sim/flightmodel/weight/fuel datarefs

[Rodeo]

For example, loading the CL650 in non-persistent mode and looking at sim/flightmodel/weight/m_fuel_total

First, the dataref's value is constant, no changes whatsoever.

I request an AC GPU via the menu, start the battery, enable the GPU, enable hydraulic 3A pump. Dataref stays still.

Then I bring up the non-persistent mode's "fuel truck" via the menu, and the internal refueling panel. No change to the dataref either.

Then I turn the refuel panel on, open the main tank valves, and click start on the fuel truck panel to start pumping -- obviously, at that point, the dataref goes up, as would be expected.

I wait a while, eventually click Finish to stop pumping, close the main tank valves, turn off the refueling panel.

The dataref stops going up, but keeps changing by microscopic amounts every few seconds or so. Keeping in mind the APU is not running, and as far as I know all fuel tank door/caps/whatever are closed, there are no leaks triggered (also, the fuel amount if not going down per se, it's going down, then up, then down and so on).

I don't quite understand what's happening here? Fuel sensor imprecision should not affect this dataref (which represents the actual quantity, not the sensed quantity), and while fuel volume is affected by density which is affected by the atmosphere, shouldn't the fuel mass stay constant?

Am I incorrect about the latter, or is the mass constant but the weight varies due to small changes in Earth's gravity? Or is there another effect affecting the fuel mass that I don't know about?

Regards,

Tim

[skiselkov]

This is just rounding noise from the aux system. During refueling, the forward and aft aux tanks get filled first due to refueling ejectors picking up fuel from the center aux. Then when you remove refueling pressure, the fuel sloshes back to the center aux under gravity. This can manifest as summing noise on the total fuel value in here.

Basically, don't worry about it.

[Rodeo]

Thanks!

Regards,

Tim