Nuclear engines useless?

[Jacob Kerman]

23 hours ago, Wheehaw Kerman said:

Strap enough Clydesdales on and you can brute force pretty much anything into Kerbin orbit without needing a sustainer.  Until I started figuring out how to work around the newness and the bugs my basic build was three XL hydrogen tanks and a SWERV with eight Clydesdales mounted radially.  You can go places with that.

"You can go places with that"

[Jacob Kerman]

But I'm inclined to say that nuke will always be better.

Spaceships that use chemical propellants benefit from tremendous thrust to get the job done. However, they also need to carry fuel and oxidizer to power that incredible upward or forward movement. On top of that, transferring cryogenic propellants—”gases chilled to subfreezing temperatures and condensed to form highly combustible liquids”—in zero gravity represents a nontrivial challenge. But using engines like that are inefficient in space, you are burning through too much to be practical for large distances. For the Mun, or Duna, or Minmus, or even Eve, it can be useful, but if you are going to another system, forget it. Nuclear is much more efficient.  In a nuclear thermal propulsion system, the reactor operates more as a heat exchanger in which a fuel such as liquid hydrogen is first heated to very high temperatures—up to 4,600 degrees Fahrenheit—that is then exhausted through a rocket nozzle to produce thrust. The thrust and use of fuel at this rate is not only efficient, lighter, and lasts longer, but is much more controllable as well. In distances and speeds like that, overreaction can be your worst enemy. Your only issue would be heat, and you can manage that, as we don't have radiation yet

 

[Fullmetal Analyst]

ok turns out this is pretty OP on minmus

[The Aziz]

Everything is OP on Minmus 

[Jacob Kerman]

no kidding.

 

[regex]

Balls OP on Minmus confirmed

[LameLefty]

2 hours ago, The Aziz said:

Everything is OP on Minmus 

Used to be a fun challenge early in KSP1 to launch a Kerbal to low Minmus orbit via jumping + EVA jet pack, and another challenge to land them again. That was before jet pack reaction gas mass was added though. I haven’t tried to see if it’s possible these days. 

[magnemoe]

On 3/14/2023 at 5:12 PM, regex said:

In order to support interstellar gameplay we're going to need engines that make the SWERV look like absolute trash, some balancing is going to be needed elsewhere than base stats.

Who is obvious, now gas core would give better ISP 
http://www.projectrho.com/public_html/rocket/enginelist2.php#miteehybrid
This match more with the SWERV  specks and much easier to build, an NTR who used the fuel first to generate power before reheating it and then use the power to speed up the exhaust. 
Gas core start at 2000 s isp and go up to 5000 if you run open cycle. 

Orion pulse nuclear is in this ballpark but is magnitude heavier and designed to move very heavy parts around as it has high trust. 
Then you get fusion, lower trust but the ISP is very high. 
And you have metallic hydrogen, some theories that you could mine it on Jool surface  
You can also create it, seen the huge reactors the size more like real life nuclear power plants, also some other parts who is metallic hydrogen or antimatter. 
Metallic hydrogen would be the fuel you bring for your lander for an interstellar trip 

[SciMan]

On 3/14/2023 at 12:38 PM, regex said:

I think the idea of sidegrades is fine if we're talking pure gameplay but if you're creating a game that has ties to actual realistic/theoretical spacecraft design, some things are going to be miles better than others because that's how reality works. You would be stupid to use a gas core nuclear engine if you had access to a plasma Z-pinch fusion torch, all other considerations being equal. Yes, you'll probably need more heat rejection mechanisms but that's not a big deal because you have so much more isp to work with.

Quite frankly if you hand me a fusion engine and it ends up being a "sidegrade" to a conventional nuclear hydrogen engine purely in terms of the resulting craft I'm going to be pretty damn angry. If it costs more in terms of precision, resources, knowledge, or build time that's fine, but if it's nerfed to be balanced in a "use everything willy nilly" game mode then I would call that an extremely dumb choice on the developer's part.

And this right here is why the NERV in KSP 1 is as bad as it is.

Cut the weight of the NERV by a ton or two, or double the thrust, or both, and then we're talking about an engine worth considering.

Why is the NERV so bad in KSP1? Well it's quite simple. Harvester saw the power of the atom, and said "there's no way this thing can be this good.... *edit* and now it's not".
He didn't want the NERV to be the "never use anything other than this in orbit" engine that it rightfully should be according to physics (assuming lack of better tech), so they gave it an absurdly low thrust, high dry mass, and made it use ONLY liquid fuel (back when we didn't have properly large fuel tanks for JUST Liquid Fuel, and you couldn't even drain the oxidizer out of regular rocket fuel tanks, meaning the NERV not only was rendered "not overpowered", it was in fact rendered "Why are you using this boat-anchor?", aka worse than the thud was considered for most of KSP1's life.
This instead of being the king of interplanetary transfers it was supposed to be.

Just goes to show you, don't let a person who thinks they know rockets because they play with firecrackers tell you the specifications of your interplanetary spaceship drive system, because they're basically apples and uranium, not just apples and oranges.

[didkodidko]

On 3/14/2023 at 2:28 PM, Fullmetal Analyst said:

i dont get the point of using nuclear engines, they seem to need huge tanks to get a reasonable amount of dV, and seem to be worse than other engines in general

here some example:

two rockets with same payload, both have almost same dV, but the hydrogen version is a lot bulkier while actually having 100 less dV

(hydrogen / terrier engine)

so whats actually the point of these nuclear engines?

they dont seem really useful compared to other fuel types

 

when i remove the truss and SAS the stats are still ridiculous

Don't sweat on it. Play more and you'll get it.

 

[JadeOfMaar]

On 3/14/2023 at 9:45 AM, Razor235 said:

It's this weird place where the NERV  sucks but SWERV is too good (tank mass excepted).

Well. While the in-game NERV is based on a pretty early (and dare I say, crippled) form of solid core NTR (and solid core tech on the whole does get a lot better if you do a little googling), the SWERV tells you loud and clear that it's advanced and it means business. It is a (closed cycle) gas core NTR, and in my opinion, a gas core fission engine (especially an open cycle one) is something you don't want to operate in atmosphere or while landed, or have it pointed and firing at any planet you want to live on.

KSP2 could be just right with such a restriction system and an associated penatly system attached to engines that use or produce fissiles (and gammas in the case of fusion and beyond).

The two engines are literally a world apart in terms of type, and therefore, performance, and would still be so even if they were made the same size (that is, you put an equally large NERV to stand beside the SWERV.)

On 3/14/2023 at 11:44 AM, jimmymcgoochie said:

The problem isn’t that the NERV is bad, but that the new SWERV is OP in comparison with its significantly higher ISP blowing the NERV out of the water.

The problem is actually that folks forget that KSP2 is not KSP1. It isn't about the tech and achievements and limitations and "nearly happened" of yester-year anymore. It's about the tech and intentions of the next 50+ years. We NEED the "so-called OP" engines in order to get anywhere with desirable payload masses in reasonable time scales. Furthermore, as in the above post by @SciMan the NERV was nerfed and was nerfed too hard for fear that it would make nearly every other chem rocket useless once you unlock it. Squad never bothered to develop a usage restriction system or a more interesting drawback to help the NERV stay niche while being rightfully OP vs chem, so it has remained a rather shameful cripple in the eyes of anyone who knows better about how nukes work.

Edited March 15, 2023 by JadeOfMaar

[regex]

8 minutes ago, JadeOfMaar said:

the SWERV tells you loud and clear that it's advanced and it means business.

The SWERV is a pretty early gas core design as well, it's likely designed to operate at lower temperatures because of material considerations. Once you're able to use metallic hydrogen engines you should be able to upgrade that to a proper gas-core design outputting some 2000 isp (or more, considering just how hot metallic hydrogen engines can operate at).

That's something I'd really like to see in the science game for KSP2, watching my engines get better as my space program's knowledge expands, maybe even being able to retrofit old craft at the orbital yards. These early designs should definitely get better.

[JadeOfMaar]

@regex Yeah I noticed. That 1450s in vac is suptidly low. It's in solar thermal rocket territory and not a comfty roughly 2000. Material considerations are probably indeed in play since each of its chambers are 1.25m or narrower. Can't let such small and naked things (there's nothing that suggests they're immediately attached to a powerful heatsink...and the engine might be un-dense for its size if we may use the NERV as a yard stick) run at peak temperatures or they'll breach themselves.

I'd love to see a true part upgrade system, now that you mention it. It would be a fabulous use of the resource "barter" system that this game seems to be pushing for.

[silent_prtoagonist]

I think the tech update will change perspective on the nuclear engines. NERV won't seem so underwhelming when it's (along with ion) the only alternative to methalox available to you, and SWERV won't seem so OP when you're choosing between it and Orion. 

Edited March 15, 2023 by silent_prtoagonist

[Fullmetal Analyst]

24 minutes ago, silent_prtoagonist said:

I think the tech update will change perspective on the nuclear engines.

well yeah i think being able to mine hydrogen in space, and being able to dock without ksp2 breaking, will make nuclear engines a lot more viable, even the small ones

[LameLefty]

Again, I keep beating this dead horse, but go look at Nertea's Kerbal Atomics mods for KSP1. A lot of this stuff has been hammered on thoroughly by a lot of players over the years Nertea was developing and updating it periodically. His entire set of mods (including cryogenic tanks with boiloff rates to contend with, advanced oxidizer-injected NTR for "afterburners", tiny little RTG-powered nuclear probe engines, plus a full system of properly scaled radiators to handle the heat rejection, etc) is almost certainly the basis of what we are going to get in the basic nuclear rocketry tech tree when KSP2 is "done." 

We will have far more advanced technologies in the game, too, but for nukes, Kerbal Atomics is where you should go look for the roadmap, I believe. 

[JadeOfMaar]

8 minutes ago, LameLefty said:

advanced oxidizer-injected NTR for "afterburners"

Where IS the NERV-US engine, anyway? It's supposed to be here!

[LameLefty]

1 minute ago, JadeOfMaar said:

Where IS the NERV-US engine, anyway? It's supposed to be here!

Someone up-thread said they found something that looks like it in the game files but I have not tried to confirm. 

[Jason_25]

2 hours ago, JadeOfMaar said:

The problem is actually that folks forget that KSP2 is not KSP1. It isn't about the tech and achievements and limitations and "nearly happened" of yester-year anymore.

Less Oregon Trail.  More Star Trek.

[LameLefty]

6 minutes ago, Jason_25 said:

Less Oregon Trail.  More Star Trek.

Maybe the devs should have just left KSP in the past, and in the hands of modders plus occasionally recompiling against the newest dev tools and libraries, and built a gamed called Kerbal Interstellar Program instead, focusing on the advanced tech, the resource systems and colonization tech, rather than building on (rebuilt) bones of the past? 

I mean, SimCity begat SimEarth, SimAnt and half a dozen more games before morphing into The Sims. The Sims doesn't start presenting the user with a regional tile map and require them to lay out their residential, industrial and commercial zones, their sewer and water lines, nor do sims risk a volcano eruption or an attack from Godzilla out of the bay ...

[KSK]

1 hour ago, JadeOfMaar said:

Where IS the NERV-US engine, anyway? It's supposed to be here!

You haven’t found it yet? You’re making me nerv-ous…

And on a more serious note,  I think @silent_prtoagonist and possibly others further upthread, had it spot on.  Discussing relative part balance in Sandbox seems a bit premature.

Edited March 15, 2023 by KSK

[Fullmetal Analyst]

1 hour ago, KSK said:

Discussing relative part balance in Sandbox seems a bit premature.

they dont really seem to have a solid plan for this either though

[Superfluous J]

On 3/14/2023 at 8:28 AM, Fullmetal Analyst said:

two rockets with same payload, both have almost same dV, but the hydrogen version is a lot bulkier while actually having 100 less dV

using this logic, the Rhino is also useless.

[RocketRockington]

5 hours ago, LameLefty said:

Maybe the devs should have just left KSP in the past, and in the hands of modders plus occasionally recompiling against the newest dev tools and libraries, and built a gamed called Kerbal Interstellar Program instead, focusing on the advanced tech, the resource systems and colonization tech, rather than building on (rebuilt) bones of the past? 

I have mixed feelings about this.  On the one hand - I kind of wish they did, because they've messed up KSP2 so badly, and I'd rather Intercept's version of KSP not be canonical.

On the other hand - what I liked about KSP was the realistic tech and realistic orbital physics.   Which they're sticking with, currently.

Now I imagine KSP2 is going to bork up Interstellar as well - they're going to add some sort of ridiculous resource management gameplay where you have to move materials between stars that would be literally cheaper/faster to make in a mass collider, in a realistic setting.   Unless the resource game consists entirely of shipping antimatter to other stars... and even then that's a dubious use.    But ehh, they don't have it out yet so I can still pretend that's not going to happen.

Anyway, there are other options if you want just an interplanetary or interstellar colony game.  Plenty of them.  

[mcwaffles2003]

On 3/14/2023 at 12:07 PM, cocoscacao said:

Paste this, out of context, somewhere on the web, and try to convince people that it came from a game forum 

Spoiler

 

Done.