JSBSim is a multi-platform flight dynamics model. The FDM is essentially the physics/math model that defines the movement of an aircraft under the forces and moments applied to it using the various control mechanisms and from the forces of nature. JSBSim has no native graphics. It can be run by itself as a standalone program, taking input from a script file and various aircraft configuration files, or it can be run as an integrated part of a larger flight simulator implementation that includes a visual system. The most notable usage example is the FlightGear simulator. JSBSim models the aerodynamic forces and moments by the classic coefficient buildup method.