I’m using px4 SITL and HITL with iris model. I’d like to integrate my copter and other sensors to perform simulation in gazebo.

I wonder if someone can give me some details on the mathematical model implemented in SITL. I think the dynamic behaviour of the copter is based on the equations for forces and moments of the rigid body. I wonder how the propulsion system is modeld, as well as all the other sensors provided in the simulation (i.e. IMU, GPS etc.). How about the aerodynamic forces for the fixed wing simulation? Are they based on real aerdodynamic coefficients?

Moreover, I’ve noted that when I’m testing SITL or HITL the battery level goes down to 51% but then it doesn’t change even if I run the simulation for a long time. How is implemented the battery behaviour?