A Review of Electric Aircraft Drivetrain Motor Technology

Jonathan Z. Bird, Portland State University


This paper reviews the power density and torque density of permanent magnet motor technology that is currently commercially developed for use in electric aircraft. The review shows that in order to meet the ambitious electrical motor power density goals recently set forth the power density of a motor needs to more than double. The requirements imposed by the maximum propeller rotor tip-speed as well as the diameter constraints set by the aerodynamic requirements will further limit the practical electric motor design sizing options. This paper advocates for considering using magnetic gearing and using an integrated contra-rotating motor propeller co-design approach as a way of both increasing propulsive thrust performance and thereby increasing the aircrafts overall power density.