Fuel crossfeed while docked problems [Workaround found]

[RYU AZUKU99]

I have a small manned craft that docked with a large fuel tank in orbit to help it on it's way to the mun, but I am having an issue. When I docked with the tank I cut the fuel flow from my much smaller main tank hoping to just use up the external tank first, but I was left scratching my head when I noticed there was no fuel flow at all. After some research I learned that fuel flow is disabled through heatshields on higher difficulties(or if you select the option in the difficulty menu) but I never selected that option at all. I can manually pump fuel from the external tank to my main crafts tank, but this is a pretty poor fix as I will have to constantly do this. Not sure if this is by design or if it's a bug as I do not dock spacecraft that often. Any help?

 

Mods: Mechjeb, Near future construction/solar/electrical, Hanger extender, Tweakscale, Mk-X spaceplane parts

Output Log link: https://drive.google.com/file/d/1qDuzVZhABqEtNjRS37U-Y04RUotTDRCr/view?usp=sharing

Edited August 24, 2019 by RYU AZUKU99

[Geonovast]

Make sure you have crossfeed enabled on all docking ports and decouplers.

It may be a fuel flow priority issue.  In your settings, do you have Advanced Tweakables enabled?  If you don't enable it, and then you can adjust fuel flow priority of each tank.  Tanks with a higher number will drain first.

[RYU AZUKU99]

Crossfeed is enabled on both docking ports and decouplers, and I already have the external tank set at highest priority.

[Geonovast]

Mind attaching some screenshots?

[Fraktal]

The only way to get fuel through a heatshield without turning off "Resource Transfer Obeys Crossfeed Rules" in the difficulty options is an External Fuel Duct attached above and below the shield. It'll automatically disconnect when you stage off whatever is below the heatshield (since I presume you've got a decoupler immediately below the shield that you'll fire prior to reentry).

[RYU AZUKU99]

7 hours ago, Fraktal said:

The only way to get fuel through a heatshield without turning off "Resource Transfer Obeys Crossfeed Rules" in the difficulty options is an External Fuel Duct attached above and below the shield. It'll automatically disconnect when you stage off whatever is below the heatshield (since I presume you've got a decoupler immediately below the shield that you'll fire prior to reentry).

I never turned that option on in the first place.

 

7 hours ago, Geonovast said:

Mind attaching some screenshots?

[Geonovast]

You have your priority backwards.  Higher numbers drain first.  10 is much higher than -9.

[RYU AZUKU99]

5 minutes ago, Geonovast said:

You have your priority backwards.  Higher numbers drain first.  10 is much higher than -9.

Even switching it does nothing. Already tried it.

Edited August 24, 2019 by RYU AZUKU99

[Geonovast]

The only other option is that crossfeed is not enabled on one of the docking ports.

[RYU AZUKU99]

Crossfeed is enabled on every single part that has it as an option.

[Geonovast]

The picture is a little confusing anyway.

According to the priority, the smaller tank will drain first.  But since you have both the fuel and oxidizer disabled, it shouldn't drain at all since they're turned off.

You also appear to be pumping fuel, but I'm not sure how that's working since you don't have a "Stop" button on the larger tank, and the larger tanks is full.  What's pumping and where?  Your SS shouldn't even be possible.

Edit: Alright, brainfart.

Your SS still confuses me, but, it is an issue with the heatshield.

Fuel cannot crossfeed through a heatshield, ever.

What the difficulty option does is prevent you from pumping fuel through it.

Edited August 24, 2019 by Geonovast

[RYU AZUKU99]

The screenshot was taken at the end of pumping between the two tanks which is probably why that looks weird. I can pump fuel between both tanks manually, but the engine will not automatically take fuel from the tanker I am connected to for whatever reason, you can see that with the fuel gauge by my engine.

[Geonovast]

1 minute ago, RYU AZUKU99 said:

The screenshot was taken at the end of pumping between the two tanks which is probably why that looks weird. I can pump fuel between both tanks manually, but the engine will not automatically take fuel from the tanker I am connected to for whatever reason, you can see that with the fuel gauge by my engine.

Exactly.  You can pump it between tanks fine, but the engine won't just drain from the big tank with crossfeed, because of the heatshield.  If you had that difficulty option enabled, you wouldn't be able to even pump the fuel back and forth.

As simple ModuleManager patch will change that for you.

@PART[HeatShield*]
{
    %fuelCrossFeed = True
}

[RYU AZUKU99]

Thanks