The diversity of concept of rotorcrafts is only matched by their extent of application field. Then a key question is raising : What is the most suitable concept facing a number of missions or specifications ? Part of the answer is the study of evaluation of flight performances and prediction of environmental impact of rotorcrafts. The project " Concepts of Rotorcraft Enhanced Assessment Through Integrated Optimization Network " (C.R.E.A.T.I.O.N.) aims to develop a multi-disciplinary and multi-level modelling calculation chain able to evaluate performances of Rotorcraft. The multidisciplinary feature comes from the involvement of different disciplines in rotorcraft design. The multi modelling levels are defined to allow the evaluation of any rotorcraft concept whatever the level of details available in the description data. The present thesis is part of this project. First steps are the implementation of statistical models able to describe the rotorcraft with some specifications, the development of a code that evaluates flight performances and its integration into multidisciplinary loops of calculations. Following is the setting up of a preliminary design conception chain by multidisciplinary optimization. Then the use of multi-objectives exploration algorithms and decision aid methods to select a best compromise solution is considered. The exploration of databases, creating response surface models are other themes explored in this thesis.
