[1.12.x] Cryogenic Engines: Liquid Hydrogen and Methane Rockets! (August 13, 2024)

[priles]

11 hours ago, modus said:

Are you sure your tank configuration is correct? 

Did you check the Dv in atmosphere or in space?

Just in space.

10 hours ago, Rodger said:

It’s basically about trading tank volume for total stage mass. LH2 takes up a lot more volume than LF for the same mass, and isp is based on the mass of the fuel (isp can be thought of as “how long does it take to burn a mass of fuel equal to the engines thrust”, so a higher isp at the same thrust means it will make the fuel last longer). If you have the same *mass* of LH2 as your LF version of the stage, you will get more dV. The other way to take advantage of it is to get a similar total dV compared to LF with a moderately larger tank, but the stage will weigh less, getting more performance out of lower stages.

This post has some good examples https://forum.kerbalspaceprogram.com/index.php?/topic/122020-1123-bluedog-design-bureau-stockalike-saturn-apollo-and-more-v1103-луна-17june2022/&do=findComment&comment=4151104

Thanks for the info!

[GusToTheMoon]

is there a config anywhere that lets me swap the fuel used by the engines (similar to how tank contents are swapped) or am i gonna have to learn how to do that myself?

[Nertea]

19 hours ago, GusToTheMoon said:

is there a config anywhere that lets me swap the fuel used by the engines (similar to how tank contents are swapped) or am i gonna have to learn how to do that myself?

There is a patch in Extras that switches the fuel types but it isn't dynamic. 

[Comm Cody]

I've run into an issue that has been mentioned in this thread, and there doesn't seem to have been any mention of how to resolve it besides a "delete the config" file.
 

I've checked all the engines that are edited in the add on stuff, and only the skiff shows the blue exhaust effect at all time. All the other changed engines from stock or restock/restock+ do not show this effect.

I've updated waterfall, updated this mod, and the effect still persists. Below is my mod list, I'm not sure what to do to revert it to looking normal beyond deleting that one .cfg that converts the skiff into a hydrolox engine, which I would very much prefer not to do.

[Rakete]

Bugreport: Etna-Engine has no Plumes on the turbopump-exhausts

@Nertea Might be of interest for you

[Comm Cody]

follow up to my post about the skiff, installing waterfall, waterfall + restock, and stock waterfall seemed to have fixed the issue.

[Clayel]

Ello, just wanna that the "Erebus" engine has a subtype called "1.25", when it is actually 1.875.

[MrYungZZz]

The tweakscale works for the cryo engines but not methane is that a part of the mod?

[Rutabaga22]

Is way to make the normal stock engines use cryo?

[Zmeya]

On 1/13/2023 at 1:24 PM, Rutabaga22 said:

Is way to make the normal stock engines use cryo?

You can edit the part config files

[Floppster]

Might just be a skill issue, but I can't really figure out the Cougar/Lynx engines. What's the proper way to set up their fuel? I get left with excess of some fuel type every time I try to use them.

Btw this is with the tri-fuel patch.

[Mutantbard64]

I have figured out the methalox problem with ifs at least for me I went into warp plugin and went into patches and deleted the B9 folder files including cryo tanks the cryo tanks from the mod no longer use liquid tritium and lqd ammonia and other nonsense but stock tank still use IFS. hope this could help

[Davi SDF]

On 3/21/2023 at 7:50 PM, Floppster said:

Might just be a skill issue, but I can't really figure out the Cougar/Lynx engines. What's the proper way to set up their fuel? I get left with excess of some fuel type every time I try to use them.

Btw this is with the tri-fuel patch.

You can try to gess the ammount of a certain propellant you will need by removing some of it from the tanks, the higher the Delta V, the more likely you are to have reached the perfect ammount.

 

Otherwise, you can just try to calculate it, most of the time, its as simple as making a ratio (like how much Kerosene you will need for a given Hydrogen+Oxidizer tank).

[Derb]

What is the intended ratio of LF/Ox/LH2 for the Lynx and Cougar? The patch config file gives 1.8 LF : 2.2 Ox : 15 LH2, but the data displayed in VAB and in flight testing gives a ratio of 0.9 LF : 1.1 Ox : 15 LH2.

It's like the patch's changes to to the LF and Ox ratios are not being properly applied - if I change the ratios in the config files for the engines in NFLV to 1.8 LF : 2.2 Ox, the ratio aligns with the ratio given in the patch file.

 

Edit: It appears the patch file is missing the @ character to change the propellant ratios for fuel and oxidizer. Changing to @PROPELLANT seems to fix it.

Edited April 15, 2023 by Derb

[xingchen]

I can't find any fuel tanks that will hold Liquid Methane.  I have the engines unlocked in the VAB, I have CryoTanks in GameData, and I can build a Liquid Hydrogen based rocket just fine.  I can see cryonic fuel tank parts that have a boiloff module that refers to Liquid Methane.  I just can't actually find a way to add a part to a rocket that actually contains the stuff.

 what can I do?

I don`t use Modular Fuel Tanks

[JadeOfMaar]

4 hours ago, xingchen said:

I can't find any fuel tanks that will hold Liquid Methane.

You must somehow not have B9 Part Switch installed. All the tanks in the CryoTanks mod have the option to hold Methane but without B9 Part Switch you're not going to get to choose it.

[mikegarrison]

6 minutes ago, JadeOfMaar said:

You must somehow not have B9 Part Switch installed. All the tanks in the CryoTanks mod have the option to hold Methane but without B9 Part Switch you're not going to get to choose it.

Yes, make sure you have the B9 Part Switch.

All the regular fuel tanks will then have an option to hold LF, Ox, LH2, LCH4, LF/Ox, LH2/Ox, and LCH4/Ox.

The specialized cryo tanks will have all those options except for the LF and LF/Ox choices.

[SimonTheSkink]

Can confirm, this works. Thank you so much!

[DaOPCreeper]

any chance you add tweak scale compatibly to the methane engines?

Edited July 2, 2023 by DaOPCreeper

[urturino]

I want  to use the extra patch for NF Launch Vehicle, and having the Lynx and Cougar using LH2.

 

My question is, there is a easy way to balance CL, Ox and LH2? I always end up with one of the 3 in the tanks, and that is obviously dead weight.

[mikegarrison]

48 minutes ago, urturino said:

I want  to use the extra patch for NF Launch Vehicle, and having the Lynx and Cougar using LH2.

 

My question is, there is a easy way to balance CL, Ox and LH2? I always end up with one of the 3 in the tanks, and that is obviously dead weight.

I'm not aware of any easy way to balance the tanks for the three-propellant rockets. I tend to not use them.

I think maybe they are supposed to work with other engines. Like, if you have nuclear engines that use H2 as reaction mass, you might have a big H2 tank. Then you can use the tri-propellant engines for high thrust when needed by drawing out of the common H2 tank.

[KawaiiLucy]

1 hour ago, urturino said:

My question is, there is a easy way to balance CL, Ox and LH2? I always end up with one of the 3 in the tanks, and that is obviously dead weight.

From my testing, I think you need two tanks: one regular LF+OX and then another tank of the same size with LH2. I think this didn't leave any residual fuel. 

[urturino]

13 minutes ago, KawaiiLucy said:

From my testing, I think you need two tanks: one regular LF+OX and then another tank of the same size with LH2. I think this didn't leave any residual fuel. 

In this way i think i will be short with Ox. Mode 1 use Cl+Ox+LH2, Mode 2 LH2+Ox, or mode 1 use less Ox than usual?

 

28 minutes ago, mikegarrison said:

I'm not aware of any easy way to balance the tanks for the three-propellant rockets. I tend to not use them.

I think maybe they are supposed to work with other engines. Like, if you have nuclear engines that use H2 as reaction mass, you might have a big H2 tank. Then you can use the tri-propellant engines for high thrust when needed by drawing out of the common H2 tank.

That's not how I thought to use them, but it looks interesting. I will try, thanks.

[KawaiiLucy]

Just now, urturino said:

In this way i think i will be short with Ox. Mode 1 use Cl+Ox+LH2, Mode 2 LH2+Ox, or mode 1 use less Ox than usual?

 

That's not how I thought to use them, but it looks interesting. I will try, thanks.

You have two modes:

- high thrust, low efficiency : LF+OX+LH2 with tank proportions 1:1:2

- low thrust, high efficiency: LH2+OX with tank proportions 1:1

Ideally you want to switch mid flight once you reach greater altitudes. Since it is a booster engine you need a lot of thrust on the launchpad, so you use the less efficient mode. But for max efficiency you should pack more LH2+OX  and a tad bit of LF+OX+LH2 just for the beginning of the flight for extra oomph.

This is just a dummy example:

Such a booster will still mainly run on LH2+OX once high enough.

From top to bottom I have a LH2 tank , LF+OX tank, and then big LH2+OX tank

 

 

[urturino]

8 minutes ago, KawaiiLucy said:

You have two modes:

- high thrust, low efficiency : LF+OX+LH2 with tank proportions 1:1:2

- low thrust, high efficiency: LH2+OX with tank proportions 1:1

Ideally you want to switch mid flight once you reach greater altitudes. Since it is a booster engine you need a lot of thrust on the launchpad, so you use the less efficient mode. But for max efficiency you should pack more LH2+OX  and a tad bit of LF+OX+LH2 just for the beginning of the flight for extra oomph.

This is just a dummy example:

Such a booster will still mainly run on LH2+OX once high enough.

From top to bottom I have a LH2 tank , LF+OX tank, and then big LH2+OX tank

 

 

Ok, thanks, i will try this way.