c172x doesn't have throttle channel, but it works when throttle command is set to different values. Why?

[xiaominy]

Where is the throttle channel for c172x? The throttle channel is not found in the aircraft/c172x.xml file. Does it mean that the throttle control command does not work on c172x?

However, I set the throttle command to different values, the plane fly different trajectories. Why?

[seanmcleod]

Does seem a bit inconsistent, but there appear to be a bunch of pre-defined channels.

jsbsim/src/models/FGFCS.h

Lines 557 to 564 in 36dda4f

	std::vector <double> ThrottleCmd;
	std::vector <double> ThrottlePos;
	std::vector <double> MixtureCmd;
	std::vector <double> MixturePos;
	std::vector <double> PropAdvanceCmd;
	std::vector <double> PropAdvance;
	std::vector <bool> PropFeatherCmd;
	std::vector <bool> PropFeather;

[bcoconni]

AFAICS JSBSim copies the throttle position to the throttle command by default so a throttle channel is not needed.

jsbsim/src/models/FGFCS.cpp

Lines 161 to 166 in 36dda4f

	RunPreFunctions();
	for (i=0; i<ThrottlePos.size(); i++) ThrottlePos[i] = ThrottleCmd[i];
	for (i=0; i<MixturePos.size(); i++) MixturePos[i] = MixtureCmd[i];
	for (i=0; i<PropAdvance.size(); i++) PropAdvance[i] = PropAdvanceCmd[i];
	for (i=0; i<PropFeather.size(); i++) PropFeather[i] = PropFeatherCmd[i];