WO2014194339A2

WO2014194339A2 - Blade arrangement for a diving fin

Info

Publication number: WO2014194339A2
Application number: PCT/ZA2014/000018
Authority: WO
Inventors: Rhys James Couzyn
Original assignee: Rhys James Couzyn
Priority date: 2013-04-12
Filing date: 2014-04-11
Publication date: 2014-12-04
Also published as: WO2014194339A3; ZA201507836B

Abstract

A dive fin comprising a blade extending from a foot pocket, the inner portion of the blade comprising a flap capable of independent movement in relation to the body of the blade when the blade is placed under pressure.

Description

BLADE AR ANGEMENT FOR A OIVI G FM

This invention relates to a diving fin having a self-adjusting angle of attack.

Back roy^d to the I

Divers use fins to move through water efficiently as huma feet being very small, provide relatively poor thrust, especially when the diver is carrying equipment that Increases hydrodynarme drag. A standard fin includes a foot pocke for accommodating the diver's foot, and a blade extending from the foot pocket, for providing thrust as the ^'diver kicks.

The basic principal of finning is that the diver uses his legs to push the blade of the fin, the blade pushes the water and, in turn, the diver is propelled forward. Types of fins have evolved to address the unique requirements of each community using them. Scuba divers, in particular, need large wide blades to overcome the wate resistance caused by their diving equipment..

Research and development on the dive fin has typically focused on providing the diver with a fin that provides the diver with a powerful kick in the most efficient manner. Patent US 8520816 provides an example of such a fin.

As the diver kicks, the water forces the fin blade to deflect relative to the foot pocket. This creates what is known as the angle of attack. This angle of attack will influence to what degree a downward or upward kick will translate into tow rd motion, One of the main concerns facing developers is to achieve a correct "angle of attack" over a variety of kicking actions. The - ngle of attack" is the relative angle between the actual alignment of the oncoming flow (a vector of the flow created by the upward or downward kicking motion a d the flow created by the forward motion of the swimmer) and the lengthwise alig ment of the blade of the fin. With traditional fins, when a diver kicks gently a small blade deflection occurs, which results in a steep angle o attack. Counter intuitively, this steep -angle of attack results in high resistance to the kicking actio (high diver effort), and favours high thrust generation (provided that a certain minimum level of blade deflection occurs). As th diver kicks harder- In an attempt to increase speed, the deflection of the blade increases, which lessens the angle of attack thus, again coynter-intuiively, reducing resistance to the kicking action and also causing the fi to generate proportionatel less forward thrust, in effect, the harder the diver kicks in an attempt to gain more thrust, the less resistance he encounters and the less proportional thrust he achieves. This is the opposite of what is desirable as a relaxed diver wishing to swim slowly actually desires less resistance and will accept lower thrust while a hard-kicking diver, wishing to swim faster, will desire more thrust and wlli accept higher resistance.

Certain current technologies such as that embodied In US4944703, seek to address this problem by fixing the angle of attack to a predetermined value, irrespective of kick strength. This is usually achieved by using some form of limiting means to restrict the blade deflection. While this technology partly addresses the abovementioned problems, two limitations remain.

Firstly, a fixed blade angle provides a constant trade-off between comfort (low angle of attack and resistance) and thrust (higher angle of attack). The fin is not able to change its properties to suit the exac diver or circumstances.

The second limitation of current designs is that at best, the angle of the blade is fixed relative to the diver and not relative to the actual oncoming flow. As the diver moves faster through the water, the apparent oncoming flow is increasingly from the front, whereas for a static diver, the oncoming flow is entirely from the bottom. The effect of this shift in (vector-based) apparent oncoming flow is that the actual angle of attack effectively reduces the faster the diver swims. Certain diving fins include further attached moveable members, specific in configuration, for assisting in increasing the performance of the fm during use. US2008002S027 provides for an improved swim fin- having at least a pair of triangular, shaped movable members disposed on the fin blade thereof. When kicked under water, the movable members are capable of wiggling independently and respectively so as to generate more lift b enhancing more water to be project from the trailing edge of the fin blade thereof. The movable members are furthermore capable of reducing the drag and turbulence exerting on the same by the water flow which will reduce the diver's fatigue and subsequently extend the swimming time and range.

There are further methods of increasing performance of a diving fin including an arrangement providing for the increased flow of water through the fin to allow for the forces of two jet streams of water to propel^' the diver in a chosen direction. US570227? provides for a blade having a scoop section designed to take In water at the top of the fin near the foot and discharge the water at the blade tip. The scoop section also channels the water to eyelet ports cut into the fi blade, enabling it to discharge water out and over the bottom surface of the fin biade while at the same time releasing it at the blade tip.

It is an object of this invention to provide a dive fin which, at least partially; alleviates any problems or drawbacks in current diving fin designs.

Summary of the Inv nt jon in accordance with this invention, there Is provided a dive fin comprising a blade extending from a foot pocket, the inner portion comprising a flap capable of independent movement in relation to the body of the blade when the blade is placed under pressure.

The flap may be connected to the blade along th trailing edge of the biade.

There Is further provided for the independent movement of the flap, in relation to the body of the blade, under pressure to result in an increased angle of attaek concurrent with the increased strength of the diver's kick. The flap may additionally be connected to the body of the blade by connection means beatable along the perimeter of the fap .

The connection means may include one or more strips of eiastorneric material, !ocatafoie between the flap and the body of the blade, for connecting the flap to the blade at localised points.

Alternatively, the connection means may include an eiastorneric membran iocatafote etween the flap and the body of the blade for connecting the flap to the blade along its entire perimeter

The connection means are intended to^■ limit the independent movement of the flap.

The fin ma additionally include support ribs extending from the foot pocket along the length of the blade. The support ribs may either extend along the outer edges of the blade, or may extend aieng the interior of the blade, between the flap and the body of the blade.

The blade may also be attached to the foot pocket by an articulated joint or hinge, Including a biasing system to prevent the hinge from moving past a predetermined limit.

The blade may fee manufactured from one or more resilient yet flexibl plastic materials, such as thermoplastic elastomers, and rigid plastic or composite panels may also be incorporated.

Brief ^'Description of ttm Srawirsas

A preferred embodiment of the invention is described below by way of example only and with reference to the following drawings, In which;

Figure 1 is a representation of a first embodiment of the invention applied to a traditional fin;

Figure 2 is a representation of a second embodiment of the invention applied to a traditional fin; Figure 3 Is a representation of the first embodiment of the invention applied to a different fin design:

Figure 4 is a representation of the second embodiment of the invention applied to a different fin design;

Figure 5 is a representation of a third embodiment of the invention;

Figure 6 is a representation of a fourth embodiment of the invention;

Figures 7 to 10 show one embodiment of the fin in use.

Detailed Description of the I nventio n

Referring to figures 1 to 8 in which like features of the invention are indicated by like numerals;

The dive fin 10 includes a blade 12 extending from a foot pocket 14. The Inner portion of the lade comprises a flap 16 capable of independent movement in relation to the body of the blade when the blad 12 is placed unde pressure. The flap 18 is connected to the body of the blade 12. along the trailing edge of the blade, situated furthest from the foot pocket 14.

Referring to figures 1 to 4, the flap 16 may be surrounded by the body of the blade 12 on all sides. Alternatively, and referring to figures 5 and 6, the flap 18 may extend almost into abutment with the leading edge 19 of the blade closest to the foot Docket 14.

Referring to figures 1, 3 and 5. the flap 16 is connected to the bod of the blade 12 by an eiastomeric membrane 20 located between the flap 16 and the body of the blade 12.

Referring to figures 2, 4 and 8 and in an alternative embodiment of the invention, the flap 16 is connected to the body of the bfede along Its length by a plurality of strips of eiastomeric material 22, located between the flap 8 and the body of the blade 12. β

The connection means 20 or 22 are intended to limit the Independent movement of the flap 16,

Referring to figures 1 to 6, the fin 10 may additionally include support ribs 2 -extending from the foot pocket. Referring- to figures 1 and 2, these support ribs 24 may extend along the outer edges of the blade. Alternatively, and referring to figures 3 to 6, the support ribs 24 may extend along the interior of the blade, between the flap 16 and the body of the blade 12.

Referring to figure 7, the blad 12 ma also be attached to the foot pocket by an articulated joint or hinge 26, including a biasing system 28 to prevent the hinge from moving past a predetermined limit.

If Is envisaged that the blade 12 will be manufactured from one or more resilient yet flexible plastic material?-,, such as thermoplastic elastomers, and that rigid plastic or composite panels may also be incorporated.

In use, and referring to figures 7 to 1.0, as the diver kicks harder, the blade 12 deflects to a degree. The eiastomeric -membrane 20 or eiastomeric strips 22 connecting the fla 16 to the body of the blade 12, stretch under pressure, allowing the flap to deflect independently of the blade. The membran or strips limit and control the amount of deflection that the flap is capable of.

The independent movement of the flap 16 under pressure results in a Increased angle of attack concurrent with the increased strength of the diver's kick, meaning that as the diver kicks harder, there is an increase in resistance but more importantly, an Increase in the thrust generated.

Referring to figures 7 to 10 which show an embodiment of the fin that utilises an articulated hinge with limiting means, the angle of the main blade is fixed, regardless of kick strength. Under light kick strength (figure 8), the flap 16 does not deflec relative to th blade 12 so they share the same angle of attack. As the kick strength increases (figure 9), the flap 16 gradually deflects so that it presents a greater angle of attack. At maximum kick strength (figure 10), the flap 16 reaches the limit of its deflection, dictated by the membrane 20 or eiastomeric strips 22, so as to prevent an excessive angle of attack that would prevent effective thrust generation. The fin 10 therefore automatically adjusts the angie of attack to suit the circumstances, ft allows for low resistance (and lower thrust) when the diver is swimming gently and then, in a continuously variable manner, adjusts to provide greater thrust (and resistance) as the diver aims to swim faster, it therefore also self-compensates for the changing direction of apparent oncoming flow.

Numerous modifications to this embodiment are possible, without departing from the scope of the invention.

The invention therefore provides a novel dive fin.

Claims

CLAMS:

1, A dive fin comprising a blade extending from a foot pocket, the inner portion of the blade comprising a flap capable of independent movement in relation to the body of the blade when the blade is placed under pressure,

2, A dive fin as claimed in claim 1 characterised in that the flap is connected to the blade along the trailing edge of the blade,

3, A dive fin as claimed in any one of claims 1 or 2 characterised in thai the flap moves independently in relation to the body of the blade when under pressure to result in an increased angle of attack concurrent with the increased strength of the divers kick.

4 A dive: fin as claimed in any of the preceding claims characterised in that the flap is connected to the body of the blade by connection means loeatabie along the perimeter of the flap.

5, A dive fin as claimed in date 4 characterised in that th connection means includes one or more strips of elastomeric material, locaiable between the flap and the body of the blade, for connecting the flap to the blade at localised points.

8. A dive fin as claimed In claim 4 characterised .in that the connection means includes an elastomehc membrane loeatabie between the flap and the body of the blade for connecting the flap to the blade along its entire perimeter.

7, A di e fin as claimed in an on o claims 4 to 8 characterised in that the connection means are Intended to limit the independent movement of the tap.

8, A dive fsn as claimed in any one of the preceding claims characterised in that the fin includes support ribs extending from the foot pocket along the length of the blade.

9, A dive fin as claimed in claim 8 characterised in that the support ribs extend along the outer edges of the blade ,

10. A div fin as claimed In claim 8 characterised in that the support ribs extend along the Interior of the blade, between the flap and the bod of the blade.

11. A dive fin as claimed in any of the preceding claims characterised in that the blade is attached to the foot pocket by an articulated joint or hinge limiting the movement of the blade.

12. A dive fin as claimed in any of the preceding claims characterised in that the blade is attached to the foot pocket by an articsjlated joint or ^'hinge which is resiiiently deformable.

13. A dive fin as ciaimed in an of the preceding claims characterised in that the blade is attached to the foot pocket by an articulated joint or hinge, including a biasing system to prevent the hinge from moving past a predetermined limit.

A dive tin as ciaimed in any one of the preceding claims characterised in that the •blade is manufactured from one or more resilient yet flexible plastic materials, such as thermoplastic elastomers, and rigid plastic or composite panels may also be incorporated.