Disabling fuel crossfeed between adjacent tanks

[michelcolman]

It would be nice if we could disable the automatic fuel crossfeed system that always steals fuel from the closest adjacent tank. You can choose whether or not fuel passes through a decoupler, but there's no such option for crossfeed between tanks.

My second stage was a bundle of 7 orange tanks with Mainsail engines, but some of those tanks were probably considered to be "closer" to certain particular other tanks due to tiny floating point rounding errors. The result was that some tanks were running out more quickly than others, and I suddenly got an asymmetric flameout with empty tanks on one side and half full on the other.

I know I could solve it with fuel lines, asparagus staging etc. (and I probably will since it will be more efficient), but it would have been nice to simply disable this crossfeeding. Just add an option to each fuel tank to optionally isolate it from adjacent tanks, like the option to let fuel pass through a decoupler or not.

[Red Iron Crown]

"Closeness" doesn't matter, it's the logical arrangement that does and floating point error doesn't figure into that. Pic of the craft or craft file would help in figuring out exactly what happened with your craft.

I'm not sure adding crossfeed enable/disable would work, IIRC that would prevent attached engines from drawing from the tank. Probably better to use decouplers, separators, docking ports, or other parts without crossfeed to isolate tanks from each other.

[KerikBalm]

I've been getting the same problems with a cluster of 3 tanks around a central tank, the central tank has fuel lines going raidally outward, but the tanks drain unevenely, and I have to do some tricky fuel transfers to get the darn thing to fly right.

At the moment, I don't have any better picks of it but here it was as the payload:

The center 2.5 tank has a mk2 lander can, and then a "half orange" above it feedes to the 3 tanks + adaptor tanks around it, each with a poodle below. Its my duna ISRU craft, and it becomes unbalanced rather fast without shutting down the fuel flow on all tanks except the center, and manually transfering fuel into the center to keep it going. Thinking that it may be related to being put in as a subassembly, I basically rebuilt the thing, put it on the launchpad, and then swapped positiongs via .cfg file editing.

The newly made one had the same problem.

[sal_vager]

Also guys, don't forget that fuel lines have trouble when going from one tank to two or more, two into one works but not the other way around.

Rockets should only be drawing from their stack as well, not adjacent tanks, only jets draw fuel from neighbouring tanks and they do so equally.

If your rockets are drawing fuel from radial tanks it's either not a stock install or you put fuel lines on it.

[fireball]

There is a mod for this, updated to KSP v1.2. It is "TankLock Redux".