[WIP] Nert's Dev Thread - Current: various updates

[RedParadize]

1 hour ago, Nertea said:

Not sure it's too complicated. Just target them the way you would any other set of nodes in MM.

But I do appreciate feedback on balance...

I can do at least that for you. First, I have to specify that I do not currently use a modded techtree and everything is under nuclear in stock. I did read a bit about some of these engine but my comment will be done mostly from a gameplay perspective. I listed them in the order i think they should appear in a tech tree:

Fission/Fusion engine:

Nuclear salt water Engine: One of my favorite. Its light, relatively inexpensive, no electric requirement, the easiest to operate, have a good TWR and its ISP is decent. Given all that, most case scenario its far more efficient than all other fusion and fission engine. Extremely flexible in its usage and great for lander... until radiation is implemented.

Z-pinch fission Engine: Average compared to other FFT engine. Quite massive but deliver allot for its mass and cost. For moderate playload it can give a decent TWR, for larger playload its lower ISP start to show and trust become too low for my taste.

Z-pinch fusion Engine: I think Z-pinch fusion is under performing compared to both Internal Confinement fusion and even Z-pinch fission. Z-pinch fission is cheaper to buy and operate, its TWR make it much more attractive so why go fusion? I believe most of the other mode of propulsion are better. As for my personal taste, it is one of the engine that grid trough my patience beyond playability.

Ablative Internal Confinement Engine: If you exclude cost, its better than Z-pinch fission. Otherwise its more or less on par with it as you can achieve the same dV cost wise. Again it lack a bit of TWR for my taste.

Tokamak Fusion Engine: Considering 95% of its fuel can be collected with a scoop. Its a attractive engine. Trust is lacking when carrying the mandatory reactor and any significant playload. I would rate it just under Nuclear salt water as its less flexible and compact.

Inertial Internal confinement Engine: Impressive ISP. But TWR is abyssal, even more when you consider the amount of radiator that thing need.

Mirror Cell Fusion Engine: The holy grail of the fusion engine. It have the trust, the ISP, coupled with a scoop, a large amount of D/He3 and just enough LH2, a good 2g can be maintained for every burn any mission would require. The only downside is its massive heat issue.

And the weird thing:

Metallic Hydrogen Engine: Interesting engine, but probably limited in its usage as there is no way to produce MH SITU yet. Classical nuclear engine are superior, until radiation obviously.

 

In a career game, I could defitively see myself using only NSW until I get the MCF. Depending on the gap in science point, I might use the Z-P fission or tokamak. I will review the antimatter engine tomorrow, but so far they don't seem to justify the upgrade, none are clearly superior to the MCF engine.

 

 

 

 

[helaeon]

For my own game I have the z-pinch fusion running at 2x thrust vs stock. Mass wise, it looks like it should weigh a lot. There would be a lot of iron, neodymium, & copper there. So current mass is fair I think.
The Inertial Internal Confinement Engine I dropped the mass by half and increased the thrust by 2x. 1.5 may be a better number, but I think I'll play at 1/2 mass and 2x for a bit. It looks like it should be fairly light from the model. The existing thrust might be okay if it were a smaller form factor. Another thought here, if it's using the reaction products as exhaust, shouldn't it not actually create that much heat for the ship to dissipate as it's being expelled in that exhaust?

A separate idea... there is already lithium implemented as a resource, what about a lithium spray radiator that fires off super heated pellets of lithium to dissipate x kW of heat per unit of lithium, player can adjust the loss of lithium to reject more or less heat per unit time?

Sharing personal choices and thinking out-loud here, use or discard as you wish.

I do have some funky stuff going on with the PW x2 fusion pellet fuel tank. It also doesn't switch the name in the VAB from fission pellet to fusion pellet though it does change the fuel in the tank. It causes anti-grav on the pad.
The x4 does not have this problem. I copied ModuleB9PartSwitch from the x4 to the x2 and changed the volume to 1800 and that did fix the fuel switch issues but not anti-grav.

[Nertea]

Point to note, I haven't really touched costs, except maybe fuel costs. And are we all using the options provided by HeatControl here, and not the stock radiators? I can practically say that using the stock radiators will not provide good results...

2 hours ago, RedParadize said:

Nuclear salt water Engine: One of my favorite. Its light, relatively inexpensive, no electric requirement, the easiest to operate, have a good TWR and its ISP is decent. Given all that, most case scenario its far more efficient than all other fusion and fission engine. Extremely flexible in its usage and great for lander... until radiation is implemented.

Mirror Cell Fusion Engine: The holy grail of the fusion engine. It have the trust, the ISP, coupled with a scoop, a large amount of D/He3 and just enough LH2, a good 2g can be maintained for every burn any mission would require. The only downside is its massive heat issue.

These are the two endgame engines. At the moment, the NSWR is probably too good, but if you compare the other engines to them, they'll suffer for sure. NSWR is at the end of the fission tree, gasdynamic mirror is at the end of the fusion tree basically (beam core AM is at the end of the AM tree too).

2 hours ago, RedParadize said:

Z-pinch fission Engine: Average compared to other FFT engine. Quite massive but deliver allot for its mass and cost. For moderate playload it can give a decent TWR, for larger playload its lower ISP start to show and trust become too low for my taste.

Z-pinch fusion Engine: I think Z-pinch fusion is under performing compared to both Internal Confinement fusion and even Z-pinch fission. Z-pinch fission is cheaper to buy and operate, its TWR make it much more attractive so why go fusion? I believe most of the other mode of propulsion are better. As for my personal taste, it is one of the engine that grid trough my patience beyond playability.

Is the doubled Isp compared to the fission not helpful? Both these engines might get their constant power drain cut by ~50% to the 50/75 Ec/s range to make them better.

1 hour ago, helaeon said:

For my own game I have the z-pinch fusion running at 2x thrust vs stock. Mass wise, it looks like it should weigh a lot. There would be a lot of iron, neodymium, & copper there. So current mass is fair I think.

Doesn't that just make it more or less the same as the z-pinch fission at 2x the Isp?

 

57 minutes ago, helaeon said:

. Another thought here, if it's using the reaction products as exhaust, shouldn't it not actually create that much heat for the ship to dissipate as it's being expelled in that exhaust?

It's more like "just" reaction products. Eg the ablative ICF uses reaction products plus vaporized ablator. No effective difference for heat generation.

49 minutes ago, helaeon said:

I do have some funky stuff going on with the PW x2 fusion pellet fuel tank. It also doesn't switch the name in the VAB from fission pellet to fusion pellet though it does change the fuel in the tank. It causes anti-grav on the pad.

This tank is the bane of my existence. I always manage to ship half the fixes it needs...

 

I'll think about some of these things.

[trias702]

@Nertea

I've noticed that some of the new engines, such as the fusion mirror, produce a tremendous amount of heat. The heatProduction of the ModuleEnginesFX is 4000 for that one. What radiator stats work to cool such massive heat output? I'm guessing not core heat xFer, as the heat source is not ModuleCoreHeat, so is it the MaxCooling stat which is relevant? I note that in the VAB, the ModuleEngineHeatDisplay for the fusion mirror reports engine heat of 1200 MW, so does the total sum of all my radiators' MaxCooling values need to equal this amount?

[Nertea]

1 minute ago, trias702 said:

@Nertea

I've noticed that some of the new engines, such as the fusion mirror, produce a tremendous amount of heat. The heatProduction of the ModuleEnginesFX is 4000 for that one. What radiator stats work to cool such massive heat output? I'm guessing not core heat xFer, as the heat source is not ModuleCoreHeat, so is it the MaxCooling stat which is relevant? I note that in the VAB, the ModuleEngineHeatDisplay for the fusion mirror reports engine heat of 1200 MW, so does the total sum of all my radiators' MaxCooling values need to equal this amount?

It's important to note that heatProduction is a really weird number and unless you know how it works, don't go by it. The VAB EngineHeatDisplay one should be real. Also note that for the variable length engines, the parts list shows the highest length engine's stats.

As to what you need well... It's hard to say. I've noticed I can get by with significantly less than HeatProduction/CoreHeatTransfer, but need more than HeatProduction/MaxCooling. I think MaxCooling is a theoretical max that the radiator can dump (eg, proportional surface area *emissive*T^4), but there is a limit to the rate at which heat is transferred to the part. Plus the engine itself radiates.

For example theoretically a Vector produces 1.5MW of heat, but can easily burn almost forever without multiple heat panels. The point is hard to find. 

[helaeon]

Doubling the thrust on z-pinch fusion still has it at roughly half the thrust of fission for a similar mass. I'm currently running at 1.75x thrust so it is closer to half. Reason I started doing this in the first place back on the first test release it was included with, was I could build the same ship but use VASIMR thrusters from NFP and make a superior ship in all respects. Double the thrust of the z-pinch and it's usually better than the NFP engines.
I'm not sure what the correct answer is for ZFusion, but it does feel weak.

I do agree that the NSWR is way too good. It's really really easy to not use anything else, which is usually a hint it's too good. Many of the real-world drawbacks are not really issues in KSP.

Sharing what I'm doing with my own game as feedback for what feels "right" to me at the moment. Others may disagree. I'll be the first to admit I'm rule of cool (but seems sane) rather than gritty realism. Certainly not asking for changes.

Tonight I was messing with the ICF and I zoomed in on it and saw all the little lasers that fire through the engine on the animation effect. Supurb little detail. Made me smile. You do excellent excellent work.

[Nertea]

7 hours ago, helaeon said:

Doubling the thrust on z-pinch fusion still has it at roughly half the thrust of fission for a similar mass. I'm currently running at 1.75x thrust so it is closer to half. Reason I started doing this in the first place back on the first test release it was included with, was I could build the same ship but use VASIMR thrusters from NFP and make a superior ship in all respects. Double the thrust of the z-pinch and it's usually better than the NFP engines.
I'm not sure what the correct answer is for ZFusion, but it does feel weak.

I do agree that the NSWR is way too good. It's really really easy to not use anything else, which is usually a hint it's too good. Many of the real-world drawbacks are not really issues in KSP.

Sharing what I'm doing with my own game as feedback for what feels "right" to me at the moment. Others may disagree. I'll be the first to admit I'm rule of cool (but seems sane) rather than gritty realism. Certainly not asking for changes.

Tonight I was messing with the ICF and I zoomed in on it and saw all the little lasers that fire through the engine on the animation effect. Supurb little detail. Made me smile. You do excellent excellent work.

Yep, no, keep the feedback coming. I have no idea what I'm doing with balance right now, so... I appreciate all opinions!

I definitely need some way to get the NSWR to be less useful, and it would be better to not do it by chopping numbers off Isp.

Glad you like the ICF lasers, a little unrealistic as they would be invisible, but I couldn't resist.

Edited August 4, 2017 by Nertea

[MatterBeam]

1 hour ago, Nertea said:

Yep, no, keep the feedback coming. I have no idea what I'm doing with balance right now, so... I appreciate all opinions!

I definitely need some way to get the NSWR to be less useful, and it would be better to not do it by chopping numbers off Isp.

Glad you like the ICF lasers, a little unrealistic as they would be invisible, but I couldn't resist.

Hi!

How are you balancing the engines? Do you use kW/kg as a balancing factor?

[Hesp]

3 hours ago, Nertea said:

Yep, no, keep the feedback coming. I have no idea what I'm doing with balance right now, so... I appreciate all opinions!

I definitely need some way to get the NSWR to be less useful, and it would be better to not do it by chopping numbers off Isp.

Glad you like the ICF lasers, a little unrealistic as they would be invisible, but I couldn't resist.

 

You did an outstanding job! First of all, thank you 

As others already said, the major issue / difficulty to overcome with all these engines is not modeled in KSP... radiation.

 

I'm throwing here a crazy idea, not even sure it can be done without a specific mod.

What about an auto-deactivation or performance limitation of all nuclear devices (engines, reactors, etc) when the ship is in close proximity to other vessels or planetary surfaces?

Of course this can be tuned accordingly to the part characteristics / need of balance.

 

Let's take the emancipator from KA for an example, I'd like to have the open-cycle-fuel disabled and throttle limited when approaching other ships or stations

Edited August 4, 2017 by Hesp
added example

[RedParadize]

3 hours ago, Nertea said:

Yep, no, keep the feedback coming. I have no idea what I'm doing with balance right now, so... I appreciate all opinions!

I definitely need some way to get the NSWR to be less useful, and it would be better to not do it by chopping numbers off Isp.

Glad you like the ICF lasers, a little unrealistic as they would be invisible, but I couldn't resist.

I do not think NSWR should not be at the end of the fission tree. Its a comparatively simple design, excluding high heat resistance materials (but , Z-pinch need them too). Anyway, what's not so simple is its fuel and its storage. I would suggest making the current highly enriched fuel more expensive and almost impossible to produce in situ. Maybe find a way to make it hard to handle. That plus the incoming radiation should adequately nerf it without killing it.

That's a subject for another topic, but that engine would most likely be illegal in earth low orbit. If a fully packed reservoir crashing on earth would be catastrophic. Maybe there is some balancing effect to get from that.

BTW why not making it bimodal? Having another mode that use a less enriched or cheaper isotope.

[Nertea]

Just now, RedParadize said:

I do not think NSWR should not be at the end of the fission tree. Its a comparatively simple design, excluding high heat resistance materials (but , Z-pinch need them too). Anyway, what's not so simple is its fuel and its storage. I would suggest making the current highly enriched fuel more expensive and almost impossible to produce in situ. Maybe find a way to make it hard to handle. That plus the incoming radiation should adequately nerf it without killing it.

That's a subject for another topic, but that engine would most likely be illegal in earth low orbit. If a fully packed reservoir crashing on earth would be catastrophic. Maybe there is some balancing effect to get from that.

BTW why not making it bimodal? Having another mode that use a less enriched or cheaper isotope.

I'm actually using the specs for low-enrichment... hehe. High enrichement is ridiculous. It really should be at the end of the tree though. It is simple (except the materials engineering which is extremely not simple), but tree location != measure of simplicity, it's a gating thing. Best engine kinda has to be at the end of the tree.  Fuel storage is also technically simple as well (comparable to ZBO cryogenics). 

So I have this other mod called Glowing Reputation that I'm working on that creates reputation, science and cost hits for exploding or operating parts in sensitive areas. Obviously that will make a lot of these engines very bad for launch engines in kerbin and in other "sensitive" places. Mod's not ready yet, but it can help a bit when the time comes:

eg.

@PART[nswr-25-1]:FOR[GlowingReputation]
{
  MODULE
  {
    name = ModuleReputationDestruction
    SafeUntilFirstActivation = true
    BaseReputationHit = 25
  }
  MODULE
  {
    name = ModuleReputationEngine
    EngineID = MainExhaust
    BaseReputationHit = 15
  }
}

// ----------
// NSWR Tanks
@PART[nsw-25-1]:FOR[GlowingReputation]
{
  MODULE
  {
    name = ModuleReputationDestruction
    SafeUntilFirstActivation = false
    BaseReputationHit = 20
  }
}
@PART[nsw-25-2]:FOR[GlowingReputation]
{
  MODULE
  {
    name = ModuleReputationDestruction
    SafeUntilFirstActivation = false
    BaseReputationHit = 10
  }
}

 

1 hour ago, MatterBeam said:

How are you balancing the engines? Do you use kW/kg as a balancing factor?

That is one factor. 

[GabrielG.A.B.Fonseca]

Very impressive. I like the concept of the 'Glowing Reputation' you mentioned!

I do have two questions tough: The first is that I seem to recall you once were experimenting with a ray-path radiation modlet, correct? Was it just an experiment, or are there future plans for it?

And my second question is, managing so many (amazing) mods seems to be very hard work. How do you manage? (I suspect you might be some sort of super-human!  )

Thanks again for your mods, Nertea.

[RedParadize]

@Nertea Glowing reputation... That's brilliant! If you ask me, these are the kind of mod I am really looking for. Anything that would refresh KSP gameplay. ( if only we add on rail acceleration...)

Some other note I did't post yesterday:

On 8/3/2017 at 2:32 AM, Nertea said:

Point to note, I haven't really touched costs, except maybe fuel costs. And are we all using the options provided by HeatControl here, and not the stock radiators? I can practically say that using the stock radiators will not provide good results...

I believe cost will play a big role in balancing these engines end their fuel. I do use HeatControl, obviously! That big fixed radiator panel look so good. But as it is, these engine require a extra 10 - 40 tons of radiator. If you include the power source as well the full package is in the 20t - 100t range. That's without fuel. This is something to consider I think. Maybe a way to balance them would be to compare each full package against each other. I will look into that tonight.

Maybe it would be good to exaggerate the fundamental difference between them, stereotyping them without breaking realism too much. It would give character to each of them. 

On 8/3/2017 at 2:32 AM, Nertea said:

Is the doubled Isp compared to the fission not helpful? Both these engines might get their constant power drain cut by ~50% to the 50/75 Ec/s range to make them better.

The Z-P Fission is fine. The way I look at it, it's right in the middle of all the others, it's the benchmark. In the last iteration I ended up reducing its heat production a bit. It was more a question of aesthetics than anything else, but if you are looking of a buff that might do. Its a indirect buff, less radiator mean less mass for the full package. As for Z-P Fusion, you will need more mass reduction than that. I would definitively increase trust too.

As for the gasdynamic mirror. Its OP and its fine, its the end of the tree. If you are looking for a nerf, I think you should increase its power requirement allot. Adding a full fledged 8t reactor on top of the already massive engine+radiator package will not kill it. It have the trust.

[Nertea]

1 hour ago, GabrielG.A.B.Fonseca said:

I do have two questions tough: The first is that I seem to recall you once were experimenting with a ray-path radiation modlet, correct? Was it just an experiment, or are there future plans for it?

It's pure software work, and when my work at is pure software (has been for the last 8 months) I don't have much desire to do this in my spare time. Maybe whenever I get back to it. I would like to finish it for sure. 

1 hour ago, GabrielG.A.B.Fonseca said:

And my second question is, managing so many (amazing) mods seems to be very hard work. How do you manage? (I suspect you might be some sort of super-human!  )

Ever since I set up a full build and deploy pipeline via Jenkins this became a bunch easier. The trick though is really to have a carefully calibrated steady flow of craft beer and high quality coffee. Without those I would be lost. 

1 hour ago, RedParadize said:

I believe cost will play a big role in balancing these engines end their fuel. I do use HeatControl, obviously! That big fixed radiator panel look so good. But as it is, these engine require a extra 10 - 40 tons of radiator. If you include the power source as well the full package is in the 20t - 100t range. That's without fuel. This is something to consider I think. Maybe a way to balance them would be to compare each full package against each other. I will look into that tonight.

That's fairly expected and I'm considering those numbers in the balance equations at least. 

1 hour ago, RedParadize said:

As for the gasdynamic mirror. Its OP and its fine, its the end of the tree. If you are looking for a nerf, I think you should increase its power requirement allot. Adding a full fledged 8t reactor on top of the already massive engine+radiator package will not kill it. It have the trust.

I'll try kicking up the amount of power needed per added segment, so the low thrust ones will be similar but the highest power ones are a little worse. 

[helaeon]

I think something to consider in balance is the annoying to use factor.
I find myself wanting to use FusionPellet fueled engines because they're simple and also shared with the Pathfinder mod. Yes, other engines might be better, but there are more things to consider, more fuel tanks and types to mess with, maybe no ISRU tool chain if I want to do that. So I'll take an engine that has a lower ISP, higher power need, higher radiator need, lower TWR etc simply because it's more straight forward on craft design and makes it more versatile.

Is it possible to have an engine direct heat at another ship or part within physics range? Maybe use heat as radiation? I figure the Kerbals would design the ship with the crazy engine to have proper radiation shielding for it, but that doesn't mean if you're trying to land at your base on Minmus with one of these engines it would be, so you'd cook your base, space station, other ship, etc. Literally cook it with the engine. Sending hundreds of megawatts per second or more of heat at the base from a kilometer away or more. Engine plumes can transmit heat to parts on the same ship, is it possible (and worth it) to turned that up fantastically for the exhaust plume of these engines?

[Nertea]

Plume damage is limited to directionally along the thrust transform unfortunately.

This ease of use question is something I always think about too. That's why I haven't gone overboard with fusion fuel types and things.... It would be very easy to balloon rapidly. I hope I hit a good compromise with essentially a "fusion" fuel type, an antimatter fuel and the pellet fuels.

The single use fuels (mtlh2 and nsw) are single-purpose and uncommon which to some extent decreases the usefulness of the fuel.

[RedParadize]

@Nertea Humm... I do not know how they position against each other in the tech tree, the ablative appear before the Z-P right? Right now the ablative is much better on every aspect. If I had to balance them against each other and give them a specific character, ablative should be more massive but generate much less heat and require less energy, since it burn ablative armor as well you should probably nerf its ISP by half, right now its insanely good. With the weight of their radiator, Ablative should still be more massive than the Z-P by quite allot. If you where to buff Z-P fusion trust to +- 250kN and reduce its weight to say 18t. it should give a edge to the Z-P at the cost of volume and complexity. That would also put it on top of Z-P Fission.

For the last of the pellet engine, the ICFE, I do not know what to do with it, technically its the Z-P fusion successor right? It's model look very light in comparison. I would suggest making it lighter, with a slightly better TWR. Then I think it should be equivalent to the Z-P fusion in term of Heat / ISP x Trust ratio, maybe slightly higher. To do that you might have to nerf it ISP quite allot. As a result, player could do much lighter ship for the same dV and acceleration. What way it would be good, without being as good as Mirror Fusion and rendering Z-P obsolete.

The tokamak is great, is it just before the mirror fusion and after the ICFE? If yes  its heat generation is about the same for the 500kN version of the mirror fusion, while being much lighter, kinda negate its ISP advantage. It could be right as it is, but it make the 500kN variant of the mirror more or less useless. And btw, once launched, mechJeb say mirror fusion has 342kN of trust instand of the 500kN. ( can we mirror fusion stats in the part info interactive menu?)

 

Edited August 5, 2017 by RedParadize

[Mekan1k]

I hate to ask this, but is there a way to increase the antimatter generation rate? Because otherwise I am going to have to find a place where the scoops can siphon a TON of antimatter in deep space, and build all my vehicles out there. Hmmmmm....

[Nertea]

Fusion Power Small Fusion Reactor		Exotic Fusion Reactions Ablative ICF	High Density Fusion Reactions Magnetic ICF Mirror Cell fusion engine
Fusion Rockets Magneto Inertial Fusion Engine	Advanced Fusion Reactions Tokamak Fusion Engine Z- Pinch Fusion Large Fusion Reactor	Antimatter Power AMCF/AIM	Unified Field Theory Beam Core AM Plasma Core AM
Experimental Nuclear Propulsion Z-Pinch Fission	Exotic Nuclear Propulsion NSWR Fission Fragment Engine
	Colossal Rocketry Metallic H2

@RedParadizeyou've got it a bit backwards, the two Z-pinch engines are lower tech than the ICF ones. Here's the structure in the CTT at the moment.

 

@Mekan1k

There's an infinite antimatter cheat, check the changelog file for the keycode.

[RedParadize]

@Nertea It seem a bit weird to have a Magnetic nozzle before a a ablative one. Whats the rationale behind this?

 

[Nertea]

By the time you can build any kind of fusion drive, you know how to make a magnetic nozzle, trust me. It's then a design decision to use an ablative (higher propellant flow, more thrust at the cost of Isp) vs a pure reaction product nozzle (higher Isp, lower thrust). It's not ablative in the sense of a chemical engine, its really more of a tradeoff.

[RedParadize]

@Nertea I see, make sense. Then you might want to reduce the amount of Ablative that is burned. As it is it get depleted before the pellet of the biggest drum. As far as I know ablative can't be replaced, so its a single use engine. It make it a much less attractive than most of the others.

[Nertea]

You can actually refurbish it with Ore and the nuclear smelter. However I should indeed calibrate it, the design goal is that it's depleted about the same time as the large drum and I think the small drum for the AMCF.

In addition I'm fairly sure that I didn't account for the mass of the ablator in balancing either of those engines, I'll have to do that.

Thanks for all this feedback though, it's really helpful.

Edited August 5, 2017 by Nertea

[RedParadize]

@Nertea Started to play with AM drive. I really wish we had on rail acceleration... I can't play with trust that low. How do you manage 1h long burn?

I hate to suggest, but a extra AM torus tank of smaller diameter. Heavier than the original but containing more. 50 or 5000 is rather limiting.

Edit:

Oh, and antimatter canalized fission engine is a weird concept. Its like having a steam train with fusion as a propellant!

Edited August 5, 2017 by RedParadize

[Captain Sierra]

So to respond to @RedParadize about antimatter tanks ...

I think we're okay because of the dual nature of antimatter consuming engines. They either eat tiny amounts of it needing no more than a couple of torus rings ... or they consume unfathomable quantities of the stuff needing bigger thanks than we already have (100k AM storage tank? Big, spherical? One more piece to the ISV Venture Star replicas? Plz?)

Now to @Nertea about the ablative engines. I've been working on some VAB numbers testing for balance. Note that none of this is flight testing so I may be over or undershooting on the thermal control needs. However KER does provide some excellent info. I'll compile everything into a spreadsheet once I'm done with it (the multi-length engines I'm not even sure how I'll handle). Back on what I wanted to mention you for, the pellet counts for the ablative engines: The AMCF is actually pretty close and consumes about 3800 pellets or a bit more than one large tank. It also consumes only 6 or 7 units of antimatter. At those points the ablator is gone.
The ablative ICF engine is a whole different beast. It actually consumes somewhere between 750 to 800 pellets, less than half of a small tank. That doesn't seem like much but for a ~23 ton mission payload its still getting 33 thousand delta V. Its thrust is also absolutely ridiculous in comparison to the nonablative ICF engine. It also needs less radiator mass and less energy charge and has the dV for most missions. The nonablative ICF engine struggles to compete against that for anything but the highest dV missions (my general balance assessment is that it's too weak compared it its direct competition).