A horizontal-axis wind-powered generator formed by a structure rotating about a vertical shaft, built into the ground, a building, or a vessel, supporting a horizontal-axis wind turbine, comprising: - at least one cylindrical horizontal-axis rotor which, in an operative position, is located perpendicular to the direction of the wind, having: ∘ at least two radial blades emerging from the rotating shaft and reaching a point close to the periphery of said rotor, dividing the rotor into equal sectors, and - an enveloping casing for at least said cylindrical rotor having: ∘ an inlet manifold occupying a surface close to the upper half of the windward face, ∘ an outlet manifold occupying a surface close to the upper half of the leeward face, and ∘ a series of ramps (6, 14, 16) channeling air into the turbine, such that, at the inlet, the force of the wind causes a first thrust on the radial blade located towards the area of the inlet manifold and a second output thrust on the generatrix blades which are located towards the outlet manifold; and - at least one wind vane (10, 12) which, with the structure rotating about the shaft, automatically orient the turbine such that the inlet manifold is located facing the direction of the wind; characterized in that the cylindrical rotor comprises a plurality of generatrix blades all of them arranged forming the same angle with the tangent to said rotor at the point in which the blades are located, and spaced from one another, having a flat operative face and an arched back which offers a smaller angle in the direction of incidence of the wind; both the radial blades and generatrix blades, as well as the shaft of the rotor all being secured at the ends thereof in respective covers forming the bases or sides of said rotor. - at least one cylindrical horizontal-axis rotor which, in an operative position, is located perpendicular to the direction of the wind, having: ∘ at least two radial blades emerging from the rotating shaft and reaching a point close to the periphery of said rotor, dividing the rotor into equal sectors, and ∘ at least two radial blades emerging from the rotating shaft and reaching a point close to the periphery of said rotor, dividing the rotor into equal sectors, and - an enveloping casing for at least said cylindrical rotor having: ∘ an inlet manifold occupying a surface close to the upper half of the windward face, ∘ an outlet manifold occupying a surface close to the upper half of the leeward face, and ∘ a series of ramps (6, 14, 16) channeling air into the turbine, such that, at the inlet, the force of the wind causes a first thrust on the radial blade located towards the area of the inlet manifold and a second output thrust on the generatrix blades which are located towards the outlet manifold; and ∘ an inlet manifold occupying a surface close to the upper half of the windward face, ∘ an outlet manifold occupying a surface close to the upper half of the leeward face, and ∘ a series of ramps (6, 14, 16) channeling air into the turbine, such that, at the inlet, the force of the wind causes a first thrust on the radial blade located towards the area of the inlet manifold and a second output thrust on the generatrix blades which are located towards the outlet manifold; and - at least one wind vane (10, 12) which, with the structure rotating about the shaft, automatically orient the turbine such that the inlet manifold is located facing the direction of the wind;