Sheffield-based Magnomatics, an industrial equipment supplier, has designed a lightweight, air-cooled propulsion motor that is rated at 86kW, has a ‘class-leading’ torque density of 30Nm/kg and is suitable for the rapidly growing Urban Air Mobility sector.

The company has recently started a NATEP (National Aerospace Technology Exploitation Programme) grant-funded project to investigate further light-weighting of this motor and is collaborating with Carbon ThreeSixty to see how composite materials can be used to further reduce the motor’s mass and potentially enhance performance to provide an increase in torque density to more than 30Nm/kg. The motor will be manufactured and tested to meet DO-160G specifications.

NASA has identified magnetic gears (an alternative to mechanical gearing that transfers torque via magnetic force as opposed to contact force and has the potential to be used without the lubrication, noise, and maintenance issues associated with mechanical gearing) as being a potential technology for electric aircraft. In 2018 they embarked on a 2.5-year programme described in its paper Magnetic Gearing Research for Electrified Aircraft Propulsion.

NASA’s original focus was on pure magnetic gears, but in the 2020 paper Outer Stator Magnetically Geared Motors for Urban Air Mobility Vehicles they concluded that the concentric combination of a magnetic gear and a permanent magnet motor would be ideal for an eVTOL UAM aircraft.

Magnomatics was spun out of the University of Sheffield in 2006 to commercialise this technology based on magnetic gears. Among its patented products is the Pseudo Direct Drive (PDD), which is an Outer Stator Magnetically Geared Motor (OMSGM); and while the first commercial priorities for the PDD were for relatively large machines for applications such as wind power, marine propulsion, and rail, the UAM motor based upon PDD technology was identified by NASA as being “roughly two-times greater than the specific torque expected of a direct drive electric motor for the same application”.

David Latimer, Magnomatics CEO, said: “We are delighted to receive support from NATEP for this project. The market for eVTOL motors for urban air mobility is forecast to be substantial and we believe we can provide motors that will deliver a significant advantage. Our long-term intention is to manufacture these motors here in Sheffield. A contribution not just to ‘levelling up’, but also to achieving ‘net zero’.”