times to provide the same power generation performance this makes the conventional techniques facing problems associated with machining precision in the manufacturing thereof as well as drawbacks associated with wastes in the respects of manufacturing and material costs in addition in use due to the increase of the size of the rotor 3 additional limitation is imposed to the installation thereof making it difficult to get popular taking a generator 4 having the same power generation capacity as an example since the speed of the incoming air flow in the present invention can be made higher when compared to the conventional rotor 1 see fig1 having a fixed air flow speed the present invention allows a reduction of the cross sectional area in other words reducing the overall size further when the hood 33 is put in rotation since no breaking of air flow occurs the noise induced by the operation thereof can be reduced as shown in fig7 9 in another embodiment the distal ends of the blades 62 that are mounted to the central hub 61 of the rotor 6 are similarly surrounded by and coupled to a horn like hood 63 and the hood 63 has a first circumferential edge portion 631 and a second circumferential edge portion 632 with an extension section 633 similarly.