Aerodynamic design and analysis of an innovative regional turboprop configuration

The Innovative turbopROp configuratioN (IRON) project complies with the European Union topic JTI-CS2-2015-CPW02-REG-01-03 (Green and cost efficient Conceptual Aircraft Design including Innovative Turbo-Propeller Power-plant) as part of the Clean Sky 2 program for Horizon 2020. The topic leader is Leonardo, CIRA (Italian Aerospace Research Center) is the coordinator and several core-partners are involved into the project. The research work is focused on the feasibility study of an innovative turboprop aircraft configuration with rear engines installed on the horizontal tailplane. This paper deals with the aerodynamic design and analyses carried out during the first loop of design concerning the baseline configuration provided by Leonardo Company. Major activities have been addressed to the design of the wing airfoil and to an efficient high lift system (including the possibility of a morphable drooped nose). Winglets have been specifically designed to improve the climb performance concurrently reducing the induced drag in cruise condition. The complete aerodynamic database assessment has been performed also by means of high fidelity analyses, such as CFD-RANS simulations, to estimate the isolated wing high lift capabilities (flap up and flap down) and the fuselage aerodynamic characteristics. To assess the complete aircraft trimmed drag polar database, a detailed weight and balance analysis has been performed. This analysis has shown that for this innovative configuration, the center of gravity excursion is very large, highlighting the inadequate sizing of the horizontal tailplane to trim the aircraft in the whole center of gravity excursion range. To overcome this issue, different aircraft configurations have been considered. Among them also three lifting surfaces has been considered. This latter has been identified as the most promising solution to best comply with the provided aerodynamic requirements.