| 摘要 |
<p>The holes (4) in the middle section (3) of the blade have an average size which is 30-50 % of that for the holes (2) in the rigid shoulder edge (1) of the blade. The middle section of the blade accounts for 20-50 % of the blade surface area and has a minimum thickness equal to ca. 30 % of the shoulder edge thickness.</p> |
