A mod pack for Kerbal Space Program, specifically supporting my other mods Kerbal Atomics and Cryogenic Engines, dealing with cryogenic fuels, their storage and their properties
This mod adds handling for two cryogenic fuels, Liquid Hydrogen and Liquid Methane. Both fuels have advantages and disadvantages,
Liquid Hydrogen is a deeply cryogenic fuel with a lot of applications. It takes up a ton of volume so you'll need a lot of tanks, but is very light by comparison. Using this as fuel will get you the best chemical efficiencies. It is best used as an upper stage fuel. If left unattended without cooling, it will 'boil off' into space - see the Fuel Boiloff section below.
By contrast, Lqd Methane is less cryogenic and has a volume somewhere between that of Liquid Hydrogen and stock Liquid Fuel. It still boils off, but more slowly and costs less to cool. It has middle of the road performance characteristics.
This mod contains patches that enables fuel switching on most parts, stock and modded, that contain LiquidFuel/Oxidizer. The parts will be able to contain the following fuel settings with correct dry mass
The mod contains a plugin that causes fuel to evaporate from improperly cooled tanks. This applies to both Liquid Hydrogen and Liquid Methane. The boiloff rate is quite low so there is only a need to deal with it if you are storing fuel on orbit or doing long interplanetary transfers.
This mod adds several ZBO tanks. These are provided in 1.25m to 5m size classes as well as several radial mount models. They have the same mass properties as other tanks, but take less power to cool. Liquid Hydrogen requires more power to cool than Liquid Methane
Either remove the SimpleBoiloff.dll file from GameData/CryoTanks/Plugins/ or remove the following code block from GameData/CryoTanks/Patches/CryoTanksFuelSwitcher.cfg:
MODULE
{
name = ModuleCryoTank
... stuff
}Adding boiloff support to a fuel or fuel tank is simple. Specify the following MODULE block:
MODULE
{
name = ModuleCryoTank
// Should be unique among all ModuleCryoTank instances
moduleID = basicBoiloff
// Base power cost of cooling, in EC per 1000 units per second (a 1000 unit tank will take 80 EC/s here)
CoolingCost = 0.08
// Whether the tank starts with cooling enabled or not
CoolingEnabled = True
BOILOFFCONFIG
{
// The fuel name to boil off
FuelName = LqdHydrogen
// The rate of boiloff, in % per game hour
BoiloffRate = 0.05
// The fuel cooling rate in EC per 1000 units per second. This is optional and additive to the rate in the base module
CoolingCost = 0.08
}
}Any number of BOILOFFCONFIGs can be used to boil off multiple fuels. Note that the CoolingCost can appear in multiple locations. This is an additive property - all instances of it will be added together.
In the following example, the total cost of cooling the tank will be 0.11 EC/s/1000 u - 0.01 from the base cost, 0.05 from the LqdHydrogen block, and 0.02 from the LqdOxygen block. This allows you to have multiple fuel types with different cooling costs in a single part. Note that any of the blocks can be omitted - no need to have a base CoolingCost or specify any of the individual fuels.
MODULE
{
name = ModuleCryoTank
// Must be unique among all ModuleCryoTank instances, if you have more than one
moduleID = basicBoiloff
// Base power cost of cooling, in EC per 1000 units per second (a 1000 unit tank will take 80 EC/s here)
CoolingCost = 0.01
// Whether the tank starts with cooling enabled or not
CoolingEnabled = True
BOILOFFCONFIG
{
// The fuel name to boil off
FuelName = LqdHydrogen
// The rate of boiloff, in % per game hour
BoiloffRate = 0.05
// The fuel cooling rate in EC per 1000 units per second. This is optional and additive to the rate in the base module
CoolingCost = 0.08
}
BOILOFFCONFIG
{
// The fuel name to boil off
FuelName = LqdOxygen
// The rate of boiloff, in % per game hour
BoiloffRate = 0.05
// The fuel cooling rate in EC per 1000 units per second. This is optional and additive to the rate in the base module
CoolingCost = 0.02
}
}It should be noted that while costs can be specified per-fuel, cooling is an all or nothing thing - you cannot enable and disable cooling separately for different fuels in a single part.
It is possible to set things so that boiloff creates another resource instead of venting into the ether. Do do this, specify an OUTPUT_RESOURCE in the BOILOFFCONFIG. You can set ratio, flow mode and resource name. With this option set, an amount of ResourceName will be produced according to the Ratio field, with the specified FlowMode.
BOILOFFCONFIG
{
FuelName = LqdHydrogen
// in % per hr
BoiloffRate = 0.05
OUTPUT_RESOURCE
{
ResourceName = Hydrogen
Ratio = 0.5
FlowMode = ALL_VESSEL
}
}In the above case, 0.05% per hour of LqdHydrogen will boil off, adding half the amount lost of Hydrogen (note the Ratio = 0.5).
It is also possible to configure such that there is a boiloff dependence on energy input from planets and the sun. This does not affect cooling cost, but allows more interesting boiloff mitigation strategies, like hiding behind planets and being in the outer solar system.
MODULE
{
name = ModuleCryoTank
// in Ec per 1000 units per second
CoolingCost = 0.08
CoolingEnabled = True
Albedo = 0.5
LongwaveFluxAffectsBoiloff = True
LongwaveFluxBaseline = 0.5
ShortwaveFluxAffectsBoiloff = True
ShortwaveFluxBaseline = 0.5
MaximumBoiloffScale = 5
MinimumBoiloffScale = 0.001
BOILOFFCONFIG
{
FuelName = LqdHydrogen
// in % per hr
BoiloffRate = 0.05
}
}Setting LongwaveFluxAffectsBoiloff will cause emission from planets to affect boiloff. This depends on the part's emissiveConstant, so ensure it is configured correctly. High emissiveConstant will increase boiloff. Modifying LongwaveFluxBaseline allows the scale of this to be changed - it defaults to a value of 0.1231, which is the flux received by an object in Low Kerbin Orbit with an emissiveConstant of 0.2. If the baseline is unchanged, the boiloff in LKO should be approximately the same as if LongwaveFluxAffectsBoiloff was disabled.
Setting ShortwaveFluxAffectsBoiloff will cause emission from the sun to affect boiloff. This depends on the Albedo field, so ensure it is configured correctly. High Albedo will decrease boiloff. Modifying ShortwaveFluxBaseline allows the scale of this to be changed - it defaults to a value of 0.7047, which is the flux received by an object in Low Kerbin Orbit with an Albedo of 0.5. If the baseline is unchanged, the boiloff in LKO should be approximately the same as if ShortwaveFluxAffectsBoiloff was disabled.
The DebugMode flag can also be set in order to observe solar input and planetary input as UI fields ingame.
Finally, the MaximumBoiloffScale and MinimumBoiloffScale fields can be configured to cap the modifier to boiloff from these modifications.
I certainly accept pull requests. Please target all such thing to the dev branch though!
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