An electric propulsion system for a vertical take-off and landing (VTOL) aircraft, the electric propulsion system including an electrical motor having a stator and a rotor. The electric propulsion system may include a main shaft possessing at least one shoulder on an outer surface of the main shaft. The electric propulsion system may include a gearbox assembly comprising a sun gear that is concentrically aligned with the main shaft at least one planetary gear that interfaces with the sun gear. The electric propulsion system may include a planetary carrier, wherein a center of the planetary carrier is concentrically aligned with the main shaft. The electric propulsion system may include a propeller flange assembly that travels through the rotor, and an axial buttress positioned in the at least one shoulder located on the main shaft.