Fuel ducts don't work with liquid fuel fuselage?

[MaxwellsDemon]

I was trying to add fuel capacity to my "Nerv"-powered stage by clustering multiple Mk1 Liquid Fuel Fuselages and linking them with each other and the core stage with external fuel ducts. But no matter how I arrange the ducts, either directly to the core stage or in a spiral series, the only fuel that's registering is that in the central fuselage (the one the "Nerv" is attached to directly). Is there a way to do this, or is it some sort of limitation of the nuclear engine?

Edited August 6, 2015 by MaxwellsDemon
Changing to "Answered"

[cephalo]

fuel ducts are directional. Are they facing the right way?

[Xannari Ferrows]

Is there any point where you have fuel flowing out of a tank in 2 ways? If so, that would explain it. If not, then this is a strange bug.

[Glaran K'erman]

Fuel ducts really need to be made two-way, if only for part count consideration. But number one thing to check is what cephalo mentioned, darn one-way ducts.....

[MaxwellsDemon]

Hm... since I wasn't aware of the directionality of the ducts, that's the most likely explanation (I haven't used them often so far). Will check and let you know.

[Yakky]

I don't believe there's a Nerv engine limitation. See if either of the following help:

(1) Are you sure you connected the ducts in the right sequence and not backward? First click is source tank, second click is destination.

(2) I've occasionally had weird bugs with fuel ducts in unusual symmetry situations, such as one tank feeding many that feed back into one, etc. Sometimes, but not always, these appear to be fixable by detaching and reattaching the fuel tanks (not just the ducts). Might give that a shot to see if it helps you.

Good luck.

Wow... severely ninja'ed. Got distracted by something else for awhile and bam!

[Snark]

Fuel ducts really need to be made two-way' date=' if only for part count consideration.[/quote']

Except that the one-wayness is a really important design consideration. Lots of designs would break if they were two-way; for example, asparagus staging wouldn't work right.

I have to say that I've never had a situation where I wished for a two-way duct-- there's always one direction I want fuel to flow, namely, towards the engine.

What's a situation where you'd want it to be two-way?

[Goddess Bhavani]

There are certain complex craft designs where 2-way ducting magically fixes fuel feed problems. Usually the type of craft you spend 3 weeks assembling and end up with phantom fuel flow issues like spaceplanes that decide to feed fuel from one side only right when it can cause total vehicle loss from spontaneous hypersonic disassembly.

I simply add a reverse fuel flow duct at the problem tank and viola.

[MarvinKitFox]

Based on the supplied images of your craft, your problem is that you have mounted the umflagulator in transverse to your retroencabulator.

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Please provide image for a question like this.

There is nothing inherently different about the nerv engine, but the type of joints used, exact placement, direction of fuel lines, etc.. all can affect the outcome.

[Glaran K'erman]

I have to say that I've never had a situation where I wished for a two-way duct-- there's always one direction I want fuel to flow, namely, towards the engine.

What's a situation where you'd want it to be two-way?

Hey, definitely agree that one-way is definitely still needed in the functionality department, but like thrust limiter on boosters you should be able to preset in VAB/SPH whether flow will be two or one-way. My number one reason for two-way flow is being able to better manage CoM issues by fuel feed. Sometimes you just simply can't get something stable but really need to get it to orbit whether it be for a station or what have you and having the ability to more precisely manage fuel flow would be welcomed over here. It's not impossible at all to acheive what I what with the current ducts, just less parts and less clicking my way.

[cicatrix]

The better way would be the ability to switch the flow direction in flight. After all - it's only a pump and a pipe. The ability of reversing the pump might solve many difficulties when you are far from Kerbin.

[cantab]

I simply add a reverse fuel flow duct at the problem tank and viola.

There's your problem, you're trying to add violas to your spacecraft. It's guitars you play in space, haven't you seen Chris Hadfield?

[Glaran K'erman]

Kerbals play ukulele's.

[MaxwellsDemon]

Not really surprisingly, reversing the direction of the fuel ducts worked. I guess it's the same principle as reversing the polarity of the neutron flow.

Thanks for the tip!

[GoSlash27]

I'm struggling to understand the utility of 2-way ducting. I've never needed it and can't imagine how I ever would.

Best,

-Slashy

[Red Iron Crown]

I'm struggling to understand the utility of 2-way ducting. I've never needed it and can't imagine how I ever would.

Most of the use cases are edge, but they exist. For example, how can I make this tug supply all five engines continuously? Fuel lines from the center outward cause the center engine to run dry first, lines from the outriggers inward cause the outer engines to run dry first.

That said, such things can often be worked around by designing a bit differently, and doubled fuel lines can make any other cases work.