x8.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="http://jsbsim.sourceforge.net/JSBSim.xsl"?>
<fdm_config name="Skywalker x8" version="2.0" release="ALPHA"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:noNamespaceSchemaLocation="http://jsbsim.sourceforge.net/JSBSim.xsd">
    <fileheader>
        <author>Alexander Quessy</author>
        <license
            licenseName="GPL (General Public License)"
            licenseURL="http://www.gnu.org/licenses/gpl.html"/>
        <note>
            This model was created using publicly available data, publicly available
            technical reports, textbooks, and guesses. It contains no proprietary or
            restricted data. It has been validated only to the extent that it seems
            to "fly right", and possibly to comply to published, publicly known,
            performance data (maximum speed, endurance, etc.). Thus, this model
            is meant for educational and entertainment purposes only.

            This simulation model is not endorsed by the manufacturer. This model
            is not to be sold.
        </note>
        <filecreationdate>2020-10-28</filecreationdate>
        <version>$Revision: 0.1 $</version>
        <description>Flight Dynamic Model of a Skywalker x8 UAV</description>
        <reference
            refID= "1"
            author= "Kristofer Gryte"
            title= "Aerodynamic modeling of the Skywalker X8 Fixed-Wing Unmanned Aerial Vehicle"
            date= "2019"/>
    </fileheader>
    <metrics>
        <wingarea unit="M2"> 0.75 </wingarea>
        <wingspan unit="M"> 2.10 </wingspan> <!-- Used b here guesing this is full span as 0.75*2.10 = 0.357 -->
        <chord unit="M"> 0.3571 </chord>
        <location name="AERORP" unit="M">
            <x> 0.0 </x>
            <y> 0.0 </y>
            <z> 0.0 </z>
        </location>
        <location name="EYEPOINT" unit="M">
            <x> 0.2 </x>
            <y> 0.0 </y>
            <z> 0.0 </z>
        </location>
        <location mame="VRP" unit="M">
            <x> 0.2 </x>
            <y> 0.0 </y>
            <z> 0.0 </z>
        </location>
    </metrics>
    <mass_balance>
        <ixx unit="KG*M2"> 1.2290 </ixx>
        <iyy unit="KG*M2"> 0.1702 </iyy>
        <izz unit="KG*M2"> 0.8808 </izz>
        <ixz unit="KG*M2"> 0.9343 </ixz>
        <emptywt unit="KG"> 3.3640 </emptywt>
        <location name ="CG" unit="M">
            <x> 0.0 </x>
            <y> 0.0 </y>
            <z> 0.0 </z>
        </location>
    </mass_balance>

    <ground_reactions>
      <!-- <contact type="STRUCTURE" name="Belly">
        <location unit="IN">
         <x> 0.0 </x>
         <y> 0.0 </y>
         <z> 0.0 </z>
        </location>
        <static_friction>  1.00 </static_friction>
        <dynamic_friction> 1.00 </dynamic_friction>
        <spring_coeff unit="LBS/FT">      10.00 </spring_coeff>
        <damping_coeff unit="LBS/FT/SEC"> 10.00 </damping_coeff>
      </contact> -->
    </ground_reactions>

    <propulsion>
        <engine file="electric800W.xml">
            <location unit="M">
                <x>0.0</x>
                <y>0.0</y>
                <z>0.0</z>
            </location>
            <orient unit="DEG">
                <roll>0.0</roll>
                <pitch>0.0</pitch>
                <yaw>0.0</yaw>
            </orient>
            <feed> 0.0 </feed>

            <thruster file="direct">
                <sense> 1 </sense>
                <location unit="M">
                    <x>0.0</x>
                    <y>0.0</y>
                    <z>0.0</z>
                </location>
                <orient unit="DEG">
                    <roll>0.0</roll>
                    <pitch>0.0</pitch>
                    <yaw>0.0</yaw>
                </orient>
            </thruster>
        </engine>
    </propulsion>

    <system name="Navigation">
      <channel name="Heading">
        <sensor name="navigation/actual-heading-rad">
          <input> attitude/heading-true-rad </input>
            <!-- <lag> 2500 </lag> -->
            <!-- <noise variation="PERCENT"> .02 </noise> -->
          <bias> 0.003 </bias>
        </sensor>
      </channel>
    </system>

    <flight_control name="x8">

        <channel name="Pitch">

            <summer name="fcs/pitch-sum">
                <description>Just clips the elevator cmd signal (-1/+1), the x8 has no trim tab</description>
                <input>fcs/elevator-cmd-norm</input>
                <clipto>
                    <min>-1</min>
                    <max>1</max>
                </clipto>
            </summer>

            <!-- Gain set to convert control deflection to radians -->
            <aerosurface_scale name="fcs/elevator-control">
                <description>Mapping to the maximum elevator deflection</description>
                <input>fcs/pitch-sum</input>
                <range>
                    <min>-30</min>
                    <max>+30</max>
                </range>
                <gain>0.01745</gain>
            </aerosurface_scale>

            <actuator name="fcs/elevator-actuator">
                <description>Converting the actuator command to a control surface movement</description>
                <input>fcs/elevator-control</input>
                <!-- <lag>60</lag>
                <bias>0.002</bias> -->
                <clipto>
                    <!-- +/- 30 degs -->
                    <min>-0.52</min>
                    <max>0.52</max>
                </clipto>
                <output>fcs/elevator-pos-rad</output>
            </actuator>

        </channel>

        <channel name="Roll">

            <summer name="fcs/roll-sum">
                <description>Just clips the aileron cmd signal (-1/+1), the x8 has no trim tab</description>
                <input>fcs/aileron-cmd-norm</input>
                <clipto>
                    <min>-1</min>
                    <max>1</max>
                </clipto>
            </summer>

            <aerosurface_scale name="fcs/left-aileron-control">
                <description>The port aileron output is in radians</description>
                <input>fcs/roll-sum</input>
                <gain>0.01745</gain>
                <range>
                    <min>-30</min>
                    <max>30</max>
                </range>
            </aerosurface_scale>

            <actuator name="fcs/left-aileron-actuator">
                <description>Port aileron actuator, max +/- 30 degrees, just pass through for now</description>
                <input>fcs/left-aileron-control</input>
                <output>fcs/left-aileron-pos-rad</output>
            </actuator>

<!--            <actuator name="fcs/left-aileron-actuator">-->
<!--                <description>Port aileron actuator, max +/- 30 degrees</description>-->
<!--                <input>fcs/left-aileron-control</input>-->
<!--                <rate_limit>1.57</rate_limit>-->
<!--                <hysterisis>0.005</hysterisis>-->
<!--                <clipto>-->
<!--                    <min>-0.52</min>-->
<!--                    <max>+0.52</max>-->
<!--                </clipto>-->
<!--                <output>fcs/left-aileron-pos-rad</output>-->
<!--            </actuator>-->

            <aerosurface_scale name="fcs/right-aileron-control">
                <description>The Starboard aileron output is in radians</description>
                <input>fcs/roll-sum</input>
                <gain>0.01745</gain>
                <range>
                    <min>-30</min>
                    <max>30</max>
                </range>
            </aerosurface_scale>

            <actuator name="fcs/right-aileron-actuator">
                <description>Starboard aileron actuator, max +/- 30 degrees, just pass through for now</description>
                <input>fcs/right-aileron-control</input>
                <output>fcs/right-aileron-pos-rad</output>
            </actuator>

<!--            <actuator name="fcs/right-aileron-actuator">-->
<!--                <description>Starboard aileron actuator, max +/- 30 degrees</description>-->
<!--                <input>fcs/right-aileron-control</input>-->
<!--                <rate_limit>1.57</rate_limit>-->
<!--                <hysterisis>0.005</hysterisis>-->
<!--                <clipto>-->
<!--                    <min>-0.52</min>-->
<!--                    <max>+0.52</max>-->
<!--                </clipto>-->
<!--                <output>fcs/right-aileron-pos-rad</output>-->
<!--            </actuator>-->

            <summer name="fcs/effective-aileron-pos">
                <description>Combine and invert deflection based on the expected roll condition</description>
                <input>fcs/left-aileron-pos-rad</input>
                <input>fcs/right-aileron-pos-rad</input>
                <gain>0.5</gain>
            </summer>

        </channel>

    </flight_control>


    <aerodynamics>

        <axis name="LIFT">

            <function name="aero/coefficient/CLo">
                <description>Alpha independent lift coefficient</description>
                <product>
                    <property>aero/qbar-area</property>
                    <value>0.0867</value>
                </product>
            </function>

            <function name="aero/coefficient/CLalpha">
                <description>Lift per radian of alpha</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/alpha-rad</property>
                    <value> 4.0203 </value>
                </product>
            </function>

            <function name="aero/coefficient/CLq">
                <description>Lift due to pitch rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>velocities/q-aero-rad_sec</property>
                    <property>aero/ci2vel</property>
                    <value>3.87</value>
                </product>
            </function>

            <function name="aero/coefficient/CLDe">
                <description>Lift due to elevator deflection</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>fcs/elevator-pos-rad</property>
                    <value>0.2781</value>
                </product>
            </function>

        </axis>

        <axis name="DRAG">

            <function name="aero/coefficient/CDo">
                <description>Drag at zero alpha</description>
                <product>
                    <property>aero/qbar-area</property>
                    <value>0.0197</value>
                </product>
            </function>

            <function name="aero/coefficient/CDalpha">
                <description>Drag due to alpha</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/alpha-rad</property>
                    <value>0.0791</value>
                </product>
            </function>

            <!-- This alpha squared could be problematic -->
            <function name="aero/coefficient/CDalpha2">
                <description>Drag due to alpha squared</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/alpha-rad</property>
                    <property>aero/alpha-rad</property>
                    <value>1.0555</value>
                </product>
            </function>

            <function name="aero/coefficient/CDbeta">
                <description>Drag due to sideslip</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/mag-beta-rad</property>
                    <value>-0.0058</value>
                </product>
            </function>

            <function name="aero/coefficient/CDbeta2">
                <description>Drag due to sideslip squared</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/mag-beta-rad</property>
                    <property>aero/mag-beta-rad</property>
                    <value>0.1478</value>
                </product>
            </function>

            <function name="aero/coefficient/CDq">
                <description>Drag due to pitch rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>velocities/q-aero-rad_sec</property>
                    <property>aero/ci2vel</property>
                    <value>0.0</value>
                </product>
            </function>

            <function name="aero/coefficient/CDe">
                <description>Drag due to elevator</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>fcs/mag-elevator-pos-rad</property>
                    <value>0.0633</value> <!-- x8 model uses elevator def squared here but not sure why -->
                </product>
            </function>

        </axis>

        <axis name="SIDE">

            <function name="aero/coefficient/CYb">
                <description>Sideforce due to sideslip</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/beta-rad</property>
                    <value>-0.2239</value>
                </product>
            </function>

            <function name="aero/coefficient/CYp">
                <description>Sideforce due to roll rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/bi2vel</property>
                    <property>velocities/p-aero-rad_sec</property>
                    <value>-0.1374</value>
                </product>
            </function>

            <function name="aero/coefficient/CYr">
                <description>Sideforce due to yaw rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>aero/bi2vel</property>
                    <property>velocities/r-aero-rad_sec</property>
                    <value>0.0839</value>
                </product>
            </function>

            <function name="aero/coefficient/CYda">
                <description>Sideforce due to aileron</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>fcs/effective-aileron-pos</property>
                    <value>0.0433</value>
                </product>
            </function>

        </axis>

        <axis name="ROLL">

            <function name="aero/coefficient/Clb">
                <description>Roll moment due to beta</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>aero/beta-rad</property>
                    <value>-0.0849</value>
                </product>
            </function>

            <function name="aero/coefficient/Clp">
                <description>Roll moment due to roll rate (roll damping)</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>aero/bi2vel</property>
                    <property>velocities/p-aero-rad_sec</property>
                    <value>-0.4042</value>
                </product>
            </function>

            <function name="aero/coefficient/Clr">
                <description>Roll moment due to yaw rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>aero/bi2vel</property>
                    <property>velocities/r-aero-rad_sec</property>
                    <value>0.0555</value>
                </product>
            </function>

            <function name="aero/coefficient/Clda">
                <description>Roll moment due to aileron</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>fcs/effective-aileron-pos</property>
                    <value>0.1202</value>
                </product>
            </function>

        </axis>

        <axis name="PITCH">

            <function name="aero/coefficient/Cmo">
                <description>Pitch moment at zero alpha</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/cbarw-ft</property>
                    <value>0.0227</value>
                </product>
            </function>

            <function name="aero/coefficient/Cmalpha">
                <description>Pitch moment due to alpha</description>\
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/cbarw-ft</property>
                    <property>aero/alpha-rad</property>
                    <value>-0.4629</value>
                </product>
            </function>

            <function name="aero/coefficient/Cmq">
                <description>Pitch moment due to pitch rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/cbarw-ft</property>
                    <property>aero/ci2vel</property>
                    <property>velocities/q-aero-rad_sec</property>
                    <value>-1.3012</value>
                </product>
            </function>

            <function name="aero/coefficient/CmDe">
                <description>Pitch moment due to elevator deflection</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/cbarw-ft</property>
                    <property>fcs/elevator-pos-rad</property>
                    <value>-0.2292</value>
                </product>
            </function>

        </axis>

        <axis name="YAW">

            <function name="aero/coefficient/Cnb">
                <description>Yaw moment due to beta</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>aero/beta-rad</property>
                    <value>0.0283</value>
                </product>
            </function>

            <function name="aero/coefficient/Cnp">
                <description>Yaw moment due to roll rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>aero/bi2vel</property>
                    <property>velocities/p-aero-rad_sec</property>
                    <value>0.0044</value>
                </product>
            </function>

            <function name="aero/coefficient/Cnr">
                <description>Yaw moment due to yaw rate</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>aero/bi2vel</property>
                    <property>velocities/r-aero-rad_sec</property>
                    <value>-0.072</value>
                </product>
            </function>

            <function name="aero/coefficient/Cnda">
                <description>Yaw moment due to aileron</description>
                <product>
                    <property>aero/qbar-area</property>
                    <property>metrics/bw-ft</property>
                    <property>fcs/effective-aileron-pos</property>
                    <value>0.1202</value>
                </product>
            </function>

        </axis>

    </aerodynamics>

    <output name="JSBoutX8.csv" type="CSV" rate="10">
        <rates> ON             </rates>
        <velocities> ON        </velocities>
        <position> ON          </position>
        <atmosphere> OFF       </atmosphere>
        <fcs> ON               </fcs>
        <ground_reactions> OFF </ground_reactions>
        <propulsion> ON       </propulsion>
        <simulation> ON        </simulation>
        <massprops> ON        </massprops>
        <forces> OFF           </forces>
        <moments> OFF          </moments>
        <aerosurfaces> OFF      </aerosurfaces>
    </output>
</fdm_config>