Patent application title: Reverse thrust swimming flipper
Gerardo Oscar Martinez (Laredo, TX, US)
IPC8 Class: AA63B3111FI
Class name: Swimming aid to increase stroke efficiency foot attached flipper
Publication date: 2012-11-15
Patent application number: 20120289105
The Reverse Thrust Flipper is a swimming flipper similar to a regular
swimming (scuba diving, exercise, recreational) flipper that has the
function of generating thrust in the opposite direction to the swimmers
direction. The purpose of this flipper is to allow the swimmer to
exercise without the need of a large body of water. The flipper's reverse
thrust reduces de forward movement while still requiring the swimmer to
exert the same amount of work. Its oscillating fin makes it possible to
produce the reverse thrust in both the upward and downward leg strokes,
thus maximizing the work out and enabling a simulated forward swimming
1. An aquatic foot flipper that produces a reverse thrust to the swimmer
allowing him to exercise with diminished forward movement. The use of
which enables the swimmer to transform the energy delivered to the
flippers trough the leg strokes into a water flow thrust that is opposite
in direction to the swimmers direction. This thrust generates a force
opposite to the direction of the forward-moving resultant force created
by the legs and arm motion in customary swimming. The cancelation of
these forces results in a decrease or elimination of forward movement.
2. The aquatic foot flipper according to claim 1, redirects water flow thrust, generated by the leg strokes, towards the direction of the swimmers heading.
3. A water contact fin that is hinged, by means of a flexible hinge or a pined hinge, to the end of a swimming flipper that allows the flipper assembly to redirect the flow of water in a direction opposite to a conventional flipper.
4. A water contact fin that is hinged, by means of a flexible hinge or a pined hinge, to the end of a swimming flipper according to claim 3, that allows movement of the fin in an upward and downward direction as to redirect the flow of water during downward and upward leg strokes without having to modify the flipper assembly.
5. The use of non permeable flexible membranes or film to connect the lateral sides of a hinged water fin to a flipper assembly so as to create a cavity and constrain the water flow created from a leg stroke in a direction opposite to the heading of the flipper (swimmer).
6. The use of non permeable flexible membranes or film to connect the lateral sides of a hinged water fin to a flipper assembly according to claim 5, so as to control de range of movement of a back hinged moving fin while allowing it to move freely during the transitional movements of the fin.
7. A rigid frame connecting a water shoe to a hinged moving (oscillating) fin and side flexible membranes with a minimal contact area that reduces the forward water thrust and transfers the forces from the shoe (swimmer) to the fin and the reacting forces from the fin to the shoe (swimmer).
BACKGROUND OF THE INVENTION
 The Reverse Thrust Swimming Flipper is an aquatic device that increases the stroke efficiency while inverting the direction of the thrust produced by the stroke. It is secured to the foot of the swimmer and includes a semi-flexible and oscillating water-contacting surface resembling webbed feet in appearance but reverse in operation.
 Regular flippers have been developed for exercise purposes but they have the disadvantage of requiring a large body of water. This, because of the increased speed the swimmer acquires when using them. Other products have tried to reduce the size or modify the shape of the flipper to diminish the speed; this also reduces the resistance in the leg strokes. This, in turn, reduces the amount of resistance the swimmer exerts with each stroke and thus reduces the effectiveness of the exercise.
BRIEF SUMMARY OF THE INVENTION
 The main idea of the reverse thrust flipper is that through its reverse thrust the swimmer can effectively simulate the use of regular flippers for exercising and not have to have a large body of water. The exercise cessions can be done in smaller pools, rehabilitation tanks, lap pools, or other aquatic facilities.
 With each leg stoke the swimmer (using reverse thrust flippers) produces a force opposite to the direction of regular swimming flippers. This force counters the forward-moving resultant force created by the legs and arm motion in customary swimming. The result of the opposite forces canceling is the need of less or no distance to be traveled to exert the same amount of work (exercise).
BRIEF DESCRIPTION OF THE DRAWINGS
 Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
 FIG. 1 shows a perspective view rendering of a reverse thrust swimming flipper that indicates the main parts of the flipper assembly according to one embodiment of the present invention.
 FIG. 2 shows a plan view rendering of a reverse thrust swimming flipper that indicates the parts of the fin section of the flipper assembly according to one embodiment of the present invention.
 FIG. 3 shows a side elevation rendering of a reverse thrust swimming flipper that indicates the parts and range of motion of the flipper assembly according to one embodiment of the present invention.
 FIG. 4 shows an inverted side elevation rendering, depicting the flipper in use, of a reverse thrust swimming flipper that indicates the pressure acting on the fin and thrust and water flow produced by the flipper during an upwards leg stroke.
 FIG. 5 shows an inverted side elevation rendering, depicting the flipper in use, of a reverse thrust swimming flipper that indicates the pressure acting on the fin and thrust and water flow produced by the flipper during a downwards leg stroke.
DETAILED DESCRIPTION OF THE INVENTION
 The Reverse Thrust Swimming Flipper is a swimming flipper similar to those worn by scuba divers. The difference with these flippers is that instead of increasing the forward thrusts of the swimmer, they do the opposite by generating reverse thrusts with every movement of the user's legs. Similar to the way a jet airplane reverses the direction of the turbines after landing by redirecting the flow of air.
 The Reverse Thrust Flipper is composed of two sections. See FIG. 1. The first is the Shoe section and the second is the Fin section. The Shoe section is similar to regular swimming flippers with full foot or open heel configuration. The Fin section, object of this patent, is divided into several components as shown in FIG. 2.
 The part of the Fin that produces de reverse trust is the Oscillating Fin. See FIG. 2, and FIG. 3. It is attached to the end of the flipper, opposite of the shoe, through a hinged connection (Hinge). The Oscillating fin has free angular movement, up and down, with respect to the flipper. See FIG. 3. The Oscillating Fin is made of semi-rigid material to allow for some deflection caused by movement while in use. It is however rigid enough to transfer the pressure created by the leg strokes to generate a controlled water flow. The Oscillating Fin is connected on its lateral sides to a flexible non permeable Membrane that allows the Oscillating Fin to move freely but does not allow the water, trapped in the cavity that is formed, to exit though the sides of the Fin. See FIG. 4 and FIG. 5. The membranes also set the Oscillating Fin's maximum range of movement (the Upper Oscillating Fin Position and the Lower Oscillating fin Position), as shown on FIG. 3, and transfer the swimmer's force to displace the Oscillating Fin and generate the reverse thrust. The flipper has two Side Stability Ribs and one End Stability Rib, they are the structural components of the flipper. Their purpose is to hold together the moving parts and to transfer the force of the Fin to the Shoe without adding substantial contact area as to produce unwanted forward moving thrust.
 The flipper produces reverse thrust during the upward and downward leg strokes, during swimming. This is because the Oscillating Fin changes position with each change in direction of the leg stroke. When the swimmer's leg pushes upward, water pressure on the top side of the Oscillating Fin causes it to resist upward movement. See FIG. 4. As the flipper moves upward it gets to a point where the Membranes (which are connected to both the Oscillating Fin and the Side Stability Ribs) tense and then begin to pull on the Oscillating fin. At this point further flipper upward movement creates a cavity of water that has only one exit towards the back of the flipper (towards the shoe). The flow of water creates a thrust that produces a force opposite to the swimmer's direction. When the swimmer's leg pushes downward, the same effect happens but with the Oscillating Fin changing to the Lower Oscillating fin Position. See FIG. 5.
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