Metalic hydrogen engines look so cool who’s looking forward to seeing those engine’s and the atomic engine’s?

[Jurassic kerbal]

I know I am 

[prestja]

1 hour ago, Jurassic kerbal said:

I know I am 

I'm most excited for the ISP of metallic hydrogen engines, a theoretical 1700s. With that extreme efficiency paired with the relative ease of equipping spacecraft with such engines, I can see myself building significantly simpler interplanetary craft.

[OHara]

We don't want interplanetary travel to be too easy, of course, because doing things that are tricky enough to be interesting is the fun of KSP.   

Another interplanetary enabler in KSP was the Alcubierre Warp-Drive mod, that keeps things interesting because it does not accelerate/decelerate the craft, only warp space around them so they are translated relative to the rest of the universe.  That opens up possibilities, but makes you think ahead about how to match velocities with the destination body.

I'm trained as a solid-state physicist, so I do cringe at the name of 'metallic hydrogen' for the fuel.  Eugene Wigner did predict possible metastability when he first extended the theory of molecular orbits to the simplest possible solids, at the dawn of solid-state theory in the 1930s, but there is no reason to expect unusual metastability all the way down to the few GPa range of reasonable pressure vessels.  We would expect to need very high pressure to contain such a fuel, nearly as much as needed to form the metal initially.  The more energy released between a metastable state and the ground state, the more likely it is to quickly slip out of that metastable state.  Nuclei stay metastable for reasonable lifetimes, at even higher energy differences to the ground state, but chemistry and solid state physics just don't have those high energy barriers that nuclear interactions provide.   I'll just re-imagine 'metallic hydrogen' as some heretofore unknown isotope of H, which is still suspension of disbelief, but feels a more honest in its suspension of disbelief.

I can get over that name if it makes a good game.  I can see how Kerbals having some monopropellant with a release energy so high, that the product is at 7000 K, would inspire development of magnetic rocket nozzles, because 7000 K would melt the solid parts of the nozzle if we let it touch.   Then magnetic rocket nozzles then open the door for for atomic rockets with even hotter product. 

That seems to open up a coherent sequence of different engines for different purposes.

[Soda Popinski]

2 minutes ago, OHara said:

We don't want interplanetary travel to be too easy, of course, because doing things that are tricky enough to be interesting is the fun of KSP.   

Another interplanetary enabler in KSP was the Alcubierre Warp-Drive mod, that keeps things interesting because it does not accelerate/decelerate the craft, only warp space around them so they are translated relative to the rest of the universe.  That opens up possibilities, but makes you think ahead about how to match velocities with the destination body.

I'm trained as a solid-state physicist, so I do cringe at the name of 'metallic hydrogen' for the fuel.  Eugene Wigner did predict possible metastability when he first extended the theory of molecular orbits to the simplest possible solids, at the dawn of solid-state theory in the 1930s, but there is no reason to expect unusual metastability all the way down to the few GPa range of reasonable pressure vessels.  We would expect to need very high pressure to contain such a fuel, nearly as much as needed to form the metal initially. 

As a physicist, do you think it's more realistic to harvest substantial amounts of negative energy exotic matter to power an Alcubierre drive ship?  If they're in the same realm of feasibility, then a metallic hydrogen drive seems like it would be obsolete by the time it was developed, when a gas core fusion rocket could provide over double the ISP and seems relatively feasible.

[OHara]

2 minutes ago, Soda Popinski said:

As a physicist, do you think it's more realistic to harvest substantial amounts of negative energy exotic matter to power an Alcubierre drive ship? 

No.  Realism by itself doesn't seem very important in a game.   But coherence seems important for the rather complicated game KSP.  For me, the use of real physics in most areas, with simple exceptions for good reasons like the 1/10-size 10× dense Kerbin, lets me remember the rules of the game easily enough for it to be fun.

It does seem that KSP2 will need to bend reality in some way to give the Met.Hydrogen engine an in-game niche alongside nuclear engines.  I am guessing that the first is a stepping stone to the latter.   Can you imagine ways to have both (unreal but imaginable) technologies each have their own advantages for different uses?

[Soda Popinski]

1 hour ago, OHara said:

Can you imagine ways to have both (unreal but imaginable) technologies each have their own advantages for different uses?

I could see in-game use of having the warp-drive function like the Frame-Shift Drive from Elite: Dangerous, where you use it for interstellar travel, but would use something less exotic/expensive for interplanetary travel, like metallic hydrogen.

That said, I believe the devs said they don't want to do any FTL travel.  If it's fine for Kerbin to be 1/10 the size of Earth, I don't see why we couldn't have another planetary system 0.4 light-years away.  That'll make something like the Orion or Daedalus drive more feasible without resorting to FTL.

In-game, the metallic hydrogen rocket looks to be something between NERVs and the pulse nuclear rockets.  It may be a bit silly since I'm pretty sure an Orion drive is more technically feasible.

[KerikBalm]

I am only looking forward to the atomic rockets. The metallic hydrogen engines need to die.

11 hours ago, prestja said:

I'm most excited for the ISP of metallic hydrogen engines, a theoretical 1700s. With that extreme efficiency paired with the relative ease of equipping spacecraft with such engines, I can see myself building significantly simpler interplanetary craft.

An Isp of 1700s, with no way to contain the exhaust and stop it from melting the engine.

"Cesium doping" for magnetic confinement makes no sense. Even if we were to accept MH metastable at low pressure (which I don't), 1700s Isp involves yet another layer of magic.... Meanwhile one could just mix the hot MH exhaust with normal liquid hydrogen (you could store hydrogen Ice if you want some more density), and have a non-magic solution to keep your engine from melting. The Isp in that case is still a very respectable 1100-1200s.

They've shown the "atmospheric" variant mixes exhaust with water, that would provide more TWR at lower Isp (500's). That could have been a simple, non-magic way to have variants suited for different purposes, but nope, they went with magic err magnetic confinement of non-ionized hydrogen by throwing some cesium in there that wouldn't be bound to the hydrogen yet somehow enables it to be confined (if it was bound, the Isp would be terrible, and less that of the water engine).

9 hours ago, OHara said:

 Eugene Wigner did predict possible metastability when he first extended the theory of molecular orbits to the simplest possible solids, at the dawn of solid-state theory in the 1930s, but there is no reason to expect unusual metastability all the way down to the few GPa range of reasonable pressure vessels.  We would expect to need very high pressure to contain such a fuel, nearly as much as needed to form the metal initially. 

Which is what the most recent experiments observe. Not to mention that there hasn't been a theoretical prediction of low pressure metastability for more than picoseconds since the 70's

9 hours ago, OHara said:

No.  Realism by itself doesn't seem very important in a game. 

I disagree, suspension of disbelief is very important, and that is related to perceived realism in many cases.

In a game like this, realism is very important for certain aspects.

I can accept unrealistic planets as fun engineering challenges (like Tylo... that should have an atmosphere, but whatevs... also, the moon seems unrealistically big compared to the planet).

What really annoys me is that they could get MH level performance with closed cycle gas or liquid core NTRs, and that would introduce even more gameplay considerations with the radiation concerns.

http://www.projectrho.com/public_html/rocket/enginelist2.php#ntrliquid

They could throw in a LANTR type NTR, where its a chemical/nuclear hybrid rocket, and you could maybe have your craft lift off on chemical power only before starting the reactors (and thus dramatically increasing the radiation emitted... yes, even a shutdown reactor will still emit radiation if it has been running a while)

http://www.projectrho.com/public_html/rocket/enginelist2.php#lantr

[mcwaffles2003]

11 hours ago, OHara said:

We don't want interplanetary travel to be too easy, of course, because doing things that are tricky enough to be interesting is the fun of KSP.   

The game has an interstellar scope.... at some point along the line of interplanetary travel will need to become easy...

[KerikBalm]

6 hours ago, mcwaffles2003 said:

The game has an interstellar scope.... at some point along the line of interplanetary travel will need to become easy...

Such as with a gas core NTR?

Or as it already is at 1/10th scale with a poodle? 

Or as it would be with thrusting-on-rails nuclear powered Ion engines?

Or Orion pulse drive... etc.

We don't need metallic hydrogen for easy interplanetary travel... particularly with the ability to set up colonies on planets.

[prestja]

1 hour ago, KerikBalm said:

We don't need metallic hydrogen for easy interplanetary travel

I disagree. Nate Simpson just confirmed that setting up efficient delivery routes depends on the performance of the craft involved. If I can build a much larger and heavier freighter because of the high thrust and efficiency of metallic hydrogen, then I'm all for that. I needn't worry about strengthening my craft to survive nuclear pulses, or plan around extremely long ion burn times. I simply strap the new "Wyvern" metallic hydrogen engine to my craft and begin burning.

[Soda Popinski]

I suspect we may be over thinking this.  Do recall most people (including me) don't play with Real Fuels.  So the current benchmark is "Liquid Fuel" which seems to cover everything from RP1 to liquid hydrogen.

I wouldn't be surprised if a lot of the new engine tech currently being called "metallic hydrogen" or "inertial confinement fusion" will be named something more generic in the final game, like "liquid fuel" or NERV (instead of NERVA) or RAPIER (istsead of SABRE) so they don't need to be constrained (or day I say, confined) to the real-life performance and limitations of this technology.  For people who do want that level of realism, I'd expect mods will fill in that niche.

[KerikBalm]

32 minutes ago, prestja said:

I disagree. Nate Simpson just confirmed that setting up efficient delivery routes depends on the performance of the craft involved. If I can build a much larger and heavier freighter because of the high thrust and efficiency of metallic hydrogen, then I'm all for that. I needn't worry about strengthening my craft to survive nuclear pulses, or plan around extremely long ion burn times. I simply strap the new "Wyvern" metallic hydrogen engine to my craft and begin burning.

What does that have to do with anything?

Interplanetary travel is already easy at 1/10 scale with chemical rockets. Sure, OP rockets can make it easier, but that doesn't mean much. With the same logic, I can say a magical unicorn fart engine must be included to make interplanetary travel even easier.

Also, if its thrust into on rails, burn time isnt so important ad transit time, and something like a nuclear piwered vasmir will be faster.

As would a gas core ntr

[SciMan]

I honestly don't care if metallic hydrogen in KSP2 turns out to be just a form of handwavium. If you don't like it, just make a simple mod that changes the name.

I know that it's "easy" to get around the planets with chemical engines in stock KSP. However, I'm tired of the abysmal TWR of the LV-N, the only nuclear engine in the game right now. Right now it's next to useless because you can get just about the same delta-V with basically any upper stage chemical engine and the appropriate fuel tanks. The LV-N needs both doubled thrust and at least a half ton less mass to make it useful. And while they're at it, they could remove the need for radiators while under thrust, because that's not particularly fun or interesting either, and it saddles any craft using this engine with even MORE dead weight, exaclty what it doesn't need.

I just hope that the engines in KSP2 aren't similarly nerfed into uselessness.

[Incarnation of Chaos]

1 hour ago, SciMan said:

I honestly don't care if metallic hydrogen in KSP2 turns out to be just a form of handwavium. If you don't like it, just make a simple mod that changes the name.

I know that it's "easy" to get around the planets with chemical engines in stock KSP. However, I'm tired of the abysmal TWR of the LV-N, the only nuclear engine in the game right now. Right now it's next to useless because you can get just about the same delta-V with basically any upper stage chemical engine and the appropriate fuel tanks. The LV-N needs both doubled thrust and at least a half ton less mass to make it useful. And while they're at it, they could remove the need for radiators while under thrust, because that's not particularly fun or interesting either, and it saddles any craft using this engine with even MORE dead weight, exaclty what it doesn't need.

I just hope that the engines in KSP2 aren't similarly nerfed into uselessness.

I haven't needed radiators for NERVA in stock for a while. But that's not the point; there's nuclear engines that could provide these TWR ratios you want that don't require magic fuels. 

I had a craft using the Enmanicipator NTR with the LFO patch that had a TWR of over 2 outside kerbin orbit (.8 within) and around 9km DV. It was 3 docked modules each massing around 80 tonnes; one of which was a conventional lander using LF/O and had a DV of around 4-5KM when separated.

That's why people like me are irritated with purple space magic in KSP2, because there's no lack of realistic alternatives that are just as easy to use and make interplanetary travel just as easy.

[DunaManiac]

33 minutes ago, Incarnation of Chaos said:

That's why people like me are irritated with purple space magic in KSP2, because there's no lack of realistic alternatives that are just as easy to use and make interplanetary travel just as easy.

In order for the devs to go into so much science into Metallic Hydrogen, they must have had a VERY good reason for it, and they probably knew that it wasn't very realistic, but why are we talking about realism where we have fuels called "Liquid Fuel" "Oxidizer" and "Monopropellant"?  If they simply picked it because it sounded sciency then why didn't they include more magic tech like Warp Drives and Antimatter? They evidently have had a lot research on the subject and I simply refuse to believe that they picked it for no reason at all. Sacrifices must be made in the name of game play.

[Incarnation of Chaos]

26 minutes ago, DunaManiac said:

In order for the devs to go into so much science into Metallic Hydrogen, they must have had a VERY good reason for it, and they probably knew that it wasn't very realistic, but why are we talking about realism where we have fuels called "Liquid Fuel" "Oxidizer" and "Monopropellant"?  If they simply picked it because it sounded sciency then why didn't they include more magic tech like Warp Drives and Antimatter? They evidently have had a lot research on the subject and I simply refuse to believe that they picked it for no reason at all. Sacrifices must be made in the name of game play.

The irony is that antimatter and warp drives are still far more grounded in actual science than metastable metallic hydrogen at this point in time.

All of them are based on proven and demonstrated principles of science, but that's not the case for metastable metallic hydrogen. It's metastability has been disproven at the pressures predicted all those years ago in the 70s which is why I'm saying they're not realistic. 

Sacrifices must be made, but the nature of those sacrifices must not corrupt the premise of the game. 

Now if they have data contradicting what's publically available, then that's their job to provide and explain. But that hasn't been done, and the explanations given haven't worked within known science. 

So again that leaves us with purple space magic that takes KSP2 from softsim to light SciFi territory, and all while realistic alternatives grounded in actual science exist. 

So personally I've drawn many of the opposite conclusions. I feel like what they've show has demonstrated that they hadn't done their homework and didn't expect the small but vocal community backlash that arose. So they desperately attempted to salvage it, and only showed how little they had looked into the concept at hand.

I expect that they're not planning on removing them from the game, so I'll be waiting for a mod to replace them with NERVA engines. Or I'll make it myself if needed.

Metastable metallic hydrogen could very well still exist, but if it did then it would behave differently than those predictions in the 70s stated. It would require much higher pressures, decompose at different rates, etc 

But again that's their job to define and demonstrate; they could even use the fact that Kerbal planets are much more dense than reality to push metastable metallic hydrogen formation into more favorable conditions.

But we got none of this, and instead got science fiction handwavium garbage and poor excuses for it's implementation.

But to sum it all up; I'm not saying it's not realistic because it's a simplification or approximation like liquid fuel or monopropellant. I'm saying it's not realistic because currently there is no way that it can be created in the form proposed or used in the way described. 

[shdwlrd]

Not the metallic hydrogen argument again.

Can we just accept it's going to be in the game and there is nothing we can do about it. 

Yes, I do think the new engines for met hydrogen do look cool. It would be interesting to see how the community uses the models in the future.

Edited July 2, 2020 by shdwlrd
adding my actual opinion about the topic

[KerikBalm]

14 hours ago, Soda Popinski said:

I suspect we may be over thinking this.  Do recall most people (including me) don't play with Real Fuels.  So the current benchmark is "Liquid Fuel" which seems to cover everything from RP1 to liquid hydrogen.

I wouldn't be surprised if a lot of the new engine tech currently being called "metallic hydrogen" or "inertial confinement fusion" will be named something more generic in the final game, like "liquid fuel" 

I don't think they are going that way. They seem to be going with a resource based system instead of funds, we already know some parts need "uranium" (not some generic "blutonium" like in KSP for the RTGs), they've said certain resources will need to be made off-world, I htink there was something about mining gas giants (He3 most likely). Orion drives are very unlikely to share a generic fuel with other engines... it seems very likely they will have multiple specific fuel types to fit in with some light colony building+crafting system. I suspect what resources are available ot various colonies will influence what drives you use in-system.

9 hours ago, DunaManiac said:

why are we talking about realism where we have fuels called "Liquid Fuel" "Oxidizer" and "Monopropellant"?

There's nothing unrealistic about a generic name. The less specific you are, the less likely you are to contradict reality. If they renamed Metallic Hydrogen to "purple space magic", or a more scientific sounding "Ultra-energetic liquid fuel", then at least it wouldn't be contradicting known science.

9 hours ago, DunaManiac said:

In order for the devs to go into so much science into Metallic Hydrogen, they must have had a VERY good reason for it, ... If they simply picked it because it sounded sciency then why didn't they include more magic tech like Warp Drives and Antimatter? They evidently have had a lot research on the subject and I simply refuse to believe that they picked it for no reason at all.

They very likely did go with Antimatter drives, which is *less* magic tech than metallic hydrogen drives. This belief that they did go deep into the science of it is exactly why I have such a problem with it. People think its realistic because all the other stuff in KSP has been so realistic (except for throttling range and restarts of LF engines in KSP, Ion engine thrust, and scale - all of which people can easily realize are unrealistic concessions to gameplay).

Nate's only statement on MH so far has been that it "exists", and that's good enough for him... which shows that he doesn't know what he's talking about, because the question isn't whether metallic hydrogen exists, but whether it displays substantial metastable properties at low pressure. Without such properties, the tech is literally the same as a rocket powered by a can of compressed air (you just have a super-duper- ultra strong can so the air is like really really really compressed... yea, ok).

8 hours ago, Incarnation of Chaos said:

The irony is that antimatter and warp drives are still far more grounded in actual science than metastable metallic hydrogen at this point in time.

All of them are based on proven and demonstrated principles of science, but that's not the case for metastable metallic hydrogen. It's metastability has been disproven at the pressures predicted all those years ago in the 70s which is why I'm saying they're not realistic. 

...

Now if they have data contradicting what's publically available, then that's their job to provide and explain. But that hasn't been done, and the explanations given haven't worked within known science. 

...

So personally I've drawn many of the opposite conclusions. I feel like what they've show has demonstrated that they hadn't done their homework and didn't expect the small but vocal community backlash that arose. So they desperately attempted to salvage it, and only showed how little they had looked into the concept at hand.

...

But we got none of this, and instead got science fiction handwavium garbage and poor excuses for it's implementation.

But to sum it all up; I'm not saying it's not realistic because it's a simplification or approximation like liquid fuel or monopropellant. I'm saying it's not realistic because currently there is no way that it can be created in the form proposed or used in the way described. 

+1

A major problem with the world right now is the dissemination of misinformation. They are attempting to portray this as real science, when its not. IMO, I'd rather have the MH engines be titled the "unicorn fart engine", and then I'd have no problem with it... but I can go for purple space magic instead. Nobody would be mislead into thinking that in a few decades we'll have this awesome fuel type that will be environmentally firendly and replace haydrocarbons, no lifestyle changes are needed, technology will save us, etc.

There is so much misinformation in today's world, it sickens me, and this is just another example.

After this post, I will no longer reference Metallic Hydrogen engines/MH as portrayed in KSP 2 (I may refer to real properties of MH). I will hanceforth refer to the KSP 2 engine as the PSM engine or purple space magic engine.

11 hours ago, SciMan said:

I'm tired of the abysmal TWR of the LV-N, the only nuclear engine in the game right now. Right now it's next to useless because you can get just about the same delta-V with basically any upper stage chemical engine and the appropriate fuel tanks. The LV-N needs both doubled thrust and at least a half ton less mass to make it useful. And while they're at it, they could remove the need for radiators while under thrust, because that's not particularly fun or interesting either, and it saddles any craft using this engine with even MORE dead weight, exaclty what it doesn't need.

Ummm, no you can't get the same dV with any upper stage LFO engine. Its only if you need a kerbin relative TWR of over 0.7 that the LV-N becomes uncompetitive. Any they did this for gameplay. Real NTRs (even standard solid cores) could get much much better TWR. They basically took the stats of the NERVA, and ignored even more advanced designs like the MITEE and Timberwind designs, or generic pebble bed designs (particular pebbles with molten cores and a shell of a material with a very high melting point, like tantalum). They also ignored chemical-nuclear hybrid designs like the LANTR.

If you want better than the LV-N, there is no need to add the PSM engine.

FYI, there is no need to add radiators for LV-Ns anymore.

Realistically, you'd need radiators during start-up/shutdown, when liquid hydrogen propellent isn't flowing past the reactor, but not during operation.

I actually liked that restriction, as you then needed radiators to use the engines (although, at unrealistic times), but then I'd also lower their mass back down to 2.25, not the current 3 tons.

Edited July 2, 2020 by KerikBalm

[mcwaffles2003]

20 hours ago, KerikBalm said:

Such as with a gas core NTR?

Or as it already is at 1/10th scale with a poodle? 

Or as it would be with thrusting-on-rails nuclear powered Ion engines?

Or Orion pulse drive... etc.

We don't need metallic hydrogen for easy interplanetary travel... particularly with the ability to set up colonies on planets.

I was just saying whatever we use there will be enough dV for timely interstellar travel.. so interplanetary travel will need to be easy since distances between are minuscule in scale.

[fragtzack]

KSP is a game first and foremost, So yes bring on all the far out physics engines the devs want.  ‘It’s fun to imagine.

 

Also fun to “drive” a rocket ship as KSP does. .. not realistic but KSP and KSP2 are first and foremost about fun...not a hard core reality physics simulator
 

Someone posted here once they are concern KSP2 might try to make the game too real, agree with this statement very much.

The fun of a GAME makes all these serious discussions about only using a technology that is hypothetical possible in the real world is just hog wash.  
 

KSP2 devs, keep KSP a game first and foremost in all design decisions

 

 

[Jurassic kerbal]

44 minutes ago, fragtzack said:

KSP2 devs, keep KSP a game first and foremost in all design decisions

Yes 

[KerikBalm]

And some games are meant to be realistic, we wouldn't have the same gameplay if this was eve online.

If we had the PSM engine in KSP, it would be bad for gameplay just like it would be bad for gameplay in KSP to have an engine with the Isp of a LV-N and the TWR of a mammoth or mastadon.... which is about what you'd get if metallic hydrogen was metastable, and you were cooling it with LH2 (would give even higher Isp)

The PSM engine is not an interstellar engine, as far as I can tell, its for interplanetary travel and landers, and seems to be just an equivalent of, "ok, you have PSM, getting around the system is trivial now"... Without the low TWR and radiation of the interstellar engines (or the massive destruction, and hopefully pulsed nature of the orion engine), and also the size constraints of the interstellar engines (too large for use on landers).

PSM, realism aside, also serms like just bad gameplay, making intersystem travel trivial (throw all that gameplay out the window), with the only design decisions for inter system travel being do I take the PSM engine, or the PSM^2 engine that doesn't work in an atmosphere.

Edited July 5, 2020 by KerikBalm

[Incarnation of Chaos]

11 minutes ago, KerikBalm said:

And some games are meant to be realistic, we wouldn't have the same gameplay if this was eve online.

If we had the PSM engine in KSP, it would be bad for gameplay just like it would be bad for gameplay in KSP to have an engine with the Isp of a LV-N and the TWR of a mammoth or mastadon.... which is about what you'd get if metallic hydrogen was metastable, and you were cooling it with LH2 (would give even higher Isp)

The PSM engine is not an interstellar engine, as far as I can tell, its for interplanetary travel and landers, and seems to be just an equivalent of, "ok, you have PSM, getting around the system is trivial now"... Without the low TWR and radiation of the interstellar engines (or the massive destruction, and hopefully pulsed nature of the orion engine), and also the size constraints of the interstellar engines (too large for use on landers).

PSM, realism aside, also serms like just bad gameplay, making intersystem travel trivial (throw all that gameplay out the window), with the only design decisions for inter system travel being do I take the PSM engine, or the PSM^2 engine that doesn't work in an atmosphere.

Got something against NSWRs? xD

[KerikBalm]

Nope, but they wouldn't be suitable for launches to and from your colonies, now would they?

[Incarnation of Chaos]

7 minutes ago, KerikBalm said:

Nope, but they wouldn't be suitable for launches to and from your colonies, now would they?

I mean these are KERBALS we're talking about, and with that much DV on tap you could just complete your deceleration with conventional or electric thrusters so the only radiation hazards are during launch and to the crew.