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[1.8+] Real Fuels


NathanKell

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Sadly inevitable question:

1.0-updated release planned soon?

(Not intended to nag, FWIW, just askin' so I can figure out what I'm doing. Don't want to be starting a new career without my real fuels unless they're a real long way off. Thanks muchly, either way.)

-c

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It's been a long time, and I've been out of KSP for a long time; but am I correct in assuming that Real Fuels supports thrust scaling according to atmospheric pressure?

Stock KSP 1.0 has that now, e.g. sea level and vac thrust are different; done in CFG files as:

atmosphereCurve

{

key = 0 310

key = 1 285

key = 9 0.001

}

I think the last entry "9 0.001" is setting the exponental function for the thrust/ISP vs Altitude curve.

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Cerebrate: Soon as in a week or two, yeah. This one I can probably get done sooner, but that's for full RO.

MKSheppard: nope, that's just a standard floatcurve (which is itself a wrapper around an animationcurve). That's a curve defined by three keys with 'automatic' tangents; you'll get a smooth curve between 0,310 and 9,0.001

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I threw around some thoughts about ISRU a while ago, which went nowhere and weren't very focused. However, the always-sharp regex has been working on something, I do believe.
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I may have something at some point in the future (I scrapped a lot of it because I realized I was going terrible out of scope) but it will mainly concern itself with processes and equipment that a realistic lander could carry. Massive refineries and 3D printing are completely out of the question for anything I do, as well as (probably) complex hydrocarbons. Collecting life support essentials and simple fuels (methane, LOX, LHyd, nitrogen, argon) will be the name of the game.

It's the sort of thing where staying in scope (or even defining scope well) is a bloody trick and a half. I ended up with a document laying out how to refine everything from Martian permafrost and Europan sub-surface water to lunar regolith into everything from liquid hydrogen to bloody UDMH, solid fuel and rocket parts...

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Hello,

I'm playing around with the tank definitions for personal use and I'm a bit confused about the mass value. This guide indicates that the mass value is tons per unit of volume, which in this case would be tons per litre correct? Except it's not because upon checking the CRP working document, it becomes clear that the mass value /= tons per litre. For example, according to CRP Kerosene has a density of 820kg/m3 which should give it a mass value of 0.00082. In RF's RealTankTypes.cfg, the mass is defines as 0.000012 in the Default tank and 0.000077 in the ServiceModule tank.

So why is there a discrepancy between CRP and RF in this? Furthermore, why is the mass inconsistent across different tank types?

Basically what I'm trying to get at is: how is the mass value in RF's tank defs determined so I can make my own?

Thanks.

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Resource masses (per liter) are in Resources (all the RESOURCE_DEFINITION stuff). What you're looking at is TANK_DEFINITIONs (i.e type types like Default or Cryogenic) and inside that the various TANK defines. In a TANK define, you're defining how much the pressure vessel masses, dry, per liter of capacity. So the mass of a part of volume V of type Default that's all kerosene is V * TANK_DEFINITION[Default].basemass + V * TANK[Kerosene].mass + V * TANK[Kerosense].utilization * RESOURCE[Kerosene].density.

Make more sense now?

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I may have something at some point in the future (I scrapped a lot of it because I realized I was going terrible out of scope) but it will mainly concern itself with processes and equipment that a realistic lander could carry. Massive refineries and 3D printing are completely out of the question for anything I do, as well as (probably) complex hydrocarbons. Collecting life support essentials and simple fuels (methane, LOX, LHyd, nitrogen, argon) will be the name of the game.

That sounds awesome, looking forward to seeing what you come up with!

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In a TANK define, you're defining how much the pressure vessel masses, dry, per liter of capacity.

I thought that's what basemass * volume was for?

V * TANK_DEFINITION[Default].basemass + V * TANK[Kerosene].mass + V * TANK[Kerosense].utilization * RESOURCE[Kerosene].density.

Where do you get volume from since capacities vary from part to part?

...the mass of a part of volume V of type Default that's all kerosene....

Isn't that the same as V * TANK[Kerosene].mass?

Thanks for taking the time answer :)

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Three components go into the mass of a RF tank part.

1. The mass of the resource itself

2. The mass of the (sub)tank that holds the resource

3. The basemass of the entire part.

As mentioned above, that comes out to the total volume of the part times the basemass, plus the mass of each tank times its volume, plus the mass of the resources.

This is because an RF tank part is actually a collection of resource tanks, not one big tank. So you have to account for the structural mass of the part (stringers, etc), and then the mass of the pressure vessel for each resource housed, and then finally you get to the resource mass itself.

The various types are set up in TANK_DEFINITION. Each tank definition describes the base mass (in terms of volume), as well as which resource TANKs it can hold (and their masses-per-volume). So a part that doesn't have any resource tanks added only has mass = basemass * volume. That's just the base structural mass. As soon as you start adding resource tanks, however, then you have to pay for the mass of those pressure vessels too (or batteries, if the resource in question is electricity). I hope that clears it up?

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Three components go into the mass of a RF tank part.

1. The mass of the resource itself

2. The mass of the (sub)tank that holds the resource

3. The basemass of the entire part.

As mentioned above, that comes out to the total volume of the part times the basemass, plus the mass of each tank times its volume, plus the mass of the resources.

This is because an RF tank part is actually a collection of resource tanks, not one big tank. So you have to account for the structural mass of the part (stringers, etc), and then the mass of the pressure vessel for each resource housed, and then finally you get to the resource mass itself.

The various types are set up in TANK_DEFINITION. Each tank definition describes the base mass (in terms of volume), as well as which resource TANKs it can hold (and their masses-per-volume). So a part that doesn't have any resource tanks added only has mass = basemass * volume. That's just the base structural mass. As soon as you start adding resource tanks, however, then you have to pay for the mass of those pressure vessels too (or batteries, if the resource in question is electricity). I hope that clears it up?

Much clearer thank you! One more question if I may...

Say I'm adding an entirely new resource (one that is not defined anywhere in RF) to a particular tank definition. How do I come up with the mass of its pressure vessel? How did you guys determine the figures for the existing resources for example?

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Much clearer thank you! One more question if I may...

Say I'm adding an entirely new resource (one that is not defined anywhere in RF) to a particular tank definition. How do I come up with the mass of its pressure vessel? How did you guys determine the figures for the existing resources for example?

If your resource represents a real-life material, research real-life containers for that material. If you know the mass of a stage that contains your resource and other resources that have already been statted, you can adjust the numbers for your resource so the final mass of that stage is in the ballpark.

If the resource you're adding is fictional or you can't find suitable published information, you can at least assign a plausible figure by looking at existing resources that are stored at similar temperatures and pressures and have similar densities. Within a general temperature/pressure/density range, more dangerous materials will tend to have heavier tanks (because the tanks get built to a higher safety margin and because some of them limit the selection of tank and pipe materials they can come in contact with).

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If your resource represents a real-life material, research real-life containers for that material. If you know the mass of a stage that contains your resource and other resources that have already been statted, you can adjust the numbers for your resource so the final mass of that stage is in the ballpark.

If the resource you're adding is fictional or you can't find suitable published information, you can at least assign a plausible figure by looking at existing resources that are stored at similar temperatures and pressures and have similar densities. Within a general temperature/pressure/density range, more dangerous materials will tend to have heavier tanks (because the tanks get built to a higher safety margin and because some of them limit the selection of tank and pipe materials they can come in contact with).

Understood. Thank you very much.

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I may have something at some point in the future (I scrapped a lot of it because I realized I was going terrible out of scope) but it will mainly concern itself with processes and equipment that a realistic lander could carry. Massive refineries and 3D printing are completely out of the question for anything I do, as well as (probably) complex hydrocarbons. Collecting life support essentials and simple fuels (methane, LOX, LHyd, nitrogen, argon) will be the name of the game.

When you'll start working on it - PM me. Will do what I can to help. Realism is great, as it gives game more challenge and thoughtfulness. And stock "ISRU" extraction of mean-to-be-hydrocarbons from crust everywhere gives me a butthurt.

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