Same stage engines using fuel at different rates.

[andeeeeeee]

I have rocket, with a main booster stage comprised of 5 big fuel tanks (orange ones). One in the center, and 4 around it. I am using asparagus staging, so this cuts down to 3 engines/fuel tanks, and then ultimately the one left in the middle.

My problem is that when it is time to decouple the first and second group of engines/fuel tanks, one still has some fuel left in it, as I'm watching the fuel gauges at launch, one is burning fuel quicker than the other. This causes 2 problems, one when I decouple as soon as one of these tanks depletes it fuel, they are jettisoned and the one with fuel in shoots of like a bullet and hits another part of my rocket. The other problem, if I wait for the second one to empty then I keel over due to excessive thrust on one side.

Is there any reason 2 identical fuel tanks/engines would use fuel at different rates? This also happens for the 2 asparagus decoupling. I've tried to modify the build but to no avail, at the moment I'm having to use Seperatrons to push them far enough away from the rocket that it doesn't damage it, but then the backlash from the engine destroys some other part of my rocket.

Here's an image for clarity

Any help would be greatly appreciated.

[allmhuran]

You have probably accidentally added fuel lines with the wrong symmetry specified, creating multiple paths for fuel to get from the outer to the inner engines. Multiple fuel paths causes unpredictable fuel flow behaviour.

Make sure that there is only one way fuel can get from any tank to any other tank.

[Spyritdragon]

Under your central stack is a structural decoupler. That seems weird, but more importantly does not allow for fuel crossfeed. And right now it even seems to me from the picture you actually have a fuel line leading to that decoupler.

Make sure all your fuel lines are exactly symmetrical, and try leading them from the pancake tanks to the orange tanks, going from the first asparagus stage pancake tank to the second stage orange tank, then from the second stage pancake tank to the central orange tank. Then allow fuel crossfeed on your central stack decoupler before launch, and you should be fine. The problem is most likely related to fuel flow, so you want to lay the pipes with in mind that fuel always comes from the farthest tank first. You want asparagus-1-orange to be the farthest, then asparagus-1-pancake, then asparagus-2-orange, then asparagus-2-pancake, etc.

Alternatively you could assign an action group rather than using the spacebar to stage, with in the action group the decouple command along with the 'engine shutdown' command.

[sojourner]

Yep, fuel lines are most likely messed up somewhere. I have to ask, what is that decoupler doing down there at the bottom of your core stage since you also have one just above the orange tank on that stage?

[Tiron]

Yep, fuel lines are most likely messed up somewhere. I have to ask, what is that decoupler doing down there at the bottom of your core stage since you also have one just above the orange tank on that stage?

A decoupler with a fuel line running into it. Might be the problem right there. Screwing up the fuel draw from the center engine?