Evolutionary Algorithms are often used as an optimization tool. We use this ability here to help explore, analyse and, on this basis, propose a controller for a complex robotics system: a flapping wings aircraft. A multi-objective optimization is performed to find the best parameters of sinusoidal wings kinematics. The obtained results are not the end of the process, but rather the begining. Their analysis provides information concerning the simulated prototype: the speed-energy relation is empirically evaluated. The analysis of the regularities of wings kinematics parameters also provides interesting insights that has led, in a further step, to the synthesis of an open-loop controller allowing to change speed during flight.