr... we got 2 different values here, but one of them is correct

    But notice how the top 2 values are the same as for hydrogen. At first i thought "Aah these must be the basic values" but actually it turns out to be a BUG.
    These are the values for the selected fuel when you change scale.
    They remain fixed until you change scale again.
    (these wont show up until you change scale)

    Lets increase scale and go back to the original

    dfMlbO9.jpg

    Tadaa problem solved. Now good thing about these values is that you get:

    Max and Min ISP
    Sea and Vac Thrust

    BUT: these do not show up unless you rescale the engine (for thermal nozzles, other engines show these by default)
    AND: do not update unless you rescale again (all engines suffer from this bug)

    Best would be to make these values show permanently, make them auto update and then remover the double data (bottom ISP data).

     

  • Now what about calculating Thrust and min ISP?
    Spoiler

    Lets start with min ISP:

    I have no idea where the basic value comes from.

    Hydrogen has a min ISP of 1050.1s with a propellant multiplier of 1 so we can assume this is the basic min ISP for the engine
    Hydrazine has a propellant multiplier of 0.744 so:
    1050.1 x 0.744 = 781.27s (actual ISP = 812.2s)

    So as you can see the propellant multiplier is not correct for min ISP

    All ISE engines have this problem

     

    Next Thrust:

    Same issue, no idea where the basic values come from.

    Again Hydrogen has a multiplier of 1 so we can use these values as basic.
    Hydrogen thrust is 655.6kN - 756.9kN

    Unfortunately the fuel thrust multiplier is not shown in the VAB so we have to look it up.
    Hydrazine thrust multiplier is 1.4 => thrust should be: 917.84kN - 1059.66kN

    It's not, actual thrust is 1285.2kN - 1427.4kN

    Again propellant multiplier is incorrect for both Sea and Vac Thrust

    All ISE engines have this problem

 

If any of my reasoning / math is wrong, please let know.

 

TLDR;

Spoiler

 

Many confusing (useless?) numbers

For all thermal nozzle

  • No default Sea/Vac Thrust & min max ISP shown in VAB
  • Does not update when changing fuel type (only after rescaling)

Other engines:

  • default Sea/Vac thrust & min max ISP is shown
  • Does not update when changing fuel type (only after rescaling)

Propellant multipliers only correct for max ISP. Min ISP and Thrust give wrong numbers (Affecting all ISE engines)


Propellant thrust multipliers not shown in VAB

 

 

Edited by Dollehz

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Posted (edited)

@Dollehz You are observant but you need to understand there are some limitations on KSP Part system because any partinfo, inclding module information, is requested at startup and cannot be changed once your in the VAB, so the thrust numbers on the thermal nozzle are just an example for that might be the performance, the actual performance depends on the reactor, fuelmode, size, throttle, time and atmospheric pressure.

Edited by FreeThinker

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Okay makes sense, so the part information is an approximation of the values you can expect. I understand the actual figures are a bit more complex.

Do you have any formula for the thrust like there is for ISP? Is it related to the reactors power output? Linear, exponential,.. ?

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Posted (edited)

Aesthetics be damned, I just slapped as many radiators on a reworked refinery as I could.

0Xt3eQ9.png

However, when I'm launching KRASH to test the whole setup, both generators shut down due to... no radiator being available.

Z8T2zNV.png

I have absolutely no idea what's wrong. Generators are connected directly to reactors, reactors are working (producing actinides and so on). I have no idea what I'm doing wrong here... :( 

EDIT: I just noticed that my generator's Cold Bath temperature (500 K) is higher than Hot Bath (300 K)... Is that working as intended?

EDIT2: Just in case - Reactor Control window

Tk4XvbI.png

EDIT 3: Looks like my initial suspicions were true - I am stupid and failed to notice key things (like the whole in-flight thermal readout function). Here's my troubeshooting, I'd be most grateful if someone more experienced verified my conclusions ^^'

  • 1.25m reactors have laughable output (6.7 MW with 4 reactors) at tier 1, while electrolyzer alone gobbles up 20 MW. I tried to reduce its power consumption to 10% with the slider, but it did little to fix the issue, it still goes at full power when activated. 
  • USI reactors apparently have their own generator integrated, so I guess the mod does not recognize them as 'proper' reactors for thermal power production.
  • My tech is tier 1, so obviously, radiators are also excrements at dispelling heat.

My plan for tomorrow is to return to 2.5m reactor, but tweak its power output so levels manageable without turning the whole refinery into a radiator chrysantemium. Guess more advanced technology will allow me to build something more ambitious in near future.

Edited by Astraph

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@Astraph yes USI reactors are their own thing.  And also, working with low tier tech is against you in every way. You don't have any good reactors, the reactors you do have don't make much power, the radiators suck, and (most significantly) your thermal electric generator is crazy inefficient and makes oodles of waste heat. I'm sorry to say it but if you're looking for big power with your tech levels, the only good solution is to add more radiators and reactors. Eventually you'll get to the technological level such that you don't need a Christmas tree of radiators, but you aren't there yet. Also, I'm pretty sure the 1.25m fission reactor has a built-in TEG. 

 

Takeaway: you have a lot of multiplicative inefficiencies, you're probably going to need something like 10x the thermal power as electricity you need to make, accompanied by enough radiators to keep the cold bath cool enough to maintain that 10% efficiency. Have you scooped up all of the science Ceti and Iota have to offer first? Might be a good idea before heading off to other planets.

Edited by Jumberlack

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@Jumberlack thanks for confirming my suspicions. I actually got the next tier of reactors (including the Interstellar's Molten Salt one), and miraculously I am finally able to generate power without crashing my whole setup. Barely 30 MW, but it's enough to actually run the H2O electrolysis without the whole thing imploding on itself. I also cheated tinkered a bit with TweakScale and by using 2.5x sized radiators managed the final iteration to look nice and actually work at the same time. :D 

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@Astraph using tweakscale in kspie is not just not cheating, it's completely intended and almost required in some cases. btw the molten salt reactor is bae.  

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Heyo! Would you be interested in a custom "Faster Than Light" node icon?

Edited by Tonas1997

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5 hours ago, Tonas1997 said:

Heyo! Would you be interested in a custom "Faster Than Light" node icon?

Yes, any Icons for additional KSPIE tech nodes would be very welcome

Edited by FreeThinker

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16 minutes ago, FreeThinker said:

Yes, any Icons for additional KSPIE tech nodes would be very welcome

Neat! I'll contact CTT's author(s) to know which deboss level they used and I'll get back to you in a few days.

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Early ideas for KSPI-E custom tech node icons

Quantum Gravity

1onu1RK.png

Represents a single graviton moving throughout spacetime, with the underlying grid representing the Planck scale.

Faster-Than-Light

4Gsqyx7.png

Inspired by this GIF from Wikipedia's page on tachyons (hypothetical particles that always move faster than c), it represents the two "virtual" images generated by one such particle, overlayed with lines representing the shockwave of the generated Cherenkov radiation.

Both images were rendered with a grey background so as to help with visualization. While they have the same resolution as CTT icons (64x64), they are still quite dissimilar as I haven't been able to replicate CTT's deboss effect... yet :D

Edited by Tonas1997

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