Many highly interdependent disciplines are concerned with the system noise assessment of small propeller aircraft concepts, including aircraft, propeller, engine design and acoustic modelling, flight trajectories calculation, noise propagation and ground effect modelling. There are no state-of-the-art simulation processes in Europe which account for all the aforementioned disciplines, as efforts heretofore have been focused on large transport aircraft concepts. This paper presents the development of such a simulation process at the German Aerospace Center (DLR). The simulation process inputs top-level aircraft design requirements, producing a valid CS-23 conceptual propeller aircraft design. It then calculates realistic flight paths for departure and approach for the conceptual aircraft and simulates noise immissions at user-specified locations. The immissions assessment would then guide design modifications, low-noise flight trajectory generation and novel aircraft design. A Reims-Cessna F406 is considered as the reference aircraft and is used to obtain the first results from the simulation process. The results are compared with measurements from a flight test campaign using the same aircraft. Important effects observed in the results and in the immissions assessments are also presented in this paper. Furthermore, the capabilities of the simulation chain will be demonstrated with sensitivity studies that show the effects of modifying operational procedures on ground noise immissions. ... Read more

The pursuit of greener aviation led to the investigation of new aircraft concepts. Disruptive aircraft configurations show great potential in reducing the ground noise impact, but extensive research is required before they can be manufactured. Tube-and-wing aircraft with over-the-wing engines, benefiting from noise shielding, are a more feasible option for midterm noise reduction targets. This work explores a low-noise version of the B747-400 considering over-the-wing engines, and a multidisciplinary procedure is used to calculate the aircraft and engine performance, the flight procedure, and the noise impact. Engine positions are found providing maximumengine noise shielding, reflected in a decrease in the sound exposure level (SEL) contours. These contours are calculated considering the wing leading edge as both a sharp and a curved edge. This work investigates whether a sharp leading-edge approximation is acceptable for first estimates of the optimal engines position and corresponding noise reduction values. From the results it is found that the maximumdecrease in theSEL obtained for the modified aircraft is 2 dB considering a sharp leading edge and 1.5 dB for a curved leading edge, for departure. For approach, the SEL contours do not show significant differences for the sharp and curved leading edge, with maximum noise reduction values of 3.5 dB for both cases. ... Read more