[STAGE_PRIORITY] flow

[Archgeek]

Alright, so before I make a support ticket outta this, does anyone know if the devs ever laid out clearly just how mono and xenon fuel flow is actually intended to work?  I've recently learned a couple of recent of designs of mine don't work as intended, as it turns out the [STAGE_PRIORITY] fuel flow rule does not, as I thought, attempt to respect staging in order, working up the stage list as tanks empty or are ditched, but instead counts decouplers out from the root part and draws from every tank with the highest decoupler count, working down as tanks are dumped or empty out.

Spoiler

If it worked as expected, the centre drop tank would not be drained until the side ones were done, and the one up top wouldn't be touched for some time.

Needless to say, this messes with my parallel-mount, pairwise staged fuel pod systems for needlessly-long-range vehicles.  But the thing is, I don't actually know if it's a bug.  If it's meant to work like that, I'll just have to redesign.  If it's not supposed to do that, then I've a bug to report.

[Wallygator]

I find the lack of a flow mode tweak able to be very frustrating both for mono and for fuel cells. 

IMO the player should have control over this setting via the vab/sph inteface. 

Sadly, it's probably going to be viewed as a feature request. 

[razark]

1 hour ago, Archgeek said:

how mono and xenon fuel flow is actually intended to work?

They drain equally from all tanks.

You can lock the tanks during building, and then unlock them when you reach the stage that should be using them.

[Archgeek]

2 hours ago, Wallygator said:

I find the lack of a flow mode tweak able to be very frustrating both for mono and for fuel cells. 

I've no need for that, only the knowledge of what it's actually supposed to do.

1 hour ago, razark said:

They drain equally from all tanks.

You can lock the tanks during building, and then unlock them when you reach the stage that should be using them.

They do not anymore, at least not necessarily.  It counts the number of decouplers from the root part, and drains them in tiers.  As you can see in my screenshot, it's draining from all three tanks that are four decouplers out.  But that's just what it is doing.  What I would know if that's what it's meant to be doing, or if it's meant to do something else, like try to respect the player's defined staging order if it can.

HEH, lock the tanks.  I fear such a technique wouldn't work too well for the likes of me:

Spoiler

'Bit of a complex arrangement to control with tank-locking.

 

[genericeventhandler]

8 minutes ago, Archgeek said:

I've no need for that, only the knowledge of what it's actually supposed to do.

They do not anymore, at least not necessarily.  It counts the number of decouplers from the root part, and drains them in tiers.  As you can see in my screenshot, it's draining from all three tanks that are four decouplers out.  But that's just what it is doing.  What I would know if that's what it's meant to be doing, or if it's meant to do something else, like try to respect the player's defined staging order if it can.

HEH, lock the tanks.  I fear such a technique wouldn't work too well for the likes of me:

  Reveal hidden contents

'Bit of a complex arrangement to control with tank-locking.

 

Try using this

The latest install is near the last page,  I use it in my fuel dump / refuelling crafts.

You set up the tanks you want to drain first as a higher priority ie 15 turn the pump on. 

 

I usually do it this way 

Lower stages get a priority of 15-14-13

Vampire craft who salvage fuel get  12-11-10  (Priority 0 on the Monoprop main tanks, 11 on the overflow tanks)

Fuel dump gets 9 - 8 - 7

and active craft upper stages get 

7 - 0

This way I know that my lower stages will burn correctly any lower fuel can be picked up by the vampire ships, fuel transfer is automatic. Vampires dock to the fuel dump and automatically dump their excess fuel into the dump. 

Any mission craft docking with the fuel dump will automatically be refuelled.

Visiting fuel trucks have one rcs tank set to 0 so that they can undock and de-orbit.

 

 

 

 

[Wallygator]

29 minutes ago, Archgeek said:

I've no need for that, only the knowledge of what it's actually supposed to do

Similarly, I would like to know all valid values for flowmode and the effects and behavior for each. Such info is not easy to find. 

Snip...

STACK_PRIORITY_SEARCH

NO_FLOW

STAGE_PRIORITY_FLOW

ALL_VESSEL 

[flowMode] defines how the resource moves throughout your vessel whenever the resource is requested by a particular part. There are 4 known methods of flow mode:

end snip

above is from the wiki and Is all I can find of consequence. Not even sure is it's updated for 1.1.3

you've probably all seen this and know it in detail. Me, not so much. 

Edited July 19, 2016 by Wallygator

[Archgeek]

41 minutes ago, Wallygator said:

Snip...

STACK_PRIORITY_SEARCH

NO_FLOW

STAGE_PRIORITY_FLOW

ALL_VESSEL 

[flowMode] defines how the resource moves throughout your vessel whenever the resource is requested by a particular part. There are 4 known methods of flow mode:

end snip

above is from the wiki and Is all I can find of consequence. Not even sure is it's updated for 1.1.3

you've probably all seen this and know it in detail. Me, not so much. 

Sounds about right.  STACK_PRIORITY_SEARCH is standard rocket flow, NO_FLOW is obvious, STAGE_PRIORITY_FLOW is for mono and xenon, and ALL_VESSEL is how mono and xenon used to work.  I forget what jet fuel does these days, but I'm more interested in the intended behaviour of STAGE_PRIORITY_FLOW and whether or not the displayed behaviour is correct.

[sebi.zzr]

Jet engines use "STAGE_STACK_FLOW_BALANCE" .The fuel is drained from drop tanks first and then equal from staked tanks.
and some explanation about resource flow

 

[sal_vager]

Stage priority doesn't use your stage list so modifying your staging won't affect it.

Instead it checks to see which monoprop or xenon tanks are furthest from the root based on the 'stages' it is physically broken up into by decouplers.

So mono tanks that are N away drain first, then N -1, etc

[Archgeek]

2 hours ago, sal_vager said:

Stage priority doesn't use your stage list so modifying your staging won't affect it.

Instead it checks to see which monoprop or xenon tanks are furthest from the root based on the 'stages' it is physically broken up into by decouplers.

So mono tanks that are N away drain first, then N -1, etc

Drat, so observed behaviour is in fact intended?  'Guess I'll have to redesign.  Thanks for the clarification!

[sal_vager]

Yeah sorry it's not very clear, I wish KSP could show your fuel flow overlayed on your craft.