A rotor body for a high-speed generator includes a rotor body with interior and exterior surfaces, a coolant inlet and outlet, and a rotor cooling path for actively cooling the rotor body. The coolant inlet and outlet extend between the interior and exterior surfaces. An interior segment of the rotor cooling path fluidly couples the coolant inlet and coolant outlet and is bounded by the rotor body interior surface. An exterior segment of the cooling path is bounded by the rotor body exterior surface and fluidly couples the coolant outlet an environment external to the rotor body.