The lack of a yoke and locating the magnets away from the central axis result in higher power-to-weight ratios than equivalent radial flux motors. The EVOA E1 and Acel outboards use axial flux motors.

The rotors are largely unchanged from standard practice for pancake-style axial-flux motors—magnets fastened to a steel disc (they can be rare-earth or not, as needs and budget allow).

In an attempt to get around the voltage limitation, [Tom] built his own axial flux motor for the bike, using 3D printed formers for the coils and an aluminum rotor with embedded magnets.

The motor has six coils in the stator, with the rotor carrying eight neodymium magnets. It’s an axial flux design, with the rotor’s magnets sitting above the coils. This makes construction ...