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The aviation industry is facing an urgent need to address the environmental impact of air traffic. This isunderlined by the Flightpath 2050 agenda of policymakers and the aerospace industry, which has…

The aviation industry is facing an urgent need to address the environmental impact of air traffic. This isunderlined by the Flightpath 2050 agenda of policymakers and the aerospace industry, which has the ambitiousgoals of reducing CO2 emissions by 75 %, NOx emissions by 90 %, and noise emissions by 65 % until 2050compared to typical capabilities of new aircraft in 2000. Various technologies are promising solutions to tacklethese goals; for example, efficient propulsion concepts, such as Distributed Hybrid Electric Propulsion (DHEP),allow the reduction or even elimination of pollutant emissions through full-electrical operation at ground levels (<900 m). Another promising option is the use of Sustainable Aviation Fuel (SAF) to reduce chemical emissionsdirectly at the source. This study takes up the potential of DHEP and SAF operation, introducing a designapproach for hybrid electric powertrains of mid-range aircraft based on the 0D in-house tool ASTOR for thethermodynamic cycle performance calculation of gas turbines. It has been adapted for on-design calculationsand extended by a combustion chamber model to enable the determination of combustion emissions of SAFs.Two approaches, 0D-chemical equilibrium (CE) and 0D-chemical reaction network (CRN), were employed tomodel the emissions of the combustion process and integrated into the hybrid electric powertrain model usinglookup tables. The hybrid electric powertrain model represents a propeller-based DHEP architecture, the gasturbine consisting of a compressor and turbine, as well as the combustion chamber. Appropriate boundaryconditions are applied to investigate different propeller-based DHEP concepts. Subsequently, a Design ofExperiments-based (DoE) design process is conducted for the SAF powered gas turbine of the hybrid electricpowertrain for take-off conidtions providing insights into power-specific fuel consumption (PSFC) and chemicalemissions, offering a database enabling new assessments of air pollution at ground level and a pollution drivendesign selection.

  Achieving climate neutrality in aviation necessitates the development of innovative technologies and operational strategies. The INDIGO project, funded under the Horizon Europe programme, intro…

  Achieving climate neutrality in aviation necessitates the development of innovative technologies and operational strategies. The INDIGO project, funded under the Horizon Europe programme, introduces a novel mid-range aircraft featuring distributed hybrid electric propulsion (DHEP) and Large Aspect-Ratio Wings (LARW).  To accurately evaluate trade-off solutions, a multidisciplinary optimization framework was developed. This framework incorporates advanced design and simulation tools to balance aerodynamic performance, fuel efficiency, and emissions reduction. The introduction of LARW-DHEP shows potential for significant emissions reductions, particularly during climb and landing operations.   The INDIGO project approach highlights the feasibility and benefits of integrating DHEP and LARW in future aircraft designs, demonstrating the importance of holistic optimization in achieving sustainable aviation goals.

The development of high-performance battery systems is a critical challenge for the advancement of hybrid-electric aircraft. This work aims to develop an optimization procedure capable of correlating …

The development of high-performance battery systems is a critical challenge for the advancement of hybrid-electric aircraft. This work aims to develop an optimization procedure capable of correlating the performance level required by design constraints to the time framework when this performance level will be available. In practical terms, the currently available maximum energy density of a given battery technology might not be enough for developing a competitive hybrid aircraft. Still, the same technology has some potential to provide the required energy density in the near future. Hence, it becomes essential to foresee in which temporal framework the technology improvements will make possible and readily available the required performance level. In this work, we introduce a risk index that quantifies the probability that a given battery technology, characterized by a specific energy density, will not reach the required level of technological maturity within a given year. An optimization process is then developed, enabling a systematic trade-off between technological potential and associated risks, supporting strategic decision-making in the selection of energy storage solutions for hybrid-electric aviation. By quantifying the maturity risk of different battery technologies, this approach provides a structured decision support tool for aircraft designers and industries, facilitating the transition to feasible hybrid-electric propulsion systems. The risk index is correlated to key battery parameters, such as energy density and maximum discharge rate, that directly influence the feasibility and efficiency of battery technologies for aerospace applications. However, different battery technologies promise to achieve specific key parameter targets at different times, depending on advances in materials and manufacturing processes. Since many of these technologies are still developing, their future performance remains uncertain. The Dempster-Shafer theory of imprecise probabilities, a mathematical framework for modeling uncertainty and combining evidence from multiple sources, is used to account for the uncertainty associated with the evolution in time of these key parameters. This theory is instrumental because it incorporates subjective probabilities through the concepts of belief and plausibility, providing a more flexible representation of uncertainty than classical probabilistic approaches. This work is part of INDIGO, a European project aimed at reducing the impact of noise and pollution in airport areas by developing a medium-range hybrid aircraft featuring distributed propulsion, in which the outermost propellers use electrical propulsion.

This study examines improvements in local air quality and noise (LAQ&N) of the Landing and Take-Off cycle (LTO cycle) with the introduction of a hybrid electric/sustainable mid-range aircraft…

This study examines improvements in local air quality and noise (LAQ&N) of the Landing and Take-Off cycle (LTO cycle) with the introduction of a hybrid electric/sustainable mid-range aircraft. Using Dortmund Airport as a case study, the results highlight significant environmental benefits. Future traffic scenarios estimate potential gains: INDIGO flights improve LAQ by up to 74% and noise impacts by 36%. When replacing 15% of the future traffic demand with INDIGO aircraft, up to a 3% benefit in LAQ&Ncan be expected. Full traffic replacement scenarios promise substantial environmental advantages, affirming the INDIGO aircrafts’ role in greener aviation.