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Show and Tell - New LANTR engine


StarSlay3r
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Seconding my vote for "NERVOUS", but I think the acronym should be "Nuclear Engine for Rocket Vehicles with Oxygen Utilisation Supercharging". The "S" could stand for something else, but I think that the NERV part has a nice parallel to the existing Nerv engine from KSP1, and it's clear that it's related to the existing engine. Bonus: using a mildly radioactive engine in Kerbin's atmosphere might make some people nervous :P

Alternatively, the engine could be named "Nerv-S" (S for supercharged) if the acronym shouldn't be too on the nose, or it could be named "Transformer" if there are no other engines that have retractable nozzles or some other method of mode switching.

LANTERN is cool as an acronym, but I think there are engines that would be better fits for the name (like one of the mentioned torch drives, perhaps).

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We're way out in the weeds as far as speculating what the balance is. All I want is a nuclear engine that has enough TWR to be able to get interestingly large amounts of payload off the ground and into LKO, with one stage. IRL, there's been research done on a "nuclear lighbulb" engine that would be capable of such things.

However, all the mods that implement such an engine make it unrealistically heavy for its thrust, and impossible to use on the surface of a planet with an atmosphere.

Basically, I want to be able to make THIS "Liberty Ship" SSTO, but in Kerbal scale.

I'm tired of the LV-N being out-done by the Poodle in most cases. Nuclear is Nuclear, and that means "enough power to make chemical engines look like a bottle rocket compared to the Saturn-V".
I'm tired of all these high tech engines having the caveat of "or you could use the old LFO vacuum engines too, and only have to carry twice as much fuel".
Electric propulsion engines should be lightweight.
Nuclear engines should be lightweight, but produce radiation, that YOU get to decide how to counter by use of distance to a crew compartment and/or shielding put in between the engine and the habitat section.

IRL it's not hard to get 10km/s delta-V out of a hydrolox rocket stage (with payload). In Kerbal, it's impossible to make a NUCLEAR stage get that much delta-V, unless the payload fraction is TINY.
That just doesn't make sense.
I'm aware that the solar system is tiny.
Yes, the amount of delta-V you need to get into orbit is tiny.
Yes, the amount of delta-V you need to get to practically anywhere is "tiny" compared to just getting to Earth orbit IRL (7.4 km/s orbital velocity, launches take roughly 11km/s to account for the various losses).
None of that changes the fact that the "game balance" for the Terrier, Cheetah, Poodle, and Rhino being the "best LFO vacuum engines" massively out-weighs the balance point of where the LV-N "Nerv" is.
The LV-N "Nerv" is NOT fine where it is, unless it's the "glimpse into the future" of what nuclear propulsion can hold
Is the LV-N better than those engines? Yes, mostly. Is it "better" by a large enough margin for me to take on the additional headaches of low TWR and crazy (not to mention unrealistic) waste heat production? Emphatically, NO IT IS NOT. So I never use it. I try to use it once every time I come back to KSP, decide it's a piece of junk, and scrap all my dreams of a Jool-V mission.

I can build in HUGE margins when I go to use the LFO vacuum engines, but every time I try to use the LV-N, I can't seem to strike the balance between "I have enough radiators to run the engine indefinitely", "I have enough fuel to get where I'm going", and most importantly, "I have enough TWR so that I don't have to split the burn into more than one burn at Pe, or lose my mind due to boredom, or lose my mission because I over-cooked the burn because I got bored and my attention went elsewhere". I'd lose the mission due to over-cooking the burn because I'd probably put on a Twitch stream or something on my tablet to kill time, and I don't know what math to use for calculating multiple Pe burns. Yes I know there's a mod for doing that math for me, but it's still "too fiddly" and not realistic compared to what a real NTR propelled vessel would do. Spacecraft and probes with electric propulsion need to split the ejection burn. Not NTR craft.
The point I'm making here is that the LV-N is just an engine like any other, but it has so many asterisks attached to it's usage that it goes from "hey use this it's 5% better" to "Don't bother chasing after that 5% when it has that many caveats". Now if that was 25-50% better, I might be able to convince myself that it's worth going thru figuring it out. As it is, it's not "better" by enough to bother. Airline operators don't switch what they're flying until they get a quote for "performance boost vs previous iteration" of 15% or more (I don't know the precise numbers, but it's around that number). And neither do I.

What I'm trying to say is that the LFO engines are fine. What's not fine is that the LV-N is... not "gooder" enough. It was nerfed so it "doesn't completely replace" the LFO vacuum engines, when they could have pulled on OTHER balance levers to accomplish that, such as engine size, form factor, maybe adding a MINIMUM thrust for it (so you have a range of like 100% to 25%, and below 25% it just entirely shuts down), etc.
It's already long and skinny which makes it hard to use as a lander engine, the shroud on it is a royal pain in the butt to deal with since it sticks to the ENGINE not the DECOUPLER (so much so that even if it's in-line and only using one, I turn it off just in case it decides to separate weirdly and take off a solar panel or something).

The vacuum LFO engines are just plain old "good enough to get anywhere" and the LV-N sits off in the corner gathering dust. I don't want that. I want all the engines to have a niche, but currently the LV-N doesn't really have a niche so much as it has a "Hey, we can do that too, but we're heavier, low thrust, produce crazy amounts of waste heat, but hey we're 'efficient' I guess?". and that's just not a convincing argument.

 

I can only hope that this 2.5m NTR isn't "LV-N, but scaled up", because that doesn't solve the issues with the LV-N. Nuclear energy is VERY POWERFUL, and it should FEEL powerful using it.

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@SciMan The LV-N is actually insanely overpowered (aside from the heat issues; heating for that part is not handled in a realistic manner)

isp of 800 for a propellant with the density that LiquidFuel has? That's hardly a piece of junk.  That's unrealistically overpowered. Ok so  it wont get you off the ground into LKO but it was based off of real technology that was in development until funding cancelled and the resulting engines would also have been orbital class only. That's what the LV-N is. Nuclear light bulb engines are still conjectural only. 

Edited by Starwaster
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On 7/26/2021 at 10:25 AM, KerikBalm said:
On 6/27/2021 at 6:00 PM, Fullmetal Analyst said:

not sure but i think this engine will make the game too easy, you could propably do everything with a single stage rocket and orbital refueling, so i guess this will be the last engine on the research tree?

*cough* metastable metallic hydrogen engines *cough*. 

About as silly as metal birds with people inside, but you don't know what physics has up its sleeve.

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12 hours ago, Bej Kerman said:

About as silly as metal birds with people inside, but you don't know what physics has up its sleeve.

Setting aside the debate as to what physics is and is not settled, and if KSP2 should include engines with no current theoretical basis behind them (even if there was a former basis, as would apply to Aether propellors), my comment was directed towards the Gameplay Concerns/Implications.

@Fullmetal Analyst was concerned that the LANTR engine would make getting to orbit too easy. As mmH would outperform a solid core (as this seems to be) LANTR engine, any Gameplay Concerns about LANTR enginges should apply even more so to mmH engines.

Furthermore, as it seems that KSP2 will make engine-radiation a factor in gameplay, and a mmH engine would not emit radiation, the Gameplay Concern  that a LANTR "engine will make the game too easy" should really not be an issue in comparison to the Gameplay Concern  that a mmH "engine will make the game too easy".

Edited by KerikBalm
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On 8/6/2021 at 8:55 AM, KerikBalm said:

Furthermore, as it seems that KSP2 will make engine-radiation a factor in gameplay, and a mmH engine would not emit radiation, the Gameplay Concern  that a LANTR "engine will make the game too easy" should really not be an issue in comparison to the Gameplay Concern  that a mmH "engine will make the game too easy".

There will be challenges beyond just getting into orbit, which is a chapter KSP 2 has moved past. The focus has been shifted from getting into orbit and getting around with what little Δv you have to creating interplanetary and interstellar infrastructure - tell me, how would you begin accomplishing this just with the KS-25 and nuclear engines of yesterday? Besides having lots of Delta-V, you'll need to get used to flip-and-burn trajectories which lend themselves to landing too close or too far to a planet or star if done wrong.

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For challenges, I hope there will still be major orbital challenges, not simply infrastructure challenges. I know Rask and Rusk have their dual systems and any planet with rings requires you to navigate well or end up crashing into lots of space rocks, but I would also like to see challenges that require you to use "worse" engines due to limitations that the better engines have. As a (bad) example, a planet with an immense magnetic field that causes computer systems and any engine that relies on magnets to fail

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2 hours ago, Bej Kerman said:

There will be challenges beyond just getting into orbit, which is a chapter KSP 2 has moved past. ... 

I don't disagree with any of that, I am just saying, it seems strange to express concern that this LANTR engine makes getting to orbit too easy, given what has already been shown... In particular the mmH engine, as it has none of the radiation drawbacks (aside from the torch ship drive and the Orion drives, it seems likely other interstellar drives will be put on craft that must be built in space - and the Orion must have some other engine for the initial liftoff, or you destroy the colony)

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  • 3 weeks later...
On 7/29/2021 at 9:28 PM, SciMan said:

(...)
Nuclear engines should be lightweight, but produce radiation, that YOU get to decide how to counter by use of distance to a crew compartment and/or shielding put in between the engine and the habitat section.

(...)

 

 

I can only hope that this 2.5m NTR isn't "LV-N, but scaled up", because that doesn't solve the issues with the LV-N. Nuclear energy is VERY POWERFUL, and it should FEEL powerful using it.

Yes Nuclear engine should be powerfull because :

Fission and fusion are two physical processes that produce massive amounts of energy from atoms. so an engine than use nuclear sould be powerfull too , good isp and thrust and nuclear reaction produce far more energy than chemical engine they should crush chemical engines by their power and isp thrust ...

Edited by Neoks
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On 6/25/2021 at 12:01 PM, KSPStar said:

and its vacuum nozzle can be retracted for use in atmosphere.

so on first glance, no!? That nozzle geometry really doesn't look suitable for atmosphere use.

If you look at other engines that can extend an extension to be used in a vacuum, their in-atmosphere nozzle is shaped more bell like instead of being long and narrow.

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19 hours ago, SpaceFace545 said:

so on first glance, no!? That nozzle geometry really doesn't look suitable for atmosphere use.

If you look at other engines that can extend an extension to be used in a vacuum, their in-atmosphere nozzle is shaped more bell like instead of being long and narrow.

It looks like they modeled the nozzle after actual conjectural NTR. Some of which did have extensible nozzles planned but those didn't have mixed atmospheric/vacuum use. They were vacuum all the way and the extensibility was only to make them more compact when stowed during launch.

PPT - Nuclear Thermal Rocket Propulsion for Future Human Exploration  Missions presented by PowerPoint Presentation - ID:4173217

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So, after playing with Nertea's "Far Future Technologies" mod for a bit, I've come to a realization:

Nuclear salt water rockets are an excellent and relatively "low-ish" tech solution for advanced propulsion concepts that are great for moving LARGE masses around in space with HIGH thrust, while still providing LARGE delta-V compared to chemical rockets and only needing a relatively SMALL fuel tank (but because water is quite dense that small fuel tank will be quite massive).
Of course, that is provided you can source the expensive and highly radioactive fuel.

If we could create an NSWR with an aerospike nozzle, that would be pretty much my ideal engine for use anywhere inside a single solar system.

Things like the fission fragment rocket engine and Afterburning fission fragment rocket engine are really only useful if you have hours to sit and watch them accelerate, or if you have another method to be able to do something else while that vessel is accelerating.

That's the principal problem with low-thrust but high ISP methods of propulsion in a video game where you can control how fast time proceeds if you're coasting: The burns are what take the longest time.
That means that you don't want "just the highest ISP, no matter what" once you're in orbit. You want the engine that has the highest thrust given an ISP high enough to do the job in a reasonably sized vehicle.
Basically, thrust is primary, ISP is something you only worry about if your rocket is so big that it's making your computer lag.
Does this mean that torch drives are the ideal? Yes. But not because they can provide 1G for days on end with a massive ship. It's more because they can provide MANY g's of thrust with a less massive ship. That less massive ship might have less total Delta-V, but what it gains is TWR, and TWR is king when you can artificially shorten only one of "burn time" and "coast time" due to how the game is programmed.

Here's hoping that KSP 2 has a way to have a vessel accelerate (or even better, execute maneuvers) while that vessel is unloaded and unfocused (in ksp 1 terms, "on rails" and outside physics range).

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38 minutes ago, SciMan said:

Here's hoping that KSP 2 has a way to have a vessel accelerate (or even better, execute maneuvers) while that vessel is unloaded and unfocused (in ksp 1 terms, "on rails" and outside physics range).

The devs have already said they are going to implement a system that you can thrust while on rails and unfocused.

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Thanks for knocking that memory loose in my brain, for some reason I couldn't get it to come to the front of my mind.

You are indeed correct, the KSP 2 devs have indeed said just that. I do wish there was a mod that added similar capability to KSP 1 so that I can get used to how to handle things like that early, but perhaps that's asking for the impossible.

However, it would be absolutely excellent if we could also program in a series of maneuvers for a craft to take, and then the game would make that craft perform those burns provided it has the capacity to do so (ie. it needs to have propulsion, attitude control, a control source, a thing to do, and enough resources to do it). It would only be a tool for orbital maneuvers, it would give the user an error telling them what they did wrong if it encounters an atmosphere or the surface.

Edited by SciMan
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21 hours ago, SciMan said:

You are indeed correct, the KSP 2 devs have indeed said just that. I do wish there was a mod that added similar capability to KSP 1 so that I can get used to how to handle things like that early, but perhaps that's asking for the impossible.

There is such a mod for KSP 1. I forget what it's called but it does allow for thrust when on-rails. Designed primarily for the ion engine but it works for anything. (AFAIK)

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21 hours ago, SciMan said:

Thanks for knocking that memory loose in my brain, for some reason I couldn't get it to come to the front of my mind.

You are indeed correct, the KSP 2 devs have indeed said just that. I do wish there was a mod that added similar capability to KSP 1 so that I can get used to how to handle things like that early, but perhaps that's asking for the impossible.

However, it would be absolutely excellent if we could also program in a series of maneuvers for a craft to take, and then the game would make that craft perform those burns provided it has the capacity to do so (ie. it needs to have propulsion, attitude control, a control source, a thing to do, and enough resources to do it). It would only be a tool for orbital maneuvers, it would give the user an error telling them what they did wrong if it encounters an atmosphere or the surface.

 

50 minutes ago, Starwaster said:

There is such a mod for KSP 1. I forget what it's called but it does allow for thrust when on-rails. Designed primarily for the ion engine but it works for anything. (AFAIK)

Given that the thrust persists through time warp, the mod is very strangely called “Persistent Thrust” :wink:

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19 minutes ago, Spaceman.Spiff said:

 

Given that the thrust persists through time warp, the mod is very strangely called “Persistent Thrust” :wink:

It's not working with the current version. The last KSP version it was working with was 1.10.x.

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