There is no throttle control channel in some aircraft congfig.xml (such as f15).

[theorynice]

Excuse me, recently I find that there is no throttle control channel in some aircraft congfig.xml (such as f15), so how the jsbsim control the speed by "fcs/throttle-cmd-norm" ? The flight control system of f15 is as follows:

<flight_control name="FCS: f15">
  </channel>
        <channel name="Pitch">
            <summer name="Pitch Trim Sum">
                <input>fcs/elevator-cmd-norm</input>
                <input>fcs/pitch-trim-cmd-norm</input>
                <clipto>
                    <min>-1</min>
                    <max>1</max>
                </clipto>
            </summer>

             <kinematic name="elevator position">
                <input>fcs/pitch-trim-sum</input>
                <traverse>
                    <setting>
                        <position>-1</position>
                        <time>0.6</time>
                    </setting>
                    <setting>
                        <position>1</position>
                        <time>0.6</time>
                    </setting>
                </traverse>
                <output>fcs/elevator-pos-norm</output>
            </kinematic>

            <aerosurface_scale name="elevator position">
                <input>fcs/elevator-pos-norm</input>
                <gain>0.01745</gain>
                <domain>
                    <min>-1</min>
                    <max>1</max>
                </domain>
                <range>
                    <min>-26</min>
                    <max>15</max>
                </range>
                <output>fcs/elevator-pos-rad</output>
            </aerosurface_scale>
        </channel>
        <channel name="Roll">
            <summer name="Roll Trim Sum">
                <input>fcs/aileron-cmd-norm</input>
                <input>fcs/roll-trim-cmd-norm</input>
                <clipto>
                    <min>-1</min>
                    <max>1</max>
                </clipto>
            </summer>

            <kinematic name="aileron pos norm">
                <input>fcs/roll-trim-sum</input>
                <traverse>
                    <setting>
                        <position>-1</position>
                        <time>0.3</time>
                    </setting>
                    <setting>
                        <position>1</position>
                        <time>0.3</time>
                    </setting>
                </traverse>
                <output>fcs/left-aileron-pos-norm</output>
            </kinematic>

            <aerosurface_scale name="Left Aileron Control">
                <input>fcs/aileron-pos-norm</input>
                <gain>0.01745</gain>
                <range>
                    <min>-20</min>
                    <max>20</max>
                </range>
                <output>fcs/left-aileron-pos-rad</output>
            </aerosurface_scale>

            <aerosurface_scale name="Right Aileron Control">
                <input>fcs/aileron-pos-norm</input>
                <gain>-0.01745</gain>
                <range>
                    <min>-20</min>
                    <max>20</max>
                </range>
                <output>fcs/right-aileron-pos-rad</output>
            </aerosurface_scale>
        </channel>
        <channel name="Yaw">
            <pure_gain name="Yaw Damper Gain">
                <input>velocities/r-rad_sec</input>
                <gain>-0.001745</gain>
            </pure_gain>

            <summer name="Yaw Trim Sum">
                <input>fcs/rudder-cmd-norm</input>
                <input>fcs/yaw-trim-cmd-norm</input>
                <input>fcs/yaw-damper-gain</input>
                <clipto>
                    <min>-1</min>
                    <max>1</max>
                </clipto>
            </summer>

            <kinematic name="rudder position">
                <input>fcs/yaw-trim-sum</input>
                <traverse>
                    <setting>
                        <position>-1</position>
                        <time>0.4</time>
                    </setting>
                    <setting>
                        <position>1</position>
                        <time>0.4</time>
                    </setting>
                </traverse>
                <output>fcs/rudder-pos-norm</output>
            </kinematic>

            <aerosurface_scale name="Rudder Control">
                <input>fcs/rudder-pos-norm</input>
                <gain>0.01745</gain>
                <range>
                    <min>-30</min>
                    <max>30</max>
                </range>
                <output>fcs/rudder-pos-rad</output>
            </aerosurface_scale>
        </channel>
        <channel name="Landing Gear">
            <kinematic name="Gear Control">
                <input>gear/gear-cmd-norm</input>
                <traverse>
                    <setting>
                        <position>0</position>
                        <time>0</time>
                    </setting>
                    <setting>
                        <position>1</position>
                        <time>5</time>
                    </setting>
                </traverse>
                <output>gear/gear-pos-norm</output>
            </kinematic>
        </channel>
        <channel name="Speedbrake">
            <kinematic name="Speedbrake Control">
                <input>fcs/speedbrake-cmd-norm</input>
                <traverse>
                    <setting>
                        <position>0</position>
                        <time>0</time>
                    </setting>
                    <setting>
                        <position>1</position>
                        <time>2</time>
                    </setting>
                </traverse>
                <output>fcs/speedbrake-pos-norm</output>
            </kinematic>
        </channel>
    </flight_control>

[theorynice]

I have found the cause in another https://github.com/JSBSim-Team/jsbsim/discussions/796.
Thanks all