The core of the project is a brushless DC motor originally intended a hydrofoil which is capable of providing 11 pounds (about 5 kg) of thrust. [Braden] has integrated it into a 3D-printed fin ...

settled on with his BLDC rewinding and rewiring project ... He started with a teardown of a small motor, to understand the mechanical challenges involved, then moved onto a larger motor.

Using a small brushed DC motor together with a larger BLDC motor can provide strong acceleration combined with good high rpm power. The brushed DC motor provides initial torque to get the bike ...