Small rocket contruction question

[Jananton]

Hi All,

To get more 'room to move' in outer space I thought up this little construct.

However, there seems no fuel flow from the three tanks to the engine although the one to three coupler part states fuel crossfeed capable.

Any thoughts on why, or is using such a coupler in this way not possible? (KSP 0.22.0 career mode)

Greets,

Jan

[Kasuha]

All constructions must make a tree, i.e. you start from one piece and branch out. What you constructed is not a tree, it branches out and then connects again. Just put the three containers on top of each other or give them each its own engine and it will work.

These kinds of constructions are possible later - either using docking ports or some mods. But there are still problems with them and it's better to avoid them if possible.

[Johnno]

Yeah the multicouplers only lead fuel one way. You'll have to add fuel lines.

Also, before you notice it yourself, only one of the tanks is actually attached to the bottom tricoupler, you'll have to add struts.

[Jananton]

All constructions must make a tree, i.e. you start from one piece and branch out. What you constructed is not a tree, it branches out and then connects again. Just put the three containers on top of each other or give them each its own engine and it will work.

Well, the idea was not to use three tanks on top of each other to avoid sway while in the atmosphere and still have the advantage of the bigger fuel load of three tanks instead of just the one in flight at a later stage. ;-)

Yeah the multicouplers only lead fuel one way. You'll have to add fuel lines.

Ah, right, somehow I expected that when it wouldn't fire up. I thought of using fuel lines, but hey, my career progress isn't there yet. For Kerbals fuel lines seem a high tech item. ;-)

Also, before you notice it yourself, only one of the tanks is actually attached to the bottom tricoupler, you'll have to add struts.

Hmm, interesting, I presume you assume that from experience, or could you see that in the image shown?

Please elaborate on this, or lead me to a tutorial that talks about these kind of contructs.

Greets,

Jan

[Johnno]

Hmm, interesting, I presume you assume that from experience, or could you see that in the image shown?

Please elaborate on this, or lead me to a tutorial that talks about these kind of contructs.

Assumption through experience and visual appearence of your craft. You can't see it as such on the image but you'll notice if when you launch, the craft editor relies on parent-child connections, you can only have one parent per part meaning anything you attach will only really be attached to one part above it.

If you look from the bottom your engine can only be connected to one part, the tricoupler. The tricoupler itself can only be connected to one part, one of the three tanks. However then each of the three tanks can only be connected to one part, thus they can all connect to the tricoupler above.

You can make a workaround with docking ports to get things attached between bi-, tri- or quad- couplers, I made a brief tutorial about it (although it references to engines it's the same building routine);

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[Sirrobert]

Without docking ports, the only work around this would be to give each of the 3 tanks it's own engine, and than only use half thrust

[Jananton]

Right, one parent, multiple childs if applicable, a good thing to know and remember.

Time to play a little with this concept, so back to the drawing board. ;-)

Thanks for the nice example.

Greets,

Jan