The overall objective of ACASIAS is to contribute to the reduction of energy consumption of future aircraft by improving aerodynamic performance and by facilitating the integration of novel efficient propulsion systems such as contra-rotating open rotor (CROR) engines. The aerodynamic performance is improved by the conformal and structural integration of antennas. The installation of CROR engines is facilitated by installation of an Active Structural Acoustic Control (ASAC) system in the fuselage. The integration of such a system in fuselage panels will annoying noise in the cabin caused by multi-harmonic sound pressure level which is radiated by CROR engines. CROR engines are able to realize up to 25% fuel and CO2 savings compared to equivalent-technology turbofan engines (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890003194.pdf). The ACASIAS project focuses on challenges posed by the development of aero- structures with multifunctional capabilities. The following concepts structural concepts a