Electric air taxis may fly up to 22% less far depending on the season

Electric vertical take-off and landing (eVTOL) aircraft, often described as “flying cars”, represent the next generation of transportation. By taking off vertically, these vehicles can potentially be used in cities without a runway for accessing airports, emergency medical transport, or simply for tourism.

To generate the propulsion required to take off and land, eVTOL use electric batteries. However, using them efficiently may not just depend on improving the battery's charge; it could also involve carefully managing heat.

This is the finding of a new study led by Professor Daisuke Sasaki of the Graduate School of Engineering at Osaka Metropolitan University. Using a computational model developed in MATLAB/Simulink, the researchers simulated eVTOL under different seasonal atmospheric conditions.

Using a mission-level electro-thermal simulation model of a representative eVTOL aircraft, the researchers found that seasonal conditions can substantially affect energy consumption and achievable flight range.

In a simulation of summer conditions, energy consumption for managing temperatures reached about 16% of the battery’s capacity.

Winter wasn’t easy either, as they also found that the additional heating requirements effectively reduced the range that the eVTOL could travel by up to 22% compared with spring—the season with the longest effective range.

These differences were likely due to summer conditions requiring increased power for cabin cooling and heat rejection equipment, and winter requiring increased heating demand and propulsion power due to changes in air density.

“Our analysis revealed that, even for the same aircraft operating the same mission, seasonal conditions substantially affect energy use and effective flight range,” Dr. Sasaki summarized.

Importantly, the study highlights the importance of modeling the thermal-management architecture when designing eVTOL. As propulsion, battery, and cabin subsystems are all interlinked, the aircraft has to balance competing demands for the same limited energy supply.

“Our research highlights the need to incorporate thermal loads into mission-level energy predictions to account for seasonal variability,” Haruka Nakayama, the study’s first author, said.

In the future, eVTOL may have to plan flights around heating and cooling requirements as well as distance. Thermal-aware flight planning, system design, and energy management strategies could be vital to maximizing the distance the vehicles can fly.

“This study provides a foundation for moving beyond the question of whether an eVTOL can fly under idealized conditions, toward future evaluations of what benefits it can realistically deliver, to what distances, and with what level of reliability,” Nakayama said. 

The findings were published in Applied Thermal Engineering.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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