Numerical computer-based modelling is used in virtually every field today from experimental biology to materials science and engineering. Models and experiments go hand in hand. Experimental data is used to create models with specific known parameters and behaviours. Model outputs and results under new conditions are used to design new experiments with predicted results to answer still-open questions. In the case of helicopter design tools, leading-edge computational fluid dynamics (CFD) models are available predicting aerodynamic flow around main rotors, isolated fuselages or even entire helicopters. However, industry lacks experimental data to validate airflow over entire helicopters, a technically challenging task requiring a large experimental test-bed. European researchers initiated the ‘Generation of advanced helicopter experimental aerodynamic database for CFD code validation’ (Goahead) project to create an experimental database and validate advanced software supporting three-dimensional (3D) CFD aeromechanics methods. Data and validated models would enable prediction of unsteady viscous flow around helicopters and assist in optimising designs. Following wind tunnel experiments on a scaled model of a modern transport helicopter together with advances to currently available solvers, conclusions were drawn regarding best practices for complete helicopter simulations. All European manufacturers of helicopters use the CFD methods developed by the Goahead consortium, enabling direct validation and improved reliability and accuracy throughout the project. Goahead numerical methods have the potential to deliver important economic benefits including reduction in helicopter development costs as well as reduction in cost of development and validation of new CFD methods. Increased accuracy and reliability of new designs should increase helicopter efficiency and performance and ease certification all at a reduced cost, enhancing the competitiveness of European helicopter manufacturers.