Positioning of the Ducted Fan Propulsive Stabiliser

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A new aircraft configuration, the Delft University Unconventional Configuration (DUUC), was recently invented by the Flight Performance and Propulsion group at TU Delft. As a solution to the concerns regarding the environmental and health impact due to increasing demand of air travel. The DUUC has a characteristic feature which consist of two ducted propellers at the empennage of the aircraft with vertical and horizontal vanes mounted downstream of the duct, spanning the whole diameter. With this newly integrated architecture the DUUC combines thrust with stability and control of the aircraft. Furthermore, with the current trend of increasingly larger bypass ratios on turbofan engines, these will at a certain point not fit below the wings anymore. Therefore, further highlighting the importance of this research than the study on the DUUC alone. From previous research on the DUUC, where the propulsive stabilizer was in a fixed, aft-fuselage position with a fixed duct aspect ratio. It has been observed that the rear center of gravity (CG) position and a large shift in CG due to the propulsive stabilizer, poses a number of challenges. Therefore, research has to be done on the positioning of the propulsive stabilizer. The objective of this research is to study the positioning of the ducted fan propulsive stabilizer, considering its impact on stability and control by development of a method to predict aerodynamic/stability & control derivatives for variable position and duct/fan size. In this study, the aerodynamic analysis tool FlightStream is used to determine the aerodynamic characteristics of the ducted propeller. These results are then used in combination with AVL and an ESDU method to determine the influence of the positioning and duct size on the aircraft stability and control. Furthermore, in order to assess the validity of FlightStream, a validation study has been performed as well and compared to analytical methods which have been used on earlier studies on the DUUC.