Cross feed capable parts

[sql_yoda]

I know this is a very basic question - but if put an engine (LV909 for example) under an RCS fuel tank and then a regular fuel tank over the pair, will the engine still draw from the regular fuel tank?

I searched for about an hour and still cannot find the answer to this very basic question.

Edited August 28, 2013 by sql_yoda
answered

[Johnno]

I know this is a very basic question - but if put an engine (LV909 for example) under an RCS fuel tank and then a regular fuel tank over the pair, will the engine still draw from the regular fuel tank?

I searched for about an hour and still cannot find the answer to this very basic question.

You could have tested it yourself far faster and easier. There's plenty of threads about crossfeed, not to mention fuel line logics, the likely reason for such a basic question not being discussed is because it takes 2 minutes to test.

But the answer is yes.

[SRV Ron]

While liquid fuel tanks won't cross feed across stack couplers, RCS ones will. That could cause you to lose all the fuel in a probe RCS tank when you intended to use the RCS fuel in the booster stage. The fix, disable the probe tank by right clicking on it and clicking on the green triangle to get a no icon. That way, the thrusters, even the ones on the probe, will use the fuel from the booster stage.

Note, the RCS fuel tank will reset if you go do something else and return later to that mission.

Like anything, if you don't know the answer, do a search or set up a test.

[magnemoe]

in short most stock parts passes fuel however it might be limits on number of parts it passes trough. I made an rover / lander with an 20Kn engine below an 1x1 structural panel where the wheels was mounted and two oscar fuel tank on top. Here I did not get cross feed, but by making an fuel pipe from tank to the 1x1 panel the engine got fuel.

As SRV says the easiest is just to test it,

[Tiron]

Easiest way to answer this sort of question: Build it, attach a launch clamp to it. Put the Launch clamp above the engine in the staging order. Try it on the pad, still attached to the clamp(s).

[sql_yoda]

the answer is yes.

I don't know how to change the listing to "answered" but yes the question is actually answered and hopefully now searchable.

[dave4002000]

Edit your original post and it will allow you to change the prefix.

[Zourin]

Crossfeed behaves strangely. Just because two parts are attached doesn't mean they'll draw fuel, even if they are crossfeed capable. I've run into several instances of this in my SSTO designs, especially when dealing with wing sections where fuel does not pass freely.

[Frederf]

Crossfeed capable only transfers fuel if the structure of your part connections is suitable for that resource flow. The hierarchy of flow dictates a certain path (X drains from Y drains from Z), crossfeed capable simply allows it.

[magnemoe]

Crossfeed behaves strangely. Just because two parts are attached doesn't mean they'll draw fuel, even if they are crossfeed capable. I've run into several instances of this in my SSTO designs, especially when dealing with wing sections where fuel does not pass freely.

Anything sideways connected either side to side or radial connected will not crossfeed. pipes solves this.