Fuel drains through decoupler even though crossfeed is turned off

[Sea_Kerman]

This glitch drained all the fuel from my mun lander, luckily I managed to find steps to reproduce

 

[ecat]

Can confirm similar occurrence of the above, though my investigation was a lot less through:

TransferStage<-Decoupler<-Rover<-JnrDockingPortPair<-SkyCraneThing (with landing legs)

Decoupler and both docking ports set to cross feed disabled

With 2 slightly different designs, both arrived at Minmus with almost empty sky crane tanks and the UI reporting about 400dV for the sky crane, it should be closer to 2000!

On the second flight I found the transfer manager, refilled the baguettes and the UI reported a dV of zero for the sky crane. After a restart the save made after the refill reports 420dV for the SC, isolating this stage in the VAB shows 1700dV.

So, yes. Fuel cross flow issue. Also deltaV calculation (recalculation? issue). If it's of any help, the rover was the 'root part' while building the vessel 

[TCAlex01]

Legs "Wombat" and "Bandicoot" causes the problem. Place them on radial decouplers is a workaround.

Link to:  same issue

Edited February 25, 2023 by TCAlex01

[Kasus]

Did some testing. There is a bug with the XS and MD landing legs. Just remove them from your build, and the drain goes away. Did in my tests. Weird tho.

[ArmchairGravy]

Can confirm medium coupler with fuel feed disabled is still passing fuel down the stack.

[LameLefty]

4 hours ago, Kasus said:

Did some testing. There is a bug with the XS and MD landing legs. Just remove them from your build, and the drain goes away. Did in my tests. Weird tho.

The workaround I found for the small legs on my Mun lander is to mount cubic struts recessed/clipped into the lander, and attach the landing legs to those. No more crossfeed. 

[Sea_Kerman]

mounting the medium legs on struts doesn't seem to help

[Cosmus]

This is happening to me as well. Let's see if patch 1 addresses/solves this issue.