Inside Joby Aviation's Electric Motor Strategy: A Conversation with Battery and Powertrain Expert Jon Wagner

Joby Aviation, a pioneer in electric vertical take-off and landing (eVTOL) aircraft, is on a mission to transform urban air mobility. Founded by JoeBen Bevirt in 2009, the company has embraced an iterative design philosophy—‘design, build, and test’—to rapidly refine its technology. Jon Wagner, who previously led battery engineering at Tesla, joined Joby in 2017 and now oversees powertrain development. In a recent interview, Wagner shared insights into the company’s engineering choices and future directions.

Wagner explained that Joby’s aircraft uses a direct-drive electric motor, which spins the propeller at relatively low speeds to minimize noise. To achieve the necessary torque, the motor has a large diameter and features a single magnet ring integrated with the propeller. The stator consists of two independent coil sets, each powered by separate inverters and battery packs, ensuring redundancy. Rather than inventing new components, Joby focuses on integrating proven technologies to optimize performance and manufacturability. This vertical integration allows the company to design highly efficient systems without the inefficiencies that typically arise from supplier interfaces.

When asked about advanced motor concepts, Wagner acknowledged the potential of superconducting motors but noted that current designs are already 90-95% efficient, leaving little room for improvement relative to the complexity and challenges, such as the need for cryogenic cooling. Superconducting technology may first find applications in larger multi-megawatt motors, where even small efficiency gains translate into significant energy savings. For now, Joby is prioritizing battery and hydrogen technologies to expand aviation’s range.

Looking ahead, Wagner emphasized the critical role of energy storage. While batteries are suitable for short-range urban flights, their energy density limits them for long-haul missions. Joby is actively developing hydrogen fuel cell systems, which offer three times the energy density of fossil fuels by mass. This could enable regional and long-range electric aviation. The challenges include hydrogen storage, ground refueling infrastructure, and efficient conversion to electricity. Wagner remains optimistic that hydrogen will be a cornerstone of sustainable aviation, even if it takes decades to fully realize.