Hello,
i am currently trying to modell the fuel system for the c182s but have the problem that the system uses much more fuel than the engine "sucks".
It matches closely the value specified in the external-flow-pps statements.
the model is basicly this:
tank0--+-->fuelSelectorSump->FuelStrainerSump->Pipe ...[2-pumps]...> manifoldTank ...feed...> engine
tank1--+
The flow rates are defined as "5" and fuel flows in the correct order. It stops to flow when target tanks are full and start when they are not full. Fuel selector also works as expected.
What is noticeable is the difference in flow rates when the aux pump is engaged: this fills the manifold at the expected rate and stops when its full. However, for each 0.01 unit it rises, it seems that the chain to the both wing tanks result in a much bigger value sucked out.
This is also true if the engine is running normal.
My assumtion was that i can use arbitary flow rates because jsbsim itself calculates how much fuel needs to be drawn for how long at that rate to transfer the fuel and the switches take care to stop at the right moment. As the tanks are connected via switches and summers, i assumed that this works out.
Currently i am out of ideas, my guess would be that there is a timing problem and the summers and switches need to be synchronized in some way or the other?
The code full code can be viewed here:
- github repo branch: https://github.com/HHS81/c182s/tree/int ... elSelector
- fuel.xml: https://github.com/HHS81/c182s/blob/int ... s/fuel.xml
To reproduce: checkout the aircraft and on the ground open the standard fuel dialog of fgfs ("Fuel and payload settings"). Activate the aux pump (lower left cockpit, near the red battery switches) and observe the filling of the manifold "tank".
Then pull the slider to 0 (empty tank) and repeat, while observing the amount of manifold fill versus the amount reduced in the tanks:
for each 0.05 pounds in manifold fill 12.6 pounds in the wing tanks are removed from EACH tank!
What am i doing wrong here?