PM brushless motors comparison for a Fenestron®type helicopter tail rotor

This paper describes requirements and design principles of an electric motor for helicopter tail rotor application. The application demands high specific power and specific torque with little possibility to adopt a liquid cooling solution. The tail rotor shall also comply with severe safety requirements that directly affect the motor design. Volume and weight constraints make the design of the electrical machine challenging. Different solutions have been investigated to propose an effective alternative to the Fenestron®mechanical actuation system. In the paper two different permanent magnet motors with external rotor are illustrated and compared.