Fuel flow problems

[mrmcp1]

I have been attempting to make a replica of a space shuttle that was never built but the fuel is not flowing properly.

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I am attempting to use the unmanned ship as a powered fuel tank meaning as both ships engines fire the manned ship expends no fuel but it is not working like this. It is similar to asparagus staging but instead of this the manned ship separates with almost no fuel left. Can anyone help me get the fuel lines to work properly?

Download link for the craft: https://www.dropbox.com/s/k03x5pntmnv5p0b/Shuttle%20II%203_4.craft?dl=0

Thanks for the help

[Signo]

Hi, there was an issue in the fuel lines. It seems to work as intended now.

Here you can download the modified .craft, I worked on it in the VAB and I tried it on the launch pad instead of the strip.

Hope this could help.

Cheers.

[Laie]

Fuel flow rules are tricky. There is a thread from Kasuha in the tutorials section explaining them in great detail, it goes over several pages and a good 20 posts just for the basics.

But what I think that bites you: much like a router, the game counts how many "hops" there are between a fuel source and the engine. Everytime you go through a fuel line is a hop; every time you go from one tank to the next is a hop. The most distant tanks are emptied first.

From the look of it, many of the tanks on your main vessel are as far or further away from the engine as the some of the detachable tanks. "Far away" in terms of how many connections there are, not in meters. Therefore the engine will start tapping the main tanks before the detachable ones are fully drained.

[Padishar]

But what I think that bites you: much like a router, the game counts how many "hops" there are between a fuel source and the engine. Everytime you go through a fuel line is a hop; every time you go from one tank to the next is a hop. The most distant tanks are emptied first.

This is not true (for rocket engines). Fuel lines are scanned first when looking for fuel sources and if the fuel lines provide fuel then the other connection methods are not followed.

Like you said, it's complicated...

[mrmcp1]

Hi, there was an issue in the fuel lines. It seems to work as intended now.

Here you can download the modified .craft, I worked on it in the VAB and I tried it on the launch pad instead of the strip.

Hope this could help.

Cheers.

Thanks for the help. The craft now detaches with much more fuel in the tanks but the right hand Oscar B fuel tanks still end up being drained of fuel. (Weird considering the fuel lines are all symmetrical)

[Xannari Ferrows]

The game has always had issues with fuel flowing out of a tank on multiple paths. It is possible to make this work with the TAC fuel balancer, but otherwise you'll have to separate transfer into multiple steps.

[Signo]

Thanks for the help. The craft now detaches with much more fuel in the tanks but the right hand Oscar B fuel tanks still end up being drained of fuel. (Weird considering the fuel lines are all symmetrical)

Sorry, my fault. If you have a closer look that fuel line goes into the "Twitch" and not to the bottom Oscar-b, that's why the tank is drained. You will need to move that.

Edited June 23, 2015 by Signo

[mrmcp1]

Thanks for all of the help but unfortunately when I tried to alter that fuel line I just made things worse. Is there any chance that you could give me a fixed version?