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Re: Help with fuel system using too much fuel

Postby Bomber » Sun Sep 10, 2017 7:50 pm

http://wiki.flightgear.org/Howto:Write_ ... _in_JSBSim

Check out the spitfires fuel system.... it might help you.
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
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Re: Help with fuel system using too much fuel  

Postby benih » Mon Sep 11, 2017 6:31 pm

Thank you very much all,
i synchronized the fuel flows now and all seems to be ok.

I still assume little too much fuel consumption, but the numbers look promising.
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Re: Help with fuel system using too much fuel

Postby Thorsten » Tue Sep 12, 2017 6:14 am

Very good. :D
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Re: Help with fuel system using too much fuel

Postby benih » Wed Sep 13, 2017 8:09 pm

I did catch another one, now the numbers add up perfectly.

Another problem was, that i included the engine fuel consumption rate in the summer because i thought that this would be neccessary.
In fact it is obsolete, because the <feed> command already lets the last tank drain by the required ammount.
With the wrong <input> active, the tanks emptied wrongly at the rate 2x.

Code: Select all
<summer name="fuel/manifold-total-flow-pps">
            <input>fuel/pump-flow-rate-pps</input>
            <input>-/systems/fuel/tank[5]/leak-flow-rate-pps</input>
            <input>-fuel/manifold-dissipate-rate-pps</input>
            <!--    <input>-/fdm/jsbsim/propulsion/engine/fuel-flow-rate-pps</input>   NOT NECESSARY: engine sucks already (see feed command) -->
            <output>/fdm/jsbsim/propulsion/tank[5]/external-flow-rate-pps</output>
</summer>


Thanks for your help! You are a very great community!
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Re: Help with fuel system using too much fuel

Postby MariuszXC » Mon Nov 28, 2022 2:54 pm

I will ask a very basic question (but pertinent to this thread).
What kind of unit is 'pps'?
This is not explained in the Wiki: https://wiki.flightgear.org/Howto:Write ... _in_JSBSim
And also JSBSim Manual (Section 1, chapter 2.3 - Units) does not define this unit.

Probably for someone used to English system it is obvious, but for someone used to Metric system it can be anything, even particles-per-second (ok, joking here a bit).
From the context of this thread I guess it is pounds-per-second, but I'd like a confirmation, before I add this definition to the Wiki.
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Re: Help with fuel system using too much fuel

Postby S&J » Mon Nov 28, 2022 3:42 pm

Pounds (of fuel) per second
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Re: Help with fuel system using too much fuel

Postby MariuszXC » Mon Nov 28, 2022 4:10 pm

Thanks for confirming. Wiki amended.
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Re: Help with fuel system using too much fuel

Postby benih » Tue Nov 29, 2022 8:03 pm

Oh dear, i think you revived one of my first posts here :)
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Re: Help with fuel system using too much fuel

Postby MariuszXC » Tue Nov 29, 2022 8:52 pm

Yes, I noticed it was not exactly new :)
But I did not want to start a new thread for a simple question, and it seemed a good place with a related content.
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