ATR72 OVERALL DRAG REDUCTION STUDY

In the framework of the product enhancement initiative ATR has decided to investigate on methods to improve the aerodynamic characteristics of the ATR72 aircraft airframe and the consequent improvement of the performance. Among the aircraft design parameters, drag characteristics due to secondary structures have been selected. The aerodynamic effect of the shapes of the “Belly fairing” and the “Karman” at the wing to fuselage junction will be analyzed and compared to alternative shapes that could provide with better aerodynamic characteristics (lower drag). Other two effects will be investigated. Effect due to the boot extension on wing leading edge and effect of wipers will be investigated via semi-empirical methodologies. The boot will be investigated through 2-D CFD computations. The aerodynamic analysis and the optimization of the shapes at the wing fuselage junction(“Karman”) and of the belly fairing of ATR72 aircraft will be performed. This will be done through the discrete panels modeling of the airframe to be analyzed using 2D and 3D methods with Subsonic 3-D panel methods with compressibility correction and integral boundary layer calculations.. The utilization of more complex and precise codes could be envisaged to be implemented later on if necessary. Following the analysis of the model the results will be validated possibly by comparison of the polar and wing pressure coefficients with the real data available from ATR. In the next phase, modified surfaces of the nose, Karman and belly fairing will be identified for the aerodynamic analysis and a sensibility study that should allow identifying the best new geometric configuration(s) of nose, Karman and belly fairing for minimum drag will be performed at different Mach numbers and AOA. A performance study is then required to show the advantages of the proposed design configuration in comparison to the current one