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

[chris-kerbal]

2 hours ago, frostdillicus said:

Really enjoying the mod so far. It definitely adds some neat new considerations that stock engines do not. However, I am having a hard time with design using the engines and associated fuels.

When I build lifters using the stock LF/O engines they are super stable. When I use the cryo engines and LH2/O I seem to always get insane SAS wobble. My rockets are indeed longer to accommodate the extra fuel requirements however they aren't any longer than anything I have made using stock LF/O parts. 

Are there extra design considerations I need to be aware of when using the cryo engines and fuels?

I'm at a loss so I figured I might get some advice from people who have been using it longer than I have.

Thanks!

I wouldn't know of any, but had issues with the Fuji engine, being wobbly for me. Which Engines are you using?

[Rakete]

I use Autostruts on grandparent mode. Works for me (KSP 1.11.2). No wobble. Maybe try this out?!

[frostdillicus]

7 hours ago, chris-kerbal said:

I wouldn't know of any, but had issues with the Fuji engine, being wobbly for me. Which Engines are you using?

Main stage is Fuji, boosters are Vesuvius. Vacuum stage is Ulysses. All of them introduce a wobble. The Ulysses is super noticeable because it loses it mind when I make minor adjustments during a maneuver. Even with the gimbal range set to 30-40% things still go crazy. I've never had to limit the gimbal on things like the Terrier and Poodle.

6 hours ago, Rakete said:

I use Autostruts on grandparent mode. Works for me (KSP 1.11.2). No wobble. Maybe try this out?!

As far as I can see autostrut is grandparent for almost anything that needs struts. I also have Kerbal Joint Reinforcement installed, so I'm not sure what else I can do to fix noodle rocket.

Edited August 24, 2021 by frostdillicus

[lordcirth]

10 hours ago, frostdillicus said:

Really enjoying the mod so far. It definitely adds some neat new considerations that stock engines do not. However, I am having a hard time with design using the engines and associated fuels.

When I build lifters using the stock LF/O engines they are super stable. When I use the cryo engines and LH2/O I seem to always get insane SAS wobble. My rockets are indeed longer to accommodate the extra fuel requirements however they aren't any longer than anything I have made using stock LF/O parts. 

Are there extra design considerations I need to be aware of when using the cryo engines and fuels?

I'm at a loss so I figured I might get some advice from people who have been using it longer than I have.

Thanks!

Is there a difference in whether you use engine plates between the two?

[Nertea]

1 hour ago, frostdillicus said:

Main stage is Fuji, boosters are Vesuvius. Vacuum stage is Ulysses. All of them introduce a wobble. The Ulysses is super noticeable because it loses it mind when I make minor adjustments during a maneuver. Even with the gimbal range set to 30-40% things still go crazy. I've never had to limit the gimbal on things like the Terrier and Poodle.

As far as I can see autostrut is grandparent for almost anything that needs struts. I also have Kerbal Joint Reinforcement installed, so I'm not sure what else I can do to fix noodle rocket.

You could be running into an engine-heavy issue. I don't seem to have any issues when I play, but because the LH2 volume is so large for a low mass, you may not have an ideal CofM for your rocket. 

I suppose one of the other things is that all the engines in my mods have a non-instant gimbal response (something like 6 degs/s). I have found if it's not fast enough (2/s) this will cause SAS issues. You could try removing this line or setting it to false and seeing if that helps. 

[frostdillicus]

9 hours ago, lordcirth said:

Is there a difference in whether you use engine plates between the two?

No engine plates on any of them. All of them are direct mounted to the 1.25/2.5m parts.

9 hours ago, Nertea said:

You could be running into an engine-heavy issue. I don't seem to have any issues when I play, but because the LH2 volume is so large for a low mass, you may not have an ideal CofM for your rocket. 

I suppose one of the other things is that all the engines in my mods have a non-instant gimbal response (something like 6 degs/s). I have found if it's not fast enough (2/s) this will cause SAS issues. You could try removing this line or setting it to false and seeing if that helps. 

Perhaps I'm just used to the gimbal from the stock engines. I did a LF/O lifter with a Mainsail and 2 boosters with 3x Otters from one of the NF (I think?) mods and they behaved fine. Is the gimbal setting only for your cryo engines or do is it set that way in the NF mods also? I didn't really have any issues with the Otters causing problems with SAS. Of course they could have just been completely overshadowed by the Mainsail.

Is there an alternative to changing the mod to calm down SAS issues? I know there used to be mods, but most of them seem abandoned. Would MechJeb Smart A.S.S. help at all?

Edited August 25, 2021 by frostdillicus

[lordcirth]

9 hours ago, frostdillicus said:

No engine plates on any of them. All of them are direct mounted to the 1.25/2.5m parts.

Perhaps I'm just used to the gimbal from the stock engines. I did a LF/O lifter with a Mainsail and 2 boosters with 3x Otters from one of the NF (I think?) mods and they behaved fine. Is the gimbal setting only for your cryo engines or do is it set that way in the NF mods also? I didn't really have any issues with the Otters causing problems with SAS. Of course they could have just been completely overshadowed by the Mainsail.

Is there an alternative to changing the mod to calm down SAS issues? I know there used to be mods, but most of them seem abandoned. Would MechJeb Smart A.S.S. help at all?

If you want the fix to be separate from the mod, you could make an MM patch to change useGimbalResponseSpeed instead.

[frostdillicus]

1 minute ago, lordcirth said:

If you want the fix to be separate from the mod, you could make an MM patch to change useGimbalResponseSpeed instead.

It's more I would like to play the mod as designed instead of changing it to deal with my short comings. Hence why my original post was asking for design tips, not demanding the author fix my issue.

The different weight considerations is a challenge I would like to overcome. If people aren't having the wobble I am seeing, then something I am doing is wrong and that is what I would rather fix.

[Rakete]

In case of oscillation behavior due to engine gimballing i usually tune down the gimbalrange of the engines a quite bit and rely more on steering fins in the atmosphere. And in Space, i tune down the engine gimbal even more (e.g. the stock vectors if used on upper stages tend to cause heavy overstearing leading to oscillation.) and rely more on precise vessel alignment before start of burn using SAS or RCS. E.g the tharsis Cryo engine needs tuning down the gimbal in my vessels. otherwise it will lead to increasing oscillation resulting in losing track.

Edited August 25, 2021 by Rakete

[frostdillicus]

11 hours ago, Rakete said:

In case of oscillation behavior due to engine gimballing i usually tune down the gimbalrange of the engines a quite bit and rely more on steering fins in the atmosphere. And in Space, i tune down the engine gimbal even more (e.g. the stock vectors if used on upper stages tend to cause heavy overstearing leading to oscillation.) and rely more on precise vessel alignment before start of burn using SAS or RCS. E.g the tharsis Cryo engine needs tuning down the gimbal in my vessels. otherwise it will lead to increasing oscillation resulting in losing track.

Dumping the gimbals to 30% of max helps some but the craft still attempts to correct itself.
 

I've also started burning my fuel from top down with LH2/O rather than bottom up like I do with LF/O and that seems to keep the CoM more balanced but SAS still wigs out sometimes. 

[Nertea]

On 8/24/2021 at 12:23 PM, frostdillicus said:

Perhaps I'm just used to the gimbal from the stock engines. I did a LF/O lifter with a Mainsail and 2 boosters with 3x Otters from one of the NF (I think?) mods and they behaved fine. Is the gimbal setting only for your cryo engines or do is it set that way in the NF mods also? I didn't really have any issues with the Otters causing problems with SAS. Of course they could have just been completely overshadowed by the Mainsail.

The engines from most of my other mods have this too (definitely NFLV). I'm generally thinking it might be the mass balance difference. If you can upload a test craft that you see this with I can take a look (minimum mod count to repro of course)

[frostdillicus]

3 hours ago, Nertea said:

The engines from most of my other mods have this too (definitely NFLV). I'm generally thinking it might be the mass balance difference. If you can upload a test craft that you see this with I can take a look (minimum mod count to repro of course)

I'll try to figure out the mod set that makes the rocket work tonight. I don't think it's going to be very long. Mostly your mods amusingly enough.

[frostdillicus]

4 hours ago, Nertea said:

The engines from most of my other mods have this too (definitely NFLV). I'm generally thinking it might be the mass balance difference. If you can upload a test craft that you see this with I can take a look (minimum mod count to repro of course)

Craft File

Mod List

Be gentle. I'm sure my rocket design sucks on so many levels.

Edited August 26, 2021 by frostdillicus

[VectorBaker]

Hey! First of all, a lot of thanks to Nertea and team for Restock, Near Future Tech and other glorious mods. They truly give new life to KSP 
But also I wanted to point out the still existing cosmetic bug, as noted by cornelius_4 back in April. I can confirm its existence - the plume of Hawk engine is facing the wrong direction.

Here's my screenshot and original reply.

On 4/7/2021 at 1:21 PM, cornelius_4 said:

I found a small cosmetic bug, the plume from the Hawk liquid methane engine is going towards the rocket rather than away from it.

 

[Rakete]

2 hours ago, VectorBaker said:

Hey! First of all, a lot of thanks to Nertea and team for Restock, Near Future Tech and other glorious mods. They truly give new life to KSP 
But also I wanted to point out the still existing cosmetic bug, as noted by cornelius_4 back in April. I can confirm its existence - the plume of Hawk engine is facing the wrong direction.

Here's my screenshot and original reply.

 

 

 

I can not confirm this bug: Newest Version of Waterfall and CE. Also works correctly in space. KSP 1.11.2

Edited August 26, 2021 by Rakete

[VectorBaker]

Oh, I see. Guess I need to install Waterfall! 

14 minutes ago, Rakete said:

 

 

 

I can not confirm this bug: Newest Version of Waterfall and CE. Also works correctly in space. KSP 1.11.2

 

[Nertea]

1 hour ago, VectorBaker said:

Oh, I see. Guess I need to install Waterfall! 

1 hour ago, Rakete said:

I should probably fix it for people who don't have WF though. We'll see. 

15 hours ago, frostdillicus said:

Be gentle. I'm sure my rocket design sucks on so many levels.

Is there any way I can get away with not needing to install the KSP expansions (due to not owning them) and USI-LS (due to lazy)?

 

[Rakete]

Obsolete posting. Sorry, can't delete it.

Edited August 26, 2021 by Rakete

[frostdillicus]

3 hours ago, Nertea said:

Is there any way I can get away with not needing to install the KSP expansions (due to not owning them) and USI-LS (due to lazy)?

 

USI-LS is easy enough. I need to switch out using a structural tube because, I think, it is from Making History.

I'll upload a new one sometime tonight.

Edited August 26, 2021 by frostdillicus

[sturmhauke]

I have a minor request, if you have the time. The MM patches that change the engine fuel type don't update the in-game name, so for instance the text might say it's an LF engine but the patch changed it to LH instead. It still uses the correct fuel type, and the details show the correct type, it's just the title that doesn't match.

[Nertea]

20 hours ago, sturmhauke said:

I have a minor request, if you have the time. The MM patches that change the engine fuel type don't update the in-game name, so for instance the text might say it's an LF engine but the patch changed it to LH instead. It still uses the correct fuel type, and the details show the correct type, it's just the title that doesn't match.

I might be willing to do that for the LF-> LH2 but not the other way. 

[sturmhauke]

29 minutes ago, Nertea said:

I might be willing to do that for the LF-> LH2 but not the other way. 

I think that's fine, thank you.

[Me.hasOwnProperty isHappy]

Some minor visual bugs:

 Tharsis's compact model floats in the air;

Etna has neither side plumes nor smoke.

Spoiler

 

[Kerbal the crazyest]

Seems good! I would test it tomorrow.

[Rakete]

On 8/15/2021 at 7:45 PM, Rakete said:

@Nertea: Bugreport - Type: Visual. Severity: Minor/Medium

Waterfall-Plume of Tharsis Engine does not move with engine gimbal movements:

Other engines of CE not checked for this. Not gamebreaking, not critical but visible.

@Nertea The engine plumes of the Tharsis Engine still not moves correctly with movement of engine gimballing. At least one of them is stuck. Maybe you want to have a look at it?

Issue re-confirmed with newest CE version and newest Waterfall version

Edited October 8, 2021 by Rakete