Engine/Airframe Interference on Transport Aircraft with ducted Propfans - The European Research Program DUPRIN -

The cooperative European research program DUPRIN (DUcted PRopfan INvestigations) was started by mid 1990 under Area 5-Aeronautics of the CEC frame program BRITE/EURAM. Main purpose of DUPRIN is to build up the know-how basis, necessary for the new engine types, currently under development. These engines are characterized by very/ respectively ultra-high bypass ratios (VHBR/UHBR), coupled with increasing nacelle diameters and hence requiring a closer coupling with the wing. Based on an existing wing tunnel complete-model of a typical twin-engine transport aircraft, plus one ducted propfan and one turbofan engine simulator, the experimental part of DUPRIN was concentrating first on the completion of the missing hardware. Due to this, a second engine simulator of each type was designed and manufactured. Following the preparation of the model, first wind tunnel tests were performed in the German-Dutch Wing Tunnel (DNW). In relation to the turbofan, the results with the ducted propfan showed an increase in installation- as well as in jet-interference drag. The installation effects were spreading over the major part of the wing span.