Developing Brake Temperature and PSI...

[legoboyvdlp]

Hi guys.
Now, you'll be on the ground in tears when I ask this.
But, how do I make a new property?
This is the most basic question, but this is my first serious effort in developing an aircraft.
I'm trying to model brake temperature and tire pressure for the Airbus A330.
Please be patient; it's my first time

[Thorsten]

If it's supposed to be a static property, you just add it to the aircraft-set.xml file

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<controls>
<my-aircraft>
<dummy type="double"> 1.0</dummy>
</my-aircraft>
</controls>

will create /controls/my-aircraft/dummy and initialize it to 1.0.

Otherwise, creating a JSBSim function of a given name will automatically create the property, for instance

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      <switch name="systems/apu/apu/apu-fuel-available">
         <default value="0.0"/>
         <test logic="AND" value="1.0">
            propulsion/tank[14]/contents-lbs GT 0
            systems/apu/apu/fuel-valve-status == 1
         </test>
      </switch>

will create /fdm/jsbsim/systems/apu/apu/apu-fuel-available

and give it a value according to the test.

Finally, doing a Nasal

Code: Select all

setprop("/controls/my-aircraft/dummy", 1.0);

will create and initialize the property to 1.0.

So there's more than one way to skin the cat (there's also autopilot tags, property rules, ...)

Most likely you'll want to write a JSBSim system.

[legoboyvdlp]

Thank you very much!
What I'm looking for is a property which sits at 1.0 until a tire bursts, when it goes to 0.0 and friction is increased on that wheel.
I'll see what I can do. Thank you very much for taking the time to help me out.

[Thorsten]

What I'm looking for is a property which sits at 1.0 until a tire bursts, when it goes to 0.0 and friction is increased on that wheel.

SpaceShuttle/Systems/failures.xml

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<channel name="Gear and tire damage simulation">

   <!-- rolling friction adjustments for blown tires -->

      <switch name="systems/failures/tire-nose-friction">
         <default value="0.02"/>
         <test value="0.1">
            systems/failures/tire-nose-condition == 0.0
         </test>
         <output> gear/unit[0]/rolling_friction_coeff </output>
      </switch>

      <switch name="systems/failures/tire-left-friction">
         <default value="0.02"/>
         <test value="0.1">
            systems/failures/tire-left-condition == 0.0
         </test>
         <output> gear/unit[1]/rolling_friction_coeff </output>
      </switch>

      <switch name="systems/failures/tire-right-friction">
         <default value="0.02"/>
         <test value="0.1">
            systems/failures/tire-right-condition == 0.0
         </test>
         <output> gear/unit[2]/rolling_friction_coeff </output>
      </switch>

   <!-- contact point position adjustment for damaged gear struts and blown tire-->

      <switch name="systems/failures/gearstrut-nose-position">
         <default value="gear/unit[0]/z-position"/>
            <test value="-265">
               systems/failures/tire-nose-condition == 0.0
               systems/failures/gearstrut-nose-condition > 0.0
            </test>
            <test value="-242.0">
               systems/failures/gearstrut-nose-condition == 0.0
            </test>
         <output> gear/unit[0]/z-position </output>
      </switch>

      <switch name="systems/failures/gearstrut-left-position">
         <default value="gear/unit[1]/z-position"/>
            <test value="-309">
               systems/failures/tire-left-condition == 0.0
               systems/failures/gearstrut-left-condition > 0.0
            </test>
            <test value="-250">
               systems/failures/gearstrut-left-condition == 0.0
            </test>   
         <output> gear/unit[1]/z-position </output>
      </switch>

      <switch name="systems/failures/gearstrut-right-position">
         <default value="gear/unit[2]/z-position"/>
            <test value="-309">
               systems/failures/tire-right-condition == 0.0
               systems/failures/gearstrut-right-condition > 0.0
            </test>
            <test value="-250">
               systems/failures/gearstrut-right-condition == 0.0
            </test>
         <output> gear/unit[2]/z-position </output>
      </switch>      
   
   <!-- friction adjustment for damaged gear struts -->

      <switch name="systems/failures/gearstrut-nose-friction">
         <default value="gear/unit[0]/rolling_friction_coeff"/>
         <test value="0.4">
            systems/failures/gearstrut-nose-condition == 0.0
         </test>
         <output> gear/unit[0]/rolling_friction_coeff </output>
      </switch>

      <switch name="systems/failures/gearstrut-left-friction">
         <default value="gear/unit[1]/rolling_friction_coeff"/>
         <test value="0.4">
            systems/failures/gearstrut-left-condition == 0.0
         </test>
         <output> gear/unit[1]/rolling_friction_coeff </output>
      </switch>

      <switch name="systems/failures/gearstrut-right-friction">
         <default value="gear/unit[2]/rolling_friction_coeff"/>
         <test value="0.4">
            systems/failures/gearstrut-right-condition == 0.0
         </test>
         <output> gear/unit[2]/rolling_friction_coeff </output>
      </switch>

   </channel>


All /fdm/jsbsim/systems/failures/<subsystem>-condition properties are created at startup in SpaceShuttle-set.xml and flicked from the Nasal limit monitoring routine (or from the instructor station).

[legoboyvdlp]

I see. Thanks again.
I'll see what I can do with your code.
Shouldn't be that hard

[legoboyvdlp]

For your information, I have completed my system, and now can burst a tire and repair at will
Just need to increase the friction, test, and I'm done.

But I got this....

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aircraft:3:..\..\..\flightgear\src\Model\modelmgr.cxx:70:Adding model [unnamed]

What's that supposed to mean?

[wkitty42]

i see quite many of this in 3.7 while testing... my WAG is that there are models defined in XML that do not have a "<name>blah</name>" or "<model-name>blah</model-name>" property... it is a WAG, though, as i don't know if such a property even exists for models...

[Johan G]

Is it not usually a file name though, like <something>.ac (or possibly <something>.xml)?

[wkitty42]

no, i don't think so... not a/the filename but the model(s) defined inside the XML file(s)... remember that there can easily be more than one model of something inside a XML file... again, though, it is just a WAG... maybe slightly educated but a WAG instead of an eWAG