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

[Capt. Hunt]

just tried it out, they're looking good so far, the only problem I've run into is that refrigeration sucks a lot of juice.  Granted, my rocket was a big 3.75m Delta IV heavy clone, with a crap-ton of LH2, but it drained a 2k battery in the minute or so between MECO and the circularization burn.  Maybe next time I shouldn't have had refrigeration set to on in the first stage.

Edited April 10, 2018 by Capt. Hunt

[MaximumThrust]

On 07/04/2018 at 3:20 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

The new models and textures on the tanks are way better  Loved the compact tanks being split in 4, and the new foil texture. Thanks!

About the balance, I'm keeping a 1.3.1 install, and will use the old configs for a while, so I cannot give input on that.

[Kerbas_ad_astra]

42 minutes ago, Capt. Hunt said:

just tried it out, they're looking good so far, the only problem I've run into is that refrigeration sucks a lot of juice.  Granted, my rocket was a big 3.75m Delta IV heavy clone, with a crap-ton of LH2, but it drained a 2k battery in the minute or so between MECO and the circularization burn.  Maybe next time I shouldn't have had refrigeration set to on in the first stage.

The boiloff rate is 0.05% per hour, so you shouldn't bother refrigerating for a span of minutes, or even days (small number of days).  Save it for fuel depots and interplanetary transit stages.

[Nertea]

I'm expecting a few bugs but I hope the mini pre-release of CryoTanks will have addressed the worst of them

CryoEngines 0.6.0

• KSP 1.4.2
• Updated bundled B9PartSwitch to 2.2.1
• Updated MM to 3.0.6
• Updated CRP to 0.10.0
• Updated MiniAVC to 1.2.0.1
• Updated DynamicBatteryStorage to 1.3.0
•  Recompiled DeployableEngines
•  Added engine nicknames to tags
•  Decreased mass of Volcano to 1.3 from 1.6t (TWR to 16.4/18 from 13.4/14.6)
•  Decreased mass of Chelyabinsk to 0.55t from 0.7 (TWR to 3.1/10.2 from 2.4/8)
•  Decreased mass of Odin to 5 to 5.75t (TWR to 19.6/21.4 from 17.1/18.6)
•  Decreased mass of Tunguska to 2.25 from 2.75t (TWR to 5.2/12.5 from 4.2/10.2)
•  Decreased mass of Mars to 11.5 from 12.5t (TWR to 20.7/23.5 from 19.0/21.6)
•  Increased thrust of Yucutan to 1850 from 1450 kN (TWR to 12.0/21.8 from 9.4/17.1)
•  Moved Odin to Heavier Rocketry
•  Updated CryoTanks to 1.0.0
  •  Fixed boiloff being disabled if a tank's fuel was disabled
  •  Fixed boiloff rates being calculated incorrectly at timewarp
  •  Redid all tank textures, particularly foils
  •  Added 3 new tank models
    •  Short 2.5m (standard, compact variants)
    •  Short 3.75m (standard, compact, bare variants)
    •  Short 5m (standard, compact, bare variants)
  •  Fixed attach nodes of 3.75m compact tank variants
  •  Rebalanced capacities, masses and costs of all tanks
  •  Decreased cooling cost of ZBO tanks to 0.05 Ec/1000u
  •  Added an optional ability to specify a set of OUTPUT_RESOURCE blocks in a BOILOFFCONFIG. This causes boiloff to produce that resource with the specified ratio and flow mode. See Config Documentation section
  •  Added the optional ability to specify boiloff as dependent on solar/planetary radiation input. See Config Documentation section

[StarStreak2109]

Awesome, my list of mods missing for my 1.4.2 install is slowly but surely getting shorter! Thanks for all the hard work you're putting into this, work and kid notwithstanding!

[Wyzard]

8 hours ago, Nertea said:

I'm expecting a few bugs

Here's one, sort of: the bundled copy of DynamicBatteryStorage has unresolved merge conflict markers in its .version file.  Same goes for the one in Kerbal Atomics.  But the one in Near Future Electical is OK, so it's not an across-the-board problem.

[garwel]

Yay, I can now play 1.4.2!

[FrancoisH]

Just a suptid question. I'm using KW Rocketry and I were able to switch some tanks to Monopropellant, but now it's gone from IFS options. I'm only getting the new kind of Hydrogen fuel you added and nothing more.

Could you help me with this?

[Zorg]

Hi guys new to the forum here. First let me say thank you to Nertea for making this mod as well as all of his other stuff. Always loved his mods but for some reason I never downloaded CryoEngines until a few days ago in my new 1.4 game after having been away from the game for a while.

Like many others I found the engines to be a bit hard to get a grip with initially. I've skimmed through most of this thread looking for advice and I think I've got a handle on some principles.

The most obvious benefit seems to be on large upper stages where you get substantial weight savings thus resulting in savings in the lower LFO stage. This has proved quite effective on a couple of existing large launchers meant to insert interplanetary payloads into LKO and I even got some substantial cost savings. Where things got challenging for me was trying to use Cryo engines for launch stages. I'll write a little bit of what I've learned, but I would really appreciate any further input or challenges to incorrect assumptions.

The Volcano, Odin and Mars all have lower TWR than their LFO counterparts and you also need to burn them longer to take full advantage of the ISP gains? This means using SRBs and often 2 pairs of SRBs with differing thrust levels to manage TWR and extend the SRB burn time such that by the time they are expended the center core will have at least 1.5 TWR on its own. The need to fine tune thrust with SRBs moved me to finally get the Space Y Launch Vehicles mod which adds a variety of well balanced SRBs that fill in some gaps and offer options above the kickback without having to build ridiculous bundles. IMO the Space Y SRBs synergizes very well with CryoEngines. 

The end result is something like this with 6 volcanos in the lower stage and 4 SpaceY R10s with staggered thrust. It gets 30T to LKO and is actually cost competitive with similar simple LFO launchers. Ok I don't go crazy optimizing for cost, I like good looking simple expendable launchers without insane stacks of asparagus...etc that still get reasonable cost per ton. I dont mind paying a little bit extra just for the cool factor  (pun intended)

Given that the objective of the rocket is to expend itself by LKO where the payloads own propulsion will take it to its (interplanetary) destination, the second stage kicks in around 25km with the apoapsis still within the atmosphere. I found the vacuum engines underpowered for this kind of use so I ended up using 2 more Volcanos. Is this whats meant by a "sustainer". Its a term I've seen throughout this thread.

Spoiler

 

Bonus downscaled  2.5m rocket 4x Volcano + 1x Volcano

Still getting stuff into low orbit is not the best use of cryogenics in real life. You want to use the ISp of the upper stage to carry that low orbit payload to higher orbits and further destination. So I decided to try to build something which can deliver a nice payload to the Mun/Minmus low orbit using the second stage. This evolution of the earlier rocket cuts down the main engines to 5 Volcanos but uses 4 (staggered) kickbacks for boost. The center core is expends just as it establishes Apoapsis and the upper stage takes over for circularization and carries a 22T payload to Minmus with some headroom for say rendezvous. This time a single Tunguska powers the upper stage with much lower stage TWR but much higher ISP. The cost per ton to destination is actually lower than my older mid size moon rocket but perhaps its because I'm designing more carefully? This mod forces you to pay closer attention to all of your performance figures for a given mission profile which is why its got me so engaged!

Spoiler

Extended upper stage with Tunguska. Extra batteries, fuel cells and Solar panels (Near Future of course!) for the journey to Minmus/Mun

At this point I'm enjoying these engines tremendously but I've come to the realisation that I;m struggling to find a use for the big and amazing looking Odin. Anytime I need more thrust its more economical by a fairly large margin to throw more Volcanos at the problem. My 30T to the moons and 65T to LKO launchers use 8 and 9 Volcanos in the first stage respectively with various configurations of SpaceY SRBs and another Tunguska for the moon rocket upper stage and 4 volcanos for the 65T lifter upper stage. 

The bigger engine does end up with slightly more Delta V due to the better engine TWR once you manage to equilise thrust levels for a stage but I'm struggling to find a combination once SRBs have been accounted for where a single Odin comes out ahead. I think this is what I'll be working on the next couple of days and I would really love to hear about or see your Odin and Mars based designs and how to solve this optimisation problem. 

Of course all that isn't to say I haven't found any use whatsoever for the Odin... I think we've all been disappointed by the Mastodon from Making history. This tribute to the legendary F1 under performs the mainsail in every respect except a slight TWR gain for vastly unjustified higher cost. Meanwhile the mainsail doesnt fit into the Saturn V 5 meter base due to the wide engine mount. I actually used a 5 meter engine plate to attach five Mainsails, then used the move tool to nudge the mainsails outwards but they are both still too bunched up in the centre to look good and the top of the plate is already clipping slightly into the shrouds. This was my 150T to LKO lifter that has already been improved by a cryo upper stage.

But now enter the Odin. With Nertea's switchable mount, the Odin looks glorious on the Saturn V base. The thrust requirement for the 150T payload also means this was way beyond what clusters of Volcanos can solve. The final design uses 5 Odins assisted by 2 thrust reduced long burning SpaceY S115 heavy SRB boosters with a single Yucatan for the upper stage. The way the staging worked out the 2nd stage kicks in at around 35-40km, with a TWR of 0.8 a single Yucatan has enough thrust to act as a sustainer and to circularise. Its a vacuum optimised engine but at 35km it has nearly full thrust. I'm glad I found a use for the Yucatan.

This rocket turned out very slightly more expensive than the 5 mainsails with Yucatan upper stage combo, but the 100 cr per ton premium is worth paying for the cool factor and lack of clipping as far as I'm concerned. The extra 15,000 cr is a small fraction of the total launch cost once the cost of a 150t payload plus launcher is factored in.

Spoiler

 

 

It's so beautiful I could cry 

The Yucatan kicks in

 

So in conclusion I guess what I've learned is 

1) great for upper stages with LFO lower stage

2) Be more attentive to design parameters when building full stack cryo launchers especially TWR and when staging occurs.

3) Burn your engines for longer where possible

4) SRBs are very important and you usually need 2 pairs with differing thrust limits (and therefore burn times). 

5) The need for large tankage is considered a downside. But I love the roomier fairings of big rockets even for lighter payloads, sometimes you just need volume for odd designs. The rocket being bigger for a given payload is a plus for me as I hate the look of bulbous fairings that are vastly wider than the core.

6) You can indeed design full cryogenic launchers (with SRBs) that are in the same ballpark cost-wise as LFO launchers.

7) I now refuse to use the Wolfhound on sheer principle 

Questions

1) What are the economical uses for single or dual configuration Odins and Mars based launchers. I've yet to build a Mars based rocket. How best to optimise for single large engines vs clusters of smaller engines? Is Mars a luxury cost no object engine?

2) Does asparagus staging work? I think not given the lower TWR and need to burn longer.. the Centre core ends up with too little TWR when the asparagus boosters are expended as the Kerbal fuel pumps are so efficient! My Delta IV heavy (ish) clone was hugely expensive for what it was. Well at least that's accurate...

Hope this post wasn't too long and looking forward to what you guys have to say about your launchers. I've become unreasonably obsessed with building full cryo launchers 

Edited April 15, 2018 by Zorg
Spelling etc

[lordcirth]

@Zorg Personally I am playing on 4x scale using Sigma Dimensions.  This means that everything takes about sqrt(4) = 2 times more delta-v.  I use the Chelyabinsk instead of the Terrier a lot, I use it for all my landers in particular.  Since in 4x two stages is usually not enough to orbit, I often use the Tunguska as a second stage; it's also a vacuum engine though.  I haven't been using cryogenic sustainer engines at liftoff.  Here's my Mun lander: Chelyabinsk, Tunguska, Bollard + Mainsail boosters with crossfeed

https://imgur.com/a/Sd9TJ

Edited April 15, 2018 by lordcirth

[Zorg]

1 hour ago, lordcirth said:

@Zorg I use the Chelyabinsk instead of the Terrier a lot, I use it for all my landers in particular. 

 

I didnt mention the Chelyabinsk earlier as my post rather unintentionally became a wall of text. But yes it does seem like super Terrier and it wasn't hard finding lots of uses for it.

I do like your lander! Nice solution with the landing legs . I might try a Chelyabinsk lander, I often use terriers for landers.

I've actually found a use for Mars as well as an upper stage for a 200T lifter (With SpaceY MultiMoa LFO lower stage) since I wrote my earlier post. Now to find a 200t payload lol. Perhaps a fuel depot or something...

[Nertea]

@Zorg Went into your post expecting complaining the cryogenics aren't better 100% of the time as usual, was pleasantly surprised. Nice analysis! Was this with the latest thrust changes in the latest version?

Addendum: you can use this with NFLV for the best volumetric experience was well.

[boeing186]

I just did a fresh reinstall of the newest version and removed the LFO folder from "extras", but the engines still only burn LF. Anyone know how I can get my engines to burn LH2?

[Capt. Hunt]

@Zorg

My go to heavy lifter is a Delta-IV Heavy clone, using three Mars engines on the Common Booster Cores, and then a Chelyabinsk on the cryogenic second stage.  She's an expensive monster, but she'll throw just about any payload wherever I need it.

[Zorg]

7 hours ago, Nertea said:

@Zorg Went into your post expecting complaining the cryogenics aren't better 100% of the time as usual, was pleasantly surprised. Nice analysis! Was this with the latest thrust changes in the latest version?

Addendum: you can use this with NFLV for the best volumetric experience was well.

Thanks! Indeed I first downloaded this mod the day you released the latest update.

I do have NFLV but I m getting through my current play through rather slowly due to high mission density, only on day 250 or so. But unlocking that node for exotic fuel storage and the big 7.5m tanks is next on my science goals.

[Zorg]

Alright I'm not going to post every time I find something cool to do with a Cryo engine but at the end of my earlier lengthy missive, I had one burning question: finding an economical use for a Mars engine. Since then I did use a Mars as an upper stage for a 200T vehicle but it left me unsatisfied as I what I really wanted deep down was to use it as a launch stage. Was I being unreasonable? Looking for a use case that did not exist by demanding it be cheap? I didn't even used to care so much about cost but this self imposed challenge kind of took hold of me.

Today I came across some very old "cheap and cheerful" challenge threads for simple expendable launch vehicles and saw some designs that used a single central Rhino sustainer core that gets all the way to orbit with (big bundles of!) stock kickback SRB side boosters. So that inspired me and I eventually came up with this:

1x Mars engine on single core stage with 5m tanks, 31.7T of LH2 and 149T of Oxidiser. 

2x S109 heavy lift SRB at 58.5% Thrust

2x SpaceY S217 Super Heavy SRB at 46% thrust

Payload to 75km circular orbit of 145T (I count the fairing cost and weight as payload as it makes picking my launch sub-assemblies easier.)

Cost 155,388 cr | Cost per ton to LKO 1,068.7 cr/T

This is the lowest I've ever gotten my launch costs for a non reusable design! I'm sure it can be optimized further by someone more skilled at rocket building than me. I'm also not great at tuning ascent profiles and so just used the mechjeb standard ascent settings with corrective steering turned on as a repeatable standard. I'm not saying that LFO launchers or hybrid launchers might not be even cheaper. But I am immensely satisfied with what I achieved with the Mars engine. 

This design not super delta V efficient as you suffer some gravity losses when the boosters are ejected. TWR on the core is just below 1 when the S217s separate but it increases fast enough to get you to orbit. But I optimized for cost, not delta V efficiency. 

Also someone who doesn't want to use SpaceY boosters or similar can always use a number of stock Kickbacks. I didn't try that but I did try a pair of "advanced boosters" instead of SpaceY SRBs: A pair of Twin Boars with a single additional Rockomax jumbo orange tank. This came out slightly more expensive (100cr/t more that the 4 spaceY SRBs config but still very reasonable). This is all turning out very SLS  

So yeah the Mars engine... luxury engine for when you're willing to splash the cash for maximum performance? Yes definitely. But its also a dirt cheap launch engine if you optimise right for a big payload. 

CryoEngines mod in general? I think its superbly balanced in all respects and you can usually find a good use for all 6 engines even while being a bit frugal (though you may have to work for it!). Thanks for putting up with my ramblings! Time to go do some missions instead of milling around in the VAB.

Images in spoiler

Spoiler

SRB's are a CryoEngine's best friend.

 

Once the SRBs are ditched this whole thing will get to orbit... could be the basis for a pseudo SSTO that can return to KSC but cant be bothered with recovery for the moment.

Ye olde Delta V and TWR stats

Twin Boar Variant was almost an afterthought but its cleaner and more attractive although very slightly more costly...

SpaceY structural adapter was used to get a smooth transition from the 3.75m boat tail engine mount to the 5m tank.

 

 

[danfarnsy]

6 hours ago, Zorg said:

Thanks for putting up with my ramblings!

These are the best kind of ramblings, though. It's refreshing to see people do their homework, put thought into it, share what they learned, and then ask questions. It may take longer to read, but you're certainly not disrespecting anybody else's time.

[Nyarlathotep-]

I have encountered a very minor problem, the engine shrouds for the cryo engines are invisible, should I just try redownloading the mod and reinstall it?

[Proply]

On 23/04/2018 at 9:08 AM, Nyarlathotep- said:

I have encountered a very minor problem, the engine shrouds for the cryo engines are invisible, should I just try redownloading the mod and reinstall it?

Ah, so it is not just me. Seems that all of the cryogenic engine shrouds appear just fine in the editor, but disappear on the launch pad.

[JANXOL]

I have a question about bioloff. Would putting radiators on the non-refrigerated fuel tank reduce or eliminate boiloff from that tank, or will it have no effect? I ahve seen someone do this with RO but not sure if that would work on its own.

[Nyarlathotep-]

On 4/24/2018 at 5:08 AM, Proply said:

Ah, so it is not just me. Seems that all of the cryogenic engine shrouds appear just fine in the editor, but disappear on the launch pad.

In that case I dont think a simple reinstall will work.

[TheSpitfire24]

I'm also getting the fairing issue. 

[Nertea]

8 hours ago, TheSpitfire24 said:

I'm also getting the fairing issue. 

I'm working on it.

On 4/25/2018 at 3:13 AM, JANXOL said:

I have a question about bioloff. Would putting radiators on the non-refrigerated fuel tank reduce or eliminate boiloff from that tank, or will it have no effect? I ahve seen someone do this with RO but not sure if that would work on its own.

No, that's abstracted as the EC cooling cost. Just turn on the cooling instead!

[DiscoveryPlanet]

On 4/24/2018 at 7:08 PM, Proply said:

Ah, so it is not just me. Seems that all of the cryogenic engine shrouds appear just fine in the editor, but disappear on the launch pad.

same happen to me

[Someone2018]

@Nertea What was your reason for not fueling these engines with LqdOxygen (the cryogenic kind) that is present in the community resource pack? The combination of LqdHydrogen (the cryogenic kind) and a non-cryogenic oxidizer seems unusual (not used in real life at all as far as I can tell), especially since you bothered with cryogenic fuels to begin with (and associated boil-off mechanics).

Edited May 7, 2018 by Someone2018