Patent ID: 7484934

Claim:
An apparatus that is rotatable around a first axis to propel an intercepted fluid in a radial direction, the apparatus comprising: a support capable of being rotated around the first axis; a first blade assembly on the support and comprising a first blade having a first substantially flat surface residing in a first plane that is substantially parallel to the first axis; and a second blade assembly comprising second and third blades respectively having second and third substantially flat surfaces residing respectively in second and third planes each extending substantially parallel to the first axis with the second blade assembly in an operative position on the support, there being a single piece that defines at least a part of the second and third substantially flat surfaces, the second blade assembly separate from the first blade assembly and joined to the support in the operative position so that the first, second and third blades cooperatively propel intercepted fluid in a radial direction relative to the first axis as the apparatus is rotated around the first axis.