Propulsors (e.g., an electric motor mechanically coupled to a rotor) are described that passively cool the electric motors via an airflow path through the electric motor and out of the rotors. One embodiment comprises a method of cooling an electric motor. The method comprises operating the electric motor of a propulsor for an aircraft to rotate a rotor of the propulsor, where the rotor has one or more air outlets, and where the electric motor has a housing that includes one or more air inlets in fluid communication with the one or more air inlets. The method further comprises generating, by rotating the rotor using the electric motor, an airflow through the electric motor from the one or more air inlets to the one or more air outlets to cool the electric motor.