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[0.20] Modular Fuel System 1.3/realistic fuels, reconfigurable fuel tanks and engines

ialdabaoth

By ialdabaoth
in KSP1 Mod Releases

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Starwaster

Starwaster

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Posted
Could someone consolidate the various fixes and edits, please? It would be quite helpful.

When ialdaobath (sp?) is able to commit time to the mod again I'm sure he'll fix any issues that have been positively identified....

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sirklick

sirklick

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Posted (edited)

I was unable to find a working Kethane config that works with kethane 0.7.7 so I converted the older MM-MF config to work with the new Kethane Module format. I hope this easy edit helps someone.

Overwrite the contents of KethaneConverter.cfg with this and save. 

@PART[kethane_2m_converter]
{
	MODULE
	{
		name = KethaneConverter
		HeatProduction = 700
		InputRates
		{
			Kethane = 9
			ElectricCharge = 25
		}
		OutputRatios
		{
			LiquidH2 = 1.2
		}
	}

	MODULE
	{
		name = KethaneConverter
		HeatProduction = 650
		InputRates
		{
			Kethane = 5.75
			ElectricCharge = 20
		}
		OutputRatios
		{
			LiquidOxygen = 0.95
		}
	}
}

Also, does anyone know where the Kethane conversion numbers for MF came from? The provided values seem kind of arbitrary and not well "balanced". Specifically the ElectricCharge requirements and the computed LOX output per second is about half of the output per second of Oxidizer with over double the energy expenditure. I have my own ideas about balanced numbers here, but I wanted at least have a short discussion before editing.

Edited by sirklick
Switched to using code tag rather then quote
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Starwaster

Starwaster

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So a rule of thumb we could go by is that a nuclear rocket operating at the same exhaust temp as LO2/LH2 (~3000 K) rocket should be 20 ISP seconds less then the LO2/LH2 rocket. We would need to bring up the temp by 300 K to make up the difference. 3500-3800 K is probably be best we could expect from even a drum reactor without going with a liquid core drum reactor: that would come to max theoretical ISP of 487 and 1050 for Water and LH2. A liquid core (drum) reactor is claimed to be able to get 1350-1500 ISP with hydrogen which would be a outlet temp of ~7500 K which I don't believe because even tungsten boils at 5800 K. A Gas Core though operating at 25,000 K with an ISP by my rough calculation (assuming nearly complete dissociation into protons and oxygen) of ~3900 for LH2 and ~1660 for H2O.

Just had a thought about this, in all the reading I've been doing on nuclear rockets the past few days, one of them actually had the propellant reaching maximum temperature just after it left the chamber... maybe that's how it's supposed to work?

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p1t1o

p1t1o

Posted
Posted (edited)
So a rule of thumb we could go by is that a nuclear rocket operating at the same exhaust temp as LO2/LH2 (~3000 K) rocket should be 20 ISP seconds less then the LO2/LH2 rocket. We would need to bring up the temp by 300 K to make up the difference. 3500-3800 K is probably be best we could expect from even a drum reactor without going with a liquid core drum reactor: that would come to max theoretical ISP of 487 and 1050 for Water and LH2. A liquid core (drum) reactor is claimed to be able to get 1350-1500 ISP with hydrogen which would be a outlet temp of ~7500 K which I don't believe because even tungsten boils at 5800 K. A Gas Core though operating at 25,000 K with an ISP by my rough calculation (assuming nearly complete dissociation into protons and oxygen) of ~3900 for LH2 and ~1660 for H2O.

Actively cooled engine parts can operate in environments that exceed their melting point, there are also techniques that can be used to prevent fuel or hot propellant from contacting engine parts at all.

Just had a thought about this, in all the reading I've been doing on nuclear rockets the past few days, one of them actually had the propellant reaching maximum temperature just after it left the chamber... maybe that's how it's supposed to work?

Any exhaust moving through a rocket nozzle MUST cool down (at a very basic level, it is that energy taken from the exhaust which is moving your ship) - UNLESS there is further energy input.

Unburned fuel igniting in the nozzle area might account for this but indicates an inefficient cycle. Nuclear rockets of course do not use combustion so thats out.

In-atmosphere, interactions with the surrounding gas (air) can cause shockwaves to be set up within an exhaust plume which can re-compress and heat the gases (google "shock diamond").

The only possibility I can think of is chemical reactions within the exhaust between various disassociated species, but I'm not sure that this would account for it.

Any idea what sort of engine you were looking at?

Edited by p1t1o
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Starwaster

Starwaster

Posted
Posted
Actively cooled engine parts can operate in environments that exceed their melting point, there are also techniques that can be used to prevent fuel or hot propellant from contacting engine parts at all.

Any exhaust moving through a rocket nozzle MUST cool down (at a very basic level, it is that energy taken from the exhaust which is moving your ship) - UNLESS there is further energy input.

Unburned fuel igniting in the nozzle area might account for this but indicates an inefficient cycle. Nuclear rockets of course do not use combustion so thats out.

In-atmosphere, interactions with the surrounding gas (air) can cause shockwaves to be set up within an exhaust plume which can re-compress and heat the gases (google "shock diamond").

The only possibility I can think of is chemical reactions within the exhaust between various disassociated species, but I'm not sure that this would account for it.

Any idea what sort of engine you were looking at?

That sounds like a Nuclear Salt-water Rocket.

http://en.wikipedia.org/wiki/Nuclear_salt-water_rocket

I think that must be the one but he explicitly mentioned that one separately at the very end. (BAD. NO SPEWING RADIOACTIVE PLUMES ALL OVER. BAD!)

So, two different rockets. There's hypothetical designs that try to keep the molten core away from the chamber walls magnetically but we're a long ways from such a thing assuming that it can be done.

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m4v

m4v

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Posted

I just gave this mod a try and found out that it refuels all the vessels in your persistent file, ie, if you have a craft with almost no fuel in orbit, install MFT, reload the same vessel, tanks now are full. This change is permanent since the fuel values are stored in the persistent file so removing the mod doesn't revert it.

Is this behaviour normal? I skimmed through this whole thread and didn't find anyone mentioning it. I had a save backup so I could remove the mod and restore my save with no issues, but other people might not be so lucky.

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Starwaster

Starwaster

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The final solution to my H2 woes!

Ok, not REALLY. There's much less fuel in there than there appears to be. That's Procedural Fairings, fuselage option. In actuality there's just 15 2.5m tanks in there. I think actual delta-v was only 8k

I was actually hoping the fairing would prevent the tanks from heating up, to prevent boiloff, but apparently that all depends on what the game says the temps are and parts don't occlude each other I guess :(

TSWSwNI.jpg?1

k0lUBH8.jpg?1

Internal view.

0dSB3Ub.png?1

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sirklick

sirklick

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Posted

Starwaster - Nice, I like the simplistic look of one giant tank. 15 tanks is quite a bit of LH2, is 8k dv all you really get from that? What are you using as the core structural component? It is difficult to tell from that last picture.

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Starwaster

Starwaster

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Starwaster - Nice, I like the simplistic look of one giant tank. 15 tanks is quite a bit of LH2, is 8k dv all you really get from that? What are you using as the core structural component? It is difficult to tell from that last picture.

It's three 2.5m KW tanks stacked. On top of that is a procedural fairing ring base. At the bottom of the stack is another such ring base and the fairing forms between them. Six more fuel stacks attach to the central stack. An array of mono tanks and flywheels probe core and the Sr port top it off. I can can get a modest boost with larger tanks but ti really boost the delta-v means replacing the outer tanks with drop tanks but that means I don't get the giant tank look. In fact for nuclear, drop tanks are probably the way to go. That's where I'm leaning towards now.

I'll probably go for a single large 3.75 KW (25600) surrounded by 3 pairs of identical tanks. That gets me to 16k

Or I might go really big and do a nova punch 5mx12m tank with 40k units of H2

Edit: I've added additional nuclear fuels, this is actually using Hydrogen Slush. It's a little denser. Doesn't give a huge boost but a noticeable one. Hydrogen Slurpee basically.

Edited by Starwaster
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s20dan

s20dan

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Posted (edited)

Sure here you go:


@TANK[LiquidFuel]
{
@utilization = 1.0
@mass = 0.0005
@amount = full
@maxAmount = 40%

This is from the Default tank section, but every tank has a similar section. Take note of @mass = 0.0005. It's using the @ sign but that line does not exist, the @ sign should be removed.

If I'm correct the @ sign is used to replace a line, if that line does not exist it is not added/changed. Therefor Liqud Fuel tanks and Oxidiser tanks have no extra mass.. IE a tank section weighs the same with no internal tanks as it does with a liquid fuel or oxidiser or both tanks.

Remove the @ sign and those tanks will have a larger base mass (Perhaps too high), but will fall in-line with LOX tanks.

There is also a bug with the Fuselage tank, they require a BaseMass to be added otherwise a tank using this will have 0 mass when drained and bad things happen, it was done by someone earlier in some configs that were posted.

Edit, the liquid fuel and Oxidiser sections should look something like this:


	@TANK[LiquidFuel]
	{
	  utilization = 1.0
	  mass = 0.0005
	  @amount = full
	  @maxAmount = 40%
	}
	@TANK[Oxidizer]
	{
	  utilization = 1.0
	  mass = 0.0005
	  @amount = full
	  @maxAmount = 60%
	}

Note that 0.005 will probbaly be too high. 0.004 or 0.0045 would be better.

I personally use 0.0025 but thats along with a reduction of Liquid Oxygen tanks to 0.003.

Edited by s20dan
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Starwaster

Starwaster

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Posted (edited)
Sure here you go:

There is also a bug with the Fuselage tank, they require a BaseMass to be added otherwise a tank using this will have 0 mass when drained and bad things happen, it was done by someone earlier in some configs that were posted.

Edit, the liquid fuel and Oxidiser sections should look something like this:

Note that 0.005 will probbaly be too high. 0.004 or 0.0045 would be better.

I personally use 0.0025 but thats along with a reduction of Liquid Oxygen tanks to 0.003.

It's also the cryogenic tank too that is using the splice (@) operator when it shouldn't. And I think there might be some other config file versions where the Default tank has the same problem because earlier I noted that certain KW tanks had normal masses (and therefore mass ratios) for liquidfuel and oxidizer and then I replaced my config and now I'm seeing 0 mass for LF/OX tanks now too.

That's why I've patched mine with:


// Fix for fuels missing mass
// Only use if you are using the 'Real Fuels' version of Modular Fuel Tanks
@TANK_DEFINITION[Cryogenic]
{
	@TANK[LiquidFuel]
	{
		mass = 0.0005
	}
	@TANK[Oxidizer]
	{
		mass = 0.0005
	}
}
@TANK_DEFINITION[Default]
{
	@TANK[LiquidFuel]
	{
		mass = 0.0005
	}
	@TANK[Oxidizer]
	{
		mass = 0.0005
	}
}

Also, @Chestburster, I've noticed that in the Cryogenic tank that H2 does not require additional mass for its tanks, is this a mistake or is the intention that because cryo tanks are a little more massive (+0.000025 basemass over default) that they require no additional insulation/cooling? That's been my interpretation....

Re: fuselage / no basemass. That's kind of odd because I was poring over the source code and saw a few lines that check for tanks with no basemass and apparently used the part's mass property instead. Sounds like a bug.

Edited by Starwaster
Other question/observation
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s20dan

s20dan

Posted
Posted
Are nuclear engines still useless?

They have a use, but it depends what you want from them. They are good as large second or third stage craft, as it will reduce the mass of your entire launch vehicle for similar DV.

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Starwaster

Starwaster

Posted
Posted
Are nuclear engines still useless?

I don't think so. There are some tank issues that make other engines more attractive. I've posted some module manager code a few times over the past few pages that fixes that. And I've got some config enhancements that will make nuclear engines more attractive as well. ( various alternate fuels and a composite fiber lightweight tank type) ill post that soon when I'm happy with it so look for that if you're interested.

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Starwaster

Starwaster

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Posted (edited)
Can you please add support for those radial tanks, so you can storage normal fuels inside and not just monopropellant.

Make a config file somewhere in your GameData directory and save the following code to it


@PART[radialRCSTank]:Final
{
    @MODULE[ModuleFuelTanks]
    {
		@type = RCS
    }
}


@PART[rcsTankRadialLong]:Final
{
    @MODULE[ModuleFuelTanks]
    {
		@type = Default
    }
}
@PART[RCSFuelTank]:Final
{
    @MODULE[ModuleFuelTanks]
    {
		@type = Default
    }
}
@PART[RCSTank1-2]:Final
{
    @MODULE[ModuleFuelTanks]
    {
		@type = Default
    }
}
@PART[rcsTankMini]:Final
{
    @MODULE[ModuleFuelTanks]
    {
		@type = Default
    }
}

Default will store pretty much anything. I used the 'Final' keyword here to ensure that it gets executed last since this is just a tweak for you to use on your side.

Edit: I also did all of the RCS tanks not just the radials, but if that's not to your liking then you can delete everything after the first two blocks.

Edited by Starwaster
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