Nertea

[1.7.x] Kerbal Atomics: fancy nuclear engines! (Sept 11)

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15 hours ago, PocketBrotector said:

I voted for the big (preferably 3.75m) thrust-optimized GCNR and the mini 0.625m engine, partly because they'd be differentiated on size from the current offerings. 

Also, the idea of a nuclear-driven launch vehicle is intriguing and to my knowledge has not been represented in KSP mods to date. I was unable to open the DC-X SSTO PDF, so I went with my gut instinct of "bigger must be better."

The DC-X engine is essentially a cluster of 6 solid-core LOX-augmented NTRs arranged in an aerospike configuration. Inject LOX to boost to altitude, switch to pure LH2 when it doesn't matter anymore, deliver 100t of cargo and return.

nucleardcx3-2.jpg

Poll results clearly favour the aerospike CC GCNTR and the small mini-nuclear rocket though!

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On 4/11/2017 at 5:41 PM, Nertea said:

Eh... I'm just frustrated with it. It would be nice if interested parties, like you, @AmpCat, @Tau137 few others who I know have used it extensively, would come together here over the next couple weeks and hash out what needs to be done to fix the existing problems. The current piecemeal thing is that I fix one thing, don't hear anything for months, then wake up to a bunch of other new bugs and things. The user base is very small so it's been in a state of "well it kinda works" for so long that it's very annoying. I really want to be able to promote it to stable

Here's what I *know* needs to be fixed:

  • Reactor startup can't be forced on an engine (stages the engine) so a solution needs to be found
  • An exclusion needs to exist to stop engine roll control turbopumps from cooling the entire reactor
  • Exhaust conflicts with radiator cooling and won't allow other radiators to cool engine part's Internal heat store (Core is fine)
  • Solid core reactors should get more realistic core temperatures

Can we try to figure out where all the problems are?

 

 

 

Here is what I see as problems (please note that I have very little time to play for the last month or two, have not even downloaded the latest version yet).

1. (NFE + KA, high priority) - reactor heat-up time for solid-core nuclear engines is too long (even if startup is linked to throttle and all heating issue addressed, it is still a problem - actual "core" in such engines should be is extremely small, only about ~100kg for LVN, so I should not babysit the engine ready for 3 minutes before launching).

2. (NFE + KA, high priority) - reactor "post-wrap" calculations that tend to blow up ships on load (only when physics-loading another ship with a reactor or fuel storage on rendezvous; when in control of a ship, switching from high warp to physics is handled ok).  Perhaps this was resolved in the latest version, dunno, but for me it was such a frustration (possible to avoid by doing numerous vessel switches just before rendezvous to settle things now, but that is also painful and time-consuming) that I literally removed NFE core and replaced reactors with stock or USI converters (modified) in the latest game.  Feel really guilty about it, but... c'est la vie

3. When using LF patch, mass of high-tech engines such as CSGC is excessively high (effectively x2, too much).

4. Nuclear turbojet/ramjet is missing....  Pretty please!?  Atomic Age model is bad since 1.2, SXT version is just too unwieldy and ugly (I still used it though, even equipped it with NFE reactor), and I could not find any other decent models for such an engine.  Interstellar has thermal jets, but I do not want to use interstellar in its current form (love realism, but only in homeopathic doses; and do not want to see "waste heat" as a resource).

Beyond that, I think that Kerbal Atomics is great, love it. 

A few more comments that should go to other threads, but again, no time...

5. (NFP only) - Choice of engines is excessive.  This is not a bad thing, and not a complaint, but (in my personal opinion) this makes the mod somewhat overloaded with parts and options.  Yes, there is variety, great choices.... at the cost of extra game loading time and lag in editor (talking about lag - later versions of NFSS really lag down my editor, especially fuel tab; of course, I have tons of other mods installed).  I would prefer to see more concise and distinct choices in engines.  Just my opinion, I am sure many will disagree, which is great... and I can always just do what I usually do - cut Vasmir and Pulse and unlock 1.25 and 2.5 ions, cut all argon tech to simplify choices and improve performance.  Also, the whole NFP in general is so damn great and efficient....  making KA practically obsolete, except perhaps for Duna and Tylo heavy landers.

6. (NFE only) Reactor heat production is inconsistent and often too low across reactor sizes (e.g., 0.625 should produce at least twice as much heat).  Should be easy enough to calculate proper numbers based on fissile fuel consumption (just take something as a base number and go from there, does not have to be "realistic"), adjusting slightly for efficiency of generators in later, higher-tech reactors.  I had the numbers somewhere when I was going through adjusting everything in NFE two months back, but cannot find them any more, sorry.

I am looking forward towards playing again (with NF*, of course) as soon as/if I get a chance.  And thank you for keeping up the work on your mods, my playthroughs would not have been the same without them!

 

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I finished the models! Well, draft versions:

First, the mini-NTR. Tentative thrust of 15 kN, Isp 900s, mass ~0.3 t. Here it is compared to the 1.25m trimodal engine.

reRvX4k.png

Decided to make it cogeneration-capable (~1-2 Ec/s), so the area under the integral radiator contains a little Stirling generator. It also folds up into quite a tiny footprint. 

WPQ0kxO.pngTH5g9uo.png

I went considerably more exotic with the GCNTR. Imagine what might happen if you stuck eight nuclear lightbulb cores around the perimeter of a plug-nozzle aerospike. So, it's a nuclear aerospike. The idea of this design is that if you pump more fuel through the core while still hitting the 5000-6000K chamber temperatures of a GCNTR, you can achieve much higher flow rates and thrusts. However the higher flow rate results in less energy transfer to the fuel and thus a lower Isp. This engine is targeted at ~15t, 1800 kN and 1100-150s

HcB8zob.pngW3xPX8J.png

It will have a toggleable boattail so that you can effectively use it as a lower stage engine with nice colour matching. And I modeled the aerospike internals with the nescessary cooling channels to cool the outside of the rim plus the 'spike itself. 

@Tau137: Thanks for taking some time out of your schedule to make some notes. 

21 minutes ago, Tau137 said:

1. (NFE + KA, high priority) - reactor heat-up time for solid-core nuclear engines is too long (even if startup is linked to throttle and all heating issue addressed, it is still a problem - actual "core" in such engines should be is extremely small, only about ~100kg for LVN, so I should not babysit the engine ready for 3 minutes before launching).

I can try some things with this, but it's a key scaling issue. Everything has to be flattened at the high end to prevent high thermal fluxes from destroying the world, which means things need to be lowered at the low end to provide any meaningful progression of thermal values. Core heat shares its thermal mass scaling with part heat so making the core heat up faster has to be a matter of increasing the flux. 

21 minutes ago, Tau137 said:

2. (NFE + KA, high priority) - reactor "post-wrap" calculations that tend to blow up ships on load (only when physics-loading another ship with a reactor or fuel storage on rendezvous; when in control of a ship, switching from high warp to physics is handled ok).  Perhaps this was resolved in the latest version, dunno, but for me it was such a frustration (possible to avoid by doing numerous vessel switches just before rendezvous to settle things now, but that is also painful and time-consuming) that I literally removed NFE core and replaced reactors with stock or USI converters (modified) in the latest game.  Feel really guilty about it, but... c'est la vie

This hasn't been a consistent issue for a pretty long time. If you come back, I could use some help tracking it down.

I mean, the bit where we discovered that radiators wouldn't cool KA engines is probably helpful. 

21 minutes ago, Tau137 said:

4. Nuclear turbojet/ramjet is missing....  Pretty please!?  Atomic Age model is bad since 1.2, SXT version is just too unwieldy and ugly (I still used it though, even equipped it with NFE reactor), and I could not find any other decent models for such an engine.  Interstellar has thermal jets, but I do not want to use interstellar in its current form (love realism, but only in homeopathic doses; and do not want to see "waste heat" as a resource).

I have a rule, which is that aero parts go in the MkIV pack, so I can keep all the headaches in the same place ;).

21 minutes ago, Tau137 said:

5. (NFP only) - Choice of engines is excessive.  This is not a bad thing, and not a complaint, but (in my personal opinion) this makes the mod somewhat overloaded with parts and options.  Yes, there is variety, great choices.... at the cost of extra game loading time and lag in editor (talking about lag - later versions of NFSS really lag down my editor, especially fuel tab; of course, I have tons of other mods installed).  I would prefer to see more concise and distinct choices in engines.  Just my opinion, I am sure many will disagree, which is great... and I can always just do what I usually do - cut Vasmir and Pulse and unlock 1.25 and 2.5 ions, cut all argon tech to simplify choices and improve performance.  Also, the whole NFP in general is so damn great and efficient....  making KA practically obsolete, except perhaps for Duna and Tylo heavy landers.

You should see the outcry I get when I remove a single part :S

21 minutes ago, Tau137 said:

6. (NFE only) Reactor heat production is inconsistent and often too low across reactor sizes (e.g., 0.625 should produce at least twice as much heat).  Should be easy enough to calculate proper numbers based on fissile fuel consumption (just take something as a base number and go from there, does not have to be "realistic"), adjusting slightly for efficiency of generators in later, higher-tech reactors.  I had the numbers somewhere when I was going through adjusting everything in NFE two months back, but cannot find them any more, sorry.

You should like what we have done with the upcoming rebalance then, waste heat numbers went up across the board and are much more consistent in terms of energy production per unit fuel.

 

Edited by Nertea

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5 minutes ago, Tau137 said:

I wonder if I should wait for 1.3 or try to squeeze in some play in 1.2 still?

I am, the create a contract system is something I didn't know that I needed until now. I just need to create a backup/make sure all my kerbals are home so they don't die if (when) stuff breaks haha.

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19 minutes ago, Tau137 said:

I wonder if I should wait for 1.3 or try to squeeze in some play in 1.2 still?

I would wait for 1.3 at this point. I rewrote another good piece of the plugin recently and that won't see the light of day until then as it's being developed on the 1.2.9 branch.

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I'm having a ton of fun with this nuclear aerospike. Finished the unwrap and put a test model ingame today. With a relatively simple launch vehicle and a single engine, I can boost ~70t to orbit, turn around, re-enter and land. Well, almost land. The point is that velocity was zero at some point very close to the ground - the falling over and exploding wasn't important. I'm a terrible pilot.

It really begs 5m/7.5m LH2 lifter-style tanks though! Getting a ~5m diameter lifter stage was a terrible kludge.

Edited by Nertea

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Deleted. Answered my own question.

But, one comment: I love the nuclear aerospike. If you need someone to test it @Nertea, I'm eager and willing. I've made many a single stage to orbit, and landable nuclear rocket with KA. Mostly Liberator based rockets. Much easier than spaceplanes.

Edited by AmpCat

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I have a balance question, can someone explain to me the reason for the dry mass to fuel ratio of ~3 for the cryogenic tanks with LH2 versus around 8 for any other tank with LF/OX.

I get that LH2 is less dense (more volume required),  but wouldn't that also mean that the tank doesn't need to mass as much ?  As an example, the max DV I can seem to get for a LV-N (no payload, just engine and tanks), is around 11k m/s.  The theoretical maximum should be north of 21k I believe from other resources I've seen.

Maybe it's some mod in my GameData constellation that is causing the issue or I'm just not wrapping my head around it.  As an example, the dry mass of the HI-530 is 28.8 tons with only 81 tons of fuel for a ratio of dry/fuel of around 2.8.   A jumbo 64 is a ratio of 8.

As it stands now, Nuclear engines don't seem to have a place in the game.  Using chemical engines can usually give me a little more delta-v (at the expense of overall mass) at a lot less cost and complexity.

I know I can use the LF-only patch, I really want to understand the LH2 mechanism though.  Simple answer is to patch the cryo tanks to weigh less.  And I may write a MM patch to do that for my game, but I'm curious the use cases people use these engines for.  By the time you add radiators and the like to manage heat your delta-v is really taxed.  

Thanks for the help.

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1 hour ago, bdlarkin said:

I get that LH2 is less dense (more volume required),  but wouldn't that also mean that the tank doesn't need to mass as much ?  As an example, the max DV I can seem to get for a LV-N (no payload, just engine and tanks), is around 11k m/s.  The theoretical maximum should be north of 21k I believe from other resources I've seen.

Yes, if you just stack a bunch of LH2 tanks on top of a Nerv, you get a max dv of about 10.5km/s. However, if you just stack a bunch of LFO tanks on top of a Poodle, you get a max dv of about 7.3km/s. So even by the arbitrary zero-payload metric, there's some improvement over chemical engines. 

More to the point, you may have noticed that Kerbal Atomics adds a variety of new nuclear engines, most of which feature significantly higher Isp - sometimes dramatically so. In stock KSP, the Nerv is simply the only engine in its class, but with KA it's much more of a starter model.

And yeah, less dense fuel means worse mass ratio for your tanks. I believe LH2 tanks do get a discount on mass compared to LFO tanks of the same volume, but it doesn't cancel the fact that the same volume of LH2 is much lighter.

Edited by PocketBrotector

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That GCNTR looks sexy as hell! @Nertea Love it. 

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16 hours ago, bdlarkin said:

 

I have a balance question, can someone explain to me the reason for the dry mass to fuel ratio of ~3 for the cryogenic tanks with LH2 versus around 8 for any other tank with LF/OX.

I get that LH2 is less dense (more volume required),  but wouldn't that also mean that the tank doesn't need to mass as much ?  As an example, the max DV I can seem to get for a LV-N (no payload, just engine and tanks), is around 11k m/s.  The theoretical maximum should be north of 21k I believe from other resources I've seen.

Maybe it's some mod in my GameData constellation that is causing the issue or I'm just not wrapping my head around it.  As an example, the dry mass of the HI-530 is 28.8 tons with only 81 tons of fuel for a ratio of dry/fuel of around 2.8.   A jumbo 64 is a ratio of 8

The short version is that Squad gave us a magic NTR that can operate on aerozine (that thing should be putting out  < 450s) with the performance characteristics of LH2. In order to provide progression that's not ridiculous, as mentioned, things need to be pulled more in line with pseudo-reality... ie. things need to have some disadvantages. I can't make a gas-core engine with 1600s of performance and a TWR > 1 with LF, it's just.... well, it obsoletes everything instantly. 

The thing is that it's really hard to store LH2. It's not a good fuel for a lot of applications despite all the NERVA-loving that goes on. The NASA Mars DRM5 with NTR option for example gives mass ratios of around 3.7 for cryogenic tanks (lifting tanks like the SLS main tank might get away with 8ish). By contrast kerolox tanks are like 15-20 mass ratio, almost double the KSP versions. If I use that same scaling (halving the RL value), I get even crappier mass ratios. Upcoming plans will move the mass ratio closer to 5 than 3, but it is never going to match plain ol' LF tanks, because that'd really go away from representing the fuel's challenges, which is the design goal with both cryoengines and KA. 

 

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Comment of engine effects (cfg files, easy fix):

ALL visual (particle) effects should be moved under Power (plume), keeping audio as it is - this will make exhaust behave more "realistically" in atmosphere by proportionally scaling back the whole exhaust (currently only "plume/dust" component is scaled, while "core/running" effects stay at full power, creating noticeable dissonance).

This applies to applies to NF-P and NF-SS engines as well.

 

Edited by Tau137

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1 hour ago, Tau137 said:

Comment of engine effects (cfg files, easy fix):

ALL visual (particle) effects should be moved under Power (plume), keeping audio as it is - this will make exhaust behave more "realistically" in atmosphere by proportionally scaling back the whole exhaust (currently only "plume/dust" component is scaled, while "core/running" effects stay at full power, creating noticeable dissonance).

This applies to applies to NF-P and NF-SS engines as well.

You should try doing this. Unless something has changed recently, it's not possible to enable multiple particle effects in a single FX group. That's why it is the way it is. 

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Oh...oh.... Nu...Nuclear aerospike engine... ... Yes, please...:D:0.0::cool::):confused:
Since i consider your NFT and KerbalAtomics as "stock" KSP for myself... 

So. Much. Yes.:)

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2 hours ago, Nertea said:

You should try doing this. Unless something has changed recently, it's not possible to enable multiple particle effects in a single FX group. That's why it is the way it is. 

Yep, I already realized that.  Sorry.  Also, it is only on somewhat critical for nuclear (other electrics will never be run in atmosphere, except perhaps by accident; and ions are easy fix as they only have one effect).

Now playing with SmokeScreen to see if I can come up with something comparable, but doubt I will go further that just modifying settings for existing RealPlume prefabs.

 

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6 minutes ago, Tau137 said:

Yep, I already realized that.  Sorry.  Also, it is only on somewhat critical for nuclear (other electrics will never be run in atmosphere, except perhaps by accident; and ions are easy fix as they only have one effect).

Now playing with SmokeScreen to see if I can come up with something comparable, but doubt I will go further that just modifying settings for existing RealPlume prefabs.

 

Yeah it's pretty frustrating... If i could have many systems per FX layer I could made some beautiful effects.

If you make some RealPlume/SmokeScreen configs I'd be happy to include them.

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Hello, can anyone help me ? I can't refuel emancipator engine with enriched uranium, i tried refuel it from nuclear fuel container and i also can't do that.

 

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On 5/3/2017 at 11:47 PM, MrFancyPL said:

Hello, can anyone help me ? I can't refuel emancipator engine with enriched uranium, i tried refuel it from nuclear fuel container and i also can't do that.

 

The Emancipator cannot be refueled due to its design (Open Cycle Gas Core).  If you need a refuel-able engine, use a different one.

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Can this be used on an interstellar mission, to reach another star in, like, 48 hours at max time warp in our time?

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47 minutes ago, The-Doctor said:

Can this be used on an interstellar mission, to reach another star in, like, 48 hours at max time warp in our time?

48 hours in real time? I mean, sure, this is KSP, if it's conceivable you can do it with enough boosters and gravity assists.

Are Nert's nuclear engines designed for that/pragmatic to use it in this manner? Absolutely not. As far as the mod technology world goes, these have a nice balance between thrust and ISP - about in the 500s-1000s range if my memory serves me right. Since these run on LH2, there'd need to be a massive amount of fuel tanks to haul up/build in orbit. So, there's still room for improvement. Near Future Propulsion has electrical engines that get close to 10000s of specific impulse with tiny amounts of thrust. You could leverage them in the right way to get there in time in an efficient manner.

But by far the best way to do interstellar is to either have a really long mission with electrical engines to set up a supply chain for orbital construction, or use RoverDude's warp drive to set up jump beacons and optimize a system for those on either side.

I play with all of Nert's mods and the USI suite + Deep Freeze, OPM, and lots of others, so I'd probably do drone construction of a supply line to build ships and send a bunch of frozen Kerbals over when I have a self-sufficient base. Long-range relays are cheap, Kerbals not so much.

 

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@Esquire42 NFT thrusters take hours and tons of fuel, I was thinking of looking at Orion nuclear pulse. Also what do you mean by a supply chain for obital construction? Also have you gone interstellar? Also what do you mean by drone construction of a supply line to build ships? What do you mean by long range relays? LOL

 

My goal, is to build a massive mothership with the help of the community here and in the FB group. The mission is to colonize all the habitable worlds in RSS Constellations, which will take hundreds if not thousand of years to fly between. The manufactures for each vessel used on the mothership will form the New Colonial Alliance, which is the group that's sending the mission. It's called the Icarus Initiative. I may even turn it into a youtube series 

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2 minutes ago, The-Doctor said:

@Esquire42 NFT thrusters take hours and tons of fuel, I was thinking of looking at Orion nuclear pulse. Also what do you mean by a supply chain for obital construction? Also have you gone interstellar? Also what do you mean by drone construction of a supply line to build ships? What do you mean by long range relays? LOL

 

My goal, is to build a massive mothership with the help of the community here and in the FB group. The mission is to colonize all the habitable worlds in RSS Constellations, which will take hundreds if not thousand of years to fly between. The manufactures for each vessel used on the mothership will form the New Colonial Alliance, which is the group that's sending the mission. It's called the Icarus Initiative. I may even turn it into a youtube series 

I play with MKS so a supply chain for orbital construction would be an extensive mining setup that includes regular ore, metallic ore, uranite, karborundium, etc, plus the infrastructure to haul those materials and construct craft in orbit (via EPL). (I highly suggesting checking out MKS and the rest of USI, it adds a great deal of depth to the game.) So thus I'd rather set up a Kerbal-less supply line first to create a self-sustaining base before sending Kerbals in. 

I'm not sure why you're confused by long-range relays. It's exactly what it says on the tin.

Motherships are expensive things. It's much easier and efficient to send smaller ships to enable orbital construction and go from there.

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I intend on building it in the VAB and docking it up. I intend on using keridian dynamics to build surface bases and using planetary domes to build surface bases. I also intend on using kerbalism which causes critical ship malfunctions, I have actually practiced a bit with it, I did a 100 year mission, the ship was fairly damaged and it was still thousands of years to proxima b. I have a LOT of planning to do for this mission, I intend on gaining help. I have actually never created a colony or surface base before lol. Do you wanna join the initiative? I still dunno what you mean by long range relays, if you mean for communications, then yeah

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