Distributed propulsion systems, characterized by multiple propellers, represent a promising approach for full-electric aircrafts, offering several advantages but also introducing technical challenges. The main objective of this paper is to quantify how the propeller performance and noise emissions of an eight-propeller full-electric aircraft configuration compare to that of a conventional fuel-based turboprop. In both cases, the key parameters driving the trade-off between noise emissions and aerodynamic performances are analysed as well as the benefits of each configuration. The propeller noise emissions are analysed in terms of the perceived noise emissions at the three certification points: approach, take-off, and flyover. Optimizations are performed as a function of blade count to investigate the performance and noise trends for different propeller configurations. The results show a promising performance for the battery-electric aircraft with distributed propulsion, achieving a propeller efficiency between 83% and 88% in cruise without incurring a major noise penalty compared to the reference turboprop aircraft, despite the large increase in aircraft size and weight.

Recent research suggests that large battery-electric aircraft can achieve greater ranges than previously assumed and can therefore be a promising solution to decarbonize the aviation sector on short distances. However, several technical challenges need to be investigated for such aircraft to become technically and commercially viable. This paper summarizes the findings of a series of research projects investigating these technical challenges, which are then incorporated in the conceptual redesign of a 90-seater battery-electric aircraft. The top-level aircraft requirements are revisited and the main configuration trade-offs are discussed. The resulting design presents a maximum take-off mass of 82.5 t and achieves a battery-only range of 750 km for a pack energy density of 320 Wh/kg, while reserves are covered by a dedicated fuel-based reserve energy system (RES). The impact of using the RES for range extension is also investigated. A comparison to conventional aircraft configurations in terms of CO2-equivalent and operating costs per passenger-kilometer demonstrates that such aircraft can become a cost-competitive solution to mitigate the climate impact of aviation on short ranges.

The preliminary design of the thermal management system for the electric powertrain of a 90-seater battery-electric aircraft is addressed in this study. The main heat loads of the powertrain are associated with the battery pack and the electronic power unit, comprising an electric motor, an inverter, and optionally a gearbox. The main operating points of the thermal management system throughout the nominal flight mission are identified as take-off, top of climb, cruise, and top of descent. Two candidate architectures are assessed and compared in terms of key performance metrics, i.e., weight, drag penalty, and electric power consumption. Moreover, the equivalent battery mass required to power and carry the thermal management system throughout the flight mission is computed. The results show that the architecture exploiting the difference in the temperature levels of the heat sources in the powertrain features superior performance than the baseline configuration. In particular, the total equivalent battery mass is reduced by 388 kg. Overall, this translates into an increase in the usable range of 11 km prior to snowball effects, highlighting the importance of the thermal management system in the design of large battery-electric aircraft.