The design of multi-phase permanent magnet brushless motor for an electrical helicopter tail rotor is introduced and described. The presented electric machine allows a substitution of the actual mechanisms in tail rotor system matching envelope, weights and performances. In order to obtain high torque with small overall dimensions of the motor, a spoke-type solution with interior PMs has been chosen. An optimization procedure has been used to combine thermal and electromagnetic requirements with the aim to improve the overall design. The motor performance has been evaluated by the FE analysis to validate the final design and start the prototype production.