An aircraft design and optimisation system is presented which adopts different levels of analysis tools (Low- and High Fidelity) for the aerodynamic, structural, aeroelastic and flight mechanic modelling. The system, called Computational Design Engine (CDE), connects modules supplied by different partners from industry, research establishments and from universities, and is distributed over several hardware platforms. In the first part, Low- and High Fidelity modules are presented and the layout of the CDE is discussed. In the second part details and results of an application of the CDE for the optimisation of a Blended Wing Body freight aircraft are presented.@en