An aircraft comprising: - at least one rotary electrical machine; - at least one wheel for imparting movement to a stream of air, linked to said at least one rotary electrical machine; - at least one system to cool; - at least one first ventilation duct (10, 15) configured to supply said wheel with air; - an electricity distribution network; - at least one power converter (40, 45) connected to said at least one rotary electrical machine and to said electricity distribution network; and - at least one control circuit configured to control said at least one power converter (40, 45); wherein said at least one rotary electrical machine is reversible and said at least one power converter (40, 45) is reversible, said at least one control circuit being configured to control said at least one reversible power converter (40, 45) for: in a first motor operating mode of said at least one reversible rotary electrical machine, taking a supply current from said electricity distribution network to electrically supply said reversible rotary electrical machine and thereby drive said at least one wheel for imparting movement to a stream of air, by virtue of which said at least one system to cool is cooled; and in a second alternator operating mode of said at least one reversible rotary electrical machine, in which a stream of air flows in said at least one first ventilation duct (10, 15) and imparts movement to said at least one wheel, providing supply power to said electricity distribution network, which power is generated by said reversible rotary electrical machine which is driven by said wheel; characterized in that said aircraft comprises at least one second ventilation duct in which are disposed said at least one reversible rotary electrical machine and at least partially said at least one system to cool, and said first ventilation duct is juxtaposed against said second ventilation duct and comprises an air inlet and an opposite air outlet, which air outlet discharges into said second ventilation duct. - at least one rotary electrical machine; - at least one wheel for imparting movement to a stream of air, linked to said at least one rotary electrical machine; - at least one system to cool; - at least one first ventilation duct (10, 15) configured to supply said wheel with air; - an electricity distribution network; - at least one power converter (40, 45) connected to said at least one rotary electrical machine and to said electricity distribution network; and - at least one control circuit configured to control said at least one power converter (40, 45); in a first motor operating mode of said at least one reversible rotary electrical machine, taking a supply current from said electricity distribution network to electrically supply said reversible rotary electrical machine and thereby drive said at least one wheel for imparting movement to a stream of air, by virtue of which said at least one system to cool is cooled; and in a second alternator operating mode of said at least one reversible rotary electrical machine, in which a stream of air flows in said at least one first ventilation duct (10, 15) and imparts movement to said at least one wheel, providing supply power to said electricity distribution network, which power is generated by said reversible rotary electrical machine which is driven by said wheel; characterized in that said aircraft comprises at least one second ventilation duct in which are disposed said at least one reversible rotary electrical machine and at least partially said at least one system to cool, and said first ventilation duct is juxtaposed against said second ventilation duct and comprises an air inlet and an opposite air outlet, which air outlet discharges into said second ventilation duct.