The aim of this work is to preliminary model a hybrid propulsion system that integrates fuel cells and a turbo-generator. The model is used to predict the performance of the propulsion system where parameters such as fuel consumption, and component efficiencies are monitored throughout a given eVTOL mission. Based on the analysed performance, the maximum payload the eVTOL can carry is estimated. With a fuel cell voltage efficiency of 43%, an eVTOL of MTOW of 3175 kg and a structural weight of 1905 can carry a maximum of 174 kg as a payload. The eVTOL propulsion system weights approximately 1041 kg, to which the fuel cell and its balance of plant components contributes the highest with 819 kg, where the turbogenerator contributes with 222 kg. According to the models prediction, the payload can be increased to approximately 200 kg , if a compressor efficiency of 85% was used.

Bachelor Thesis: Design Synthesis Exercise 2023
Group 13: Electric General Aircraft
in collaboration with
Group 10: Mid-Flight Recharging System

Addressing the pressing need for sustainability amid climate change, the aviation sector is under pressure to mitigate its significant carbon emissions. As aviation accounts for over 2% of global emissions, achieving zero-emissions aviation by 2050 is crucial. The challenge lies in finding alternatives to jet fuel. One option is battery-powered electric aviation, but limitations such as range constraints and emissions during production and disposal must be considered.

This report proposes a solution to extend the range of all-electric passenger aircraft. The ElectriFly aircraft can currently fly 600km at 110m/s before requiring recharging. To achieve perpetual flight capability, a mid-flight recharging system is introduced using a drogue and probe system, similar to military refueling technologies. This approach not only increases range but also reduces turn around time at airports.

Powered by four parallel-connected solid-state batteries with an energy density of 600kWh/kg, the ElectriFly aircraft features 14 propellers using distributed propulsion and potential plasma actuators. This setup improves aerodynamic performance, reduces noise, and allows for regenerative braking, easing the burden on the recharging drone. Real-time data sensors enable predictive maintenance, minimizing downtime and providing pilots with crucial flight anomaly information.

This research presents a promising solution for electric aircraft limitations through mid-flight recharging. The proposed ElectriFly aircraft offers extended range capabilities and improved operational efficiency, supporting the goal of sustainable aviation.