Kerbal Space Program

Kerbal Space Program

inchulk2013 Oct 6, 2017 @ 1:27pm
Fuel Lines
I just watched a tutorial on how to build a rocket and copied it exactly but my fuel lines dont flow how his did. Its an asparagus rocket that is supposed to drain two outermost tanks into the 2nd layer of tanks and the 2nd layer drains into the center tank. But mine just all drain at the same rate not filling the center tank like his did. Here is video for context - https://www.youtube.com/watch?v=KavWahnbQsk
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Showing 1-7 of 7 comments
RoofCat Oct 6, 2017 @ 3:51pm 
rocket design in that video is bad. Don't copy it.

as for fuel flow - roughly a year ago fuel flow prorities were added to the game.
1. you may have to activate advanced tweakables in settings for them to become available.
Since that was introduced, fuel flow was also slightly changed allowing for more freely fuel flow across the whole ship.
2. tanks with higher fuel flow priority will be emptied first. You have to compare values outside of parentheses for tanks. Those in () just indicate the shift from the default value so you can find your way back to default for that tank.
3. decouplers and fuel lines still work the way they did before. Decouplers need crossfeed to be activated and fuel lines let fuel flow only in one direction.
4. fuel can't flow across heat shields. Use fuel lines to circumvent that when needed.
5. moving tanks or other parts around them in staging sequence will automatically readjust tank priorities and may ruin your setup. Check it after all adjustments to staging.

If you follow these simple rules, everything should work just fine.
Last edited by RoofCat; Oct 6, 2017 @ 3:53pm
Astronaut Oct 6, 2017 @ 3:55pm 
Originally posted by RoofCat:
rocket design in that video is bad. Don't copy it.

as for fuel flow - roughly a year ago fuel flow prorities were added to the game.
1. you may have to activate advanced tweakables in settings for them to become available.
Since that was introduced, fuel flow was also slightly changed allowing for more freely fuel flow across the whole ship.
2. tanks with higher fuel flow priority will be emptied first. You have to compare values outside of parentheses for tanks. Those in () just indicate the shift from the default value so you can find your way back to default for that tank.
3. decouplers and fuel lines still work the way they did before. Decouplers need crossfeed to be activated and fuel lines let fuel flow only in one direction.
4. fuel can't flow across heat shields. Use fuel lines to circumvent that when needed.
5. moving tanks or other parts around them in staging sequence will automatically readjust tank priorities and may ruin your setup. Check it after all adjustments to staging.

If you follow these simple rules, everything should work just fine.
The definition of this comment is opinion. Make sure 2x symmetry or whatever you want is on. Fuel flows in direction indicated by arrows. Other than that, read roofcat's post but ignore the bad design comment.
RoofCat Oct 6, 2017 @ 4:21pm 
that design is bad. Not because of me. Because of math and physics laws. This game is about math and physics last time I checked. Can't fake numbers.
Astronaut Oct 6, 2017 @ 4:22pm 
Originally posted by RoofCat:
that design is bad. Not because of me. Because of math and physics laws. This game is about math and physics last time I checked. Can't fake numbers.
Well, what about orbital dynamics and thermodynamics and science (the expierments in mods are modeled after real expierments)
RoofCat Oct 6, 2017 @ 4:27pm 
Originally posted by camichint:
Originally posted by RoofCat:
that design is bad. Not because of me. Because of math and physics laws. This game is about math and physics last time I checked. Can't fake numbers.
Well, what about orbital dynamics and thermodynamics and science (the expierments in mods are modeled after real expierments)
either you just lost me or the topic. What mods?

No, actually don't answer. You are just trolling away from the discussion. Been there, seen that already.
Enorats Oct 6, 2017 @ 10:45pm 
As roofcat stated.. that video is just incredibly bad. I mean.. it works, but wow. That's not exactly a "good" way to build a rocket.

I don't really recommend asparagus staging in the first place anymore, but if you really want to make one that way there are several ways to go about it now. With fuel priorities in game now you can actually just set the priorities of the tanks in such a way that they drain in the order you drop them. Set your first set to a higher value, the next ones to something lower, then the next to something lower, and your final core to the lowest value. Everything above that should of course be higher than all of that though, as you don't want your sustainer or transfer stages being drained by your booster stage. All of that is also assuming you have actaully unlocked fuel lines, because if you haven't then decouplers won't have fuel crossfeed functionality anyway.

Now, all of that reduces part count.. but I'm old fashioned. Honestly, I use fuel lines to do this sort of thing. It's easy, just do something like this:

1 > 2
\/
C
/\
2 < 1

Basically 1 drains into 2, which drains into the core. 1 will empty first and be dropped, leaving you with 2 arranged symmetrically still. Then 2 will empty and be dropped. You can also use a 6x symmetry to get 6 boosters instead of 4, with booster 1 draining into 2, 2 draining into 3, and 3 draining into the core.

Now, as I said at the beginning.. I don't really do asparagus anymore myself. Adding boosters can have a lot of drawbacks, especially when you have more than two of them. They add drag as you add more of them, and if you have more than two you end up having to put them in less than ideal configurations for seperation. Instead of having your boosters on the "sides" you can end up with boosters "above" and "below" the rocket at seperation, which will cause the booster "above" to impact the rocket almost instantly if you don't push it away with a powerful enough sepetron. Personally, if I find I need more delta-v I add more fuel to my sustainer stage and core booster stage.. in other words, I just make the rocket bigger. If my thrust to weight ratio (TWR) gets too low and my rocket takes off too slowly, I add 2, 4, 6, or even 8 solid boosters to it. Solid boosters are cheap and fairly efficient thrust at sea level, so they generally work out better than these asparagus designs anyway. You still have to put on sepetrons and the like generally, especially with 8 booster designs, and even more so when you get to larger and larger boosters, but I absolutely love the awesome effect of watching the boosters "bloom" outward from the rocket in a flower shape.
MAD Oct 8, 2017 @ 4:29am 
When you add a fuel line, click from where, drag and click where it is going to.
There are arrows showing you flow direction.
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Date Posted: Oct 6, 2017 @ 1:27pm
Posts: 7