An overhaul to the stock propellant system, replacing generic LiquidFuel, Oxidizer, MonoPropellant and SolidFuel with a handful of real chemicals.
This mod is distinct from RealFuels in that it deals with only a small set of primary liquid propellants, for a more straightforward and curated propellant system more in line with e.g. Nertea's Cryogenic Engines. In fact, Nertea's mods are a particular target of this overhaul, which can be thought of as a Nertea-like soft alternative to RealFuels.
Each propellant has a part upgrade which provides switch subtypes on relevant parts when unlocked in the tech tree. Most propellants only appear in game if a using-mod is present, while the following six are used in a pure stock configuration:
LqdOxygenKeroseneHTP (High-test peroxide)HydrazineLqdHydrogenNTO (Dinitrogen tetroxide)Bipropellant engines are categorised into particular fuel-oxidizer combinations with fixed mixture ratios. Any fuel can be paired with any oxidizer, though not all combinations are necessarily configured or available depending on which supported mods you use. The bipropellants used in stock are:
Kerosene / 3 HTPHydrazine / 9 NTOKerosene / 5 LqdOxygenLqdHydrogen / 1 LqdOxygenMonopropellant engines and tanks have a choice of two propellants: HTP which is cheap and available at the beginning of career mode, and Hydrazine which is unlocked later and more expensive but yields a significantly higher specific impulse.
Solid rockets have a similar progression from PBAN to the slightly more performant HTPB.
Liquid fuel jet engines use Kerosene, with the rocket mode of multimodal engines running on Kerosene and LqdOxygen.
Some mod engines have bespoke propellant configurations which are not typical monopropellants or bipropellants. For example, Near Future Launch Vehicles' KR-701 'Cougar' and KR-74 'Lynx' are bimodal hydrolox engines with an additional kerosene-augmented mode, based on their real-world analogues the RD-701 and RD-704:
Kerosene / 4 LqdHydrogen / 3 LqdOxygen (equivalent to 1 part kerolox + 2 parts hydrolox)This mod replaces all CryoTanks fuel switch types to Chemical Technologies tank types. One particular feature of this is the removal of CryoTanks' native 1.5x hydrogen packing density buff, which not-insignificantly affects the use of LqdHydrogen in the game. This is not just an arbitrary change purely motivated by realism. The ~14% higher density of LqdOxygen over Oxidizer and adjusted methalox mixture ratio (higher oxidizer mass fraction) make cryogenic bipropellants much more attractive, removing the need for any sneaky volume buffs in chemical rockets. Hydrolox suffers a little bit, but I've found this actually balances better against their high Isp. Nuclear engines naturally suffer the most, but again, these engines are very high Isp and it should really be expected that you'd need to haul massive tanks everywhere. I've always wanted my CryoTanks to be bigger, personally.
Engines and RCS can easily be patched to replace their propellants with one of the supported resources by setting one or more chemTechPropellant, chemTechFuel or chemTechOxidizer fields on the module, the values of which are a resource name:
chemTechFuel: A fuel which should be paired with an oxidizer or used in an air-breathing engine.EthanolKeroseneAnilineLqdAmmoniaHydrazineLqdMethaneLqdHydrogenPentaboraneDiboranechemTechOxidizer: An oxidizer which should be paired with a fuel. Supported resource names:LqdOxygenIWFNAHTPNTOLqdFluorineN2F4chemTechPropellant: A single propellant which should not be combined with any specified fuel or oxidizer. All above resources are supported, plus the following:WaterLqdCO2LqdCOLqdNitrogenFor example, the following patch converts a multimode engine with a pure LiquidFuel mode and a LiquidFuel-Oxidizer mode to use LqdHydrogen and LqdOxygen:
@PART[partName]:BEFORE[zz_ChemicalPropulsion]
{
@MODULE[ModuleEngines*]:HAS[@PROPELLANT[LiquidFuel],!PROPELLANT[Oxidizer]]
{
chemTechPropellant = LqdHydrogen
}
@MODULE[ModuleEngines*]:HAS[@PROPELLANT[LiquidFuel],@PROPELLANT[Oxidizer]]
{
chemTechFuel = LqdHydrogen
chemTechOxidizer = LqdOxygen
}
}
Some patches for additional propellant options are provided in the Extras folder.
Adds HTP as an oxidizer option to all kerolox engines, which is more expensive and yields slightly lower Isp than LqdOxygen, but has two main advantages:
Adds an alternative pair of cheaper, lower-performance fuel and oxidizer to all hypergolic engines:
Aniline - Low-tech alternative to HydrazineIWFNA (Nitric acid) - Low-tech alternative to NTOAdds four exotic propellants which are unlocked late in the tech tree and can replace certain conventional propellants for increased thrust and Isp:
Pentaborane - Can be used in place of Hydrazine as a hypergolic fuel or Kerosene as a jet fuelDiborane - Can be used in place of LqdMethane as a cryogenic fuelN2F4 - Can be used in place of NTO as a hypergolic cryogenic oxidizerLqdFluorine - Can be used in place of LqdOxygen as a cryogenic oxidizerAdds four high-thrust, low-Isp propellant options to nuclear thermal rockets (multipliers vs. LqdHydrogen):
Water - +92% thrust, -58% IspLqdCO2 - +142% thrust, -69% IspLqdCO - +158% thrust, -72% IspLqdNitrogen - +158% thrust, -72% IspThe following mods are recommended to make the most of core set of propellants.
I would also suggest at least a couple of these mods for more bipropellant rockets and useful tanks, or all of them if you like having hundreds of parts.
Some mods are explicitly patched to work with Chemical Propulsion, while others are patched implicitly or are simply unaffected and have been found compatible.
Distributed under the GNU General Public License.
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