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[1.8+] Real Fuels

NathanKell

By NathanKell
in KSP1 Mod Releases

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smartdummies

smartdummies

Posted
Posted

I believe that there is an issue with the SRB calculations (using RSS 7.3, Procedural Parts 0.9.18, and useRealisticMass is set to true). Looking at the stats for the Space Shuttle SRB, they were:

12.17 ft diameter (3.71 m) -> call this 3.75 for Kerbal purposes

149.16 ft length (45.46 m) -> call this 45.5

ISP 2424/268 (sl/vac)

Thrust 11MN/12MN sl/vac roughly (seen varying sources ranging from 10.5 to 14 soo.... 11/12 is decent midrange here)

Dry Weight ~200,000 lb (90.7t)

Propellent 1,100,000 lb (499t)

Burn Time 120 s

I see that the stock SRBs are almost useless (values pulled using a TR-2V decoupler with MechJeb on top and the SRB underneath, tech level set to default for SRB)

RT-10

Thrust 250kN

Dry Mass .76t

Wet 14.4t

Burn Time 126s

TWR 1.76

BACC

Thrust 315kNDry 1.22t

Wet 28.08

Burn Time 209 s

TWR 1.14

SRB-KD25

Thrust 650 kN

Dry 2.4t

Wet 91.46

Burn Time 430s

TWR 0.72!!

Pulling in the Procedural SRB (tech level set to 4 for 245/268 ISP) I need a 5m diameter SRB to get the thrust comparable to the Shuttle (11.3MN/12.4MN using maximum nozzle size) and a length of 4.5m for a burn time of 121s. With these settings the weight is fairly comparable (20.29 dry / 590.2 wet) with a final TWR of 2.14. Using the dimensions of the Shuttle SRB (3.75m diameter) I end up with with thrust of 6.41MN/7.01MN and the TWR drops below 1 at 10m length (25.36t/737.7t dry/wet mass) and has a burn time at that point of 267s. The only SRB that are useful are short ones otherwise you get horrendous TWR.

Look at things I saw that solid fuels burn from the center of the cylinder outward and not bottom up (this made me think of the model rockets built as a kid where the solid engine was hollow in the center so I think this would be correct). Extrapolating here (I am certainly not an expert) this would make a taller cylinder provide more thrust as the surface area exposed for burning is increased and a wider cylinder would increase the burn time as the liner dimension of the burn is increased. And then based on the dimensions and weight of the Shuttle SRBs I think that the weight of the solid fuel is too high. (http://www.braeunig.us/space/propel.htm has information on the density of the fuels but I am too tired right now to do that math)

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Ralathon

Ralathon

Posted
Posted
I believe that there is an issue with the SRB calculations (using RSS 7.3, Procedural Parts 0.9.18, and useRealisticMass is set to true). Looking at the stats for the Space Shuttle SRB, they were:

12.17 ft diameter (3.71 m) -> call this 3.75 for Kerbal purposes

149.16 ft length (45.46 m) -> call this 45.5

ISP 2424/268 (sl/vac)

Thrust 11MN/12MN sl/vac roughly (seen varying sources ranging from 10.5 to 14 soo.... 11/12 is decent midrange here)

Dry Weight ~200,000 lb (90.7t)

Propellent 1,100,000 lb (499t)

Burn Time 120 s

I see that the stock SRBs are almost useless (values pulled using a TR-2V decoupler with MechJeb on top and the SRB underneath, tech level set to default for SRB)

RT-10

Thrust 250kN

Dry Mass .76t

Wet 14.4t

Burn Time 126s

TWR 1.76

BACC

Thrust 315kNDry 1.22t

Wet 28.08

Burn Time 209 s

TWR 1.14

SRB-KD25

Thrust 650 kN

Dry 2.4t

Wet 91.46

Burn Time 430s

TWR 0.72!!

Pulling in the Procedural SRB (tech level set to 4 for 245/268 ISP) I need a 5m diameter SRB to get the thrust comparable to the Shuttle (11.3MN/12.4MN using maximum nozzle size) and a length of 4.5m for a burn time of 121s. With these settings the weight is fairly comparable (20.29 dry / 590.2 wet) with a final TWR of 2.14. Using the dimensions of the Shuttle SRB (3.75m diameter) I end up with with thrust of 6.41MN/7.01MN and the TWR drops below 1 at 10m length (25.36t/737.7t dry/wet mass) and has a burn time at that point of 267s. The only SRB that are useful are short ones otherwise you get horrendous TWR.

Look at things I saw that solid fuels burn from the center of the cylinder outward and not bottom up (this made me think of the model rockets built as a kid where the solid engine was hollow in the center so I think this would be correct). Extrapolating here (I am certainly not an expert) this would make a taller cylinder provide more thrust as the surface area exposed for burning is increased and a wider cylinder would increase the burn time as the liner dimension of the burn is increased. And then based on the dimensions and weight of the Shuttle SRBs I think that the weight of the solid fuel is too high. (http://www.braeunig.us/space/propel.htm has information on the density of the fuels but I am too tired right now to do that math)

Are you using Hotrockets? My SRB's worked fine until I installed that, now their TWR's are .....

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RedAV8R

RedAV8R

Posted
Posted

@smartdummies: Why yes, SRBs are essentially useless with RSS UNLESS you have an engine pack that includes SRBs. Realism Overhaul, RftS, Stockalike all possibilies, Realism Overhaul - RealEngines models 37 real life solid motors of various types with more to come.

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smartdummies

smartdummies

Posted
Posted (edited)

Found my issue - ModuleManager 2.3.3 is not pulling in the override for the solid fuel density and so is weighing 7.5kg/L. Switching to ModuleManager 2.2.2 solid fuel weighs 1.780kg/L

EDIT: Just checked 2.3.4 and it is loading the correct density for the solid fuel.

Edited by smartdummies
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Starwaster

Starwaster

Posted
Posted
Found my issue - ModuleManager 2.3.3 is not pulling in the override for the solid fuel density and so is weighing 7.5kg/L. Switching to ModuleManager 2.2.2 solid fuel weighs 1.780kg/L

EDIT: Just checked 2.3.4 and it is loading the correct density for the solid fuel.

Are you talking about the file with the multiplier for density? Seems strange unless there were some change in the math parser or related code....

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komodo

komodo

Posted
Posted

Hi folks, awesome mod. Are there any TAC LS and SDHI users in the crowd? I've been having a peculiar problem where some MM patches don't seem to be applying in the right order (perhaps). I'll quote myself from the SDHI thread for brevity.

I had been meaning to ask: Has anyone run into trouble with TAC Life Support + Real Fuels where SDHI is concerned? Everything is up to date, to the best of my knowledge, and the SDHI patch (SDHI_SMS_MMPatch_TACLifeSupport) seems to work, as it is correctly replacing the resources in the Mk1-2 pod. While the resources never appear in the service module, the converters do. I am using the stockalike engine configurations, but a look through their configs show only the engine part being adjusted.

The relevant patches are tacked on here as well. From SDHI 

@PART[Mark1-2Pod]:NEEDS[TacLifeSupport]:FINAL {

	// Remove MFT support
	!MODULE[ModuleFuelTanks] {}

	// Use replace (%) rather than edit (@), to ensure that the following values are loaded regardless of the presence/absence of MFT/RealFuels 
	%RESOURCE[Food]
	{
		%amount = 8.776
		%maxAmount = 8.776
	}
	%RESOURCE[Water]
	{
		%amount = 2.175
		%maxAmount = 2.175
	}
	%RESOURCE[Oxygen]
	{
		%amount = 333.114
		%maxAmount = 333.114
	}
	%RESOURCE[CarbonDioxide]
	{
		%amount = 0
		%maxAmount = 287.739
	}
	%RESOURCE[Waste]
	{
		%amount = 0
		%maxAmount = 0.8
	}
	%RESOURCE[WasteWater]
	{
		%amount = 0
		%maxAmount = 2.772
	}
}


// Modifies the SDHI SM to provide an additional five Kerbal days of Water and Oxygen, the equivalent in WasteWater and CarbonDioxide storage, and built-in Carbon Extractors / Water Purifiers / Fuel Cell
@PART[SDHI_2.5_ServiceModule]:NEEDS[TacLifeSupport]:FINAL {

	// Here, we *don't* apply a MM patch to remove MFT/Real Fuels, since:
	// - MFT/Real Fuels is needed to allow users to have reconfigurable fuel tanks or non-stock fuels
	// - The TAC LS patch that uses MFT/RealFuels doesn't cater for the unusual situation where a Service Module is used to hold life support provisions

	RESOURCE
	{
		name = Water
		amount = 3.625
		maxAmount = 3.625
	}
	RESOURCE
	{
		name = Oxygen
		amount = 555.19
		maxAmount = 555.19
	}
	RESOURCE
	{
		name = WasteWater
		amount = 0
		maxAmount = 4.62
	}
	RESOURCE
	{
		name = CarbonDioxide
		amount = 0
		maxAmount = 479.565
	}

	// Standard TAC-LS Carbon Extractor using the Bosch process
	MODULE
	{
		name = TacGenericConverter
		converterName = Carbon Extractor
		conversionRate = 8.16
		inputResources = CarbonDioxide, 0.001703210064733, ElectricCharge, 0.039783051310155
		outputResources = Oxygen, 0.001713537562385, false, Waste, 0.000001209166498, true
	}

	// Standard TAC-LS Water Purifier
	MODULE
	{
		name = TacGenericConverter
		converterName = Water Purifier
		conversionRate = 8.16
		inputResources = WasteWater, 0.000014247685185, ElectricCharge, 0.007123842592593
		outputResources = Water, 0.000012822916667, false, Waste, 0.000001994675926, true
	}
}


// Modifies the SDHI Avionics Ring to only have the built-in Carbon Extractors / Water Purifiers / Fuel Cell
@PART[SDHI_2.5_AvionicsRing]:NEEDS[TacLifeSupport]:FINAL {

	// Standard TAC-LS Carbon Extractor using the Bosch process
	MODULE
	{
		name = TacGenericConverter
		converterName = Carbon Extractor
		conversionRate = 8.16
		inputResources = CarbonDioxide, 0.001703210064733, ElectricCharge, 0.039783051310155
		outputResources = Oxygen, 0.001713537562385, false, Waste, 0.000001209166498, true
	}

	// Standard TAC-LS Water Purifier
	MODULE
	{
		name = TacGenericConverter
		converterName = Water Purifier
		conversionRate = 8.16
		inputResources = WasteWater, 0.000014247685185, ElectricCharge, 0.007123842592593
		outputResources = Water, 0.000012822916667, false, Waste, 0.000001994675926, true
	}
}

and from RF: 

@PART[SDHI_2.5_ServiceModule]
{
	//!RESOURCE[LiquidFuel] {}
	//!RESOURCE[Oxidizer] {}
	//!RESOURCE[MonoPropellant] {}
	//!RESOURCE[XenonGas] {}
	MODULE
	{
		name = ModuleFuelTanks
		volume = 4510
		type = ServiceModule
	}
}

While TAC LS does this: 

@TANK_DEFINITION[ServiceModule]:FOR[TacLifeSupport]:NEEDS[RealFuels]
{
	TANK
	{
		name = Food
		amount = 0.0
		maxAmount = 0.0
	}
	TANK
	{
		name = Water
		amount = 0.0
		maxAmount = 0.0
		//mass = 0.00001
	}
	TANK
	{
		name = Oxygen
		amount = 0.0
		maxAmount = 0.0
		utilization = 221.1347
		//mass = 0.00001
		note = (pressurized)
	}
	TANK
	{
		name = Waste
		amount = 0.0
		maxAmount = 0.0
		fillable = false
	}
	TANK
	{
		name = WasteWater
		amount = 0.0
		maxAmount = 0.0
		//mass = 0.00001
		fillable = false
	}
	TANK
	{
		name = CarbonDioxide
		amount = 0.0
		maxAmount = 0.0
		utilization = 476.2173
		//mass = 0.00001
		note = (pressurized)
		fillable = false
	}
}

Sorry for the apparent wall of text, ack. So much for brevity. My guess it that the problem is in the SDHI component, but i'm uncertain. Is someone more versed in MM-fu than I able to see what might be clashing here? I thought the FINAL tag would override prior patches, but it's likely i'm mistaken.

In any case, thanks for reading this far (and for the mod, much more interesting than just LFO tanks :D )

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Starwaster

Starwaster

Posted
Posted (edited)

If this sounds like a stupid or insulting question I apologize.

Have you actually verified on the launch pad that the service module is missing those resources?

If not, do so please.

If it truly is then please post your output_log.txt file (if on Windows) or player.log file (if on Mac or Linux)

Edit: Just an FYI, regarding order, you don't say what version of Module Manager we're talking about. But the order should be something like this

The different passes are as follows and execute in the order given

FIRST

LEGACY (2.3.4 or later and ONLY if FIRST, BEFORE, FOR, AFTER or FINAL are not specified)

(These require a mod name which can either the name of the folder the mod lives in or the mod's plugin dll)

BEFORE[mod_name]

FOR[mod_name]

AFTER[mod_name]

FINAL

RealFuels patch // No order specified, runs in :FIRST or LEGACY (if 2.3.4 )

// Adds Modular Fuels support and nothing else.

TAC patch // Runs in :FOR pass and only adds resources to the MFT / RF ServiceModule tank type.

SDHI_SMS_MMPatch_TACLifeSupport // Adds resources, modules.

None of those really conflict with each other so the resources should be there which is why I asked for confirmation that they arent appearing even in the world and that logs be provided if confirmation is provided

Edited by Starwaster
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Autochton

Autochton

Posted
Posted

Awesome. I'm mulling some thoughts on an ISRU mod with a little more resolution than "Dig up thing, grind into fuel". I figure combining light metal (as in, aluminium, titanium, magnesium et al. rolled into one) and hydrocarbons (catch-all for refined liquid hydrocarbons) into solid fuel seems reasonable. :-)

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smartdummies

smartdummies

Posted
Posted
Are you talking about the file with the multiplier for density? Seems strange unless there were some change in the math parser or related code....

This is not math. The relevant entry from the ResourceFuels.cfg file is

@RESOURCE_DEFINITION[SolidFuel]
{
    @density = 0.00178
}

This should replace the density of solid fuel to be .00178t per unit - which is liters for RealFuels, but for whatever reason MM 2.3.3 was not loading this. Strange, absolutely. Fixed? Absolutely in 2.3.4.

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smartdummies

smartdummies

Posted
Posted
Yeah.

When we do the fuels update that regex has been working on, we'll add separate resources for the major solids; but for now that seems fine to me. :)

Question -

Will you also allow for various burn configurations for solids as well to adjust thrust during the burn? I know that this is accomplished by the bore pattern in the fuel and do not know if KSP will allow you to modify this.

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Starwaster

Starwaster

Posted
Posted
This is not math. The relevant entry from the ResourceFuels.cfg file is

@RESOURCE_DEFINITION[SolidFuel]
{
    @density = 0.00178
}

This should replace the density of solid fuel to be .00178t per unit - which is liters for RealFuels, but for whatever reason MM 2.3.3 was not loading this. Strange, absolutely. Fixed? Absolutely in 2.3.4.

Yes, I know what units are. I just got it confused with another file that was performing multiplication but as it turns out it was doing it on amount/maxAmount and not density.

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regex

regex

Posted
Posted (edited)
Yeah.

When we do the fuels update that regex has been working on, we'll add separate resources for the major solids; but for now that seems fine to me. :)

I was wondering when he'd let this slip...

Anyway, does anyone have some favorite solid fuel concoctions they'd like to see? The initial fuels update is mainly focusing on naming conventions and getting some of the odder mixtures in, as well as some of the more primitive fuels. The important thing to remember is that we're still trying to keep it fairly reasonable (we don't need four variants of IRFNA that only differ in inhibitor, for instance) so if there is a solid fuel mixture you'd like to suggest, ensure it differs from others in some significant gameplay manner rather than just by name or ... well, whatever gives it 0.5Isp more than another.

Edited by regex
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komodo

komodo

Posted
Posted
If this sounds like a stupid or insulting question I apologize.

Have you actually verified on the launch pad that the service module is missing those resources?

If not, do so please.

If it truly is then please post your output_log.txt file (if on Windows) or player.log file (if on Mac or Linux)

Edit: Just an FYI, regarding order, you don't say what version of Module Manager we're talking about. But the order should be something like this

The different passes are as follows and execute in the order given

FIRST

LEGACY (2.3.4 or later and ONLY if FIRST, BEFORE, FOR, AFTER or FINAL are not specified)

(These require a mod name which can either the name of the folder the mod lives in or the mod's plugin dll)

BEFORE[mod_name]

FOR[mod_name]

AFTER[mod_name]

FINAL

RealFuels patch // No order specified, runs in :FIRST or LEGACY (if 2.3.4 )

// Adds Modular Fuels support and nothing else.

TAC patch // Runs in :FOR pass and only adds resources to the MFT / RF ServiceModule tank type.

SDHI_SMS_MMPatch_TACLifeSupport // Adds resources, modules.

None of those really conflict with each other so the resources should be there which is why I asked for confirmation that they arent appearing even in the world and that logs be provided if confirmation is provided

Not stupid or insulting at all, it just took me this long to get back to you.

It is missing the resources both in the VAB and on the pad. I've installed a minimal set of mods as a proof of concept and to aid the log reading.

The log may be found here. https://www.dropbox.com/s/9kczey1svfttgzo/Player.log?dl=0 I can upload some screenshots I took as well, but they show pretty much what you would expect, empty real fuel service module tanks which offers an auto configure for the engine type as mounted. (LV909b in this case.)

Like I said, it's more weird than bug. And thanks for the refresher on the MM order of operation; that's about how I understood it. It's probably some edge case of mod collisions, but I thought you guys would like to know about it.

Thanks!

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Autochton

Autochton

Posted
Posted

I've read a bit, now, about the use of gaseous hydrogen in cold-gas thrusters. Basically, using the boiled-off gas from your cryogenic LH stores as RCS fuel. Cold-gas thrusters don't have much oomph and their Isp is kinda crap (high-pressure nitrogen may hit as high as 68s), but in this case, it would be free, since you'd get LH boil-off anyway. I think something like that would fit well with Real Fuels' concept. Thoughts?

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Guest

Guest

Posted
Posted

I know how that could be handled. Make an RCS thruster variant that, when attached to a tank that has boiloff, would be able to work for free as long as the fuel is in the tank. It's Isp (and thus, thrust) would depend on the boiloff rate and the percentage of tank that is still filled (essentially, on the ullage gas pressure). They would be very weak, especially when attached to a tank of something other than hydrogen (say, LOX, which also boils off).

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SanderB

SanderB

Posted
Posted

I've installed all the required and highly recommended mods (and no others) for realism overhaul on a clean install of ksp 0.24.2 and now it seems the TweakScale mod and RealFuels arent interacing correctly. Fuel tanks with tweakscale show themselves as being of different mass compared to the info from the map view on the launch pad. (Ie. when launched on its own without anything attached.) this happens with and without fuel tanks, empty or full. The info display is accurate when I remove tweakscale from GameData, though I cant design sensible rockets without it.

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RedAV8R

RedAV8R

Posted
Posted
I've installed all the required and highly recommended mods (and no others) for realism overhaul on a clean install of ksp 0.24.2 and now it seems the TweakScale mod and RealFuels arent interacing correctly. Fuel tanks with tweakscale show themselves as being of different mass compared to the info from the map view on the launch pad. (Ie. when launched on its own without anything attached.) this happens with and without fuel tanks, empty or full. The info display is accurate when I remove tweakscale from GameData, though I cant design sensible rockets without it.

Known issue. Has been corrected for the next release. Patience.

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