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[WIP] Nert's Dev Thread - Current: such nuke, wow


Nertea

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On 2/19/2021 at 3:04 PM, SpaceFace545 said:

kinda of a bummer, 3.75 is a bit too small but also not big enough for anything

If you want to make a starship/super heavy there's a mod for that, it is not this mod.

19 hours ago, KSPrynk said:

These models look great and also make me glad I recently upgraded to 64 GB of RAM (yikes).  I've been looking forward to this for a long time.  A few questions:

- Will each single-engine model have "compact" mount variants to pack more across a given tank/base diameter?

- Will there be a corresponding set of switchable variant and single port CH4/Ox RCS blocks in different thrust sizes, or a patch for existing Stock/ReStock RCS selections?  The individual port configuration RCS blocks with integrated fuel cells in NFLV NearFutureMethalox seem overly complex for a compound-curvy KSP-ish Starship.

I don't have any intentions for RCS.

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The engines look great! Also the plumes - very nice. :)

One very small (also very... nitpicky? aggravatingly particular? OCD-like?) suggestion - is it possible to change the order in which B9 tank types are listed in the switcher? For LH2 cryo tank options, the first combo in the list is LH2-Ox, then pure LH2; it would be nice if the methalox were in the same order (LCH4/Ox first, then pure LCH4). However, obviously this is such a small thing that it does not really matter, so disregard or not as it pleases you.

Out of curiosity - are there other uses for LCH4, like there are for LH2 (in nuclear engines via Kerbal Atomics, for instance)?

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14 minutes ago, AccidentalDisassembly said:

Out of curiosity - are there other uses for LCH4, like there are for LH2 (in nuclear engines via Kerbal Atomics, for instance)?

That's actually an interesting idea...

Maybe instead of the NTR LF patch it could be a Methane patch. That way it's not as easy as LF, which is dense and has no boiloff. Methane is denser than LH2 but less dense than LF, and has less boiloff and power requirements.

I think that could be a good way to strike a happy medium between LF and LH2 NTRs while not being too OP

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1 hour ago, Spaceman.Spiff said:

That's actually an interesting idea...

Maybe instead of the NTR LF patch it could be a Methane patch. That way it's not as easy as LF, which is dense and has no boiloff. Methane is denser than LH2 but less dense than LF, and has less boiloff and power requirements.

I think that could be a good way to strike a happy medium between LF and LH2 NTRs while not being too OP

It think methane in a ntr would be too heavy. Hydrogen is used in ntrs and vasimir thrusters because of its low eight allowing it to be accelerated at very high velocities but methane is a bit too heavy to be efficient 

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6 minutes ago, SpaceFace545 said:

It think methane in a ntr would be too heavy. Hydrogen is used in ntrs and vasimir thrusters because of its low eight allowing it to be accelerated at very high velocities but methane is a bit too heavy to be efficient 

I was thinking gameplay-wise, it makes more sense than Kerosene.

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1 hour ago, Spaceman.Spiff said:

That's actually an interesting idea...

Maybe instead of the NTR LF patch it could be a Methane patch. That way it's not as easy as LF, which is dense and has no boiloff. Methane is denser than LH2 but less dense than LF, and has less boiloff and power requirements.

I think that could be a good way to strike a happy medium between LF and LH2 NTRs while not being too OP

Yeah, but.. I think you're missing the point. I'm pretty sure the reason for the LF patch is so users don't need CryoTanks. I can see it for the ones that by default can take LF though, like the Nerv

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5 hours ago, WarriorSabe said:

Yeah, but.. I think you're missing the point. I'm pretty sure the reason for the LF patch is so users don't need CryoTanks. I can see it for the ones that by default can take LF though, like the Nerv

Actually, Methane NTRs have come up before (see KA forum in April 2020), for the same reason Methalox is the Great New Thing in combustion rockets. As @Spaceman.Spiff points out, you have better performance than kerosene, but less than Hydrogen.  It also runs cleaner then Kerosene, and doesn't freeze into solid goo after you've been in orbit for a while.  It doesn't require much power to keep cryogenic, and you don't have individual H atoms making your tank walls brittle or diffusing all the way out to the other side.  It's easy to source raw materials, since Carbon can be be found just about every place there's water, and you don't need a bunch of steps to create a complex hydrocarbon molecule, so ISRU is easy.

I think Nertea's noted before that he's using extremely dense values for LH2, on the order of slush, because many people have a hard time understanding why they need huge LH2 tanks.  The mass of those low propellant density tanks, plus the mass for zero-boil off cooling and insulation, almost cancels out the performance gains of LH2, unless, like many launch vehicles, you're topping off right before launch and burning it before boil-off and tank embrittlement become a problem.  That's fine for starting your trip, but trouble at your destination, months or years away.  In KSP, my Hydrolox upper stages forego solar panels and eclipse shadow batteries, because I'm leaving active tank cooling turned off.  But I need that mass overhead on my LH2 NTRs if I still want propellant for the trip home.

I've modded KA engines to run on LiquidMethane (changed the resource name and lowered Isp) and the resulting vehicle performance is outstanding.  Perversely, not because of the engine performance, but because I could cram much more propellant mass into a fixed payload fairing volume.  CoaDE has a whole section on how tank mass fractions ultimately cap your maximum delta v. 

The big unknown for Methane NTRs is whether they'd deposit a reactor channel-clogging layer of Carbon soot during high temp CH4 decomposition.  How all those molecules recombine depends on operating temp and pressure.  If all you get is Methylene (CH2) and loose H2, you're probably golden.  It may be you WANT some free Carbon, because some fuel rod designs are surrounded by graphite, which gets eaten away by free Hydrogen.

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39 minutes ago, KSPrynk said:

Actually, Methane NTRs have come up before (see KA forum in April 2020), for the same reason Methalox is the Great New Thing in combustion rockets. As @Spaceman.Spiff points out, you have better performance than kerosene, but less than Hydrogen.  It also runs cleaner then Kerosene, and doesn't freeze into solid goo after you've been in orbit for a while.  It doesn't require much power to keep cryogenic, and you don't have individual H atoms making your tank walls brittle or diffusing all the way out to the other side.  It's easy to source raw materials, since Carbon can be be found just about every place there's water, and you don't need a bunch of steps to create a complex hydrocarbon molecule, so ISRU is easy.

I think Nertea's noted before that he's using extremely dense values for LH2, on the order of slush, because many people have a hard time understanding why they need huge LH2 tanks.  The mass of those low propellant density tanks, plus the mass for zero-boil off cooling and insulation, almost cancels out the performance gains of LH2, unless, like many launch vehicles, you're topping off right before launch and burning it before boil-off and tank embrittlement become a problem.  That's fine for starting your trip, but trouble at your destination, months or years away.  In KSP, my Hydrolox upper stages forego solar panels and eclipse shadow batteries, because I'm leaving active tank cooling turned off.  But I need that mass overhead on my LH2 NTRs if I still want propellant for the trip home.

I've modded KA engines to run on LiquidMethane (changed the resource name and lowered Isp) and the resulting vehicle performance is outstanding.  Perversely, not because of the engine performance, but because I could cram much more propellant mass into a fixed payload fairing volume.  CoaDE has a whole section on how tank mass fractions ultimately cap your maximum delta v. 

The big unknown for Methane NTRs is whether they'd deposit a reactor channel-clogging layer of Carbon soot during high temp CH4 decomposition.  How all those molecules recombine depends on operating temp and pressure.  If all you get is Methylene (CH2) and loose H2, you're probably golden.  It may be you WANT some free Carbon, because some fuel rod designs are surrounded by graphite, which gets eaten away by free Hydrogen.

Yes, none of this is new information to me. It's just not relevant because it defeats the entire purpose of the patch, which is to make KA not require Cryo Tanks

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1 minute ago, Spaceman.Spiff said:

Your old post and this one make some excellent points. It's a cool :cool:(get it?) idea, but whether or not Nertea wants to spend the time making configs is the real deciding factor. It would be interesting to see though. 

The config changes were pretty easy after I did the first one; just a matter of consistent parameter scaling, and I didn't care that they were the same models.  To really make it clean, it would just be an additional fuel mode selection, and maybe some cost penalties and/or an additional tech level upgrade prerequisite (like NearFutureSolar).  I was lazy and copy-pasted into a new, unique partname config which otherwise referenced everything the original config did.  That's probably not Nertea's style though....

I wanted to do plume coloration, which should probably be something between LH2 and LF, and I was going to research Real Plume, but since then, we've had Waterfall and SystemHeat, neither of which I've researched the parameters on.  Of the two, SystemHeat is the one I wonder about most, because mass flow rates change (I think - I scaled up thrust to inversely correspond with the drop in Isp, so it may cancel out), and I don't know if the reactor cares or the working assumption is that it's chugging out a fixed amount of waste heat kilowatts for a given power setting, regardless of propellant or how much is passing through.   When SystemHeat finally went mainstream, I was curious if I could do reactor cooling by turning down the reactor power, but keeping the throttle open.  That's open cycle cooling, which you need to do for NTR burns if you don't have radiators (which a bi-modal NTR would, for electrical power during transit coast).  It doesn't seem that easy, so I'm resigning myself to making sure I have the minimum required amount of radiator capacity installed.

33 minutes ago, WarriorSabe said:

Yes, none of this is new information to me. It's just not relevant because it defeats the entire purpose of the patch, which is to make KA not require Cryo Tanks

Yeah, it's just hard for me to suspend disbelief and think anyone would feed RP-1 into an NTR.  That's practically rollin' coal....:D

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