Motive force produced by the rotation of blades (usually two or three) inclined back from their leading to trailing edges. Although the blades rotate in circular paths, the leading edge of each blade can displace a fluid backwards and thereby drive an object forwards. It has been suggested that swimmers doing the front crawl use their hands like rotating propeller blades within a single armstroke, with the hands forming a new blade each time they change direction. See also propeller propulsion.
Subjects: Sports and Exercise Medicine.