The JSBSim Tutorial series (notably Bill Galbraith’s JSBSim Script Tutorials) is widely considered the "gold standard" for anyone transitioning from flying flight simulators to actually building them.
“How’d you learn it so fast?”
In this tutorial, you've learned the basics of JSBSim and how to create a simple simulation. You've also been introduced to some advanced topics. With this foundation, you can explore the many features and capabilities of JSBSim. jsbsim tutorial
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. JSBSimReferenceManual
JSBSim --script=scripts/c172_trivial.xml --aircraft=c172_tutorial
This is the heart. Aerodynamics are defined using function blocks. when you run the simulation
JSBSimReferenceManual.xml: Located in the aircraft folder. This is not a text document; it is a fully commented XML file showing every possible tag and property in the system.position/h-sl-ft, velocities/u-fps).