Show and Tell - New engine exhaust effects

[Nate Simpson]

Thanks to all who did my Googling for me! Digging into this now. Cheers!

[Gargamel]

Reading this thread is why I think KSP2 is in the right hands.    Keep it up guys!

[Guest]

@Nate Simpson @KSPStar

Great Work!

Edited March 7, 2021 by Guest

[Wubslin]

4 hours ago, Nate Simpson said:

Thanks to all who did my Googling for me! Digging into this now. Cheers!

Yep, https://wodeshu.gitee.io/roprop/text00023.html

is where I got them from. But to be honest, I literally just had typed "vacuum exhaust plume" into google images and scrolled until I found something I liked several months ago. As drawing reference, so I could doodle space ships from the Expanse! But those images were really helpful to me too. As simple as it is, you never realize that neither you nor anyone else had really included it in their art but exhaust velocity is BLINDINGLY fast compared to any ship's velocity or acceleration that can be achieved.  And luminosity! Vacuum plumes aren't always certain to look so clean because some parts are more visible than others. I think. All I know is that something something cosine losses. Rocket exhaust goes all over the place in space, you know? That's one of the three solid non-storytelling hallmarks of a work of science fiction I know I'm going to enjoy. Story takes place in almost constant zero-g, ships have radiators burning an angry red, and rocket engines sing out into the void in all directions. The expanse gets a one out of three in this department, but hard future sci-fi is shockingly hard to come by so I'll take it. Doesn't hurt that the authors and show runners are masters of their craft...

Speaking of radiator-level hard sci-fi, I was wondering if the team has ever taken a look at the game Children of a Dead Earth in their travels while working on this game. There are some parts of the UI which really suck (like sliders jumping from 0.00045 m/s to 63543685 m/s when planning a burn or the game just not letting you plan maneuvers because of gravity losses), but there are some things that I really like that would be excellent in KSP 2, especially since the game is going to have non-impulsive transfers. Tugging on the normal and binormal sliders when creating a burn has the thrust vector always relative to your ship's orientation, so all three axes are linearly independent and you don't need to screw with your prograde slider when doing a plane change, for instance. I think the game, for all its flaws, has some really cool ideas! Oh, and a little too much waste heat to reject. Aren't NTR engines open cycle? Why do those things need to shine like the sun, anyway?

 

 

Edited March 7, 2021 by Wubslin

[Lewie]

It’s beautiful! You guys down at Intercept have fun outdone yourselves once again!

[Stormpilot]

Can’t wait to mess around with these in the game! Keep up the great work!

[Azimech]

Thanks guys, looking wonderful.

Can I make a plea for not having jet engine smoke at low altitudes? It has always bothered me in KSP. It's unrealistic and ugly.  The only times you get jet engine contrails at low altitude is due to specific atmospheric conditions or if there's a problem with the engine.

[Guest]

8 minutes ago, Azimech said:

Thanks guys, looking wonderful.

Can I make a plea for not having jet engine smoke at low altitudes? It has always bothered me in KSP. It's unrealistic and ugly.  The only times you get jet engine contrails at low altitude is due to specific atmospheric conditions or if there's a problem with the engine.

Yes That Would Be Good.

[Wubslin]

15 minutes ago, Azimech said:

Thanks guys, looking wonderful.

Can I make a plea for not having jet engine smoke at low altitudes? It has always bothered me in KSP. It's unrealistic and ugly.  The only times you get jet engine contrails at low altitude is due to specific atmospheric conditions or if there's a problem with the engine.

Maybe Kerbals design their turbomachinery to be run like a household two-stroke. They put gallon of 10W-40 in every fuel ton, you know?

[Azimech]

16 minutes ago, Wubslin said:

Maybe Kerbals design their turbomachinery to be run like a household two-stroke. They put gallon of 10W-40 in every fuel ton, you know?

Might as well let go of the whole endeavor of improving the effects of the rocket engines. Why improve graphics anyway? Let's go back to 2012. The graphics were good enough.

[Wubslin]

48 minutes ago, Azimech said:

Might as well let go of the whole endeavor of improving the effects of the rocket engines. Why improve graphics anyway? Let's go back to 2012. The graphics were good enough.

Who peed in your cheerios?

[Bej Kerman]

2 hours ago, Azimech said:

Might as well let go of the whole endeavor of improving the effects of the rocket engines. Why improve graphics anyway? Let's go back to 2012. The graphics were good enough.

Not in the mood for humour?

[Vanamonde]

Please don't make the discussions personal, guys. 

[Wubslin]

15 hours ago, Vanamonde said:

Please don't make the discussions personal, guys. 

Ha, sorry. There's a specific type of conduct you take to certain communities on the internet and you're right that outdoor voices are not the place here. Still though, this ain't the Nasaspaceflight Forums. Those guys can really take you down a peg. What's going on over there? Certainly not a whole lot of horsing around, ha ha. Mess with the all important signal to noise ratio and they'll nuke your comment. Once a moderator literally went in and edited my own reply to stealithily expunge a section where I simply acknowledged the existence of a guy who was getting really anti-nuclear in the power generation for Starship thread. That guy got made into an unperson on that thread. Spooky!

So anyway, speaking of nuking and signal to noise ratios, I'll bring it back around to vacuum exhaust plumes. Vacuum exhaust plumes! A super niche spaceflight topic that for how much it should influence people's art, gets almost no mainstream thought.

Chemical rocket exhaust is great and everything, but I think the first section of the video deserves a lot more attention. More specifically, we are totally looking at the first professional depiction of the exhaust of a nuclear salt water rocket! (no offense Nertea, your mods are literally the backbone of my modern KSP experience and they are beautiful.) So, I want to pick apart these couple of images we've been fed to try and glean some information to how the fine folks over at Intercept have decided to construct the thing.

So, I'm sure most of us have a basic idea over the general workings behind Robert Zubrin's nuclear salt water concept. An aqueous solution of some kind of salt, where the cation is in fact a fissile material, is sprayed using electric pumps (hilariously referred to as 'Wileys' after the coyote in some project rho reference material) into a "combustion chamber" such that a critical mass is reached and a prompt supercritical reaction sets up. Heat from the fission products directly manifest as X-rays, those X-rays absorb into the water and vaporize and even dissociate it, and you get a reaction force. A film cooling layer of pure water or otherwise some liquid which cannot sustain a reaction is injected at the outer boundary of this flow to prevent internal surfaces from ablating or vaporizing.

From the footage we've been given above, we see two prominent parts of the rocket engine's exhaust. There is a proudly luminescing column of fluid which tapers as it moves aft of the mouth of the engine, and there is a much fainter conical shroud of fluid which fans out in all directions. A faint blue twinge is present in the blinding light, which I will interpret as Cherenkov radiation produced as beta rays permeate the dissociated soup of hydrogen and oxygen plasma.

We have seen closeups of the engine in prior media, and for what it's worth I think there are two major designs that this thing could actually be. The huge chamber-looking thing just forward of the engine bell might be a "combustion chamber".  Considering that Kerbals have the ability to produce and store metallic hydrogen it isn't completely out of the question to imagine that they might have built a vessel capable of holding what is basically a constant nuclear explosion. The mean free path of a 1 MeV photon (edit: in water) produced from insanely ludicrous heats is on the order of centimeters, so it isn't technically impossible per se. Looking more closely at the "advanced propulsion concepts" video has shown a very real throat to this shower head engine bell thing.

The second concept, and the one that I personally believe is more realistic of the two, is the "pusher plate" design. Nuclear Salt Water is injected at high enough speed and in the right geometry that it only supercritically inserts some distance aft of the engine's most sensitive hardware. That giant incandescent column shooting out the back of the engine sure looks like a region of sustained supercritical burning, but then again that's also what we would expect to see were the engine of the combustion chamber variety. Who knows!

Edited March 9, 2021 by Wubslin

[Azimech]

Well, I apologize. I've been inactive for a number of years now. The 1.4 update really threw me off and since then I've felt the game has been going in a direction I don't like. I've lost my confidence in the original KSP developers. And I certainly do not like hanging on to relics of, in my opinion, bad design decisions.

But I could've written it in a less snarky way.

[shdwlrd]

On 3/8/2021 at 9:14 AM, Azimech said:

Thanks guys, looking wonderful.

Can I make a plea for not having jet engine smoke at low altitudes? It has always bothered me in KSP. It's unrealistic and ugly.  The only times you get jet engine contrails at low altitude is due to specific atmospheric conditions or if there's a problem with the engine.

Unless they are modeled after some of the Russian and older US engines. Under full throttle, they won't burn cleanly and produce a ton of soot.

[mcwaffles2003]

Wow... these look pretty...

Thank you devs

[Kernel Kraken]

Will there be a way to negate the plume for performance reasons?

[The Aziz]

I don't think the plume, if implemented correctly, will have a big impact on performance. Sure the usual particle systems are sometimes hard for the hardware if there's too much of them on the screen at once, but maybe they did it right.

[EnderKid2]

3 hours ago, Kernel Kraken said:

Will there be a way to negate the plume for performance reasons?

if this is done in the way I think it is, it should be less performance intensive than our current particle-based plumes

Edited March 10, 2021 by EnderKid2

[shdwlrd]

On 3/5/2021 at 11:00 AM, KSPStar said:

Our VFX artist Aaron Lundquist continues to create new engine exhaust effects. The first of these engines runs on an as-yet-announced fuel (guesses welcome)! The other two are metallic hydrogen and jet engine.

We're all really proud of Aaron's shock diamonds! The score, as always, is by the incomparable Howard Mostrom.

Hold on. Are you saying that jet engines can use metallic hydrogen? 

Beautiful work on the plumes and afterburner exhaust. 

[Drakenred65]

I suspect it’s possible for you to use metallic hydrogen in a old black iron cauldron, let alone a jet engine. Can you imagine a MH turbofan? Ity bity engine...Ginormose fan the size of 747 body’s 

[The Aziz]

I don't think anything else could handle burning MH aside from the engine specifically designed for it, considering the temperature.

[shdwlrd]

1 hour ago, [email protected] said:

I suspect it’s possible for you to use metallic hydrogen in a old black iron cauldron, let alone a jet engine. Can you imagine a MH turbofan? Ity bity engine...Ginormose fan the size of 747 body’s 

All I'm thinking is compressor blades flying everywhere once it warms up.

56 minutes ago, The Aziz said:

I don't think anything else could handle burning MH aside from the engine specifically designed for it, considering the temperature.

I can understand using MH for the afterburner. But as the normal fuel source, no.  The combustion area is already near the critical temperature for the components using standard kerosene based aviation fuels.

[Redneck]

On 3/5/2021 at 11:00 AM, KSPStar said:

Our VFX artist Aaron Lundquist continues to create new engine exhaust effects. The first of these engines runs on an as-yet-announced fuel (guesses welcome)! The other two are metallic hydrogen and jet engine.

We're all really proud of Aaron's shock diamonds! The score, as always, is by the incomparable Howard Mostrom.

yeah....its methane

On 3/5/2021 at 11:00 AM, KSPStar said:

Our VFX artist Aaron Lundquist continues to create new engine exhaust effects. The first of these engines runs on an as-yet-announced fuel (guesses welcome)! The other two are metallic hydrogen and jet engine.

We're all really proud of Aaron's shock diamonds! The score, as always, is by the incomparable Howard Mostrom.

those mach/shock diamonds are not easy to recreate. Been trying to get just the right look and feel in blender for starship raptors engines is a challenge 

 

 

Edited March 12, 2021 by Redneck