Fuel crossfeed through radial decoupler?

[KBluey]

Have the rules for fuel transfer changed? I'm using TT-38K radial decouplers to attach LFO tanks and rocket engines around a central core stage (which contains liquid fuel and turbojet engines). The turbojets in the center stage are pulling fuel from the LFO tanks even though there's a radial decoupler in between and no fuel duct! Maybe I somehow screwed things up by adding mods or something...? The only way I can think of to fix this would be TweakableEverything.

[Mad Rocket Scientist]

Turboramjets now pull fuel from every unlocked source of fuel, whether it's in the same stage, or not. It's for airplanes, so they don't get unbalanced. Rockets shouldn't do that, if they do you may have a bug of some sort.

[Red Iron Crown]

MRS has the answer for this particular case, all airbreathing engines and the Rapier in rocket mode ignore crossfeed rules and drain evenly from tanks in the same stage, with stage being determined by the number of decouplers between the tank and the root part.

For posterity for anyone finding this thread later I should point out something unexpected: Radial decouplers don't block crossfeed. The reason you don't see it much is because it only works when there's a non fuel tank part attached to the decoupler.

[Kryxal]

This sounds like a measure to help with in-flight stability as tanks drain...

[KBluey]

Aha! I see the point, but it would be nice to be able to block the crossfeed when I don't want it. Thanks for clarifying....I do vaguely remember reading about the new crossfeed rule but I didn't see it mentioned in any of the wiki articles.

[Red Iron Crown]

The wiki people have had their hands full with all the changes in 1.0 and its patches, a few gaps here or there are to be expected.

The behavior can't be disabled as far as i know, about the only thing you can do is to disable the tanks you want to save in the right click menu until you need them.

[Moesly_Armlis]

Now I find this thread after my vessels kept going off balance and dropping full tanks of fuel.

Girders also have this ability to transfer fuel.

Shutting the tanks flow off was the solution.

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I completed this experiment last evening and was going to follow up today on this forum with the report.

[se5a]

Ok so... has this changed again?

from what I'm reading in this thread, crossfeed is not blocked for air breathers but is for rockets. 

However I'm finding that the "Enable Crossfeed" toggle works properly for air breathers, but not at all for rockets:

https://www.dropbox.com/s/mc0w9jaekpd3j8v/Screenshot%202016-01-10%2013.32.38.png?dl=0

In the linked picture, only the tanks that are attached to engines drain. neither the central column nor the outer tanks drain. Crossfeed has been enabled on all radial decouplers. 

This is a bit of a pain since fuel lines are kinda deep into the tech tree. 

Previous messing with junos taught me that the toggle works fine for air breathers (or junos at least), excepting that if you toggle while in flight the UI does not change to show that it's been enabled.

(I had a couple of drop tanks on the wings of an aircraft, toggled in flight and nothing happened, gave up and continued flying. a little while later I had trouble with the damn thing rolling, figure out one drop tank was empty and the other was full...) 

 

 

[Val]

Yes, the rules changed for air breathers + RAPIER closed cycle in 1.0.5. They now respect crossfeed settings.

Normal rocket engines work exactly as before. They need fuel lines for fuel that is not in the same stack.

[se5a]

Seems a little non intuitive for new players (me)