Interested in flight, aircraft, or physics?

JSBSim is an open source flight dynamics model (FDM) that compiles and runs under many operating systems, including Microsoft Windows, Apple Macintosh, Linux, IRIX, Cygwin (Unix on Windows), etc. The FDM is essentially the physics/math model that defines the movement of an aircraft, rocket, etc., 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 vehicle configuration files. It can also be incorporated into a larger flight simulator implementation that includes a visual system.

http://jsbsim.sourceforge.net/

Robert