We demonstrate an application of the ontology driven methodology to develop trajectory simulations in a function-oriented style. We adopt a model based approach to software development, guided by the domain engineering process, to promote knowledge and software reuse. MATLAB Simulink® block definitions have been generated from the function specifications in the Trajectory Simulation Ontology, called TSONT. MATLAB implementations of the blocks have been generated from the DAVE-ML definitions of the functions, which are incorporated in TSONT. Finally, the simulation has been put together by manually connecting the blocks. © 2007 ECMS.