Powertrain Optimization for Efficient Range Extension in eVTOL Eight-Rotor Drone for Sustainable Urban Air Mobility (UAM)

Urban Air Mobility (UAM) is emerging as a transformative solution for sustainable urban transportation, offering a potential alternative to traditional ground-based transport. With the rapid advancements in electric Vertical Take-Off and Landing (eVTOL) aircraft, UAM aims to alleviate congestion, reduce emissions, and enhance mobility in densely populated cities. The need for more efficient and complex solutions beyond pure battery-powered systems has become increasingly evident due to batteries' limitations in terms of energy density, which restricts the operational range and flight time. Hybrid systems that integrate alternative power sources have emerged as viable solutions, allowing eVTOL aircraft to achieve longer flight durations, reduce weight, optimize fuel consumption and enhance operational flexibility. Thus, adopting hybrid solutions over pure battery systems is essential for enhancing range, reliability, and overall performance, which are critical for realizing the widespread integration of UAM in urban environments. This paper presents the optimization of a range-extender powertrain for an eight-rotor eVTOL drone designed for short urban missions. Maintaining a purely-electric baseline configuration, various hybrid layouts are explored, including different Internal Combustion Engine (ICE) concepts powered by synthetic fuels and a hydrogen Fuel Cell (FC). The study compares the hybrid powertrains to the baseline, aiming to maintain the same overall weight while extending operational range. The findings highlight the trade-offs between powertrain options and tank sizes, providing insights into their viability for urban drone applications. This research contributes to the development of efficient, eco-friendly aerial vehicles for urban transportation, supporting the transition to sustainable mobility solutions.