Magnet retention in exterior rotor electric machines

A gas-turbine engine comprising:

• an electric machine comprising:
• a stator;
• and
• a rotor configured to rotate around the stator, the rotor comprising:
• a rotor body having an inner surface and an outer surface;
• magnets;
• and
• one or more retention rings attached to the rotor body and configured to radially retain the magnets to the inner surface of the rotor body, wherein at least one of the one or more retention rings is discontinuous, wherein the at least one retention ring is configured to be compressed during installation in the electric machine;
• a core section comprising at least one compressor and at least one turbine that both rotate about a longitudinal axis of the gas-turbine engine;
• a core vane assembly coupled to the core section, wherein the core vane assembly comprises a plurality of core vanes configured to modify core fluid flow;
• and
• a fan connected to the core section and configured to be rotated by the at least one turbine, rotation of the fan providing thrust to a vehicle that includes the turbine engine,
• wherein the electric machine is integrated into the core vane assembly and positioned in the core section aft of the fan and fore of the at least one compressor, and
• wherein the rotor rotates about the longitudinal axis.