| 摘要 |
A propeller comprises a hub (1) having a pair of blades (3) extending therefrom. Each blade (3) has a root, a tip, a first blade portion (10a) extending between said root and said tip and a second blade portion (10b) extending between said root and said tip adjacent and substantially parallel to said first blade portion (10a) . The first and second blade portions (10a, 10b) each have an arcuate concave face (11a, 11b) , the radius of curvature of the concave face (lla) of said first blade section (10a) being greater than the radius of curvature of the concave face (11b) of the second blade section (10b) . The concave faces (11a, 11b) of said first and second portions (10a, 10b) facing in substantially opposite directions such that, in use, said concave face (11a) of said first blade portion (10a) faces rearwards and said concave face (11b) of the second blade portion (10b) faces forwards. |
