To strengthen the competitiveness of the European aero-engine industry, with due concern for environment and safety, gas turbine engines must provide better performance at reduced weight. For the compressor, the objectives are a higher-pressure ratio realised with fewer blade rows, implying higher aerodynamics loading. In parallel, development and time-to-market costs must be reduced through improved engineering methods. This project exploits advanced 3D steady and unsteady viscous methods for multi-stage compressor design. Building on the partners' collective experience, these tools will be used to maximise performance improvement by control of internal flow structures; particularly tip and end wall regions and blade row interactions. The design-by-computation approach will be supported by an experimental programme, giving systematic verification of design rules and analytical accuracy for each element of the design process.