Onion staging mit multiple tanks, where to put the fuel lines?

[Navy2k]

Hi,

when ich have a simple onion staging craft and lets say i have in the center stage a capsule, 3 tanks and an engine. Surrounded by boosters consisting of also 3 tanks and an engine.

Between which tanks must i place the fuel lines so that all outer tanks get emptied first and the inner 3 tanks are completly full.

Thanks

Ben

[TheDarkStar]

It would really help to post a picture.

If I'm reading what you said right, then you should probably put fuel lines leading from the outer tanks to the inner ones. Each outer tank should give fuel to only one inner one since looping fuel flow is unpredictable and usually leads to imbalances.

[Anton P. Nym]

You can put the fuel lines from any of the three tanks in the boosters, to any of the three tanks in the core stage; the fuel feed logic will drain the boosters first. For extra stability, though, I'd recommend putting the fuel lines from the bottom tank of each booster so that the top tanks in each booster drain first. Fuel flow logic, so far as I've gathered, takes fuel from as far away from the engine as possible.

-- Steve

[Navy2k]

Thats not what i experienced (Inner topmost tank looses fuel while there still was some in the boosters). But then again the constellation was a lot more complex than my example.

The information about trying so get the further away fuel first is worth looking into it. I will give it some tests and come back to it.

[Taki117]

Generally speaking you want to place fuel lines on the lowest tank in a stack. This is because fuel flows from top to bottom in a stack.