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.
