Periodic Reporting for period 3 - SENECA ((LTO) noiSe and EmissioNs of supErsoniC Aircraft)
Reporting period: 2024-01-01 to 2024-12-31
In SENECA, eleven academic and industrial aerospace entities from all over Europe have teamed up to address the challenges raised in the call LC-MG-1-15-2020 titled “Towards global environmental regulation of supersonic aviation”. The focus of the consortium lies on the new generation of supersonic aircraft due to enter into service in the near future. However, it is assumed that the next generation of supersonic aircraft will not be permitted to fly over land at supersonic speeds, i.e. will not have completely solved the problem of the supersonic boom. Therefore, the project will only consider supersonic flight over water and subsonic flight over land. As a consequence, SENECA will mainly focus on noise and emissions in the vicinity of airports and the global climate impact of supersonic aircraft. The project’s goal is to develop a deep understanding and detailed modelling of emissions, LTO noise, and the global environmental impact of supersonic aircraft. Using the knowledge gained, the development of technologies beyond the current state of the art to further reduce the environmental impact of supersonic aviation will be made possible. SENECA will enter its project results into the ICAO level discussions in order to scientifically accompany and strengthen the European perspective on the necessary regulations for novel supersonic aircraft. Key milestones of the project dissemination and exploitation plan are aligned with the CAEP work program and agenda and the entire project plan is designed to work towards these milestones.
Project SENECA commenced in January 2021. The first 18 months were primarily dedicated to defining the specifications and design of four civil supersonic aircraft — two business jets and two airliners — and their respective propulsion systems, targeting different cruise Mach numbers. During the following 18-month period, aircraft systems and advanced take-off procedures were iteratively optimised. In the final project year, the environmental impacts were assessed through detailed LTO noise and climate impact studies.
In WP2 “Specification of Platforms”, two business jets with cruise speeds of Mach 1.4 and 1.6 and two airliners cruising at Mach 1.8 and 2.2 were designed and their aerodynamic characteristics determined. For the two business jets and the Mach 1.8 airliner, the mission profiles were iteratively refined to achieve an optimal match with the engines designed in WP3. Advanced take-off trajectories employing variable noise-reduction strategies — including variations in take-off speed, delayed rotation, and programmed lapse rate — were developed and transferred to WP5 for subsequent noise evaluation.
In WP3 “Engine Design and Integration”, the final engine configurations were developed in close coordination with WP2. The main challenges included managing the continuous thermal loads associated with high thrust requirements in supersonic cruise, preventing inlet spillage in supersonic operation, and simultaneously meeting LTO noise constraints. Achieving consistent performance across subsonic, transonic, and supersonic regimes remained a key design objective.
In WP4 “Emissions and Environmental Impact”, the expected traffic patterns of a hypothetical civil supersonic fleet were modelled. Using the engine data from WP3, emission indices were calculated and mapped to planned global routes, enabling an estimation of the fleet’s overall climate impact. A comprehensive sensitivity study was conducted to assess the effects of NOx and H2O emissions on atmospheric chemistry and climate as a function of flight altitude and route distribution. The formation and evolution of supersonic contrails were analysed using advanced numerical modelling.
For LTO noise assessment in WP5, jet noise was investigated using both empirical and numerical methods. Early in the project, empirical models were benchmarked, and detailed CFD simulations were conducted for realistic nozzle configurations, complemented by a small-scale jet noise test campaign evaluating multiple plug nozzle concepts. Studies on fan noise shielding, liners, and inlets were carried out to address supersonic-specific aspects of noise propagation. Together with WP2, the advanced take-off trajectories for the Mach 1.4 1.6 and 1.8 aircraft were optimised for noise certification. Results showed that all three aircraft can achieve ICAO Chapter 14 noise limits with significant margins. To ensure the robustness of these findings, harmonisation and uncertainty analyses were also performed.
Within WP6 “Dissemination and Exploitation”, project results were shared regularly with the Advisory Board during biannual consortium meetings and broadly disseminated to the scientific community through more than 30 publications, with additional papers in preparation. Together with the MORE&LESS project, SENECA organised a joint workshop at ICAS 2024, where key findings were presented. Moreover, results from SENECA were introduced into ICAO CAEP/13 Working Groups 1 and 3, providing valuable input to ongoing discussions and decision-making processes related to future supersonic aircraft certification standards.
In WP2 “Specification of Platforms”, two business jets with cruise speeds of Mach 1.4 and 1.6 and two airliners cruising at Mach 1.8 and 2.2 were designed and their aerodynamic characteristics determined. For the two business jets and the Mach 1.8 airliner, the mission profiles were iteratively refined to achieve an optimal match with the engines designed in WP3. Advanced take-off trajectories employing variable noise-reduction strategies — including variations in take-off speed, delayed rotation, and programmed lapse rate — were developed and transferred to WP5 for subsequent noise evaluation.
In WP3 “Engine Design and Integration”, the final engine configurations were developed in close coordination with WP2. The main challenges included managing the continuous thermal loads associated with high thrust requirements in supersonic cruise, preventing inlet spillage in supersonic operation, and simultaneously meeting LTO noise constraints. Achieving consistent performance across subsonic, transonic, and supersonic regimes remained a key design objective.
In WP4 “Emissions and Environmental Impact”, the expected traffic patterns of a hypothetical civil supersonic fleet were modelled. Using the engine data from WP3, emission indices were calculated and mapped to planned global routes, enabling an estimation of the fleet’s overall climate impact. A comprehensive sensitivity study was conducted to assess the effects of NOx and H2O emissions on atmospheric chemistry and climate as a function of flight altitude and route distribution. The formation and evolution of supersonic contrails were analysed using advanced numerical modelling.
For LTO noise assessment in WP5, jet noise was investigated using both empirical and numerical methods. Early in the project, empirical models were benchmarked, and detailed CFD simulations were conducted for realistic nozzle configurations, complemented by a small-scale jet noise test campaign evaluating multiple plug nozzle concepts. Studies on fan noise shielding, liners, and inlets were carried out to address supersonic-specific aspects of noise propagation. Together with WP2, the advanced take-off trajectories for the Mach 1.4 1.6 and 1.8 aircraft were optimised for noise certification. Results showed that all three aircraft can achieve ICAO Chapter 14 noise limits with significant margins. To ensure the robustness of these findings, harmonisation and uncertainty analyses were also performed.
Within WP6 “Dissemination and Exploitation”, project results were shared regularly with the Advisory Board during biannual consortium meetings and broadly disseminated to the scientific community through more than 30 publications, with additional papers in preparation. Together with the MORE&LESS project, SENECA organised a joint workshop at ICAS 2024, where key findings were presented. Moreover, results from SENECA were introduced into ICAO CAEP/13 Working Groups 1 and 3, providing valuable input to ongoing discussions and decision-making processes related to future supersonic aircraft certification standards.
SENECA has advanced the state of the art in the environmental assessment of future supersonic transport (SST) operations by integrating refined modelling capabilities across climate, emissions, and noise domains. The project developed an enhanced global SST emission inventory, replacing legacy datasets, and applied high-resolution routing simulations to perform a comprehensive climate impact assessment. The final results of this analysis are forthcoming and expected to deliver a robust scientific basis for future policy and regulatory decisions.
Through a coordinated benchmarking exercise, partners compared and validated their noise generation and propagation models, achieving improved predictive accuracy and consistency across tools. These studies demonstrated that supersonic aircraft employing current-generation technologies can comply with ICAO Stage 4 noise certification limits. Moreover, the benefits of advanced engine design concepts—such as two-stage fans and variable-area nozzles—were quantitatively assessed for their noise reduction potential during approach and departure operations.
The findings of SENECA have already contributed to discussions within relevant ICAO working groups and will continue to inform international standard-setting activities. The project’s outcomes are expected to support the development of evidence-based environmental frameworks aimed at mitigating the climate and acoustic impacts of future commercial supersonic aviation. In the broader societal context, SENECA contributes to ensuring that future high-speed air transport evolves in an environmentally responsible and publicly acceptable manner.
Through a coordinated benchmarking exercise, partners compared and validated their noise generation and propagation models, achieving improved predictive accuracy and consistency across tools. These studies demonstrated that supersonic aircraft employing current-generation technologies can comply with ICAO Stage 4 noise certification limits. Moreover, the benefits of advanced engine design concepts—such as two-stage fans and variable-area nozzles—were quantitatively assessed for their noise reduction potential during approach and departure operations.
The findings of SENECA have already contributed to discussions within relevant ICAO working groups and will continue to inform international standard-setting activities. The project’s outcomes are expected to support the development of evidence-based environmental frameworks aimed at mitigating the climate and acoustic impacts of future commercial supersonic aviation. In the broader societal context, SENECA contributes to ensuring that future high-speed air transport evolves in an environmentally responsible and publicly acceptable manner.