Abstract: An apparatus for aircraft propulsion includes a propeller and a hybrid-cooled electric engine mounted to a support structure and configured to rotate the propeller. The electric engine is located in an enclosure, with a first heat transfer element thermally coupled to the electric engine via a fluid flow path, partially located outside the enclosure. A second heat transfer element, integral to or thermally coupled to the electric engine, provides air cooling. Both heat transfer elements are housed within the aircraft's support structure. At least one air inlet on the upper side of the support structure receives propeller downwash. A first cooling path directs a portion of the downwash from the air inlet to the first heat transfer element, and a first air outlet exhausts the downwash.

Abstract: A VTOL aircraft includes a plurality of lift propellers configured to rotated by lift motors to provide vertical thrust during takeoff, landing and hovering operations. The lift propellers are configured to generate a cooling airflow to cool the lift motors during use. During a cruise operation when the VTOL aircraft is in forward motion, the lift propellers may be stowed in a stationary position. Therefore, the cooling airflow may be reduced or eliminated when it is not needed.

Abstract: A VTOL aircraft includes a plurality of tilt propellers configured to be rotated between a forward cruise configuration and a vertical lift configuration. A nacelle or other structure may be configured to form a low pressure zone from the wake of the tilt propellers when operating in the lift configuration. The low pressure zone may include an outlet side of a cooling path. Due to the low pressure, airflow may be induced through the cooling path even in the absence of strong air pressure at the inlet side. During a cruise operation when the VTOL aircraft is in forward motion, the nacelle or other structure may be aligned with a baffle to form an exhaust channel for the cooling airflow.

Abstract: A VTOL aircraft includes a plurality of lift propellers configured to rotated by lift motors to provide vertical thrust during takeoff, landing and hovering operations. The lift propellers are configured to generate a cooling airflow to cool the lift motors during use. During a cruise operation when the VTOL aircraft is in forward motion, the lift propellers may be stowed in a stationary position. Therefore, the cooling airflow may be reduced or eliminated when it is not needed.

Abstract: A VTOL aircraft includes a plurality of tilt propellers configured to be rotated between a forward cruise configuration and a vertical lift configuration. A nacelle or other structure may be configured to form a low pressure zone from the wake of the tilt propellers when operating in the lift configuration. The low pressure zone may include an outlet side of a cooling path. Due to the low pressure, airflow may be induced through the cooling path even in the absence of strong air pressure at the inlet side. During a cruise operation when the VTOL aircraft is in forward motion, the nacelle or other structure may be aligned with a baffle to form an exhaust channel for the cooling airflow.

Abstract: A VTOL aircraft includes a plurality of lift propellers configured to rotated by lift motors to provide vertical thrust during takeoff, landing and hovering operations. The lift propellers are configured to generate a cooling airflow to cool the lift motors during use. During a cruise operation when the VTOL aircraft is in forward motion, the lift propellers may be stowed in a stationary position. Therefore, the cooling airflow may be reduced or eliminated when it is not needed.