• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

P3D v4 Fuel imbalance; Starboard tank fuel not being used in-flight

M

MarkEd

Messages
16
Country
us-washington
I have a freeware aircraft, (admittedly FSX) but works very well in P3d v4, everything works brilliantly except for 1 kinda-big problem... when flying, fuel is used/is being drawn from 2 tanks only instead of 3, and the result is that after a while, one side of the aircraft lists. Obviously the range also is severely effected, and also when the center tank hits 0 fuel the engines flame out -- even through there is still fuel in left tank (because the center tank drains fastest) and the fuel in the right tank remains at 100% full always.

In the 2D panel, the aircraft does have a popup window with the old FSX CRJ fuel panel, and in the VC one can see the same fuel panel in the center console, but in both cases, the Fuel Xflow button on that Fuel panel gauge has absolutely has no effect on the problem described.

Here's the scenario:
2 jet engines, 3 fuel tanks specified in the aircraft .cfg, (left, center, right -- see snip below) If I manually change number_of_tank_selectors= to 1 then fuel flows from the center tank only.. If number_of_tank_selectors= 2 then the port and center tanks are used. The Starboard tank never gets used.

I've tried a couple of things:
1) Removed the center tank from the aircraft.cfg (thinking that the aircraft was set up for only 2 tanks) .... the aircraft engines simply do not run at all
2) Fiddled with the number_of_tank_selectors= If set to =2, fuel flows from the center and port side tanks only. Setting this to =1 get gets fuel flowing from the center tank only; In desperation I tried setting it to 3 :) .. no effect. Perplexing thing is that you'd then expect that the port side would therefore get lighter over time as the fuel draws down on that side, but, after landing with a clear left-right fuel tank fill imbalance (with the starboard tank still at 100% full) the aircraft lists to port! -- I'd expect that with the Starboard side tanks being "full/unused" that the the aircraft would be heaver on that side causing a list to starboard, but it seems to be the opposite case!

Here's the aircraft.cfg Fuel section.
[fuel]
Center1= 0.0, 0.0, -1.5, 824.52, 0.0
LeftMain= 0.0, 6.5, -0.8, 424.68, 0.0
RightMain= 0.0,-6.5, -0.8, 424.68, 0.0
fuel_type=2
number_of_tank_selectors=2 //setting this to 1 get fuel from the center tank flowing only; setting to 2 causes fuel to flow from left/port and center only. In desperation it tried setting it to 3 :) .. no effect.
electric_pump=2 //setting this to 1 or 2 makes no difference

Also, while searching for answers, I saw this cfg Fuel section in another thread, and while I did not think it was a solution for my problem, just for kicks, I pasted it into my aircraft.cfg Fuel section to see what would happen ... Interestingly, these Fuel section settings caused fuel to flow from the right/starboard and center tank, and now the Port side remains as-is never used, full! The behavior with this fuel section was opposite to the original Fuel Section provided above! ... I provide this observation so maybe this can be more information that someone way smarter than me will use as and additional clue to help figure out what's happening.
[fuel]
number_of_tank_selectors = 2 // MUST BE 2
Center1= 0.0, 0.0, -1.5, 824.52, 0.0 //this sample did not have a center section, and my aircraft would not run at all, so I added it and then see the behavior (of right an center tanks used only) described above.
LeftTip = -7.50, -3.3, -0.45, 27, 3 // REPRESENTS LEFT TIP TANK
LeftAux = -7.92, -10.0, -0.45, 15, 0 // REPRESENTS LEFT WING TANK
LeftMain = -7.54, -18.0, 0.10, 15, 0 // REPRESENTS LEFT CORE TANK
RightTip = -7.50, 3.3, -0.45, 27, 3 // REPRESENTS RIGHT TIP TANK
RightAux = -7.92, 10.0, -0.45, 15, 0 // REPRESENTS RIGHT WING TANK
RightMain = -7.54, 18.0, 0.10, 15, 0 // REPRESENTS RIGHT CORE TANK
electric_pump=2 // OPTIONAL AS NEEDED


How do I fix this fuel flow imbalance problem please?
Happy to answer any questions you may have or install gauges or run tests if that helps.
Thanks!
 
hi... so I found where the problem was.

Given how correct the aircraft cfg Fuel entries seemed to be when I compared them to other aircraft (and I even pasted the Fuel sample into other aircraft cfg files where I know there was no fuel problem, and the sample did not cause any problems there, I came to the conclusion that it was probably some possible gauge incompatibility in the panel or some sort of "localized" model problem scoped to just this aircraft.

So I went with the easier panel-testing option first. I began by creating a new, blank 2d panel file that had no windows, no vc settings, just a simple background image, with no gauges except for a couple of fuel flow, pressure quantity gauges, and fuel selector...which all worked perfectly. So I then knew that there was some other gauge contained in the original panel that was probably mucking things up. I then started adding the other gauges into my new panel from the ones that existed in the original panel in blocks of 3-4 at a time, while refreshing the aircraft in P3d after each block was added, to check to see at what point the fuel flow problem restarted.

Cut a long story short, buried in the list of gauges for the aircraft's panel was a custom fuel update xml gauge, probably placed there by some panel designer over the ages as the aircraft was posted and shared, which, when I removed it from the panel, solved the problem. My fuel flow and selectors now all work perfectly, and all the imbalance problems I mentioned above are gone.

For those interested in the fuel gauges I used to identify the flow problem, there is a great little gauge set called hjajet which contains a lot of great little gauges. Be warned...some of them admittedly have really "brightly" colored (no kidding, pinks, and greens and canary yellow) gauge UI, but they function really well... And if you can get past the exuberant and gaudiness colors (or change the colors in their source files/images to your liking) it contains a number of fuel flow and selector gauges that I have added to some of my other aircraft . BTW the "incompatible" /custom flow update gauge did not come from this collection. PS: I have no affiliation with it, or know who the brilliant authors of that public domain gauge-set are, but if you want it, its contained in an F14D tomcat model that can be found on Simviation... search for its zip file: fsxf14d3.
Cheers.
Mark
 
Last edited:
You must log in or register to reply here.
Back
Top