[1.12.x] Cryogenic Engines: Liquid Hydrogen and Methane Rockets! (Jan 22, 2022)

[MaximumThrust]

8 hours ago, PocketBrotector said:

My only suggestion is to provide documentation and/or lead time to facilitate the updating of other mods that use the CryoEngines ratios/density. I know that BDB and SpaceY have some tanks/engines that use LH2(/O), and I think USI does too? And probably a number of others have one or two parts or patches that would be affected.

I don't know if there's a way to get a full list (maybe if I learned how to query CKAN to see what mods have CryoTanks as a dependency, I guess). But the CryoEngines paradigm gets used as a sort of de factor community standard, and I'm sure you'd prefer to cut down on the number of times that people ask why LH2O tanks have the "wrong" propellant ratios when used with engines from mod XYZ.

I think that should be easier and less problematic to change only the tanks, without touching the engines. This maybe can also keep the old ships working, IIRC, tanks in existing ships don't update when changing configs.

I'm playing around with the LH2 tanks, and liking very much. So far I didn't see the need to make the tanks more compact, and they would still be huge with a 30% reduction.

I also edited some things in the boil-off configs in my install. I changed the Ec use from 0.09 to 0.1 for the normal tanks, so it gives round numbers that are easier to calculate before launching. And changed to 0.05 in the insulated tanks, so I have something that justifies the higher cost and lower heat tolerance (and also give round numbers), but don't make the normal tanks obsolete for vacuum operations. I was thinking in making them lighter, but that would mess too much with the balance of the engines, especially the nuclear ones.

[PocketBrotector]

13 hours ago, KSPrynk said:

I was curious about this too.  Does every mod with a tank part have to "get on board" with the changes, or is Cryo Tanks simply applying a patch that calculates the appropriate LH2/O mass and mix ratio based on the starting LFO capacity?

CryoTanks has a patch that adds LH2 configurations to most tanks, but some mods handle it on their own - last time I looked at USI Kontainers, for example, they had their own fuel-switching configs, so they're exempt from the CryoTanks patch.

13 hours ago, MaximumThrust said:

I think that should be easier and less problematic to change only the tanks, without touching the engines. This maybe can also keep the old ships working, IIRC, tanks in existing ships don't update when changing configs.

That's a question for Nertea, I think; but the way that I read his post is that the "densification" of the tanks would be driven by the change in propellant ratios, and the change in propellant ratios necessarily means changing the engines (each engine specifies its own propellants, including ratios).

[MaximumThrust]

40 minutes ago, PocketBrotector said:

That's a question for Nertea, I think; but the way that I read his post is that the "densification" of the tanks would be driven by the change in propellant ratios, and the change in propellant ratios necessarily means changing the engines (each engine specifies its own propellants, including ratios).

Yes, what I meant is: keep the 15:1 ratio, and increase the capacity, cost and mass of the cryo tanks. It would achieve a similar result, without messing with the engines.

[Nertea]

You really can't expect everything in the world to stay static. I didn't intend that my mods would become a standard, except for CTT, and if I want to change some things, then I can totally do that... unfortunately others might have to adapt. 

Squad sticking with the same screwed up balance forever, for example, is why KSP's balance is utter excrements because they were too concerned with not breaking anything ever, and now it's too late.

This is still just a proposal with gathering feedback. 

49 minutes ago, PocketBrotector said:

That's a question for Nertea, I think; but the way that I read his post is that the "densification" of the tanks would be driven by the change in propellant ratios, and the change in propellant ratios necessarily means changing the engines (each engine specifies its own propellants, including ratios).

Yes that's correct. If you just stuff more crap in all the tanks, you create inconsistency which I hate even more than anything else. 

[Wyzard]

On 3/22/2018 at 2:59 PM, Nertea said:

I'm thinking of doing a thing in the next update which will break stuff. Currently combustion ratios for the engines are a bit hydrogen heavy (15:1 cfg ratio). I would change that to 10:1, which has the advantage of making it a little closer to realism, mass-flow wise.

I'd be interested in this, and breakage won't bother me because I'm not starting a 1.4 game until after you've updated all your stuff. 

Tank size/volume is the thing that's always bothered me most about CryoTanks — it always feels like the tanks are too small for the engines they're meant to go with.  The tallest 1.25m cryo tank doesn't hold enough fuel to get the dV I want with the mass of a 1.25m, engine, and the tallest 2.5m tank doesn't hold enough to get the dV I want with a 2.5m engine.  I end up using a 2.5m tank with a 1.25m engine on the back, or a 3.75m tank with a 2.5m engine on the back.  (And/or festooning the craft with additional radial tanks.)  So ~30% more fuel per tank would be appreciated.

But yeah, ripple effects on other mods with cryo tanks (like USI) is an issue.  I've submitted patches to USI in the past to fix inconsistencies with your stuff, and I'll probably do so again (if necessary) once I start playing 1.4, but there's still the lag time for adjustments to get released in USI and whatever other mods, and people designing spacecraft in the meantime based on old/inconsistent ratios.  On the other hand, with many players starting new careers and/or waiting for mods to be updated to 1.4, now is probably a better time than any other to do it.

As far as "gamifying" the balance, I think storing ArgonGas at 320atm pressure sets the precedent. 

[techgamer16]

Has this mod been updated for 1.4.1 or not quite yet? Thanks.

[JadeOfMaar]

8 hours ago, techgamer16 said:

Has this mod been updated for 1.4.1 or not quite yet? Thanks.

The thread title...  

[Maffif]

I agree with @Wyzard and many others here, an increased gamefication of Hydroloxi would be very welcome

[Nertea]

It seems like there's little disagreement that something here needs to change. Now, I'm not aware of a huge number of mods that specifically depends on CryoEngines for balance and function. Typically my patches will handle all tank mods unless the mods specifically implement their own version. If you all know any mod authors that might be affected by a ratio change please direct them here to discuss. I have heard that SSTU and @Shadowmage follows the same numbers at least so I'd appreciate input on how unpleasant this would be. If USI also uses these ratios, maybe @RoverDude could chime in?

For reference:

• A proposed combustion ratio change to 10 LH2 : 1 OX (closer to reality based on mass flows) instead of 15:1
• A proposed tankage change to match this
• A modification of tankage values to normalize volume utilization across the board (currently too low for LH2/Ox mixture)
• A set of changes to cooling costs to make all this nicer

Remember, with cases like this we can only improve by being willing to break things.

Of course, MH introduced an abysmally balanced J2 and SPS pair, with 400+ Isp on the latter, which probably screws CE balance no matter what. I'm just going to ignore that data point...

Some specific answers:

On 3/22/2018 at 7:57 PM, KSPrynk said:

@Nertea, if you're re-balancing the tank ratios, I would also suggest a fresh look at the thrust levels of the cryo- and NTR- engines.  I've enjoyed the realism of LH2 causing design heartache on the volume front, made up for by the efficiency of the high Isp engines for orbital use, but I've always found it disconcerting to have to use outrageously large engines - compared to the tanks they go with - for getting into orbit, much less off the ground.  I personally haven't had problems with large vehicle assembly in orbit, but that may be a function of my recent use of KJR and/or weldable construction ports....  

I will have a look when I do this. It might solve itself naturally with the changes, but there is an intent that a given cryogenic engine has less TWR than the equivalent LF/OX engine. 

On 3/23/2018 at 2:00 PM, lordcirth said:

I'm playing Career with KSP 1.3.1, with NFLV, CryoEngines, and CTT.  The CTT engine placement seems odd.  The Chelyabinsk and Tunguska, successive sizes of vacuum engine,  are both in Heavier Rocketry(160).  I seem to remember the Chelyabinsk being in Heavy Rocketry(90) in the past.  The Volcano and Odin, 2 sizes of sustainers, are both in Very Heavy Rocketry(550).  Why are different sizes of engine in the same node?  Unless this is a bug?

Might be a bug. Might be worth a look. 

On 3/23/2018 at 8:47 PM, KSPrynk said:

I was curious about this too.  Does every mod with a tank part have to "get on board" with the changes, or is Cryo Tanks simply applying a patch that calculates the appropriate LH2/O mass and mix ratio based on the starting LFO capacity?

Typically I mass-patch tanks, unless a mod distributes engines or specifically coded LH2 tanks, adjustment would be automatic. It would not be fun for ships in flight, but since I'm winding down my KSp modding activities, this is probably the last time this will happen. 

[Shadowmage]

18 minutes ago, Nertea said:

I have heard that SSTU and @Shadowmage follows the same numbers at least so I'd appreciate input on how unpleasant this would be.

Indeed, I use the ratios defined by CryoEngines/CryoTanks for SSTU's HLOX fuel type.

As I haven't yet updated SSTU for KSP 1.4+ (and I've already stated it would be save-breaking update), this change wouldn't cause any real problems on my end.  I would have to change one 'fuel type' definition used by the fuel tank system, and adjust configs in a few engines for the new ratio.  Worth the effort to maintain compatibility with your engines and tanks.

I appreciate your considerations, and don't foresee any problems adapting to the changes on my end (I'll just have to remember to make the changes ).

[theonegalen]

25 minutes ago, Nertea said:

I'm winding down my KSp modding activities

You make me sad. Near Future has been an essential part of my install for years, but that's a long time to put in a lot of effort for very little game. Thank you for everything you've done as a KSP modder. 

Regarding changing CryoTanks, I think it's a good idea now that I've gotten over my initial fear of things changing or being left behind in the change. Feel free to ignore the MH engines; it is a trivial matter to fix those with mm patches.

[Kerbas_ad_astra]

SMURFF and VSR lean on CryoTanks for some of their patches, but VSR has other things that need resolving before a 1.4 update is published, and since RSS hasn't been updated for 1.4 yet, I doubt anyone's using SMURFF with KSP 1.4 right now, so the 'pain' of adapting to a new tank balance is minimal at this time.  Do what you gotta do, I'll adapt.

[PocketBrotector]

6 hours ago, Nertea said:

If you all know any mod authors that might be affected by a ratio change please direct them here to discuss.

Here is what I happen to recall from mods that I have used personally at some point in time.

• I think BDB has at least one engine that uses LqdHydrogen, or at least has an option to do so. @CobaltWolf
• SpaceY has one or more engines that can switch to using LqdHydrogen. @NecroBones
• WildBlueTools has a CryoEngines patch. @Angel-125
• I know that @benjee10 was thinking of including LqdHydrogen configs for reDIRECT so I'll include him here too...

6 hours ago, Nertea said:

It would not be fun for ships in flight, but since I'm winding down my KSp modding activities, this is probably the last time this will happen. 

Say it ain't so. This will be the end of a great era when it happens. The Near Future etc. mods were and are among the very best content for KSP. Many thanks to you and @Streetwind for all your fine work.

Edited April 3, 2018 by PocketBrotector
re-tagged names

[Jso]

23 hours ago, Nertea said:

A proposed combustion ratio change to 10 LH2 : 1 OX (closer to reality based on mass flows) instead of 15:1

This I'm opposed to because I don't think it's necessary.

The stoichiometric fuel/oxidizer ratio for Oxygen/Hydrogen is 8:1. I believe the most efficient ratio for a rocket engine is 4:1, but that's very volume inefficient so real engines compromise and run in the 5:1 to 6:1 range. The current 15-1 ratio we all use is about 4.7:1 by mass, and at a 10-1 ratio it would be about 7:1 by mass. So it's not really closer to reality, just different. But this is not RO and none of that is relevant 

This image shows the current problem with the mixed tanks well. Since 15-1 works out to 3-1 by volume you can use 4 identical tanks, with 3 holding pure LH2 and the other holding Oxidizer. The left half of the image is the vessel using pure tanks, and the right half is mixed tanks. They should be identical but the mixed fuel setup has both a heavier dry weight and less total fuel. If you do not agree they should be identical in both total fuel and dry mass we have different ideas of "balance".

While switching to a 10-1 ratio would improve fuel mass, simply correcting the above issue would by itself have a significant impact on vessels using mixed tanks.

Ratio	Tons Fuel per 1000 units of volume
15-1 Current	1.213
15-1 Corrected	1.516
10-1 Proposed	1.903

Note that the dry mass is also too heavy on the current tanks so the difference is more dramatic than just the fuel mass the table shows.

There is also the proposal to compress the hydrogen to 150% to allow smaller tanks on pure LH2 vessels. Doing that to the pure tanks means you should do it to the mixed tanks as well. Only the LH2 portion is compressed from 5:1 to 7.5:1, the Oxidizer portion remains 1:1 per unit of volume. That gives you this:

Ratio	Tons Fuel per 1000 units of volume
15-1 150% LH2	2.021
10-1 150% LH2	2.447

So by correcting the volume issue, compressing the hydrogen, and changing the mixture to 10-1, and you are doubling the mass of fuel in mixed tanks compared to current. I think that might be more than some people are bargaining for. (It's actually slightly more fuel than the old double density tanks held: 2.425 tons per 1000).

A less gamey approach to compressing to 150% would be compressing to not more than 120% and calling it slush hydrogen. That's at least a thing. I don't really have a strong opinion there and you can do what you want with compression without effecting other mods. Changing to 10-1 means other mods have to follow suit or we have incompatible engines and tanks.

 

[Kerbital]

On 4/2/2018 at 5:28 PM, theonegalen said:

You make me sad. Near Future has been an essential part of my install for years, but that's a long time to put in a lot of effort for very little game. Thank you for everything you've done as a KSP modder. 

Regarding changing CryoTanks, I think it's a good idea now that I've gotten over my initial fear of things changing or being left behind in the change. Feel free to ignore the MH engines; it is a trivial matter to fix those with mm patches.

Yup. Same here. I can't play KSP without Nertea's mods. Once NF mods become incompatible and outdated it'll be time to put KSP away for good. Such a pitty, Nertea put some much work in these. But I guess life happens. One can't expect the modders to go on forever. Such is the nature of mods.

[Nertea]

Well, let's just try 150% density on it and see what happens. 

 

On 4/3/2018 at 3:12 PM, Jso said:

They should be identical but the mixed fuel setup has both a heavier dry weight and less total fuel. If you do not agree they should be identical in both total fuel and dry mass we have different ideas of "balance".

No need to be so snarky

[Jso]

46 minutes ago, Nertea said:

No need to be so snarky

Apologies, not meant that way. I need a proof reader sometimes.

[Kerbas_ad_astra]

On 4/3/2018 at 6:12 PM, Jso said:

This image shows the current problem with the mixed tanks well. Since 15-1 works out to 3-1 by volume you can use 4 identical tanks, with 3 holding pure LH2 and the other holding Oxidizer. The left half of the image is the vessel using pure tanks, and the right half is mixed tanks. They should be identical but the mixed fuel setup has both a heavier dry weight and less total fuel.

Part of the issue there is that the mixed-tank definition of 6 units of LH2 and 0.2 units of Oxidizer per liter only adds up to 0.8 L, so the mixed tanks are only 80% utilized.  Increasing the per-liter contents by 25% (7.5 U LH2, 0.25 U Ox) would make the two setups hold identical amounts of fuel.  (Normally I'd also increase the dry mass per unit by the same amount, but that would exacerbate the gap in dry masses, so some other tinkering may be required -- possibly an issue with the math in the tank-switcher patch, since keeping a consistent 20% LH2 and 12.5% Ox mass fraction should work out the same for four mixed tanks or four pure tanks.)  It would also let people get away with rockets 20% shorter than they currently fly.

Edited April 7, 2018 by Kerbas_ad_astra

[Nertea]

A test version of CryoTanks with most of the planned balance changes can be downloaded by pulling my dev branch. I'd appreciate input, it's pretty messy and needs cleanup but the basics should be there. Mainly:

• 7.5 units of LH2 per volume unit (instead of 5)
• Mixed tanks made consistent
• Dry masses cleaned up

Edited April 7, 2018 by Nertea

[KSPrynk]

18 hours ago, Nertea said:

A test version of CryoTanks with most of the planned balance changes can be downloaded by pulling my dev branch. I'd appreciate input, it's pretty messy and needs cleanup but the basics should be there.

@NerteaMy thoughts so far:

1. I love the new short tank clusters, and especially the "compact" and "bare" configurations.

2. The tank contents switching utility seems to work fine with a small sample of stock and mod tanks I've tried out, including Fuel Tanks Plus, SpaceY Heavy Lifters, and Home Grown Rockets. The LFO engines appear to pull the appropriate ratios evenly, so that's working as expected.

3. The gold foil texture for the tanks seems closer to foam, in fact more so than the older textures I think.  I think that's a function of them having low contrast between the bright and dark areas of the "crinkles", a softer apparent transition between those bright and dark areas, and a relatively low specular reflection overall on the tank.  I think USI's Kontainer Tank textures are a good example to refer to for improvement.  The default gold texture on those parts looks much more metallic.

4. I'm withholding judgement on the densification to "gameify" the tanks until there are updated Cryo and NTR engine parts.  As I've noted earlier, I think both sets of engines were chronically underpowered to begin with.  This impacted the utility of the LH2/O2 engines for second stages to finish the last leg of the climb and circularize to orbit.  For the NTRs (without O2 thrust augmentation), I thought the engine count or size class to get a large Duna-bound craft to no less than a 0.1g TWR to keep gravity losses reasonable during ejection burns (even from high orbit) was also a bit disappointing.

Either way, I'm looking forward to the updates.

Edited April 8, 2018 by KSPrynk

[Wyzard]

19 hours ago, Nertea said:

• 7.5 units of LH2 per volume unit (instead of 5)

This seems a little weird to me — it's sort of an indirect way of changing the volume ratio from 15:1 to 10:1, by keeping the 15:1 numerical ratio but changing the units in which the 15 is measured.  It's a bit confusing because it breaks the usual CRP rule (if I understand correctly) that 1 liquid unit is 1 liter.  But I recognize that it's probably simpler than actually changing the volume ratio, and less likely to have "ripple effects"  since engines don't need to change.  So I think it's weird, but I'm not really opposed to it.

BTW, I noticed a few small issues with the tank models:

• There's some Z-fighting on the bottom of the H250-16 tank, around the 1.25m attachment plate.
• The HR-1 tank looks like it's missing one of the metal supports that hold the tank.  (There's a groove in the tank texture that shows where the metal piece is supposed to be.)
• The part icons (in the VAB's part menu) for many of the tanks show only the foil tank part of the model, not the metal support structure.  Looks like all the tanks that have switchable full/compact/bare alternatives are affected.  (I think I've read somewhere that this is quirk of B9PartSwitch, related to how switchable meshes are set up.)

[Nertea]

 

1 hour ago, KSPrynk said:

3. The gold foil texture for the tanks seems closer to foam, in fact more so than the older textures I think.  I think that's a function of them having low contrast between the bright and dark areas of the "crinkles", a softer apparent transition between those bright and dark areas, and a relatively low specular reflection overall on the tank.  I think USI's Kontainer Tank textures are a good example to refer to for improvement.  The default gold texture on those parts looks much more metallic.

No. I spent probably 30 hours developing this style, evaluating it, and porting it to everything. I don't think that the USI container is a good model of what I'm going for. These are. 

1 hour ago, KSPrynk said:

For the NTRs (without O2 thrust augmentation), I thought the engine count or size class to get a large Duna-bound craft to no less than a 0.1g TWR to keep gravity losses reasonable during ejection burns (even from high orbit) was also a bit disappointing.

I'm not going to change this much if at all. Here's why:

Item	TWR	Isp
LV-N (LF)	2.0387	800
LV-N (LH2)	2.7183	900
Neptune	2.9695	950
Poseidon	3.0096	925
Liberator	7.5989	1625

 

 

 

 

 

They're already better in every way than the stock LV-N. For more thrust, you *should* use thrust augmentation.

25 minutes ago, Wyzard said:

• here's some Z-fighting on the bottom of the H250-16 tank, around the 1.25m attachment plate.
• The HR-1 tank looks like it's missing one of the metal supports that hold the tank.  (There's a groove in the tank texture that shows where the metal piece is supposed to be.)

I'll look into that.

55 minutes ago, Wyzard said:

• The part icons (in the VAB's part menu) for many of the tanks show only the foil tank part of the model, not the metal support structure.  Looks like all the tanks that have switchable full/compact/bare alternatives are affected.  (I think I've read somewhere that this is quirk of B9PartSwitch, related to how switchable meshes are set up.)

I don't have this, do you have B9PS 2.2.1? This was fixed for 1.4.2 quite recently.

 

[Wyzard]

14 minutes ago, Nertea said:

I don't have this, do you have B9PS 2.2.1? This was fixed for 1.4.2 quite recently.

Oops, didn't notice it'd been updated.  (AVC didn't tell me about it, strangely.)  Part icons are good now — sorry for the false alarm.

[blowfish]

7 hours ago, Wyzard said:

Oops, didn't notice it'd been updated.  (AVC didn't tell me about it, strangely.)  Part icons are good now — sorry for the false alarm.

Due to the way B9PartSwitch's AVC file is configured, you won't see an update notification if you upgrade KSP but keep an older version of B9PartSwitch.

[Critter79606]

On 4/7/2018 at 1:20 PM, Nertea said:

A test version of CryoTanks with most of the planned balance changes can be downloaded by pulling my dev branch. I'd appreciate input, it's pretty messy and needs cleanup but the basics should be there. Mainly:

• 7.5 units of LH2 per volume unit (instead of 5)
• Mixed tanks made consistent
• Dry masses cleaned up

Nertea, got a chance to load the dev branch into 1.4.2.  Everything looks good, and I like the textures a lot better than the old gold ones.  I especially like the compact version of the multi tank unit.