The Influence of Noise Minimal Aircraft Design on Noise Optimized Curved RNP

Abstract

An optimization process to design RNP approaches with minimal noise impact was designed previously within the DLR project MIDAS. This optimization uses curved segments to mitigates noise from populated areas to less populated ones. This design process uses simplified best practice noise calculations to determine the noise impact on the population in terms of highly annoyed persons or highly sleep disturbed persons by avoiding higher populated regions with the used of radius to fix turns in during the approach. The results show an approach with low noise impact that fulfills design requirements by A-RNP or RNP-AR rules. The used simplified best practice noise model produces realistic results for well-known aircraft. It is difficult to include new aircraft designs into this noise model especially for a revolutionary noise minimal aircraft design. Such a revolutionary aircraft design has been done in the DLR project SIAM. The research presented in this work as part of this project shows the impact of new noise reduced aircraft designs on possible noise reduction using curved RNP approaches by new noise reduced aircraft designs. This question has been assessed with two main approaches, one by extending the existing simplified noise model (SIMO) and one by trying to use high fidelity methods noise models in the optimization (HIMO). The SIMO results show on several examples how the noise impact potential can be reduced and how the approach designs shift with the use of noise reduced aircraft models, while the reduction potential is mostly defined by the population structure. Due to its high-fidelity methods, the HIMO approach requires about 10000 times more computing time to calculate the noise impact at one observer position. Therefore, methods to summarize operation positions have been developed to overcome these challenges and to enable the use of high-fidelity methods in the design process while remaining within 10 times of the original overall SIMO calculation time. The paper will briefly explain the tested methods and why the approach failed in the end. With the lessons learnt from the HIMO approach a modified design toolchain has been developed to include the benefits from the fast-simple noise calculation and the precision of high-fidelity models. The paper will explain this new toolchain that pre-selects promising approach designs using the simple noise calculation to then be investigated with a detailed noise calculation.