Magnomatics has designed a lightweight, air-cooled propulsion motor suitable for the rapidly growing Urban Air Mobility sector. The 86kW motor with a class-leading torque density of 30Nm/kg will, it says, challenge other established motors in the market.

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

NASA has identified magnetic gears as being a potential technology for electric aircraft. In 2018 it embarked on a two and half year programme described in their paper Magnetic Gearing Research for Electrified Aircraft Propulsion. Their 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 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). The first commercial priorities for the PDD were for relatively large machines for applications such as wind power, marine propulsion, and rail. In 2019 Magnomatics built and tested the largest PDD to date, with an incredible 200,000Nm rating. This was subsequently tested at the Offshore Renewable Energy Catapult at Blyth in the UK. Based on the results a large global engineering company is now evaluating the PDD technology for a number of sectors.

The UAM motor designed is based upon PDD technology, identified by NASA as being “roughly two times greater than the specific torque expected of a direct drive electric motor for the same application.”

Magnomatics says that key features of the motor include: Highest continuous torque density; less than 60% size and mass of a PM machine; high efficiency; fault tolerance; built-in passive torque fuse (protecting drivetrain); low maintenance; and high reliability.

David Latimer, Chief Executive Officer of Magnomatics, says: “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.”