| 摘要 |
A fan having a hub, a plurality of arms each extending radially outwardly of the hub and at an acute angle to the rotational plane of the fan, and blade structures, one secured to each arm, each blade structure having a flexible, resilient trailing airfoil portion, comprising the major portion of the blade structure, which decambers as rotational speed increases, and a less flexible leading airfoil portion comprising a slat extending forward of the respective arm and disposed at an angle thereto lying within the above specified acute angle, with the trailing and leading portions mutually constructed to have the leading and trailing edges of the blade define therebetween a chord disposed at a predetermined chord angle to the rotational plane of the fan.
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