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[1.11.x] Cryogenic Engines: Liquid Hydrogen and Methane Rockets! (Mar 9, 2021)


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Recently, I built two probes headed to the moons of jool, one with NFP Hall Thrusters, and one with Cryogenic H2/LOX. The payloads were similar, but the Cryo engine probe was better in every way (more dV, higher twr, less expensive). I've decided to put moratorium on using Cryo stuff outside of LKO in the interest of realism (read:masochism).

Yet I must ask. Is there any possibility of implementing H2 bleed off? Perhaps as an optional 'hardcore' version along the lines of the recently announced changes to Heat Control?

I can't speak for development goals, but I must admit that you have me really curious how you managed to get more dV and less vessel weight at the same time with identical payload, between a 0.625m electric engine and a 1.25m cryo-engine with less than 1/5th the Isp (assuming a Gyro-One, which is the weakest electric engine in the pack). The cryo-engine alone without fuel should be heavier than the hall thruster plus fuel just through the size difference alone. Could you share some screenshots and/or craft files?

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I can't speak for development goals, but I must admit that you have me really curious how you managed to get more dV and less vessel weight at the same time with identical payload, between a 0.625m electric engine and a 1.25m cryo-engine with less than 1/5th the Isp (assuming a Gyro-One, which is the weakest electric engine in the pack). The cryo-engine alone without fuel should be heavier than the hall thruster plus fuel just through the size difference alone. Could you share some screenshots and/or craft files?

I'm going to refine my statement because you rightfully poked holes in it. Keep in mind this is feedback not criticism!

The goal of these two missions was to place survey scanners into orbit around Joolian moons to map for Ore/MKS resources. When I imagined a mission to Jool with 2+year transit time and no landing requirements, my first thought was 'Ion engines are made for this kind of thing!' Turns out that for this mission, a cryo engine was cheaper and felt easier to execute. I'll detail as follows:

By payload I meant the essential equipment/hardware(probe core, reaction wheel, science stuff, batts & solar panels) bound for the Jool system (not fuel and engines). Thus, the payload of my two vessels was each under .5t.

I built two probes, one powered by a Gyro-One, and one Powered by the 1.25m cryo. The cryo setup does weigh 4x more, and you are correct, as configured, the cryo-engine alone has more mass than the entire Ion setup.

These two configurations had similar dV values and can both perform the same mission, but the cryo version costs less (even after swapping up to larger solid boosters for a more expensive LV), and is easier to fly with 12x better TWR and no risk of losing power while in a planet's shadow.

Maybe I'm preaching to the wrong crowd here, but the whole thing felt like a bit of a letdown. In real life, if it wasn't for the fact that cryogenic hydrogen is a) cryogenic and B) invariably leaks, then it would be the ultimate chemical fuel. Currently, those two factors aren't a part of the mod. I feel that incorporating the cryogenic nature and leakyness of LH2 isn't a nerf, it's an opportunity to add an interesting gameplay mechanic in the same way the Heat Control added a really interesting game mechanic during 1.0.2.

That being said, I feel like the mod already adds tremendously to the game. It gives interesting, powerful and realistic options for launches and upper stage boosters. I simply felt that the balance breaks down at a certain point, and it's worth mentioning since Nertea clearly values balance between his own mods.

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Recently, I built two probes headed to the moons of jool, one with NFP Hall Thrusters, and one with Cryogenic H2/LOX. The payloads were similar, but the Cryo engine probe was better in every way (more dV, higher twr, less expensive). I've decided to put moratorium on using Cryo stuff outside of LKO in the interest of realism (read:masochism).

Yet I must ask. Is there any possibility of implementing H2 bleed off? Perhaps as an optional 'hardcore' version along the lines of the recently announced changes to Heat Control?

Nah. Morally opposed to it :P . RealFuels is what you want.

Can you make the frames for attachment optional via ModuleJettison, like it is done in Ven's revamp, or via some other way? These are perfect for clustering.

OP has what you need, plus I've answered it like 20 times in the thread.

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Minor bug report: In CryoEnginesFuelTankSwitcher.cfg you have :NEEDS[!modularFuelTanks]:NEEDS[!RealFuels], however, MM will only accept one NEEDS node, meaning that this will be applied even in the presence of RF. It should be :NEEDS[!RealFuels&!ModularFuelTanks]

EDIT: CryoEnginesModularFuelTanks.cfg also needs :NEEDS[!RealFuels] on all of its patches

Just bumping this issue. I've fixed it for myself, but I've seen others with RF installed encounter it. The part switcher patches should also have something like :FOR[zCryoEnginesPatches] so that they apply after any part duplication patches.

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I have removed a line in your Cryo MFT CFG (bold type in red). I don't think it was your intention to edit the available tanks, but just add to them.

/ CryoEngine MFT (Modular Fuel Tanks) Configuration File
// by funk 06/04/2015 released under ... Public License
//------------------------------------------------------//


// Adds LqdHydrogen to default tank definition
@TANK_DEFINITION[Default]
{
TANK
{
name = LqdHydrogen
amount = 0
maxAmount = 0
mass = 0.0000625
utilization = 10
}
}


// Adds LqdHydrogen to fuselage tank definition
@TANK_DEFINITION[Fuselage]
{
TANK
{
name = LqdHydrogen
amount = 0
maxAmount = 0
utilization = 10
}
}


// Adds LqdHydrogen to fuselage tank definition
@TANK_DEFINITION[Structural]
{
TANK
{
name = LqdHydrogen
amount = 0
maxAmount = 0
mass = 0.000375
utilization = 10
}
}


// Adds LqdHydrogen to ServiceModule tank definition
@TANK_DEFINITION[ServiceModule]
{
TANK
{
name = LqdHydrogen
amount = 0
maxAmount = 0
mass = 0.0000625
utilization = 10
}
}


// Adds tank definition for CryoEngines
TANK_DEFINITION
{
name = Cryogenic
basemass = 0.000625 * volume
baseCost = 0.815 * volume
TANK
{
name = LqdHydrogen
mass = 0.0000625
amount = full
maxAmount = 50%
utilization = 10
}
TANK
{
name = Oxidizer
amount = full
maxAmount = 50%
}
}
//------------------------------------------------------//


// Adds tank type Cryogenic to all default tanks
@PART
[*]:HAS[@MODULE[ModuleFuelTanks]]:FINAL
{
@MODULE[ModuleFuelTanks]:HAS[#type[Default]]
{
[B][COLOR=#ff0000] %typeAvailable = Default[/COLOR][/B]
typeAvailable = Cryogenic
}
}

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  • 2 weeks later...
Hey, thanks for the notes about the bugs in the various patches. I'll ensure they are added to the next version of the mod.

It might help with crowdsourced bugfixing if you put everything in a Github repository. That way people could fork, edit, and submit pull requests, and all you have to do is review and merge :)

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Muck kudos for this mod, I use it for almost all my rocketry needs. I have a question and a request...

Question. Is the Tunguska supposed to have the same thrust as the Volcano?

Request. Would it be possible to add a low profile 'lander' style engine to the pack?

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Muck kudos for this mod, I use it for almost all my rocketry needs. I have a question and a request...

Question. Is the Tunguska supposed to have the same thrust as the Volcano?

Request. Would it be possible to add a low profile 'lander' style engine to the pack?

The Tunguska is an upper stage. Having the same thrust as a smaller lower stage rocket isn't unreasonable. Also to my knowledge, landers don't tend to use cryogenic fuel, especially hydrolox.

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Blowfish covered it pretty much - low profile hydrolox engines are unlikely. Methalox engines are more likely to be low-profile and lander based, there is a RS-18 analogue in NFSpacecraft, and I have considered expanding CryoEngines with a few methalox-based engines in the future. Main problem is the lack of designs, there would be the BE-4 and the RD-0162, the RS18 and maybe the Morpheus lander engine. And of course, the Raptor, but there's really no reference for that yet ;).

Nathan... I'm working on it, the dev branch of NFE is now 100% git and I'm transitioning the rest ;).

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Nathan... I'm working on it, the dev branch of NFE is now 100% git and I'm transitioning the rest ;).

That's just the plugin code though, isn't it? It would be great to also have the rest of the mod on github, like the part definitions and patches and stuff. Then I could for example open a pull request for fixes like the reactor internal/skin ratio thing.

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I put CryoEngines, InterstellarFuelSwitch and that BD animation thing in GameData, deleting CryoEngines got rid of the problem, but I've lost all my subassemblies, craft, and my one ship in orbit, luckily this wasn't my main save file, only my RSS one.

What error message did the game give you when you loaded the save? If your craft did not load because of invalid parts, you will get a pop up saying so, and what parts are missing/invalid.

As for the craft files, they would not have been deleted. The craft files would still show up in the editor with the "contains locked or invalid parts" warning on them. If you tried to load them, then they would break along with the rest of the game.

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Would you consider making a plugin for the Rapier (and the Broadsword from your own Mk4 mod) to use LH2/LOX instead of LF/LOX during closed cycle alongside an increased ISP of 460 (or a bit less if you want to balance it with the regular cryogenics)? Open cycle would still use LF.

Edited by More Boosters
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Would you consider making a plugin for the Rapier (and the Broadsword from your own Mk4 mod) to use LH2/LOX instead of LF/LOX during closed cycle alongside an increased ISP of 460 (or a bit less if you want to balance it with the regular cryogenics)? Open cycle would still use LF.

Actually, the SABRE engine burns hydrogen from the runway all the way to orbit. At no point does it use Kerosene or Jet fuel of any type.

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Well, ACTUALLY the SABRE engine only exists as a concept. What TRL is it at? TRL 3 maybe?

In that ballpark. Going by NASA's TRL definitions (http://esto.nasa.gov/files/trl_definitions.pdf)

and this video from 2012 (showing precooler testing):

looks like they were working on TRL 4-ish things ("Component/subsystem validation in laboratory environment") in 2012 ...

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