Docking Ports Fuel Exchange?

[SpaceTrashCan]

hey

I'm currently working on a interplanetary ship, to fly to Jool. My plan is to have multiple launches and dock the ship together in Kerbin Orbit.

I have send up a Fuel Tank with docking ports so far. Now I'm gonna send up my engines and dock them.

My question is: Does fuel transfer threw docking ports or do i have to connect it in some other way in order to have the fuel reach teh engine?

Thanks in advance

[Choctofliatrio2.0]

3 hours ago, SpaceTrashCan said:

hey

I'm currently working on a interplanetary ship, to fly to Jool. My plan is to have multiple launches and dock the ship together in Kerbin Orbit.

I have send up a Fuel Tank with docking ports so far. Now I'm gonna send up my engines and dock them.

My question is: Does fuel transfer threw docking ports or do i have to connect it in some other way in order to have the fuel reach teh engine?

Thanks in advance

I believe you can transfer fuel through the ports. I'm not sure if it naturally flows, but you can manually pump it.

[eddiew]

You should be able to right click the docking ports and enable/disable fuel crossfeed from the menu there   So yes, fuel does transfer - unless you don't want it to.

[Guest]

1. By default, crossfeed is disabled in docking ports. I.e., if you have a rocket burning on one stage, it'll flame out when that stage is drained, even if there's fuel in a stage separated with a docking port.
2. As @eddiew states, you can enable crossfeed for each port through right-click, in-flight or in construction. This means the rocket will drain the next stage also
3. You can also manually transfer fuel between tanks across docking ports by alt-clicking each tank and clicking "out" or "in" as desired.
4. In 1.2-pre, there is an advanced difficulty option "fuel transfer obeys crossfeed." This means that if crossfeed is disabled in the docking port, you won't be able to transfer fuel.
   • ...but this is currently broken: sometimes it's not possible to transfer fuel if the option is set even if crossfeed is enabled on the port, and I get the impression that Squad doesn't consider this very high priority to fix.

Summa summarum, the vessel you want to make is completely feasible (and in fact I just made one like it for a Duna mission).

 

[Martian Emigrant]

36 minutes ago, Brikoleur said:

You can also manually transfer fuel between tanks across docking ports by modifier-clicking each tank and clicking "out" or "in" as desired.

There.

I fixed it for you.

On Linux the Alt key cannot be used (For a Linux reason). So the modifier key is the Right Shift.

So you are half correct mon ami.

 

ME

[Higgs]

@Brikoleur If the fuel xfeed issue isnt a high priority fix in 1.2 its going to be one fast once its in gen pop. Having fuel stations for example is a big thing and if fuel fails to cross docking ports because of a feature that is broken, its gonna be a big problem.

[Sharpy]

Caveat: fuel really hates flowing "up" the vessel. Make sure that your root part points "skywards" and the ports on the tank are on the bottom end, pointing downwards. That way after enabling crossfeed, everything will work automagically. If you put these ports on your nose, you may be in for a lot of manual pumping.

[Guest]

49 minutes ago, Higgs said:

@Brikoleur If the fuel xfeed issue isnt a high priority fix in 1.2 its going to be one fast once its in gen pop. Having fuel stations for example is a big thing and if fuel fails to cross docking ports because of a feature that is broken, its gonna be a big problem.

Well, there is a simple workaround -- just uncheck the option in difficulty options. 

IMO they ought to remove the option if they can't get it working properly. The issue is here: http://bugs.kerbalspaceprogram.com/issues/12244

I'm quite sure it's a bug as fuel transfer does work if I assemble the docked craft as docked; it only doesn't work if I dock them in orbit.

[Higgs]

@Brikoleur "Dock in orbit" is the issue i see. Which is why i mention fuel stations. If the system refuses to flow fuel between docking ports regardless of the the tick box saying yes then thats a major problem. One Squad will be completely unable to ignore. Sitting in my car I can think of a way to circumvent this but purists who refuse mods wont like it. KIS/KAS attachable ports