Ariane 5 Performance Optimization Using Dual-Bell Nozzle Extension

To evaluate the impact of dual-bell nozzles on the payload mass delivered into geostationary transfer orbit by Ariane 5 Evolution Cryotechnique Type A (ECA), detailed studies were conducted. For this purpose, a multitude of Vulcain 2 extension contours were designed. The two variation parameters were the starting point and the inflection angle of the nozzle extension. As the most upstream starting point, the position of the turbine exhaust gas injection was chosen. Geometrical restrictions were imposed by the launch pad ELA 3. Considering these parameters, an analytical and a numerical method were applied to predict the impact of the dual-bell nozzle on the payload mass. The analytical approach yields a correlation between specific impulse, nozzle mass, and payload mass increment. The numerical approach was conducted applying German Aerospace Research Center’s trajectory simulation code Trajectory Optimization and Simulation of Conventional and Advanced Transport Systems. Both calculation procedures yield good agreement, and the payload gain into geostationary transfer orbit was evaluated to be up to 490 kg. The study revealed the potential of a new class of dual-bell nozzles whose mode transitions already occur during engine startup, under sea-level conditions. A payload gain up to 200 kg was found. These nozzles were designated as “sea-level transitional dual-bell.”