Nertea

[1.6.x] Cryogenic Engines: high Isp chemical rockets! (January 21)

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I don't get this. In KSP these cryogenic engines are very rarely more efficient than LF/LOX engines, usually only good for upper stages (ironic as cryogenics are mostly used at lower stages in real life) and that's because it keeps the upper stages lighter.

Am I missing something? Because if what you say is true and these cryos are more effective than in real life, then how come cryogenic engines are considered better if more expensive?

for now cryo engines should be barely better (dV wise) than stock engines. However the key lies in tank weight. For example if cryogenic engines are coupled with dedicated composite cryogenic tanks (already built by NASA for SLS) you can squeeze much more dV from all stages:

4pIzebi.png?1

Someone really should make a high-tech composite LH2/Ox tanks mod :P so that player could unlock 40% lighter LH2/ox tanks thus making cryogenic engines much more viable in later game.

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for now cryo engines should be barely better (dV wise) than stock engines. However the key lies in tank weight. For example if cryogenic engines are coupled with dedicated composite cryogenic tanks (already built by NASA for SLS) you can squeeze much more dV from all stages:

http://i.imgur.com/4pIzebi.png?1

Someone really should make a high-tech composite LH2/Ox tanks mod :P so that player could unlock 40% lighter LH2/ox tanks thus making cryogenic engines much more viable in later game.

Near Future Propulsion has dedicated LH2 or LH2/LOX tanks but they only carry like 10% more than regular tanks. How much they differ in weight IDK.

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Near Future Propulsion has dedicated LH2 or LH2/LOX tanks but they only carry like 10% more than regular tanks. How much they differ in weight IDK.

you can just decrease weight of LH2 tanks to 60% (NFP to 66%) of their original masses and you'll have composite tanks stats. Then cryogenic propulsion will be a lot more viable for you than standard one :)

As a side effect NFP engines running on LH2 will get a boost too :P

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you can just decrease weight of LH2 tanks to 60% (NFP to 66%) of their original masses and you'll have composite tanks stats. Then cryogenic propulsion will be a lot more viable for you than standard one :)

As a side effect NFP engines running on LH2 will get a boost too :P

I do believe they are already lighter though. 2.43 t dry mass for a Jumbo-sized LH2 tank vs 4t for Jumbo. Though it still doesn't seem to make the thing much more efficient and costs an arm and a leg. The tallest 3.75m tank has a cost of around 49k, just for the tank itself!

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IIRC, the dry mass for LH2 tanks in this mod (and many others, except KSPI-E and possibly RF) includes the mass associated with the extra insulation, tank wall thickness, and machinery required for a zero boiloff LH2 tank.

That's why they have such abysmal mass ratios.

No hydrolox rocket stage yet flown IRL has included cryocooling equipment or the large amount of extra insulation, SPECIFICALLY because they absolutely wreck the payload mass fraction.

There are spherical tanks in KSPI that have a mass ratio of 10:1, but they require power to keep the contents from boiling. Of course running KSPI means you're never at a lack of power for "maintinence" tasks like running the cooling equipment on a LH2 tank, so it's no big deal there.

Perhaps having some sort of boil-off would be usable? And if NFP is installed, maybe a module that takes a bit of power to keep the LH2 from boiling off.

Otherwise, I don't really see a point to using this mod when I could use the RAM for something like NFP and NFE.

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I don't get this. In KSP these cryogenic engines are very rarely more efficient than LF/LOX engines, usually only good for upper stages (ironic as cryogenics are mostly used at lower stages in real life) and that's because it keeps the upper stages lighter.

This is false. There exists only one launch vehicle IRL with a real cryogenic first stage: the Delta IV. And only the Heavy configuration actually flies in pure, unassisted hydrolox mode without boosters. ULA's top brass has described it as a "failed experiment" and stated that they won't be doing that anymore with future launch vehicles.

All other launch vehicles with large cryogenic ascent stages use them in a "sustainer" configuration. The low-thrust sustainer stage ignites on the pad together with the booster stage, which is generally made up of large solid rocket motors, and burns all the way to orbit. Examples for this are the Ariane 5, the STS (space shuttle), the HII-B and the planned SLS. The vast majority of launch vehicles meanwhile - Proton, Soyuz, all of the Long March's, the PSLV and GSLV's, Atlas V, Dnepr, Rokot, Safir, Simorgh, Falcon 9, Pegasus, Vega, Angara, Antares, Minotaur, Unha, Zenit etcetera etcetera all use kerosene, solid fuels or hypergolics in their ascent stages. The world-famous Satrun V moon rocket also used kerosene in its first stage, while both upper stages were cryogenic.

Someone really should make a high-tech composite LH2/Ox tanks mod :P so that player could unlock 40% lighter LH2/ox tanks thus making cryogenic engines much more viable in later game.

The problem with composite tanks is that they dissolve or shatter when loaded with cryogenic fuel :P

No, really. The industry has desperately sought to make them work for a long time. And it's only very recently - in the past year, in fact - that we've actually seen launch vehicles announced that aim to use composite tanks. And they will not use them for "hard cryogenic" fuels like hydrogen, but rather for the moderate to soft oxygen and methane. Nobody knows what they've done to make it work yet, because they keep their secrets closely guarded and the rockets aren't flying yet.

Composite tanks for cryogenic fuels are a future technology, and while that doesn't rule out a "high tech" mod like you suggest, I just wanted to point out that it's far less simple than you think it is ;)

The tallest 3.75m tank has a cost of around 49k, just for the tank itself!

Near Future engines, tanks and other equipment are all absurdly expensive because they outperform stock propulsion by so much (especially the hydrogen engines, which are statted up too good right now), and because they're not meant for expendable use. Those are not launch vehicle tanks, which are just barely sufficient shells around the fuel that only need to survive a couple minutes. They're things you're supposed to launch into space and then keep using over and over in orbital tugs, or to fly mission profiles so aggressive that no other solution can give you the dV.

IIRC, the dry mass for LH2 tanks in this mod (and many others, except KSPI-E and possibly RF) includes the mass associated with the extra insulation, tank wall thickness, and machinery required for a zero boiloff LH2 tank.

*snip*

Perhaps having some sort of boil-off would be usable? And if NFP is installed, maybe a module that takes a bit of power to keep the LH2 from boiling off.

This is correct. The LH2 tanks are inspired by those described by NASA in their Mars Design Reference Architecture for multi-year storage of hydrogen. That's why their mass ratios are around 3:1, while launch vehicle grade tanks can get as high as 15:1 - 20:1.

There will be no boiloff mechanics implemented unless Nertea changes his mind, because he has stated in the past that he doesn't care for it. It would require extra plugin coding just for a function that complicates things unnecessarily and potentially aggravates players. Near Future is not a realism mod, it is a stock extension. The amount of extra mechanics it has is already very large as is. And Cryogenic Engines is mostly a stand-alone engine pack that Nertea made because he randomly got inspired to model engines one day and people poked him to release them. :P

Edited by Streetwind

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The problem with composite tanks is that they dissolve or shatter when loaded with cryogenic fuel :P

No, really. The industry has desperately sought to make them work for a long time. And it's only very recently - in the past year, in fact - that we've actually seen launch vehicles announced that aim to use composite tanks. And they will not use them for "hard cryogenic" fuels like hydrogen, but rather for the moderate to soft oxygen and methane. Nobody knows what they've done to make it work yet, because they keep their secrets closely guarded and the rockets aren't flying yet.

Composite tanks for cryogenic fuels are a future technology, and while that doesn't rule out a "high tech" mod like you suggest, I just wanted to point out that it's far less simple than you think it is ;)

Thx for info. Yah, "NASA Completes Successful Battery of Tests on Composite Cryotank", however it is scaled 1:2. They mentioned something about the project is high-risk/high-reward so I guess the development might still fail when they start doing 1:1 scale tank. And yah for now I guess they concentrate mainly on upper stage LH2 tank for SLS.

Having said that the 1:2 scale tank has 5m diameter and it completed all tests in a test chamber. This fares well for technology especially for smaller tank manufacturing. For now they are talking about 30% mass reduction and 20% cost reduction (I thought they wouldn't need to use autoclave for manufacturing composite cryo tanks but recently NASA's got composite layering robot along with autoclave so I don't know whether or not they would need it).

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Hey Nertea, Streetwind, I've updated to the last release and recognized an old MFT-patch. I made a new one in July regarding the dry mass fraction changes and RealFuels. Here you can download it...

Regarding tank switch I'm not sure if it's working without "typeAvailable = Default". For me it works as intended with it. After all the cryo tanks are just changed default tanks, either by changing the fuel fraction in "default" or switching to "cryogenic". Nevertheless, there aren't many complains about it, so it seems most people are using IFS.

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I'd love to see an extension of this mod using some... not so practical (putting it lightly) propellants like fluorine or boron compounds, metallic hydrogen, difluoride dioxygen, etc. If anyone can figure out a way to use these types of things, it'll be the kerbals :sticktongue:

I guess I forgot to mention that I really like this mod, the engines look great and are reasonably well balanced. Playing with 6.4x, KWRocketry, and this. I also tried Bobcat's soviet engine pack, and while they are great, they are of course not balanced for a serious career playthrough :P

Edited by Nnimrod

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This is false. There exists only one launch vehicle IRL with a real cryogenic first stage: the Delta IV. And only the Heavy configuration actually flies in pure, unassisted hydrolox mode without boosters. ULA's top brass has described it as a "failed experiment" and stated that they won't be doing that anymore with future launch vehicles. **snip**

Everything in this post is awesome and educational. I find the costs are well balanced for the delta-v you get, that's a fair payment for high efficiency engines (to be re-used, of course).

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I'd love to see an extension of this mod using some... not so practical (putting it lightly) propellants like fluorine or boron compounds, metallic hydrogen, difluoride dioxygen, etc. If anyone can figure out a way to use these types of things, it'll be the kerbals :sticktongue:

I guess I forgot to mention that I really like this mod, the engines look great and are reasonably well balanced. Playing with 6.4x, KWRocketry, and this. I also tried Bobcat's soviet engine pack, and while they are great, they are of course not balanced for a serious career playthrough :P

High-reactivity propellants like fluoride compounds could be possible, but the propellant cost is extreme. Look here.

Metallic hydrogen cannot be produced reliably, not even in the near future.

Several other propellant incur a high cost or high storage mass penalty that does not make them commercially worthwhile.

I suggest you look into liquid methane/liquid propane as the fuels of the future.

Thx for info. Yah, "NASA Completes Successful Battery of Tests on Composite Cryotank", however it is scaled 1:2. They mentioned something about the project is high-risk/high-reward so I guess the development might still fail when they start doing 1:1 scale tank. And yah for now I guess they concentrate mainly on upper stage LH2 tank for SLS.

Having said that the 1:2 scale tank has 5m diameter and it completed all tests in a test chamber. This fares well for technology especially for smaller tank manufacturing. For now they are talking about 30% mass reduction and 20% cost reduction (I thought they wouldn't need to use autoclave for manufacturing composite cryo tanks but recently NASA's got composite layering robot along with autoclave so I don't know whether or not they would need it).

How do the Near Future cryogenic tanks compare to the much lighter but lossy cryo tanks from Realism Overhaul?

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How do the Near Future cryogenic tanks compare to the much lighter but lossy cryo tanks from Realism Overhaul?

Well, Nertea doesn't want to implement boiloff losses, and therefore the hydrogen tanks provided in Near Future are inspired by zero-boiloff design concepts (as mentioned above). These pay a mass penalty for insulation and active cryocooling, all of which are handwaved into a static tank with a certain dry mass for simplicity. The design inspiration is from a "real" source, but I don't know if that's only a paper design or if something like it has actually been built.

I haven't actually looked at how the fuel switch configs stat up normal fuel tanks when having CryoEngines installed, not sure if they use similar fuel mass ratios.

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Hi guys. Love this mod, it's my favourite engine mod. Is it safe to use with 1.0.5? Thanks to mod author for all the good work.

Kind regards,

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[quote name='DrGonzo94']Hi guys. Love this mod, it's my favourite engine mod. Is it safe to use with 1.0.5? Thanks to mod author for all the good work.

Kind regards,[/QUOTE]

It seems to work if you install the 1.0.5 version of Interstellar Fuel Switch after installing the mod. Get it here: [url]http://forum.kerbalspaceprogram.com/threads/117932-1-0-5-Interstellar-Fuel-Switch-1-18-%28updated-10-11-2015%29[/url]

There's still a warning message on startup, and there may be some bugs that I haven't found. But it seems to work okay when I tried it. Please don't post bug reports in this thread until Nertea posts an official update.

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Update 0.1.11, nothing major at all. Mostly contained plugin updates.
[list]
[*] Updated for KSP 1.05
[*] Updated ISFuelSwitch plugin to 1.18
[*] Updated to latest CRP version (0.4.7)
[*] Updated ModuleManager version (2.6.13)
[*] Updated funk's MFT patch
[/list]
  • Like 3

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It seems that Ven's Stock Revamp is no longer compatible with this. Actually that's only partially true. The STOCK tanks altered by Stock Part Revamp are incompatible, though strangely the new parts (namely the orange ones) that contain fuel are compatible.

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4 hours ago, GregroxMun said:

It seems that Ven's Stock Revamp is no longer compatible with this. Actually that's only partially true. The STOCK tanks altered by Stock Part Revamp are incompatible, though strangely the new parts (namely the orange ones) that contain fuel are compatible.

I believe that has to do with how the modulemanager patch which applies the fuelswitch properties to the tanks is interacting with Vens. Now, I know this mod works seamlessly with Fuel Tanks Plus, which also performs a model replacement of the stock tanks. If you can isolate what FTP does differently from Vens, then you have identified the cause of this issue (I dont have Vens so I'm not in a position to test this myself) and I can stretch my modulemanager knowledge to find a workaround. It may be as simple as getting MM to load this patch after Vens (which I know can be done but dont remember the syntax right now).

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12 hours ago, Captain Sierra said:

I believe that has to do with how the modulemanager patch which applies the fuelswitch properties to the tanks is interacting with Vens. Now, I know this mod works seamlessly with Fuel Tanks Plus, which also performs a model replacement of the stock tanks. If you can isolate what FTP does differently from Vens, then you have identified the cause of this issue (I dont have Vens so I'm not in a position to test this myself) and I can stretch my modulemanager knowledge to find a workaround. It may be as simple as getting MM to load this patch after Vens (which I know can be done but dont remember the syntax right now).

Not so sure about that. I tried putting the fuel tank switch on :FINAL, and it won't work on Ven's tanks. I'm going to investigate this further.

 

EDIT: It's that I had the original fuelswitch patch. :P After having removed it, it works fine!

Edited by GregroxMun

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Please note:

I find I'm losing track of bugs that I've fixed and bugs for most of my mods (too many mods and not enough time), so I'm moving all bug reporting to GitHub.  It would be really helpful if anyone reporting an issue logged it on the CryoEngines GitHub page, and possibly checked the list to see if it's already been reported. It will hopefully help my scatterbrainedness.

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Newbie question about this mod: by design does it really use less oxidizer when operating in a vacuum? I was using these engines to build a Delta IV-like rocket, but then I noticed all the excess Oxidizer when I dumped the first stage.

EDIT: Never mind, it's not doing it on my only-cryo test setup. I will have to troubleshoot...

Edited by leops1984

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3 hours ago, leops1984 said:

Newbie question about this mod: by design does it really use less oxidizer when operating in a vacuum? I was using these engines to build a Delta IV-like rocket, but then I noticed all the excess Oxidizer when I dumped the first stage.

EDIT: Never mind, it's not doing it on my only-cryo test setup. I will have to troubleshoot...

All engines should have the same fuel and oxidizer flow regardless of ambient conditions.

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14 hours ago, blowfish said:

All engines should have the same fuel and oxidizer flow regardless of ambient conditions.

After some troubleshooting I found the mod that caused the behavior when installed: Modular Fuel Tanks. Which makes no sense whatsoever.

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I'm having some problems with the LqdHydrogen IS Fuel Switch config when used alongside AtomicAge. Both include configs for IS Fuel Switch, but they don't work together. If I install both, only one of them will function. Can anyone explain how to fix this problem to me?

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