Jsbsim Tutorial May 2026

The root of your aircraft is an XML file. Open my_plane.xml in a text editor. It contains five critical sections:

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="http://jsbsim.sf.net/JSBSim.xsl"?>
<fdm_config name="Cessna 172P Tutorial" version="2.0" release="experimental">
<metrics>
<wingarea unit="FT2"> 174.0 </wingarea>
<wingspan unit="FT"> 35.8 </wingspan>
<chord unit="FT"> 4.9 </chord>
</metrics>
<mass_balance>
<emptywt unit="LBS"> 1663.0 </emptywt>
<location name="CG" unit="IN">
<x> 2.5 </x>  <!-- Forward of the aerodynamic center -->
<y> 0.0 </y>
<z> 0.0 </z>
</location>
<ixx unit="SLUGFT2"> 948 </ixx>
<iyy unit="SLUGFT2"> 1346 </iyy>
<izz unit="SLUG*FT2"> 1967 </izz>
</mass_balance>

Launch the shell:

JSBSim --interactive --aircraft=c172_tutorial

Inside the shell:

> set loglevel 3
> run 100
> get aero/qbar-psf
> get forces/fbz-lbs
> property-list aero/

The property-list command is a lifesaver. It shows every available property under that branch.

JSBSim’s native scripting language is powerful for automation. Create a file called climb_test.xml in the scripts/ folder.

<?xml version="1.0"?>
<runscript>
  <use aircraft="c172_tutorial" initialize="reset"/>
<run start="0.0" end="100.0" dt="0.01">
<!-- Set initial conditions -->
<property value="1000">ic/h-agl-ft</property>
<property value="100">ic/vc-kts</property>
<!-- Execute the simulation -->
<event name="Start_Climb" time="10.0">
  <set name="fcs/elevator-cmd-norm" value="0.1"/>
</event>
<event name="Level_Off" time="50.0">
  <set name="fcs/elevator-cmd-norm" value="0.0"/>
</event>
<!-- Output to CSV for analysis -->
<output type="CSV" filename="climb_test_output.csv">
  <property>sim-time-sec</property>
  <property>position/h-sl-ft</property>
  <property>attitude/phi-rad</property>
  <property>attitude/theta-rad</property>
  <property>velocities/vc-kts</property>
</output>

</run>
</runscript>

Run this script with:

JSBSim --script=climb_test.xml

Open climb_test_output.csv in Excel or a text editor. You now have a validated flight test dataset generated purely from your XML model.

Information about the plane: name, author, type.

JSBSim exposes a property tree via Socket or HTTP. Enable the socket server in your script:

<output type="SOCKET" port="5123" protocol="TEXT" rate="30">
  <property>position/lat-deg</property>
  <property>position/lon-deg</property>
</output>

Then write a simple Python script to read from localhost:5123 and update a 3D model. jsbsim tutorial

JSBSim has a built-in PID controller system. Let's add a simple altitude hold to your XML.

Inside the <systems> section of your aircraft file, add:

<system name="autopilot">
  <pid name="altitude_hold">
    <input>position/h-sl-ft</input>
    <reference>5000</reference>   <!-- Hold 5000 feet -->
    <kp>0.001</kp>
    <ki>0.0001</ki>
    <kd>0.01</kd>
    <output>fcs/elevator-cmd-norm</output>
    <clipto>
      <min>-1.0</min>
      <max>1.0</max>
    </clipto>
  </pid>
</system>

Now, when you run the simulation, the aircraft will automatically pitch to maintain 5,000 feet. This is the same logic used in real autopilots.

JSBSim is an open-source flight dynamics model (FDM) used for aircraft simulation and flight control development. This brief tutorial shows how to install JSBSim, run a basic simulation, inspect outputs, and create a simple script to trim and trim-run an aircraft.