[1.8+] Real Fuels

[chrisl]

I was wondering why some gases (Nitrogen, Oxygen, CarbonDioxide, Helium) seem to have a higher pressurization level than other gases (NitrousOxide, ArgonGas, KryptonGas, Hydrogen, XenonGas).  Isn't it feasible for most gases to be stored at the same psi?

[Starwaster]

16 hours ago, chrisl said:

I was wondering why some gases (Nitrogen, Oxygen, CarbonDioxide, Helium) seem to have a higher pressurization level than other gases (NitrousOxide, ArgonGas, KryptonGas, Hydrogen, XenonGas).  Isn't it feasible for most gases to be stored at the same psi?

Are you sure that they are not? Some of those gasses that you've compared from group two  are notably less dense than the ones in group one (oops flipped those). However, KSP resource units are reported to us by volume. Real Fuels does also show mass, though I think we're only showing the wet mass of the tank.

In other words, if you're comparing the volumes of different resources, don't interpret that to necessarily mean that pressurization is different. It might just be an illusion of the math. Look at the resource mass if you want to be sure.

Edit: Accidentally reversed the comparison of the two groups. Hmmm looking at the tanks in the VAB and some of the numbers do seem off.... I dunno, I'll look at it some more later

Edited May 13, 2016 by Starwaster

[chrisl]

1 minute ago, Starwaster said:

Are you sure that they are not? Some of those gasses that you've compared from group one  are notably less dense than the ones in group two. However, KSP resource units are reported to us by volume. Real Fuels does also show mass, though I think we're only showing the wet mass of the tank.

In other words, if you're comparing the volumes of different resources, don't interpret that to necessarily mean that pressurization is different. It might just be an illusion of the math. Look at the resource mass if you want to be sure.

Basically I'm looking at the "amount" each liter can hold.  Take a procedural tank and set it to Type: ServiceModule with a 1000L volume.  You can put 200kL of Nitrogen, Helium, Oxygen or CarbonDioxide in it.  Or you can put 100kL NitriusOxide, Argon, Krypton, Hydrogen or Xenon.  I'm just trying to understand why some gases can be stored 100/L and others are 200/L.  And I'm assuming density isn't really a factor since CarbonDioxide has a density of 0.000001951 and is stored 200 units per Liter while NitrousOxide has a density of 0.00000196 and is stored 100 units per Liter.

[Starwaster]

34 minutes ago, chrisl said:

Basically I'm looking at the "amount" each liter can hold.  Take a procedural tank and set it to Type: ServiceModule with a 1000L volume.  You can put 200kL of Nitrogen, Helium, Oxygen or CarbonDioxide in it.  Or you can put 100kL NitriusOxide, Argon, Krypton, Hydrogen or Xenon.  I'm just trying to understand why some gases can be stored 100/L and others are 200/L.  And I'm assuming density isn't really a factor since CarbonDioxide has a density of 0.000001951 and is stored 200 units per Liter while NitrousOxide has a density of 0.00000196 and is stored 100 units per Liter.

I would say density is a factor because it affects mass. If the mass of a given volume of gas is twice as much as an identical volume of another gas then the pressure would be correspondingly higher. (opposite of Boyle's law, I guess)

To keep the pressure the same you'd have to cut the volume of the denser gas down. 

That said, (assuming you missed my edit of my post) some of the numbers do look wrong to me. In your specific example, the density of those two gasses are too similar to justify giving CO₂ a utilization value twice as high as N₂O and I don't know why they were given those values. I agree they look off.

[chrisl]

1 hour ago, Starwaster said:

I would say density is a factor because it affects mass. If the mass of a given volume of gas is twice as much as an identical volume of another gas then the pressure would be correspondingly higher. (opposite of Boyle's law, I guess)

To keep the pressure the same you'd have to cut the volume of the denser gas down. 

That said, (assuming you missed my edit of my post) some of the numbers do look wrong to me. In your specific example, the density of those two gasses are too similar to justify giving CO₂ a utilization value twice as high as N₂O and I don't know why they were given those values. I agree they look off.

I don't actually have an issue with all the gases having the same utilization level.  I believe 1 mole of any gas always fills approximately 22.4L of space at standard temp and pressure.  Therefore, if all gases are considered to be pressurized the same, they'd all end up with the same volume (but different masses due to density, of course).  I just thought it weird the way it currently stands.

[bulletmagnet578]

i dont know what i have done wrong. but i only seem to have liquidfuel and oxidizer tho i have a the UI for realfuels. can anyone tell me what it going on. i have RSS and RP-0.

[NathanKell]

@bulletmagnet578 You have Modular Fuel Tanks installed, as that window says. Please start fresh with a clean KSP and this time use CKAN.

[bulletmagnet578]

thx that did it tho i didnt need to reinstall

[NathanKell]

v11.2.0

• Correct a bug in tank basemass calculation such that parts sometimes mass less than they should in flight. Thanks soundnfury for finding this!
• New UI skin thanks to Agathorn!
• Fix an issue with scaling down tanks during utilization changes.
• Round displayed available volume when below 1mL (no more -322 femtoliters).

[McKerbin]

On 5/11/2016 at 7:44 PM, jstnj said:

 

@McKerbin@NathanKell

Do I just place the ROmini config file in the main RO folder in GameData/ ? Or do I need to modify/delete the global config that already exists there?

I created a folder called RealismOverhaul in my GameData folder, then put the ROmini.cfg in there (along with the RemoteTech setting cfg, which I also wanted).

As long as its some where in your GameData or a subfolder, the magic that is ModuleManagers will find and work.

(Sorry for taking a while to respond.  Life caught up to me and beat me down again.)

 

[Phineas Freak]

@McKerbinjust a warning for the folder name: some mods that search for a specific mod via ModuleManager might get confused about it and think that RO is installed.

Edit: not something serious but it might get you into trouble some time later and it would not be the first thing that it would come into your mind.

Edited May 16, 2016 by Phineas Freak
Typo

[McKerbin]

1 hour ago, Phineas Freak said:

@McKerbinjust a warning for the folder name: some mods that search for a specific mod via ModuleManager might get confused about it and think that RO is installed.

Edit: not something serious but it might get you into trouble some time later and it would not be the first thing that it will come into your mind.

Very good point.  Thanks for catching me on that.

[Qigon]

I'm having issues with igniting engines, it's probably me not doing the right thing but now I can't get to orbit without having problems with fuel stability.

How do I deal with it? I tried adding small rockets to help with ullage when going from flameout to next stage, I tried igniting the next stage when the previous was still burning, and other creative approaches but still no luck. I don't remember it being that hard on ksp 1.0.5 (now on 1.1.2 with RO), and it doesn't look like a bug.

[NathanKell]

Both those approaches should be sufficient as long as you stage high enough. How low are you staging?

[Qigon]

I had a couple of runs at low altitude because I could test it after a 9s launch, ~10km altitude about Mach 1.

But I get about the same results above 80km. I'm beggining to suspect the problem is that the decoupler staging itself makes that thing unstable.

Then there's this other thing I noticed, that I once had an engine successfully ignited about 100km altitude, with fumes and TWR and stuff, and then 2 seconds after ignition it got vapor in the lines and shut down. I didn't try to reproduce it, and I'm sure it had TWR below 1, but that never happened to me before or after. I've been using low TWR engines for the last stages a lot in 1.0.5, taking for granted they worked without problems.

Another thing I noticed is whenever fuel goes unstable the best way to make them stable is turn the ship retrograde. Works every time, I'm not sure if it's the centrifuge force when spinning or what. Dynamic pressure at this point is always very low, and we're talking centre of mass acceleration < 0.1 according to KER (70-100 km altitude usually).

I still have a couple of things to check before finding the culprit.

 

[Bezzier]

Hey, I'm in the middle of revamping a tank pack from a while ago, and have a question regarding an RF config. Specifically, I'm trying to get new configs up for a set of spherical tanks. They ought to have different usable volumes depending on what's being stored in them.  If there is a fuel mix, they must be (probably concentric) double spheres, and the inner wall volume must eat into the storage volume, leaving only approximately (according to my calcs) 87-88% available. If, on the other hand, they have a single fuel in them, they don't need the extra pressure barrier, and their storage volume should rise to approximately 94-95% of total volume (spheres are efficient that way). Incidentally, there is also a small difference between a cryogenic double sphere and an ambient or low temp double sphere, and the fuel mix ratio plays a part as well. There is a difference yet again if the sphere is highly pressurized or left with only a small pressure.

Is there a mechanism to simulate this at least crudely, by changing the volume available with the tank type or contents?

[xx_mortekai_xx]

@Bezzier

 

Im not sure how it would function, but I do think something like this would be possible.

I say this purely based on the fact that my ProceduralParts RealFuels tank has a Utilization slider that can raise or lower the amount of usable space within a tank.  I often up the space for balloon tanks and lower it for thicker tanks.

And now having looked at the config for this part, there is an entry under the ModuleFuelTanks node called utilizationTweakable which is set to true.

At the very least, you can include this parameter and adjust the tanks manually

----------------------------------------------------------------------------------------------------------

On another subject, I have a question that I can perhaps get answered here.

 

I am trying to write a somewhat general catch-all patch for my engines, allowing them to use different fuel configurations.

 

However, I have noticed that all of the configurations have the same plume.

Is there a way to configure what plume will be used with the different fuel configurations?

Edited May 20, 2016 by xx_mortekai_xx

[GGumby]

Hello Nathan, i was wondering if it would be possible to have the tanks for Real Fuels in a separate mod so that way they can be introduced into other mods. Im currently reviving Civilian Populations and there are some unused assets, Namely these massive spherical storage tanks that don't store anything. I really like the power that Real fuels gives you when it comes to filling your tanks up; you can choose, specifically, how much you want to store based upon how much space you have in a tank. I feel like if someone knew exactly what they wanted in a tank but didn't exactly agree with the choices i provide to them, it would lend them the flexibility to change it themselves.

My primary concern is that i don't want the standard fuel types to be changed because that isn't my mod's goal.

[blowfish]

@GGumby I believe you're looking for Modular Fuel Tanks.  It's based on the same tank switching code as RealFuels.

[GGumby]

10 hours ago, blowfish said:

@GGumby I believe you're looking for Modular Fuel Tanks.  It's based on the same tank switching code as RealFuels.

thank you kindly!

[Raptor831]

On 5/18/2016 at 6:48 PM, Bezzier said:

Hey, I'm in the middle of revamping a tank pack from a while ago, and have a question regarding an RF config. Specifically, I'm trying to get new configs up for a set of spherical tanks. They ought to have different usable volumes depending on what's being stored in them.  If there is a fuel mix, they must be (probably concentric) double spheres, and the inner wall volume must eat into the storage volume, leaving only approximately (according to my calcs) 87-88% available. If, on the other hand, they have a single fuel in them, they don't need the extra pressure barrier, and their storage volume should rise to approximately 94-95% of total volume (spheres are efficient that way). Incidentally, there is also a small difference between a cryogenic double sphere and an ambient or low temp double sphere, and the fuel mix ratio plays a part as well. There is a difference yet again if the sphere is highly pressurized or left with only a small pressure.

Is there a mechanism to simulate this at least crudely, by changing the volume available with the tank type or contents?

Utilization parameters are probably best for this, as @xx_mortekai_xx mentioned. Also, different tank types can be applied to simulate cryo or balloon types. You can either do this per part, or set up a part to possibly use differing tank types (like Procedural Parts does). Not sure if it affects utilization directly, but you'll pay a mass penalty for cryo but save mass for balloon. See here: https://github.com/Swamp-Ig/ProceduralParts/blob/master/Parts/ZOtherMods/RFTank.cfg#L173

19 hours ago, xx_mortekai_xx said:

...snip...

I am trying to write a somewhat general catch-all patch for my engines, allowing them to use different fuel configurations.

 

However, I have noticed that all of the configurations have the same plume.

Is there a way to configure what plume will be used with the different fuel configurations?

You can set up a plume per CONFIG node in a ModuleEngineConfigs set. See here: https://github.com/Raptor831/RFStockalike/blob/master/GameData/RealPlume/RealPlume-RFStockalike/VenSR.cfg#L53

[xx_mortekai_xx]

4 hours ago, Raptor831 said:

You can set up a plume per CONFIG node in a ModuleEngineConfigs set. See here: https://github.com/Raptor831/RFStockalike/blob/master/GameData/RealPlume/RealPlume-RFStockalike/VenSR.cfg#L53

Thank you much.  Thats exactly what I was looking for.

[Starwaster]

On 5/18/2016 at 6:48 PM, Bezzier said:

Hey, I'm in the middle of revamping a tank pack from a while ago, and have a question regarding an RF config. Specifically, I'm trying to get new configs up for a set of spherical tanks. They ought to have different usable volumes depending on what's being stored in them.  If there is a fuel mix, they must be (probably concentric) double spheres, and the inner wall volume must eat into the storage volume, leaving only approximately (according to my calcs) 87-88% available. If, on the other hand, they have a single fuel in them, they don't need the extra pressure barrier, and their storage volume should rise to approximately 94-95% of total volume (spheres are efficient that way). Incidentally, there is also a small difference between a cryogenic double sphere and an ambient or low temp double sphere, and the fuel mix ratio plays a part as well. There is a difference yet again if the sphere is highly pressurized or left with only a small pressure.

Is there a mechanism to simulate this at least crudely, by changing the volume available with the tank type or contents?

As @Raptor831 says you can use utilization to control how much of a tank is usable. However, your specific use case scenario would call for each nested internal tank to have its own utilization set separately and the short answer is that that is not really supported the way you would need. It would be far easier and probably better to just assume common bulkheads. (i.e. if the tank has two fuels then the tank is split. Assuming 50/50 then it would be split down the middle for example)

[Lilienthal]

Boiloff formulae?

I was wondering whether there is a guide to how the boiloff is calculated. This would be very useful to see whether I still can run LqdHydrogen missions to the Moon.

Is the shape important? The size of the tank? The temperature?  (The type of the tank, and the fuel seem to be obvious )

Thx!

Gustav

[Phineas Freak]

@LilienthalIIRC it depends on the following parameters:

• Tank size
• Tank material
• Tank temperature (both skin and internal)
• Tank fill ratio
• Propellant thermal mass
• External temperature
• External thermal flux
• Radiator efficiency (if installed)

And probably some more that i have missed...