초록 ▼

Methods are disclosed for increasing lift and decreasing drag on hydrofoils and swim fins. These methods include providing a hydrofoil with a highly swept back leading edge portion and orienting the hydrofoil at a significantly reduced angle of attack in which the reduced angle of attack occurs at a

Methods are disclosed for increasing lift and decreasing drag on hydrofoils and swim fins. These methods include providing a hydrofoil with a highly swept back leading edge portion and orienting the hydrofoil at a significantly reduced angle of attack in which the reduced angle of attack occurs at an angle that is substantially transverse to the hydrofoil's direction of movement through a surrounding fluid medium. The lee surfaces of the hydrofoil is provided with a substantially unobstructed flow path as well as a separation reducing contour so as to permit lift generating attached flow conditions to form along such lee surfaces. Substantially rigid structural reinforcement is provided to prevent the hydrofoil from deforming significantly during use. Methods are disclosed for providing a hydrofoil with a substantially longitudinal recess or venting system located substantially along the center axis of the hydrofoil. The attacking surfaces of such a hydrofoil is provided with an anhedral contour that forms a substantially lengthwise channel with the recess or venting means located along the center axis of this lengthwise channel. The anhedral contour directs water toward the center axis of the lengthwise channel, and the central recess or venting system permits water to flow through it toward the lee surfaces in order to reduce the occurrence of outward directed spanwise flow conditions along the attacking surfaces and encourage inward directed spanwise flow conditions to occur along the attacking surfaces. The central recess or venting system also permits the water flowing in an attached manner along the lee surfaces of the hydrofoil to merge with the water flowing from the attacking surfaces through the recess or venting system so that lift is efficiently generated. Methods are disclosed for applying these lift generating and drag reducing methods to both non-flexible and flexible hydrofoil blades that are used in reciprocating propulsion strokes through a fluid medium. Methods are disclosed for permitting flexible hydrofoils to deform in a manner which permits such efficient flow conditions to form under significantly light reciprocating strokes while simultaneously providing sufficient structural reinforcement to enable such flow conditions to be maintained without experiencing undesirable forms of deformation. Also provided are methods for significantly controlling and reducing the build up of torsional stress forces within a flexible hydrofoil as it is encouraged to twist to a reduced angle of attack during use so that such a twisted form is created with significant improvements in efficiency, contour, and ease.

대표청구항 ▼

[ What is claimed is:] [1.] A swim fin comprising:(a) a foot receiving portion arranged to attach to a foot of a swimmer,(b) an blade member secured to said foot receiving portion, wherein said blade member extends a significant longitudinal distance in front of said foot receiving portion to form a

[ What is claimed is:] [1.] A swim fin comprising:(a) a foot receiving portion arranged to attach to a foot of a swimmer,(b) an blade member secured to said foot receiving portion, wherein said blade member extends a significant longitudinal distance in front of said foot receiving portion to form a substantially lengthwise extension of said foot receiving portion, wherein the lengthwise dimension of said swim fin is substantially greater than the transverse dimension of said blade member, and said blade member having opposing surfaces, outer side edges, inner edges that may twist, a root portion proximate said foot receiving portion, and a trailing portion spaced from said root portion and said foot receiving portion,(c) two elongated stiffening members secured to said blade member proximate said outer side edges,(d) a substantially longitudinal opening formed in said blade member which originates at a predetermined position proximate said trailing portion and extends substantially toward said shoe member of said blade member and terminates at a base of said longitudinal opening which is located a predetermined distance from said shoe member, wherein said longitudinal opening is sufficiently large enough to substantially divide a significant portion of said blade member into two half blade portions, and(e) said blade member has sufficient resiliency to permit a significant portion of said blade member to twist under varying load conditions created as said swim fin is kicked through a fluid medium during the act of swimming.