[1.8+] Real Fuels

[HoneyFox]

Ok I read up on the problem and I used 2 seperatrons as ullage motors and got a very stable flow to no avail, thinking about taking out the engine ignition mod but I cant remember what I changed when I added it, Maybe ill keep messing with it.

I'm not familiar with the Rtfs engine config, could you go to VAB/SPH and mouse-over the engine that failed to ignite and tell me what information is given?

[darshiki]

In the Parts mode it give the ignition type which is electric, the next line states that .5 EC is required to ignite and last line says need setting down fuel before ignition. (which is in blue and has been done, the rest of the text is red) In the Action groups mode it says the same when moused over and and when clicked on it gives you the real fuels menu with all the different fuel types, I've been using the UDMH and N2O4.

[HoneyFox]

In the Parts mode it give the ignition type which is electric, the next line states that .5 EC is required to ignite and last line says need setting down fuel before ignition. (which is in blue and has been done, the rest of the text is red) In the Action groups mode it says the same when moused over and and when clicked on it gives you the real fuels menu with all the different fuel types, I've been using the UDMH and N2O4.

So make sure: you have >= 0.5 EC (which i think should be sufficient in normal cases), and you still have ignitor count available (see the engine's context menu during flight, check "Ignitor: Electric (?/?)"), and you have fuel stable (which you have stated).

[darshiki]

Yeah I think it can only do 1 ignition even though it the description it says that with hypergolic fuels the number of lights is infinite. Ill make it work, thanks for the help!

[xZise]

Yeah I think it can only do 1 ignition even though it the description it says that with hypergolic fuels the number of lights is infinite. Ill make it work, thanks for the help!

That is actually depending on the engine definition. I'm not sure what description you mean, but the info "Ignitor: ? (?/?)" is the definite configuration, and this doesn't has to bound to specific "rules" (like hypergolic -> infinite). You could define that electrically started engines can be ignited infinite times.

Fabian

[guto8797]

Hmm... looking at this mod, I am intrigued. How would it work with other mods, such as engine and tank packs, FAR, interstellar, Kethane, any major mod incompatibility? Or things like having two of the same yet different fuels (Like two hydrogens, one from one mod and one from the other, and not interchangeable)

[Ralathon]

Hmm... looking at this mod, I am intrigued. How would it work with other mods, such as engine and tank packs,

Most of the big modpacks (KW, Novapunch, FASA etc) have configs for this mod, so they work just fine.

FAR

Works fine. Recommended even, if you're going for the realistic experience. The only issue is that current jets aren't configured for Realfuels yet, so I had to manually change their liquidfuel to kerosene.

interstellar

Works fine although it duplicates some resources. You'll end up with 2 versions of hydrogen. Using a modulemanager file you can easily fix this, although I am unsure how balanced the frankenstein result will be.

Kethane

Works fine, Realfuels has a config that adds the new fuels to the big converter. The small converter isn't changed however, and since no engine will actually use Oxidizer and Liquidfuel with this mod it become completely worthless.

any major mod incompatibility?

As shown above, most work okay. You just have to be careful with the small unknown mods, or mods that are still in development. If you are comfortable with config editing you can make almost anything compatible.

Or things like having two of the same yet different fuels (Like two hydrogens, one from one mod and one from the other, and not interchangeable)

This happens quite often sadly. Main culprits are hydrogen and oxygen because they're so common. You can play around it or do some config-fu to fix it.

[Guest]

Any news on ModuleEnginesFX compatibility? I want to get back into RSS, and this keeps messing my plans up. Everything else besides the ECLSS has been updated, but RF doesn't work, and it's the most important part of the RSS modlist.

[Titan Space Agency]

Does anyone have a config for this mod that allows engines to use almost any fuel? You know, like the way the old modular fuel tanks used to do it? I love this mod, but the stock config just doesn't give enough variety. Also the config has to work with these mods:

RLA Stockalike

Kosmoss space station parts pack

Tri Hexagonal struts

AIES Aerospace

Nova(slug)Punch

KwRocketry

B9Aerospace

Space shuttle engines

Kethane

Thank you.

[Scripto23]

Does anybody know what the mixture ratio should be for a methane/LOX engine? e.g. the SpaceX Raptor engine or the Russian RD-192 and RD-0162.

Edit; Encyclopedia Astronautica is telling me around 3-3.5 LOX:methane ratio. If this seems wrong to anyone let me know.

Edited March 8, 2014 by Scripto23

[Ralathon]

Does anybody know what the mixture ratio should be for a methane/LOX engine? e.g. the SpaceX Raptor engine or the Russian RD-192 and RD-0162.

CH₄ + 2O₂ ==> CO₂ + 2H₂O + energy.

So the ratio of LOx to Methane is 2 to 1. Oxygen has a molecular mass of 32u while methane has 16u. So for every 1kg of methane you need 4kg of LOx. RF calculates volume in liters, the density of LOx is 1.141 and the density of liquid methane at 0k is 0.716.

1/4 * 1.141/0.716 = 0.3985 ~ 0.4

So for every unit of methane burned you need to burn 0.4 units of LOx.

[Scripto23]

CH₄ + 2O₂ ==> CO₂ + 2H₂O + energy.

So the ratio of LOx to Methane is 2 to 1. Oxygen has a molecular mass of 32u while methane has 16u. So for every 1kg of methane you need 4kg of LOx. RF calculates volume in liters, the density of LOx is 1.141 and the density of liquid methane at 0k is 0.716.

1/4 * 1.141/0.716 = 0.3985 ~ 0.4

So for every unit of methane burned you need to burn 0.4 units of LOx.

Ok, so in the engine cfg the relevant section should look this then?

PROPELLANT
        {
            name = LqdMethane
            ratio = .72
	    DrawGauge = True
        }
        PROPELLANT
        {
            name = LiquidOxygen
            ratio = .28
        }

[Ralathon]

Ok, so in the engine cfg the relevant section should look this then?

PROPELLANT
        {
            name = LqdMethane
            ratio = .72
        DrawGauge = True
        }
        PROPELLANT
        {
            name = LiquidOxygen
            ratio = .28
        }

Not too familiar with the KSP engine configs, but yea those ratios are close enough. Looks like it would work.

[NathanKell]

Few engines actually run at stoich. The only cite I've found for a LCH4/LOx engine is a mass ratio of 3.4 (The RD-182/183/185, here: http://www.b14643.de/Spacerockets_1/Diverse/Russian_Rocket_engines/engines.htm ). Which is about .32 / .68, right, for volume?

Regarding ModuleEnginesFX: per prior statements I had hoped to do that this weekend, but I'm sick enough that coding is a Really Bad Idea. I'll get to it as soon as I can, though if anyone else wants to tackle it meanwhile they're welcome to. No way people should be denied HotRockets/SmokeScreen/Horizons.

[Starwaster]

Ok, so in the engine cfg the relevant section should look this then?

Not too familiar with the KSP engine configs, but yea those ratios are close enough. Looks like it would work.

Few engines actually run at stoich. The only cite I've found for a LCH4/LOx engine is a mass ratio of 3.4 (The RD-182/183/185, here: http://www.b14643.de/Spacerockets_1/Diverse/Russian_Rocket_engines/engines.htm ). Which is about .32 / .68, right, for volume?

Regarding ModuleEnginesFX: per prior statements I had hoped to do that this weekend, but I'm sick enough that coding is a Really Bad Idea. I'll get to it as soon as I can, though if anyone else wants to tackle it meanwhile they're welcome to. No way people should be denied HotRockets/SmokeScreen/Horizons.

The figure I came up with previously for CH4/LOX was .35/.65

Not sure those configs are compatible anymore.... and I've not got around to revising them

[jsimmons]

Hello Nathan.

I like to ask you to include a new configuration in your RealFuels mod. It is for the new Procedural Parts mod that is in development. You can get it at http://www.infradead.org/~jsimmons/ProceduralParts.cfg. Thank you.

[Guest]

Regarding ModuleEnginesFX: per prior statements I had hoped to do that this weekend, but I'm sick enough that coding is a Really Bad Idea. I'll get to it as soon as I can, though if anyone else wants to tackle it meanwhile they're welcome to. No way people should be denied HotRockets/SmokeScreen/Horizons.

I hope you get well soon. With more and more mods using the custom FX (HotRockets, CSS, Horizon... I'm also hoping FASA would switch someday), if RF doesn't support it, it'll become incompatible with more and more mods.

[Scripto23]

Few engines actually run at stoich. The only cite I've found for a LCH4/LOx engine is a mass ratio of 3.4 (The RD-182/183/185, here: http://www.b14643.de/Spacerockets_1/Diverse/Russian_Rocket_engines/engines.htm ). Which is about .32 / .68, right, for volume?

Regarding ModuleEnginesFX: per prior statements I had hoped to do that this weekend, but I'm sick enough that coding is a Really Bad Idea. I'll get to it as soon as I can, though if anyone else wants to tackle it meanwhile they're welcome to. No way people should be denied HotRockets/SmokeScreen/Horizons.

The figure I came up with previously for CH4/LOX was .35/.65

Not sure those configs are compatible anymore.... and I've not got around to revising them

Thanks guys. This is helpful. Out of curiosity, why do engines not run at stoichiometric ratios? I'm guessing there's some inefficiency at some point along the way, incomplete combustion maybe?

[Guest]

First, heat. The exhaust is cooler that way. Second, efficiency. Usually, fuel is lighter than oxidizer, and both are always lighter than combustion products. That means the rocket gets more energy from expelling exhaust gases with lower atomic mass (the same reason why H2 is the best NTR fuel). Peak efficiency is therefore achieved with a slightly fuel-rich mixture, and the effect is more pronounced the higher the atomic mass difference between the fuel and exhaust products.

[Scripto23]

Interesting, thanks!

[Sax Man Aeronautics]

When I have a Stretchy SRB tank that has a Bi-propellant engine, how can I balance the amount of Oxidizer and Fuel so that one of them doesn't run out quicker than the other?

[Scripto23]

When you attach an engine and then fill the tank from the action group manager menu there should be a button at the very bottom (scroll down) that says something like "Configure for ___ engine 35% Fuel 65% Oxidizer"

[Scripto23]

Ok, another stoich question. I'm working on a Sabatier Converter cfg, using the Kethane converter part as a framework, that will use hydrogen and IntakeAir (in place of C02) for in-situ resource utilization on Mars to create methane and oxidizer. The overall equation for the reaction is 2 H2 + 3 CO2 → CH4 + 2 O2 + 2 CO. I'm having trouble converting this accurately into KSP units, mostly because I haven't taken gen chem in almost a decade . If somebody could give me a hand with the KSP ratios I would greatly appreciate it . I'll post the cfg for others to use once complete. The relevant part of the cfg is below, with essentially random values at the moment:

InputRates
{	
	IntakeAir = 0.7
	LiquidH2 = 0.3
	ElectricCharge = 100
}
OutputRatios
{
	LqdMethane = 0.35
	LiquidOxygen = 0.65
}

[Starwaster]

Ok, another stoich question. I'm working on a Sabatier Converter cfg, using the Kethane converter part as a framework, that will use hydrogen and IntakeAir (in place of C02) for in-situ resource utilization on Mars to create methane and oxidizer. The overall equation for the reaction is 2 H2 + 3 CO2 → CH4 + 2 O2 + 2 CO. I'm having trouble converting this accurately into KSP units, mostly because I haven't taken gen chem in almost a decade . If somebody could give me a hand with the KSP ratios I would greatly appreciate it . I'll post the cfg for others to use once complete. The relevant part of the cfg is below, with essentially random values at the moment:

InputRates
{	
	IntakeAir = 0.7
	LiquidH2 = 0.3
	ElectricCharge = 100
}
OutputRatios
{
	LqdMethane = 0.35
	LiquidOxygen = 0.65
}

Real world ratios will be mass, so start there. Determine what the mass requirements of each are then convert that to volume, which is what those input/output rates are. Low density resources like hydrogen as input will require more volume.

Real Fuels volumes are in liters which is ~70kg per cubic meter (liquid H2 not gaseous though). (it's really really light)

I'm a bit hurried right now so I can't actually sit down and do the math on this for you, at least not now.

I'll leave you with this though, if your input is LiquidH2 (assuming you're shipping it to the Red Planet as the plan called for) then you're going to need a lot more intakeAir.

(unless..... does the Kethane converter take mass into account at all? If so then.... I have no idea how that affects what I just told you.... ugh)

[Scripto23]

Real world ratios will be mass, so start there. Determine what the mass requirements of each are then convert that to volume, which is what those input/output rates are. Low density resources like hydrogen as input will require more volume.

Real Fuels volumes are in liters which is ~70kg per cubic meter (liquid H2 not gaseous though). (it's really really light)

I'm a bit hurried right now so I can't actually sit down and do the math on this for you, at least not now.

I'll leave you with this though, if your input is LiquidH2 (assuming you're shipping it to the Red Planet as the plan called for) then you're going to need a lot more intakeAir.

(unless..... does the Kethane converter take mass into account at all? If so then.... I have no idea how that affects what I just told you.... ugh)

So if I've done my math correctly, the equation should be as follows: 0.0556L liquidH2 + 71.7L CO2 → 37.8L liquidCH4 + 55.8L liquidO2 + CO. Does this look right?

2 H2 + 3 CO2 → CH4 + 2 O2 + 2 CO

4g H2 + 132g CO2 → 16g CH4 + 64g O2 + 56g CO

LiquidO2 density = 1.146/cm3

LiquidH2 density = 0.072g/cm3

LiquidCH4 density = 0.4238g/cm3

InputRates
{	
	IntakeAir = 0.717  //Mars atmosphere is 95% CO2, to be adjusted later
	LiquidH2 = 0.0000556
	ElectricCharge = 100
}
OutputRatios
{
	LqdMethane = 0.3775
	LiquidOxygen = 0.5584
}

Are the numbers in the code all in liters?

Edited March 11, 2014 by Scripto23