rexresearch.com



Robert NELSON

Improved Swim Fins






This simple modification increases the propulsive power of swim fins by 15 - 20 % :

  
Gen-I

Gen-III



Prior Art :

US8480446



Apparatus, devices and methods of using and operating multiple high aspect ratio hydrodynamic horizontal ladder oriented vanes with pliable hinges and rotation limiting flexible webs that are attached between flexible support beams on swim fins. The fins can have a foot pocket for attaching to a swimmer or diver's foot. A pair of roughly parallel support beams can be secured to the foot and toe portion of the foot pocket and support a plurality of hydrofoil vanes therebetween in a resisted pivotal arrangement. Pivotal rotation of the hydrofoil vanes can be restricted by flexible membranes, between the hydrofoil vanes and the support beams, to provide an optimum angle of attack for the hydrofoil vanes during a swimming stroke. Methods for increasing lift and decreasing turbulence and drag on hydrofoils and swim fins part of the fins.; The fins can have at least one pivoting vane region connected to the fin with a flexible hinge member made from reduced vane cross sectional area, and injection molding of the flexible material of the foot pocket. Methods are provided for limiting the rotation of at least one of the pivoting vanes using flexible web members between the vanes and the support beams. Methods for forming flexible hinges with pivotal resistance to encourage propulsion during small kick movements and at kick reversal points are included. Injection molding assembly methods with chemical bonds and mechanical bonds are provided. A novel method for manufacturing a swim fin having a complex articulated system with few injection molding steps is also included.




US7614928
WO2009075715



A swim shoe (1) comprising a foot-covering portion (3) and a pair of lateral fins (4a and 4b) located on opposing sides (5a and 5b) of the foot-covering portion (3), where said lateral fins do not extend beyond the front (16) of the foot-covering portion (3). The lateral fins may further extend upward from the foot-covering portion and include a bend (8) a particular distance from the foot-covering portion such that the lateral fins extend outward from the foot-covering portion. The swim shoe may additionally comprise a secondary pair of lateral fins (7a and 7b) located below the first pair (4a and 4b). The secondary lateral fins (7a and 7b) may further extend upward from the foot-covering portion (3) and include a bend (10) a particular distance from the foot-covering portion (3) such that the secondary lateral fins extend outward from the foot-covering portion.



fin3

US7527540



A fin and a method providing thrust from an unusually low drag kick by a swimmer are disclosed. The fin includes a fin for use by a swimmer comprising a foot pocket adapted to receive a foot of the swimmer; a foil shaped blade extending from the foot pocket; composite hydrodynamic flex control framework configured to allow the blade to bend within a narrow range of angles of attack under a wide range of loads while enhancing hydrodynamic performance. The method comprises providing a fin comprising a foot pocket, a foil shaped blade, an aperture, and two living hinges positioned adjacent to foot pocket. The method also comprises bending the blade relative to the foot pocket about an axis that is nearer the heel of the swimmer to reduce centrifugal forces while controlling the bending of the blade by providing living hinges formed to increase resistance as kicking power increases.; This method additionally allows low drag kicking by a swimmer that is similar to walking in place with the swimmer's feet staying within the swimmer's slip stream.



US6482059
US7101240



Methods are disclosed for increasing lift and decreasing drag on hydrofoils and swim fins. Methods are disclosed for providing a hydrofoil with a substantially longitudinal recess or venting system located substantially along the center axis of the hydrofoil. Methods also include providing the attacking surfaces of hydrofoils 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. Methods are also disclosed for arranging a central recess or venting system to permit 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. Methods are disclosed for applying 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 also provided for 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.



GB746764



A swim-fin of resilient material comprises an envelope 10 for the wearer's foot and a paddle portion 12 extending beyond the said envelope, each side-edge of the fin being provided with an upstanding flange 15, 16, extending over the length of said paddle portion and at least partly over the length of said envelope, the paddle portion being formed with a plurality of furrows or corrugations 14 extending in an approximately longitudinal direction substantially from end to end thereof. The fin is completed by the provision of a heel strap 11. Although the fin shown is symmetrical in shape one side may be longer than the other the longer side being arranged on the outer side of the foot when the fin is in use. A hole is provided in the bottom of the envelope for drainage purposes.



GB749221



In a swim-fin comprising a fin portion, stop means for limiting forward movement of the foot over the fin portion and attachment means engaging the foot or ankle to restrain separating movement between the foot and the stop means, a bridge-piece of flexible material defines with tne nn portion an open-ended pocket for the reception of the wearer's toe3 and/or adjacent part of the foot. and the stop means comprises a pillar or pin or the like projecting between the bridgepiece and the fin portion to be received between the great toe and the adjacent .toe when the swim-fin is worn. The fin shown comprises a fin portion 10 having integrally moulded therewith a bridgepiece 11 and toe-engaging pillar 12 together with a separately formed adjustable foot encircling strap 13 and a separateiy formed adjustable ankle strap 14. The fin 10 is formed with ribs 18, 19, 20, 21, 22, edged with beading 31, and provided with two openings 23, 24, beneath the bridge-piece. Slots 25, 26, 27, 28, 29, and notches 32, 33, at the inner edges of openings 23, 24, respectively, for the reception of strap 13, are provided in the bridge-piece 11 and fin 10. Slots 34, 35, are formed in the bridge-piece for the reception of strap 14. The hn is fitted to the foot as shown in Fig. 6 the strap 13 being passed through slots 25, 27, 29, 28 or 25, 27, 33, 32, or 26, 27, 29, 28, depending upon the size of the wearer's foot. The strap 13 is buckled by engaging a head portion 37 formed at one of its ends with one of a series of slots 38 formed at its other end. Slots 38 are formed at both ends of strap 14 and for connection to the slots 34, 35, connecting links 41 comprising head portions 43, 44 and strap portion 42 (Figs. 11, 12) are used each link being passed through a slot 38 and either slot 34 or 35. The fin portion 10 may be moulded of thermo-plastic material of such stiffness and resilience that when a wearer of the fin wa:ks in air at a speed between one and four miles per hour the fin portion becomes bent as the wearer's weight is transferred to the toe of the foot in the action of walking, and does not return from its bent shape to its flat shape in less than two seconds which is sufficient time for the wearer to return that foot to the ground again. The thermo-plastic material may be polyvinyl chloride having a British Standard hardness of be- .tween 3 and 40. Polyethylene having the required properties may also be used. In a modified fin the fin portion may comprise metal strengthening ribs either embedded between two sheets of thermoplastic material or moulded within a single sheet. Specification 749,204 is referred to.



US4209866



A swim fin which achieves increased efficiency by increasing drive (forward propulsive thrust) and decreasing effort (resistance to vertical motion) to provide a greater drive-to-effort ratio. The blade of the fin which is pivotally mounted to the foot section along a pivot line aft of the leading edge of the blade, has a reversible effective streamlining camber. These features in combination with a large open flow passage defined between the toe portion and blade make possible the attainment of efficient propulsion through vertical motion of the legs of the wearer of the swim fins.



US6146224


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.






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