Art style: Please avoid neon lights. Please improve metallic hydrogen engine star-like exhaust.

[Bej Kerman]

11 minutes ago, regex said:

4 hours ago, Rutabaga22 said:

its a metallic hydrogen engine,

I wonder where they got that concept art and why it's wasting half the fuel...

I'm not going to pretend to understand how the engine works. Hence why I'm not going to pretend that I understand enough to say that this is "wasting fuel". Maybe you should follow.

[regex]

I've been looking through Google for a good thirty minutes and I can't find any metallic hydrogen engine concept art where it's exhausting before the nozzle. In fact, most of the concept art looks more like the four surrounding engines. That central engine is something different IMO, but I can't really guess what. Maybe some sort of fusion engine?

Regardless, the exhaust near the base should be even more diffuse than that coming out the nozzle when thrusting in a vacuum, you'd be hard-pressed to get those tight streams (and if you're wasting power doing that why not direct it out the back where you can get more thrust?).

Edited October 25, 2022 by regex

[Bej Kerman]

8 minutes ago, regex said:

I've been looking through Google for a good thirty minutes and I can't find any metallic hydrogen engine concept art where it's exhausting before the nozzle.

Intercept didn't use Google to come up with the star pattern, they used their qualifications.

[regex]

10 minutes ago, Bej Kerman said:

Intercept didn't use Google to come up with the star pattern, they used their qualifications.

I'd love to know where they're getting such "qualifications". How are we supposed to critique such art if we don't know what's actually portrayed? And quite frankly if they're doing something that literally flies in the face of sensible rocket design then that would raise some red flags about the game; KSP has always been grounded in reality, even speculative reality. We don't have Dean Drives and warp coils, we have realistic engines or engine concepts grounded in realistic physics.

[Gargamel]

Thread has been temp locked. 

[Vanamonde]

Some grumpy stuff removed. Play nice, please. 

[darthgently]

4 hours ago, Bej Kerman said:

Intercept didn't use Google to come up with the star pattern, they used their qualifications.

I have to side with @regexon this one.  That perpendicular thrust has been annoying me from the first time I saw it.  It is certainly worth seeking an explanation as one doesn't need to be a rocket scientist to wonder why a lot of thrust is perpendicular to the desired direction of motion

Edited October 25, 2022 by darthgently

[Bej Kerman]

Just now, darthgently said:

I have to side with regards on this one.  That perpendicular thrust has been annoying me from the first time I saw it.  It is certainly worth seeking an explanation as one doesn't need to be a rocket scientist to wonder why a lot of thrust is perpendicular to the desired direction of motion

Who said that the material coming out the sides accounts for a non-negligible amount of dV? Do feel free to ask Nate yourself instead of picking sides in a silly argument.

[KSACheese]

From a purely aesthetic point of view, I agree that the star-effect is a little off putting. Though, I know this is an older thread, so perhaps this has been modified or edited in some way. Either way, I do hope they at least tone down how much it sticks out. Plus, I'm sure there'll be mods to change the plume if people don't like it.

[darthgently]

14 minutes ago, Bej Kerman said:

Who said that the material coming out the sides accounts for a non-negligible amount of dV? Do feel free to ask Nate yourself instead of picking sides in a silly argument.

I think by posting in this thread @Nate Simpson or any of the devs, is being asked.

I completely agree it is a silly argument.  Hopefully we don't accidentally stumble into the Abuse Clinic next ( Monty Python reference )

Edited October 25, 2022 by darthgently

[regex]

[snip]

I mean... There's rocket exhaust blowing out the sides of that engine onto the other engines. If that's not heating up or damaging the other parts then that's a pretty blatant violation of science I'd say.

Since I don't know what sort of engine it is (it doesn't look like any metallic hydrogen engine concept I can find) then I have to assume it's something else. At that point I want to ask why the base exhaust is so tightly focused into that particular pattern, why they bothered to collimate the streams instead of directing it out the back of the engine where it can deliver thrust (because if you can collimate those streams like that you should definitely be getting thrust instead of wasting it!) Even if it's some sort of heat management scheme it seems like a huge waste of power to focus those streams so tightly (in space it should look more like the actual exhaust but perhaps directed more rearwards). That's why I thought it was some sort of z-pinch plasma fusion, with those streams being directed inwards instead of being, what, some kind of heat management? Maybe radiation management (and then you're neutron embrittling those other parts, good lord...)?

This is stuff I and others have already brought up in this thread.

Edited October 25, 2022 by Vanamonde

[regex]

[snip]

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

Check out Engine List 3 as well. You could also do some Googling and read up on advanced engine concepts, people publish papers and concept art all the time (where do you think these engines in the game come from?)

Edited October 25, 2022 by Vanamonde

[Vanamonde]

More grump stuff removed. We don't want to have to close the thread, guys. Make your points without attacking each other, please. 

[Deddly]

Some interesting thoughts here. Looks to me like everyone in this conversation actually has the same concern - the developers have consistently stated that they aren't inventing stuff or using sci-fi technology, they are using existing research to decide how to do things. So it's only logical to react when we see something that looks out of place, like this odd "star exhaust". That doesn't mean it shouldn't be there, though; from the approach taken by the dev team, I can only assume there must be a very good reason for that strange effect.

What is it? I have to believe the developers got it from somewhere other than pulling it out of their hat. Since we don't actually know, it would be great to find out, then we can either criticise its inclusion or defend it based on facts instead of taste. I did a bit of searching and couldn't find anything, either - yet. 

[Ember12]

According to the Next Gen Tech video, when designing the metallic hydrogen engines they consulted a Dr. Uri Shumlak at the University of Washington, who is an expert of things like plasma confinement.  So there's probably some good reason for the star-exhaust, although I have no idea what it might be.

[Strawberry]

Just guessing here, but I think the basic idea is that this is the water doped engine, and the water gets injected into that area, causing it to rapidly expand, and the mostly water metallic hydrogen mix comes out in that star plume, while the hotter more productive and pure metallic hydrogen end products come out the bottom. Its not the most efficient thing in the world, but it means your engine isn't a molten bundle of junk. The star plume not damaging other parts nearby seems like either an oversight, or just something that was intended to be gotten too, doubt its an active design choice.

[Deddly]

@Strawberry if that's true, what's the snazzy magnetic confinement nozzle for? 

 

[GoldForest]

4 hours ago, Strawberry said:

Just guessing here, but I think the basic idea is that this is the water doped engine, and the water gets injected into that area, causing it to rapidly expand, and the mostly water metallic hydrogen mix comes out in that star plume, while the hotter more productive and pure metallic hydrogen end products come out the bottom. Its not the most efficient thing in the world, but it means your engine isn't a molten bundle of junk. The star plume not damaging other parts nearby seems like either an oversight, or just something that was intended to be gotten too, doubt its an active design choice.

It's not water doped, it's cesium doped to give the plume magnetic properties, allowing the magnetic nozzle to keep the flames away, thus limiting heat transfer. 

As for the flame, I don't know anything about magnetic hydrogen, but if I had to guess, it's escaped plumage. Metallic hydrogen that doesn't have enough cesium to be contained and thus shoots out where it can, following the path of least resistance. 

As to why the heat from said escaped plumage doesn't harm the other four metallic hydrogen engines, well, do you see the number of radiators on that thing? Also, it's probably a titanium or even tungsten metal being used for those engines, so a little more heat it can probably handle. 

[Vl3d]

3 hours ago, GoldForest said:

Also, it's probably a titanium or even tungsten metal being used for those engines, so a little more heat it can probably handle. 

Titanium melts at 1600 C, tungsten melts at 3400 C. Metallic hydrogen burns at 5700 C.

[GoldForest]

29 minutes ago, Vl3d said:

Titanium melts at 1600 C, tungsten melts at 3400 C. Metallic hydrogen burns at 5700 C.

Wow, didn't realize it was THAT hot. 

[regex]

8 hours ago, GoldForest said:

It's not water doped, it's cesium doped to give the plume magnetic properties, allowing the magnetic nozzle to keep the flames away, thus limiting heat transfer. 

As for the flame, I don't know anything about magnetic hydrogen, but if I had to guess, it's escaped plumage. Metallic hydrogen that doesn't have enough cesium to be contained and thus shoots out where it can, following the path of least resistance.

I don't think that works the way you think it works. That cesium would have to be bound to the hydrogen which means you'd get much lower performance than the hydrogen alone. And, once again, the exhaust at the base would be very diffuse rather than coalescing into discrete beams; it would quickly turn into a cloud that looked more like the exhaust. If you're wasting the power to make those tight beams you can direct it out the back for more thrust instead of wasting it.

Naturally the Atomic Rockets site has a listing for metallic hydrogen. They even link to a paper on it. Neither mention cesium doping, probably because it won't work. What they do mention is water cooling which would also reduce performance, but in turn reduces the temperature. Now, you could probably learn from making a closed cycle gas core nuclear engine, a "nuclear lightbulb", how to handle the heat (gaseous uranium hexafluoride is much, much hotter than metallic hydrogen would be) but at that point you're going to get better performance from the nuclear engine.

No, I think that central engine is something different than a metallic hydrogen engine. The outer engines look like they probably are, and somewhat match concept art I've seen, but the central engine is something different. It looks much more like a fusion engine of some kind.

[GoldForest]

31 minutes ago, regex said:

I don't think that works the way you think it works. That cesium would have to be bound to the hydrogen which means you'd get much lower performance than the hydrogen alone. And, once again, the exhaust at the base would be very diffuse rather than coalescing into discrete beams; it would quickly turn into a cloud that looked more like the exhaust. If you're wasting the power to make those tight beams you can direct it out the back for more thrust instead of wasting it.

Naturally the Atomic Rockets site has a listing for metallic hydrogen. They even link to a paper on it. Neither mention cesium doping, probably because it won't work. What they do mention is water cooling which would also reduce performance, but in turn reduces the temperature. Now, you could probably learn from making a closed cycle gas core nuclear engine, a "nuclear lightbulb", how to handle the heat (gaseous uranium hexafluoride is much, much hotter than metallic hydrogen would be) but at that point you're going to get better performance from the nuclear engine.

No, I think that central engine is something different than a metallic hydrogen engine. The outer engines look like they probably are, and somewhat match concept art I've seen, but the central engine is something different. It looks much more like a fusion engine of some kind.

Im just repeating what Nate Simpson says in one of the previous vidieos. I believe it was next gen tech. In it he calls one of the engines a torch engine I believe, which uses a magnetic nozzle to confine and direct metallic hydrogen doped with cesium. 

In that video, they show that specific craft. 1 magnetic engine surrounded by 4. He says there are two mh engines in game when that comes up. Conventional mh and magnetic mh. The outer engines are obviously the conventional bell mh engines and the middle one is the magnetic mh engine he spoke of. 

Now, things could have changed, and I'd they did, it hasn't been announced. I'm going off last know information and will gladly accept the change to water if it is confirmed. 

[regex]

30 minutes ago, GoldForest said:

Im just repeating what Nate Simpson says in one of the previous vidieos.

Which video is that?

[GoldForest]

30 minutes ago, regex said:

Which video is that?

I said next gen tech episode, but I found the specific time. Around 2:30 to 2:40.

Also, I was wrong. The conventional bell is atmospheric metallic hydrogen engine and the magnetic bell is vacuum metallic hydrogen.

The atmo engine is using water, but the magnetic one does use cesium to control the hydorgen. @Strawberry i apologize. You were right about the atmo engines being water doped. 

Edited October 27, 2022 by GoldForest

[regex]

13 minutes ago, GoldForest said:

Also, I was wrong. The conventional bell is atmospheric metallic hydrogen engine and the magnetic bell is vacuum metallic hydrogen.

The atmo engine is using water, but the magnetic one does use cesium to control the hydorgen.

<sigh>

I have a real fear they're probably going to use isp values way beyond what is projected, and that cesium doping thing is basically only them talking about it. At least, I can't find anything other than the KSP devs referencing it. And that engine art is kind of a nightmare. Welp.

Edited October 27, 2022 by regex