WO1994009877A1

WO1994009877A1 - Throw and fly device

Info

Publication number: WO1994009877A1
Application number: PCT/FI1993/000437
Authority: WO
Inventors: Jukka Petri Kaisio; Jari Kalevi Kukkonen
Original assignee: Jukka Petri Kaisio; Jari Kalevi Kukkonen
Priority date: 1992-10-27
Filing date: 1993-10-26
Publication date: 1994-05-11
Also published as: FI930676A0; FI930676A; AU5179093A; FI93426B; FI93426C

Abstract

A throw and fly device used as a toy, for recreational purposes and as sporting equipment. In a device constructed according to the present invention the base-part (1), the axle (2) and the flange (3) form a spool for the string (4). When thrown the device glides and the string (4) unwinds from the said spool accelerating the speed of rotation of the device. The energy thereby stored in the form of rotational movement returns the device back to the user and the device is ready for a new flight.

Description

Throw and fly device

This invention is a throw and fly device which returns to the person throwing it. The device may be used as a toy, for recreational purposes and as sporting equipment.

An existing device which in some degree resembles this invention is the so-called yo-yo, a relatively heavy apparatus which returns to the user by means of a string fixed to its axle and freely winding around it. The maximum length of a yo-yo string is about one meter, one end of which is attached to the user's finger. When the fully wound yo-yo is released, the string from the reel formed by the yo-yo unwinds. Thereupon the potential energy released due to the action of the force of gravity is converted into energy of motion, dividing into rotational and to some extent also into translational kinetic energy which acts in a direction parallel to that of the unwound string. Most of the converted energy is stored as rotational movement. As the string unwinds to its full length, the yo-yo continues to rotate, thereby reeling up towards the user, its rotational momentum acting against the force of gravity. A yo-yo does not glide on the air and the essential directions of its movement are parallel to the direction of the force of gravity.

Another device somewhat resembling the present invention is the saucer shaped flying disc, for example US Pat. No. 3,359,678, Headrick et al. This is an object symmetrical with respect to its upright axis. Stabilized by its rotation around said axis it flies translationally and is supported by air, wherein it operates as an airfoil. As it does not return to its user, for satisfactory use it usually requires at least two users who throw the disc to one another. Using this sort of a device alone is frustrating, as one must fetch it after each throw.

An earlier existing device which endeavours to solve this problem is presented in US Pat. No. 3,802, 117 by Engelhardt. In its basic form this device consists of a flying disc reel attached to a string which is fastened at its other end to a casting wand. Although this kind of apparatus may be operated single-handedly, such operation is rather difficult. As the reel is positioned beneath the disc and at a distance relatively remote from it, the device tends to dive very easily when the string tightens during flight. The solution proposed in the cited patent publication is an additional weight added to the lower end of the reel - this, however, reduces the usable length of the string.

An attempt has been made to solve the problems of the preceding device in publication WO 92/11913 by Tomberlin. This flying toy consists of two identical rotary elements furnished with wings joined by an axle around which a string is wound. Due to this structure the toy loses the fascinating flight-properties of a flying disc: the lift- producing wings occasion considerable deceleration and drag in flight. Such a toy lacks the elegance of a flying disc.

An additional flaw in all known solutions employing any kind of string arrangement is the inability to resolve their fully-developed aerodynamic properties. Each of these solutions contains excessively prominent components, reels and such like, occasioning heavy air-resistance and, in particular, leading to turbulent air flow.

These and other limitations encountered in the field are avoided in the configuration favoured by the present invention, wherein an aerodynamically favourable and visually clear-cut form is achieved. The present invention is characterised by the claims appended hereto.

By contrast with the yo-yo, the throw and fly device glides supported by air. Further differing from a yo-yo, which mostly converts a difference in gravitational potential energy, the energy of motion of the throw and fly device is almost exclusively furnished by a horizontally-directed throw. The kinetic energy of the throw is converted into sufficient rotational momentum to return the device to its user. A device applying the present invention can be constructed in a streamlined and aerodynamic form. Such constructions are clear-cut, aesthetically pleasing and simple. In this respect the present invention makes a breakthrough, overcoming the drawbacks of Engelhard 's device. The location of the string in relation to the centre of gravity is also a notable improvement over Engelhardt's device. These improvements contribute significantly to the flight-performance of a device constructed according to the present invention. Furthermore it is an advantage of the present invention that it harmonises two familiar, even cherished ideas: the yo-yo and the flying disc; encouraging the user to form a mental image of how the invention functions and thereafter to try it for himself. The gliding flight of a throw and fly device is visually intriguing and mastering it is both a challenging and edifying experience.

The following description refers to the accompanying drawings, in which:

FIG.1 is a side view of one possible embodiment of the present invention without a string.

FIG.2 is a partially cross-sectioned top view of one embodiment of the present invention.

FIG.3 is a top view of one possible embodiment of the axle of the present invention.

FIG.4 is a top view of another embodiment of the axle of the present invention.

FIG.5 is a cross-sectional side view of the axle in FIG.4

FIG.6 is a cross-sectional side view of a part of yet another possible embodiment of the present invention.

FIG.7 is a cross-sectional side view of one possible embodiment of the flange of the present invention.

FIG.8 is cross-sectional side view of one embodiment of the flange of the present invention.

FIG.9 is a cross-sectional side view of a part of the flange similar to the one presented in FIG.8 but in a different embodiment.

FIG.10 is a schematic top view showing the air current around a flying device constructed according to the present invention. FIG.11 shows a top view in identical circumstances to those in FIG.10, but the device employs a embodiment other than that of FIG.10.

FIG.12 shows a side view of the situation illustrated in FIG.10.

FIG.13 shows a side view of the situation illustrated in FIG.11.

FIG.14 is a partially cross-sectional side view of a possible embodiment of a detail which may be incorporated in the present invention in order to prevent excessive twisting of the string.

In figures 1 and 2, the throw and fly device constructed according to the present invention includes a base-part 1 which, as with the whole device, is made of a suitable polymer, for example polyethylene or polypropylene. Materials other than polymers may also be used. The base-part 1 , an axle 2 and a flange 3 substantially coaxial with the symmetry-axis of the base-part form a reel for the string 4. The term "string" is used here in a loose sense to include strings, braids, bands, ribbons, plaits, strands, lines, cords or any other corresponding flexible material. The base-part 1 is loosely convexo-concave so that the rim 12 extending downwards from the circular plate-area 11 forms a hollow beneath the plate-area 11. This plate-area is either level or slightly conical in either direction. The flange 3 is mounted on the convex side of the base-part 1 providing for smooth and unhindered reeling of the string 4.

The throw and fly device realised as in figure 2 is thrown by hand in the manner of a flying disc, thereby imparting some rotational motion, clockwise in the case of figure 2, while it is simultaneously flung firmly forward. The string 4 is attached to the user's hand, for example by tying a loop around the wrist.

During the flight upwards on the paper in figure 2 the energy imparted by the throw further accelerates the spinning device in a clockwise direction. With a relatively thick string, a change in the depth of the unreeled string for each rotation is achieved, thereby accelerating the spin of the device after release. This is an essential point, as by adjusting the thickness of the string and the angular momentum of the device in this manner, the energy of the throw is gradually converted into the spinning motion of the device which acts as a flywheel, this energy being utilized during the returning flight.

By the time the string has entirely unwound from the reel, the translational speed has fallen and without any noticeable jolt the device reverses its direction of flight and returns to the user by virtue of its rotational momentum. At the turning point the rate of rotation is high and the translational speed correspondingly relatively low because most of the kinetic energy is now stored in the form of rotational movement. This characterizes the present invention, whereby the loss of energy during the reversal of the direction of flight also remains small.

To effect the result described above it is essential, in the present invention, to select a thick enough string 4, to make the axle 2 quite short and to make the interstice of the flange 3 and the base-part 1 sufficiently small, for example 1-2 string diameters. In this case the string 4 spirals around the axle 2 as shown in figure 2, thereby effecting the intent of the present invention. The need to construct the device so that the centre of gravity lies above the string 4, or at least as close as possible to the level of the string, is most clearly seen at the point of reversal in the direction of flight. This ensures, particularly at the turning point, and allowing for some variation in flight speed and wind, that any inertia tending to change the aspect of the device, with the string 4 serving as its fulcrum, favourably influences the stability of the device and thus optimizes the return flight performance. If so desired, by shifting the centre of gravity significantly to the side of the flange 3 or otherwise exploiting the pendulous swing of the said centre at the turning point, a return flight at a large angle may be brought about, the device returning steadily and safely inclined against the air. In principle an additional weight might even be incorporated above the flange 3 or under the base-part 1 in order to effect these aims. A device constructed according to the present invention forms an airfoil which glides on the air, stabilized in flight by the spinning motion. The flange 3 is an essential part of the aerodynamic system. The string 4 is rigidly attached with respect to the axle 2, for example by means of a loop around it or in some other manner. By the time the throw and fly device described in the preceding example has returned to the user, it is ready for a new flight. This time the device is thrown forward, simultaneously imparting to it some spinning counter-clockwise motion. When throwing, it may be held holding the thumb outside and other fingers inside the base-part 1.

FIG.3 shows a possible embodiment of the axle 2, in which the symmetry is broken by a groove leading to the centre of the axle 2. Immediately following the point of change of direction of flight, either of the curved walls gradually increases the angular momentum and smooths the beginning of the returning flight. In figure 3 the string 4 is attached to the axle 2 by a knot 41 , and is propped by the walls of the groove. Otherwise the axle may be circular or at least more or less round. The walls of the groove may be circular in form, but other curves may also be applied. The essential point in embodiments employing this type of axle is that an adequate portion of the axle perimeter is left ungrooved. Thus a couple of revolutions of the device will substantially smooth out the symmetry.

In figure 4 there is a type variation of the axle in figure 3. The basic axle 21 and a low edge 22 are encircled by a freely revolving ring 23. The string 4 passes through a hole 24 in the ring 23 and is fastened to the axle 21 by a knot 41.

In figure 5 the same axle construction, or one of the same type, is illustrated from the side. The numbering follows that of the preceding example. The edge 22 is sufficiently low to allow unrestricted lateral movement of the string, yet high enough to support the ring 23 as it revolves. In principle the edge 22 may be built into either the flange 3 or the base-part 1 or both. Exploiting this construction it is possible to increase the angular momentum at the turning point of the flight even more gradually than in the construction represented in figure 3 and to maintain the circular periphery of the axle throughout the flight.

Figure 6 illustrates a embodiment in which the axle 21 provides a spool for a reduced diameter tail 42 of the string 4 so that the string 4 itself is supported by the spool-like function of the ribs 25. This type of embodiment enables the use of a thinner and lighter string 4, thereby extending the range of the flight. It is noteworthy that the same ends can be accomplished using the constructions in figures 4 and 5.

FIG.7 shows a embodiment of the flange 3 shaped in such a way that the upper surface forms an aerodynamic arch so that in small angles of flight the air-current mainly traverses the hollow 31 in the centre of the flange 3. The edges 33 of the hollow 31 rise upwards appropriately in order to bend down again forming a rim-area 34. A flange of this type may be constructed in an aerodynamic but lightweight manner. It can be injection moulded in a one-piece durable arched form. If so desired, the construction may also be covered.

Figures 8 and 9 illustrate two possible embodiments of a technical detail which enhances the reeling performance in negative angles of attack of a device constructed according to the present invention. In this case, especially during the latter part of the return flight, the device ascends. The plane of the flange 31 and the angle of the string 4, as shown in figure 8, together with the twisting of the string 4 due to inter-surface friction tend to impair the returning properties of the device. In figure 8 the edge of the flange 31 is encircled by a ring-like revolving element 32, these combining to form a bearing-action that resolves the above problem. In figure 9 the revolving element is mounted above the flange 31 and extends beyond it.

A throw and fly device flying to the right and spinning clockwise is shown in figure 10. In this embodiment of the present invention both the base-part 1 and the flange 3 are substantially homogeneous with respect to the surface level of hypothetical concentric circles extending throughout the radius of the device. Air-currents indicated by flow lines show laminar and turbulent flow, which properties should be compared with those shown in the next three illustrations.

Figure 11 depicts a embodiment according to the present invention with considerably enhanced flight performance. The downward-sloping surface-part 12 of the base-part 1 is furnished with part-spherical indentations which increase the friction between the base-part 1 and the air-current, thereby causing turbulence in the air flow. Given proper positioning and forms of the indentations, the laminar air-current continues further backwards, thereby reducing the overall drag and also reducing the Reynolds number of the device in an advantageous manner.

Comparing figures 10 and 11, the manner in which successful shaping, size, number and positioning of the dimples leads to a reduction in turbulence in the wake of the device may be observed.

In figure 12 there is a radially homogeneous surface-level construction, as in figure 10, whereas figure 13 illustrates a surface-construction similar to the embodiment in figure 11. Reducing the Reynolds number reduces the drag of the flying device while the fast-rotating periphery of the device brings about lifting force. Most of the lifting force acts on the stringless side of the device both during the outward and return flight. It is therefore possible to compensate for the lifting effect of the string, which remarkably improves the stability of flight. The reduction in air-resistance and the action of the lifting force on the upper surface of the device reduce the flight angle a, as can be observed by comparing figures 12 and 13. This reduces the frictional forces acting on the string 4 during unreeling, and if the embodiment is so constructed, also during the return flight. If the angle a is sufficiently small at the turning point a device constructed according to the present invention will return nicely to the user. The lift generated keeps the device essentially on a level path during the entire flight providing that it is thrown straight.

The benefits illustrated by referring to figures 10 to 13 can be achieved by incorporating indentations defined in shape by the surfaces of revolution of various curves, and by correct positioning of these indentations over the base-part 1 and/or on the flange 3. Projections or ridges of various shapes and modifications may also be used instead or in addition to indentations, either solely or in combination, provided that they cause turbulence around the spinning device. It must be noted that excessive turbulence increases air-resistance. These properties can be optimized depending on the intended use of the embodiment of the device concerned.

Figure 14 shows an example of a turning joint 5 with a pin 51 rigidly attached to a stem 52, rigidly fastened in turn to one end of the string 4. The other end of the pin 51 is thickened and, exploiting this feature, it is mounted inside the partially hollow stem 53 in a socket permitting free rotational movement around the pin 51. The assembly is constructed so as to simultaneously withstand pulling force and rotational movement while the friction remains sufficiently low. This kind of joint allows the string 4 to turn freely and can be used, if so desired, in different embodiments to enhance the reeling performance and to make it easier to wind the string by hand when preparing the throw and fly device for a throw. In such cases the string 4 otherwise tends to twist.

It must be understood that the invention is capable of considerable variation and modification without departing from the spirit of the invention. Therefore we do not wish to be restricted to the precise details of the constructions set out herein, but desire to avail ourselves of such variations and modifications as fall within the scope of the appended claims.

Claims

1. A returning throw and fly device comprising a substantially convex discoid base-part (1), axle (2) mounted on the convex side of the base-part (1) substantially on its perpendicular center-axis and parallel to it, and a flange (3) mounted substantially perpendicularly to, and at the top of the axle (2), with a string (4) or corresponding elongated flexible part attached to the axle (2) or its immediate proximity, characterized in that the length of the axle [2) being the same as or to some extent greater than the diameter of the string (4) , being reeled between the base-part [1) and the flange (3) and enabling the string to be wound about the axle (2) so that only approximately one circumvolution occurs at a given radius, the diameter of the flange (3) being not less than approximately one half of the diameter of the whole device.

2. A device according to claim 1, characterized in that the diameter of the flange (3) is at least 60% of the diameter of the whole device.

3. A device according to claim 1 , characterized in that at least part of the surface of the device is provided with surface deformations providing a means of air flow spoiling for a translationally moving and/or rotating device.

4. A device according to claim 3, characterized in that said deformations comprise projections on the surface of the base-part (1) and/or the flange (3).

5. A device according to claim 3, characterized in that said deformations comprise cavities on the surface of the base-part (1) and/or the flange (3).

6. A device according to claim 5, characterized in that said cavities on the surface of the base-part (1) have projections interior to the said cavities.

7. A device according to claim 1 , characterized in that the flange (3) also have a basically convex shape wherein there is a hollow central portion with a substantially flat bottom area.

8. A device according to any of the foregoing claims, characterized in that a freely revolving element (32) , adapted for connection either to the edge of the flange (3) or to the axle (2), the said element revolving in the process of reeling the string (4) in and out, when the string come

> to push against the said element (32).

9. A device according to claim 1, characterized by a rounded-off, walled groove internal to the axle (2), with the string (4) attached to the bottom of the said groove.

10. A device according to claim 9, characterized in that the axle (2) is encircled by a freely revolving ring (23) through which the string (4) passes.

11. A device according to claim 10, characterized in that at least one edge-like extension (22) of the axle (2) is faced the grooved sector of the axle and supporting the said ring (23).

12. A device according to any of the foregoing claims, characterized in that the base-part (1) and flange (3) have opposed ribs (25) supporting the string (4), but having an extension tail (42) of the string (4) passing through in order to be wound around the axle (2).

13. A device according to claim 1, characterized in that the string (4) being of a type that permits untwisting of the twisted string by means e.g. of a freely revolving joint (5) or corresponding feature.