Abstract
This paper presents the newly introduced Virtual Test Aircraft (VIRTTAC) model for use in benchmarks for aeronautics research. This model is shared in a black-box form and the core of an open-source benchmark suite. The model needs to remain undisclosed to fulfill its purpose but the principles underlying its internal structure are described in the paper. They permit to ensure that the model equations, parameters, and states are not accessible to the user, that the model can be easily ported to other simulation environments than MATLAB/Simulink, and that it is well maintainable on the long-term.