[WIP] NearFuels (Design Stage)

[NonWonderDog]

This doesn't exist yet.

I'm fully intending to implement this as a branch of RealFuels, but for now I'm just wondering if anyone has any comments on a bit of a design document I've put together:

NearFuels

by NonWonderdog, based on work by taniwha, NathanKell and ChestBurster for

Modular Fuel Systems Continued.

ialdabaoth (who is awesome) created Modular Fuels, and this is a fork of the RealFuels branch.

License remains CC-BY-SA as modified by ialdabaoth.

ModuleManager is required.

KSP Alternate Resource Panel is recommended to show friendly resource pictures, in addition to all its other great features.

DESCRIPTION

NearFuels is a minimal implementation of RealFuels, intended to provide maximal mod compatibility. LiquidFuel, Oxidizer, and MonoPropellant are still present, but now represent actual chemistries. 100% Community Resources Pack compatibility is assured -- installing this won't prevent you from colonizing Duna.

The major goal of this mod is to allow more choices in design, without forcing them upon you. You'll be able to choose whether to build a kerosene or hydrogen launch vehicle, but if you don't care to do so you can just slap parts together and hit launch. Storable propellants or off-world refueling will be necessary for long missions, however, due to cryogenic boil-off.

A secondary goal of this mod is to allow realistic Kerbal-scale rockets in a 6.4x scale solar system. The desired effect will be similar to using RealFuels in 64K, but without the sacrifice in mod compatibility that comes along with that. Game balance should be only slightly "harder" than stock, but will allow realism mods such as FAR and AJE without having to design around super-heavy engines and fuel tanks. An investigation of command pod and structural part densities is planned for the future.

• Kerosene (Kero) - Kerosene
  
  Low sulfur grade A-1 kerosene. Jet fuel. Truck fuel. Boat fuel. Rocket fuel. High energy density and stability makes it very flexible.

  
  

• Liquid Hydrogen (LH2) - LiquidHydrogen
  
  The most efficient fuel available, with Isp values some 30% better than Kerosene mixtures. Unfortunately the low density means huge tanks are required for sufficient delta-v, and the extremely low cryogenic temperature leads to significant boil-off.

  
  

• Liquid Methane (LCH4) - LqdMethane
  
  A denser fuel than hydrogen, with boil-off rates similar to liquid oxygen. It's a middle of the road solution, providing neither the density of Kerosene, nor the Isp of hydrogen, but it's easy to synthesize from just about anywhere in the solar system.

  
  

• Hydrazine (N2H4) - MonoPropellant
  
  Simple hydrazine provides better performance then UDMH, but is too difficult to use in large rockets. It's used as a monopropellant.

  
  

• Unsymmetrical dimethylhydrazine (UDMH) - LiquidFuel
  
  A more stable, but no less dangerous, formulation of hydrazine used in bipropellant rockets. It's liquid at room temperature and can be stored indefinitely. It differs from regular old hydrazine by increased thermal stability and a lower freezing point, making it useful for cooling rocket engine nozzles. It's also quite cheap -- at least if you don't read the warning labels.

  
  

• Liquid Oxygen (LOX) - LiquidOxygen
  
  The most obvious oxidizer, and the easiest way to make things burn. It's stored at low temperature, so some will be lost to boil-off.

  
  

• Dinitrogen Tetroxide (NTO) - Oxidizer
  
  A powerful oxizider that bursts instantly into flames when put in contact with any of the various forms of hydrazine. Like hydrazine it is liquid at room temperature and can be stored indefinitely.

  
  

• NTO/UDMH
  
  This is what people usually think of when they think "rocket fuel." Explosive, caustic, volatile, and near instantly lethal if inhaled. Naturally, it's your default fuel. The two propellants can be stored indefinitely and ignite instantly when in contact with each other, making it popular for spacecraft and launch vehicles alike. This mixture can be used in any size of engine, from RCS thrusters to massive launch cores.

  
  

• Kerolox
  
  Kerosene and liquid oxygen. It's easy to handle, cheap, and performant. This is the generic fuel for launch vehicles and spaceplanes, and the oxygen boil-off is irrelevant over short periods.

  
  

• Hydrolox
  
  A difficult fuel to use due to the low density and rapid boil-off, but by far the most efficient. It has the further benefit that it can be produced from water, given exorbitant amounts of electricity.

  
  

• Methalox
  
  A middle of the road fuel that excels at nothing, and will rarely be the best option for a rocket. If you can make it on Duna, however...

  
  

• Kerosene
  
  Kerosene is jet fuel, we just happen to be using it for bigger explosions most of the time. Feel free to run it in your jet engines as well.

  
  

• Hydrazine
  
  Hydrazine passed over an alumina-iridium catalyst, yielding a high-temperature mixture of nitrogen, hydrogen and ammonia. This is the default option for RCS thrusters.

  
  

• Solid Fuel
  
  Ask Jeb.

  
  

• Liquid Hydrogen
  
  Nuclear engines get best efficiency with light propellants, and so they use the lightest substance available -- pure hydrogen.

  
  

• Liquid Methane
  
  Putting a heavier fuel in a nuclear rocket, however, gives greater thrust. Increased density means it might also yield more delta-v in practice

  
  

• Ammonia
  
  Ammonia is not a very good nuclear rocket propellant, but it has a very, very low boil-off rate.

  
  

• Enriched Uranium
  
  Fuel for nuclear reactors. Decays into depleted uranium over time.

Electric propulsion using Xenon and Argon isn't covered by this mod, partly because the storage density of Xenon is wrong by a factor of 65 (supercritical Xenon is *heavier* than liquid oxygen). I'll leave that to others to contemplate.

| Propellant | Name | Real Density | mass | L per unit | price |
|------------|----------------|--------------|------------|------------|--------|
| 100LL | AvGas* | 0.72 | 0.0036 | 5.000 | 0.1 |
| Kerosene | Kerosene* | 0.82 | 0.0041 | 5.000 | 0.1 |
| LH2 | LiquidHydrogen | 0.07085 | 0.0004 | 5.649 | 0.5 |
| LCH4 | LqdMethane | 0.42262 | 0.00186456 | 4.333 | 0.2* |
| UDMH | LiquidFuel | 0.791 | 0.004* | 5.000 | 0.8 |
| N2H4 | MonoPropellant | 1.004 | 0.005* | 5.000 | 1.2 |
| LNH3 | Ammonia | 0.682 | 0.000681 | 1.000 | 0.2* |
|------------|----------------|--------------|------------|------------|--------|
| LOX | LiquidOxygen* | 1.141 | 0.0057 | 5.000 | 0.1 |
| NTO | Oxidizer | 1.45 | 0.00725* | 5.000 | 0.18 |
|------------|----------------|--------------|------------|------------|--------|
| Solid | SolidFuel | 1.75 | 0.0075 | 4.292 | 0.6 |
| Xenon | XenonGas | 1.36 | 0.0001 | 0.074 | 4 |
| Argon | ArgonGas | 0.54 | 0.00005 | 0.093 | 0.25 |

Asterisks mark new or changed resources. Real densities are in kg/L. Mass is tonnes per unit, while the last column shows the number of liters in each unit.

AvGas, Kerosene, and LiquidOxygen are new, while LiquidFuel, Oxidizer, and MonoPropellant have tweaked masses. LqdMethane and Ammonia have no prices defined in the CRP, so I added some. AvGas is just there for mod propeller engines, just so they don't have to run on Kerosene.

| Mixture | Mass Ratio | Volume Ratio | Bulk Density | BD (kg/L) |
|---------------|------------|--------------|--------------|-----------|
| NTO/UDMH | 2.22 | 55/45 | 0.00579 | 1.158 |
| Kerolox | 2.32 | 62.5/37.5 | 0.0051 | 1.02 |
| Hydrolox | 6.11 | 27.5/72.5 | 0.00178 | 0.365 |
| Methalox | 3.46 | 56.67/43.33 | 0.00416 | 0.832 |

Mass ratio is the mixture ratio I ended up at, oxidizer/fuel. Volume ratio is the mixture ratio using CRP densities. The volume ratios were adjusted to be whole numbers that give something between a reasonable mass ratio and a reasonable volume ratio, with weight given to the mass ratio. Bulk densities are within 2% of reality assuming 1 Unit = 5 L. That ends up being true for methalox, too; a tank of methalox in game has a mass within 2% of what the equivalent volumes of methane and oxygen would weigh at the same mixture ratio, because methalox tanks are magically bigger.

For nuclear engines, pure LH2 or pure LCH4 tanks hold 10% more than they should.

---------------------------

Essentially, there are low efficiency/long duration, high efficiency/short duration, and intermediate options. The mixture ratios of the engines are set to semi-believable whole number ratios that yield a realistic combined fuel/oxidizer density. This isn't even a stretch, as real rocket engines can run a wide range of mixtures with little impact on efficiency (Saturn IVB could even vary mixture ratio in flight, and Soyuz and Fregat runs their engines extra rich in order that the UDMH and NTO tanks can be the same size.) Obviously in real life thrust and Isp change by a few percent dependent on mixture ratio according to the chamber pressure, the expansion ratio, the altitude, and some horrifically complicated chemistry... but that's real rocket science, and I'm not touching it.

This will depend on a generic Modular Fuel Tanks configuration that applies to every fuel tank, except for those explicitly exempted or overridden. A FL-T400 will mostly still hold 400 units, however. That will be true for both Oxidizer/LiquidFuel (which still uses a 55/45 ratio) and LiquidOxygen/Kerosene. Due to the way LiquidHydrogen and LqdMethane are defined by other mods fuel tank amounts get more complicated with those fuels.

The plan is to change engines in a generic way as well. I want to do as little work as possible here, partly out of laziness but mostly for the sake of mod compatibility. I'll attempt as much as possible to write ModuleEngineConfigs using the new Module Manager variable support, change things only as much as necessary, and do minimum curation. I may end up bending ModuleManager to the breaking point, but that's sarbian's fault for adding variables . I'll probably end up with two options using the UseRealMass flag from RealFuels -- one for stock 1x Kerbin balance, and a 6.4x focused set that represents my best guess of what real Kerbal-sized rocket engines would do.

I've decided, however, that I won't be keeping the default LiquidFuel and Oxidizer masses, and maybe not the MonoPropellant and SolidFuel masses. They're just too restrictive when it comes to balancing the new fuels (no real fuel/oxidizer combination uses propellants of the same den, and changing them should have the least impact on compatibility of any of my options -- or at least, the most knowable effect on compatibility. No resources from other mods will be changed.

Edited February 6, 2015 by NonWonderDog
LF/O are now UDMH/NTO

[blowfish]

I'd just like to point out that there was a mod that attempted to do something like this though it has ceased development.

I very much like the idea of this, but you're very correct that there are a lot of questions that need to be answered. I agree that option 2 is probably the most reasonable - make hydrazine the default but allow it to be swapped for UDMH+NTO.

How would engines that might be able to handle more than one mixture be handled? I know that RF already has a system in place to allow an unlimited number of mixtures, but a lot of work would still have to be redone. Of course lower stages would probably allow Kerolox or Hydrolox and upper stages would allow Hydrolox or UDMH+NTO, but where does methane fit in? What about nuclear rockets - hydrogen is an obvious default propellant, but denser, higher thrust options like methane and hydrolox might also work - are those two different enough in terms of performance to allow both?

One thing I recommend keeping from the More Fuel Types mod is the ability to mitagate boil-off with active cooling (i.e. consuming electricity). Perhaps it would require additional equipment which would only be unlocked later in the tech tree...

[NonWonderDog]

I saw the old mod, briefly, and saw a few problems:

1. It was a ground-up implementation, when RealFuels already existed. It was a lot of duplication of effort for what turned out to be no benefit in the end, as RealFuels has all the same features.
   
2. ModuleManager variable support didn't exist. The only way to do it was either to edit every single mod engine by hand or build a re-implementation of ModuleManager in "a .dll so massive, that it would have appreciable gravity."
   
3. It (apparently) made minimal effort to approximate realistic fuel trade-offs. This isn't a killer, but hydrolox was (apparently) unrealistically impossible to use due to the bulk.
   
4. It tried to set up a new ISRU framework. Na ga ha pen. That's better left to ISRU mods, using the Community Resources Pack as an interface.
   
5. As a meaningless nitpick, including Aerozine-50 is way too US-focused.
   

I'm doing this on top of RealFuels and ModuleManager, and I'll probably need to do very little by way of C#. Everything I'm thinking of should be doable with ModuleManager configs, as excessively complicated and hard to debug as they might end up having to be. I'm still working through the math on tanks and engines, though, and haven't really gotten to the implementation stage. At least the generic Modular Fuel Tanks config is already half-done and working.

Available mixture ratios should be gateable by the specific impulse and thrust of the original engine in ModuleManager with a bit of outside-the-box thinking (by using progressive string comparison on numbers, or possibly by doing stack-style math with variables), if we don't just want to give every mixture to every engine. Or something more complicated (and easier) in C#. I'll have to see if RealFuels allows me to gate fuels by tech level, as well. Anything more specific would need a config. I'm not really against every fuel on every engine, though. UDMH/NTO was responsible for a LOT of first stage launches (Proton, every Chinese rocket, Ariane-1), and even more if we count UH25 and Aerozine-50 (which we should). And the Soviet N-1 rocket used kerolox on every stage, and was possibly the most kerbal rocket ever developed, so why not allow kerolox upper-stage engines?

It's probably better to make UDMH/NTO the default, with kerolox an option for cheaper, more efficient launch vehicles. My problem with that is mostly terminology: the generic "LiquidFuel" and "Oxidizer" wouldn't be the defaults. Those need to be kerolox for the math to work. (If only there were a "PartResourceDefinition.displayName")

Nuclear-thermal rockets can be expanded upon later, but that's one for the roadmap. The problem there is the tangled web of other mods adding specific nuclear-thermal rockets. I don't really want to step all over them, but then again I do need to make sure they don't run on kerolox.

Finally, active boiloff mitigation is a funny thing. I'm actually tangentially related to such a project IRL, but the physics are very unintuitive. I have to confess that I don't understand any of it. I'm just going to blindly follow the RealFuels implementation for now, since I don't know enough to improve on it. There does need to be a cryocooler part somewhere in the tree, though. Perhaps one that runs on electricity, and a more realistic one that runs on hydrolox just to confuse people.

Edited January 21, 2015 by NonWonderDog
Doh! Proton, not Soyuz

[Raptor831]

Hooray! I was hoping someone would take up the "NearFuels" idea again. RealFuels proper has a lot of fuels and it's a big turn off to some people.

I'll have to see if RealFuels allows me to gate fuels by tech level, as well.

You can do this via the engine configs. It's a bit of a roundabout way, but each CONFIG node can be restricted to tech level. If you can do this on all configs with the same mixture, that's done. I do that with the Stockalike configs for some engines.

I'm not really against every fuel on every engine, though. UDMH/NTO was responsible for a LOT of first stage launches (Soyuz, every Chinese rocket, Ariane-1), and even more if we count UH25 and Aerozine-50 (which we should). And the Soviet N-1 rocket used kerolox on every stage, and was possibly the most kerbal rocket ever developed, so why not allow kerolox upper-stage engines?

I'd be on the side of choice-over-realism. You don't have a crazy amount of mixtures that would be required for any one engine. Basically 5 for "normal" engines (kerolox, hydrolox, UDMH/NTO, methalox, hydrazine). 6 if you added UDMH as a monopropellant mix. RCS would have three mixtures if you went there. NTRs have one, possibly two if you add a trimodal-type engine (i.e. NTR with afterburner!). If you're really fancy you can probably do this with one generic MM config, at least if MM can handle it.

As to your MonoPropellant problem, I'd just change the densities to match what you need. It's pretty easy to do a MM config to globally adjust the amount of a resource, so you can scale your density change to your resource change. For example, in my RF configs for Karbonite, I scale karbonite's mass down 1/5th, but increase the amount of resources in each karbonite-carrying part by 5x. Ends up with the same mass anyway. I'm not sure specifically how your math would end up. Alternatively, we're dealing with little green people in a game. If anyone is going to be upset with hydrazine or UDMH not being exactly the right stats, then they should be playing full-on Real Fuels anyway.

In short, make the gameplay work the way you want, and fudge the numbers to get it that way.

In any case, good luck!

[BFGfreak]

What are you plans concerning engines that already run off monoprop such as RLA stockalike's engines?

[Shania_L]

What are you plans concerning engines that already run off monoprop such as RLA stockalike's engines?

I suppose you should add to this all the specialist engines with their own rules, like Karbonite/Kethane engines, KSPI engines etc etc etc.

I would like to put my support behind maximum flexibility, all fuel types available for all engines, if someone wants to build an upper stage hydrolox command module than let them ..... (with ofcourse special treatment on NTR and mono engines)

Are you intending to build this on top of RealFuels, or as an independent mod?

Either way, I'll follow this development with much interest.

[NonWonderDog]

As to your MonoPropellant problem, I'd just change the densities to match what you need. It's pretty easy to do a MM config to globally adjust the amount of a resource, so you can scale your density change to your resource change. For example, in my RF configs for Karbonite, I scale karbonite's mass down 1/5th, but increase the amount of resources in each karbonite-carrying part by 5x. Ends up with the same mass anyway. I'm not sure specifically how your math would end up. Alternatively, we're dealing with little green people in a game. If anyone is going to be upset with hydrazine or UDMH not being exactly the right stats, then they should be playing full-on Real Fuels anyway.

The problem there is ISRU mods. For some reason nobody thought to make ModuleResourceConverter or REGO_ModuleResourceConverter obey conservation of mass. Instead of outputting a mass ratio of resources at an efficiency they output volumes, which is just silly. There might be other mods that start violating basic laws of physics if I go around changing resource densities willy-nilly as well, which one of the reasons the CRP exists.

That said, it's pretty trivial to change all the ModuleResourceConverter nodes that touch MonoPropellant using ModuleManager. Changing REGO_ModuleResourceConverter and KolonyConverter nodes that way is much, much harder, but it's probably possible with a combination of regexes and variables.

It's easier just to let you store hydrazine at 20% compression. I think that's all I actually need to do. I don't want to do that to adjust the bipropellant densities because I'd rather the tanks stay one volume, so I didn't really think it over.

What are you plans concerning engines that already run off monoprop such as RLA stockalike's engines?

I guess they'd get the choice of MonoPropellant or UDMH/NTO, just like RCS. For MonoPropellant engines I might gate UDMH/NTO in the tech tree, or maybe having to send fuel to your RCS with big yellow pipes would be penalty enough. Maybe I could add a late-game HAN fuel (250 Isp, 1.6 kg/L), but that would probably just obsolete MonoPropellant.

Edited January 20, 2015 by NonWonderDog

[regex]

RealFuels used to be fairly reasonable ... until I stuck my fingers in the pie and decided it needed to be "complete".

Anyway, this looks pretty cool! One suggestion: Allow nukes to use methane as well. This would provide a nice, realistic, "outer-worlds-obtainable" high-thrust fuel for landers, etc... especially if you're going to provide for ISRU-compatibility and don't want to go down the "magical fairie-poop" route (please keep your dignity!)

[Tellion]

especially if you're going to provide for ISRU-compatibility and don't want to go down the "magical fairie-poop" route (please keep your dignity!)

I lol'd at that

[NathanKell]

Another suggestion: consider using HAN as a monopropellant. It offers mostly-similar performance to hydrazine but is not DEATH DEATH TOXIC DEATH, and has a different (maybe more helpful) density.

[bs1110101]

I'm a huge fan of this, at least if it doesn't make me faff about with configs for hours to make all my mods work. There should be basic compatibility with everything, as in it would auto-generate configs for mods, which might be not well balanced, but still better then nothing. I say make all engines be able to work with all fuel types. Why? Because memory limits and only having some engines use some fuel types limits choice of engines, and thus you need more mods, which you cant get because ksp is 32 bit (or crazy glitchy, or on Linux). Anyway, the more choice the better, and yay for a new mod for this.

[White Owl]

I find in my 6.4x game, I only want a few fuels. I want something good for first stages, so kerosene and LOX. Something good for upper stages, so liquid hydrogen and LOX. Finally I need only one mix of hypergolics, and couldn't care less which. Pick one hypergolic and stick with it, please. I even deleted the options for realistic RCS fuel and am using stock monopropellant, because I don't care how unrealistic it is; matching every single RCS port to one of the list of RCS fuel options was far more annoying than fun. So this mod sounds real good.

I'll vote to give all stock engines configs for all three main fuel types. There have been times I wanted to use an engine as an upper stage and was annoyed to find no option to run the thing on hydrogen.

[Sauron]

I'm a big fan of this! If I had the time and the ability I'd have loved to do something similar!

That said, I would prefer a slightly "gamier" interpretation of fuel types that does the following:

-Names propellants using a (simplified) kerbal psuedo-chemistry rather than RL options with kerbal element names. This should produce fuel consumption (and ISRU yields) that are round numbers

-Exaggerates performance differences between fuels slightly to make for a more important choice

-Using the kerbal pseudo-chemistry create the opportunity for interesting ISRU cycles that are a bit less involed than, say, KSPI's

Also, please make all engines universally compatible. I would personally prefer making Storeable Fuel and Monoprop one and the same. It's a lot cleaner and I don't really see a compelling reason for the distinction between Hydrazine and UDMH.

[bs1110101]

I totally agree with the third one, odd, kerbal ways of ISRU seem fun. Not sure about renaming the stuff though. I don't like the idea of exaggerating engine performance anymore then you'd need to to counteract the odd twr and high dry masses of kerbal tanks. For me, the main goal is to make rockets that look and preform like their real world counterparts (in 3.2 or 6.4 scale kerbin at least), Something like the shuttle or a Delta 4 has a huge fuel tank, and small engines, trying to make something like this work in normal ksp is hard, and a real fuels mod would be nice to fix that. Also, i like the idea of a built in engine igniter thing, with built in ways of switching between modes, instead of being held to one way as in the mod that already does this. Stuff like making engines have more then 1 ignition should be easy to add, though weigh a lot on larger engines, and take a while to unlock in the techtree, causing more kerbal rockets with stage and a half setups, or weird systems of srbs and liquid engines so it's always under thrust.

[zengei]

That said, I would prefer a slightly "gamier" interpretation of fuel types that does the following:

-Names propellants using a (simplified) kerbal psuedo-chemistry rather than RL options with kerbal element names. This should produce fuel consumption (and ISRU yields) that are round numbers

-Exaggerates performance differences between fuels slightly to make for a more important choice

-Using the kerbal pseudo-chemistry create the opportunity for interesting ISRU cycles that are a bit less involed than, say, KSPI's

I disagree, the fuels should be based on real chemistry so that there's a sane basis for compatibility and reasoning. It's frustrating to have compatibility issues because no one can quite agree on what an "ElectricCharge" is. It's also educational since people will learn about the real properties of real things.

Gameplay balance can be achieved through other means, like tweaking the efficiency of engines or simply selecting different fuels altogether. But if you add "LiquidKerbogen" now you throw out any sort of intuition people have or could possibly acquire.

[Sauron]

The thing is, the differences between (say) storable and kerolox aren't nearly as big in in KSP than real life because (even RSS) we're dealing with a very simplified model. Besides boiloff, most of the engineering considerations that distinguish the two aren't a factor in KSP.

From the perspective of adding gameplay richness, more pronounced advantages and disadvantages are in order. (Or just ditch Kerolox and use Methalox, Storable, and Hydrolox). There really is something to be said for a leaner, more gameplay-focused take on this (because speaking just for myself at least, when I want the fiddly stuff I'll play RSS/RO). If ISRU isn't really a factor methalox could probably go but for the fact that you need the option for nukes. (Also, regarding nukes, it's an interesting balance decision as to whether or not there should be a storeable fuel (ammonia) or not. If nukes always had to deal with fuel boiloff that would make for a very interesting set of gameplay choices OTOH it could be really irritating.

I think an adequate description of the fuels and oxidizers solves the intuition issue. People who use RSS and similar, even on 6.4x Kerbin generally have a good sense of how rockets work and what shoots out the back end

The point about standardization is well taken.

Edited January 24, 2015 by Sauron

[NonWonderDog]

-Names propellants using a (simplified) kerbal psuedo-chemistry rather than RL options with kerbal element names. This should produce fuel consumption (and ISRU yields) that are round numbers

-Exaggerates performance differences between fuels slightly to make for a more important choice

-Using the kerbal pseudo-chemistry create the opportunity for interesting ISRU cycles that are a bit less involed than, say, KSPI's

I've thought about using some gamey names for UDMH and NTO, just because I want them to be the default and it seems stupid to switch from NTO/UDMH to Oxidizer/LiquidFuel, but I can't come up with anything catchy.

UDMH is obviously RocketFuel, but that seems slightly wrong when contrasted with LiquidFuel.

NTO I have no idea. StorableOxidizer isn't punchy enough, and doesn't communicate why you can't use it with LiquidFuel.

They're all going to remain real chemistries, though, if only so I have a sane starting point for balancing. I'm not getting involved in ISRU other than supporting it implicitly through the Community Resources Pack, so Karbonite can continue to use whatever fantasy chemistry it wants.

Anyway, I have a spreadsheet that I've been working on, a bit less far along that I would have hoped: https://docs.google.com/spreadsheets/d/1KSPXBB7VRV1kYvwpdRBPyFg87KAmiN1FJNQKBQJN-AE/edit?usp=sharing

(I have Office365 through work, so that's just a copy of my Excel sheet. It's spectacularly overcomplicated (although a bit better in Excel).)

The "Propellants" tab shows the current plan. The "PropellantsRemass" tab shows a perfect world where I'm free to change masses to whatever I want. I got them closer than I expected after a bit of fiddling, and with whole numbers in the fuel tanks. The only really wrong things are the volume ratio of kerolox and the density of methalox. The "Tanks" and "Engines" tabs are what I'm doing next.

Also, please make all engines universally compatible. I would personally prefer making Storeable Fuel and Monoprop one and the same. It's a lot cleaner and I don't really see a compelling reason for the distinction between Hydrazine and UDMH.

UDMH and hydrazine are separate because I think they're different enough (hydrazine is 20% denser), and I want to allow a bipropellant RCS mixture somewhere in the tech tree. Soyuz uses NTO/UDMH for all the spacecraft thrusters now, after all, and the Shuttle used something close enough (MON3/MMH). I also want to make certain tanks -- the ones in command pods, or the radial spheres -- capable of holding only a single fuel type at once. Combined with the different flow behaviors you'd get a choice between simplicity (Hydrazine) or efficiency (NTO/UDMH), made more complicated if you aren't using NTO/UDMH for your service engine.

But I'll take that as a vote for option 5 in the OP.

(Of course in real life Buran used GOX/Kerosene RCS, and LOX/LH2 and LOX/LCH4 RCS are under heavy development. Maybe for the end of the tech tree.)

Edited January 24, 2015 by NonWonderDog

[AngelLestat]

I love the idea of compatibility with CRP.

Something that I hate, is to have water, oxygen or hydrogen from a life support mod, but there are not the same resources than in real fuels.

I dont like to have 50 fuels options, meanwhile in reality mostly all rockets use 10 as much.

I hate the fact that with realfuels each engine only works with certain types of fuel, so you need to have as 30 engines types to keep some liberty in craft creation, then mostly all those mod engines does not have in-fairing when you place a decoupler under.

I love the idea to have a default set fuel for the clasic fuel+oxydizers from the game. Maybe RP1??

Things that I dont understand yet:

This version would work in Stock, 4x (next kerbol system size mod) and 10x (real solar system)?

Or only in one of these versions?

Also.. what is that of 6x or 64x??

[saabstory88]

Take a look at my sig. It has a link to all of the old development work I did on this. The way I had it built, it assigned fuels to tanks and engines based on the tech tree, with a re-worked system to make it play nice with procedural parts. Also, feel free to take a look at the work i did on making something like this compatible with B9, because those firespitter tanks were a bear. All had to be manually adjusted. Anyway, good luck with this, it's something that's needed, but is difficult to do right. I'm still basically swamped at work, but if I ever get any time off, I'd love to give you a hand with this. Feel free to PM me if you want to discuss.

[blowfish]

Also, feel free to take a look at the work i did on making something like this compatible with B9, because those firespitter tanks were a bear.

I imagine that would have been painful :/ B9 already has configs for RF/MFT though, so it's probably easier to just piggy back off of those.

[FreeThinker]

Please do not call Liquid Oxygen (LOX) a.k.a. "Oxidizer" when the game representation is clearly similar to Dinitrogen Tetroxide (NTO) as KSP "Oxidiser" can be stored indefinitely

Question what ratio do you use Hydrolox (LiquidHydrogen and LiquidOxigen) as a rocket fuel?

Edited January 25, 2015 by FreeThinker

[NonWonderDog]

Please do not call Liquid Oxygen (LOX) a.k.a. "Oxidizer" when the game representation is clearly similar to Dinitrogen Tetroxide (NTO) as KSP "Oxidiser" can be stored indefinitely

Question what ratio do you use Hydrolox (LiquidHydrogen and LiquidOxigen) as a rocket fuel?

The problem with that is that Oxidizer and LiquidFuel have the same density, and although the relative densities are wrong they yield a combined density very similar to LOX+Kerosene when used together.

Real NTO is nearly twice as dense as UDMH, and when used together are stored at a density 15% greater than that of LOX+Kerosene.

That, and most of the resources in the Community Resources Pack are given densities assuming that LiquidFuel+Oxidizer represents kerolox. If I want to use Oxidizer for anything, it has to be LOX. I'm planning on setting most rocket engines to use NTO/UDMH by default to keep things close to stock.

Mixture ratios by mass and volume are in the "propellant details" box. None of them are "right," but they should be "near enough." I've set hydrolox to a mixture ratio of 5.36 (a bit too hydrogen rich), but since CRP's LiquidHydrogen is too dense the tanks are only 70% hydrogen by volume. It ends up taking up as much total space as if you were running a mixture ratio of 5.85 (but if you run NTRs on straight hydrogen you can carry 10% too much).

[EDIT]

It's not impossible to set Oxidizer to mean NTO, it just means I have to give up on tank volume being consistent.

With the system described in the OP, a 200 unit tank holds 200 units (or 250 for MonoPropellant or methane). If I set it so that Oxidizer means NTO, that isn't true anymore. See next post...

Edited January 27, 2015 by NonWonderDog

[NonWonderDog]

I spent more time playing with the numbers, and it's actually looking a lot better than I thought.

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If I go with LiquidFuel/Oxidizer as UDMH/NTO, then I gain in compatibility and realism, but lose any last vestige of the tank units as volume.

By setting LiquidFuel/Oxidizer to Kerosene/LOX, all I really gain are whole numbers in single-resource tanks.

[EDIT] I've understood the RealFuels math a bit better, and managed to get whole numbers into all the bipropellant tanks. I've updated the images.

Any thoughts? I think I'll go with this unless anyone can give me a good reason not to.

Edited January 31, 2015 by NonWonderDog

[FreeThinker]

Please support all propellants curretly used in KSPI, that way, I will be easier to make it fully compatible with KSPI. I also would like to have both a Cryogenic version of LqHydrogen and a non Liquid version. Also add all Propellants which can be found in the Athmosphere, which Includes Nitogen, Oxigen, Argon, Helium, Helium 3, Deuterium, Neon, Krypton. etc.

Edited January 27, 2015 by FreeThinker

[Shania_L]

The whole point of this mod is to reduce the number of fuels used in standard engines. It simply replaces the stock "liquidfuel/oxidiser" with a handful of different types of liquid fuels and oxidisers, but far fewer than the RealFuels mod adds.

It does not however affect the total number of resources, so KSPI resources are entirely untouched.