GB2035106A - Catapult - Google Patents

Abstract

A catapult, preferably for launching fishing bait, comprises a frame (1) having spaced-apart arms (2), an elastic member (15) being attached to anchor members (7) mounted in arms (2) for rotation about parallel axes which are perpendicular to the length of the respective arm. The anchor member may have a loop (8) joined by a shank (7) to a ball held in a bearing cup mounted in a stepped bore (3) in the arm (2). <IMAGE>

Description

SPECIFICATION Improvements in or relating to a catapult This invention relates to catapults and more particularly to a method of mounting and attaching the elastic therefor to the arms or forks of the catapult.

It is common problem with catapults that after firing, the elastic becomes twisted or tangled because the pouch attached thereto for launching the projectile does a somersault about an axis passing through the points of attachment of the elastic to the catapult forks.

As a result, it can be inconvenient before using the catapult to have to unravel the twisted elastic.

Another problem with catapults is that the elastic is usually fitted directly into a hole in each catapult fork, either directly or in a bush located therein, the elastic being knotted on the other side of the fork to prevent it from pulling back through when the elastic is tensioned during launching. Repeated use of the catapult results in the elastic abrading on its mounting in the catapult fork and subsequently severing. As the elastic often has to be a tolerance fit in its hole in the fork to prevent the knot from pulling through during use, this tends to exacerbate the problem of abrasion.

Another problem with catapults is that because the hole in the fork in which the elastic is fitted tends to be of a smaller diameter than that of the elastic, it can be difficult to thread the elastic through the hole during assembly or replacement.

It is an object of the invention therefore to provide a method and means for mounting a catapult elastic which overcomes or at least substantially reduces these disadvantages.

According to one aspect of the invention there is provided a method of attaching a catapult elastic end to a catapult frame comprising releasably attaching said elastic end either directly or indirectly to an anchor point mounted in the frame for rotation about the axis of the elastic.

Preferably, each elastic end is not directly attached to its respective rotatable anchor point but instead is releasably attached to a flexible inextensible link member which is itself attached to the anchor point. Conveniently, said link member is a continuous loop of string or similar material which is connected to the elastic end by means of a clovehitch or other suitable, preferably cinching, knot. However, a single length of string could be used if desired, each end being suitably attached to the elastic end and the anchor point by an appropriate knot.

Other features and advantages of the invention witl become apparent from the following description of a preferred embodiment, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a catapult showing the method of connecting the elastic to the frame on one side only for ease of illustration, and Figure 2 is a cross section through the end of one fork of the frame of Fig. 1 showing the anchor to which the elastic end is attached.

Referring to the drawings, there is shown in Fig. 1 a catapult frame 1 made of any suitable rigid material such as a metal alloy, wood or a synthetic plastics material or a combination thereof. In the following description, the frame is made of a metal alloy.

The frame 1 has a pair of forks 2 each of which is provided with a through bore 3 having a first portion 4 of a larger diameter than a second portion 5. A bearing cup 9, preferably of a material suitable for use as a bearing material such as brass, polyacetal or nylon is a press fit in the bore portion 4, said cup having a central opening 6 therein through which passes shank 7 of a swivel or anchor 8, the shank having a bead 10 at its end end inside the bearing cup 9 which seats in the bottom of the cup on the periphery of the central opening 6, and an eye 11 at its other end. It should be noted that the maximum width of the eye 11 is less than the diameter of the second bore portion 5 to permit its insertion therethrough. In some arrangements it may be possible to omit the bearing cup altogether or alternatively the cup 9 may be made of metal.Furthermore, it may be possi ble ble to simplify the construction, by omitting portions 1 2 of the bearing cup which keep the bead 10 therein.

With the construction illustrated, it will be seen that each eye 11 is able to rotate in the direction of arrow A (see Fig. 1) i.e. about the axis of its shank 7. It is also free to move laterally within the limits of the bore portion 5.

As can be seen from Fig. 1, elastic 1 5 is connected at each end 1 6 (only one is illustrated) to the catapult frame 1 by means of a flexible inextensible link 1 7. In the illustrated embodiment this comprises a piece of natural or synthetic string or cord, the ends of which are connected together in any suitable fashion but preferably by a metal sleeve 1 8 which is crimped to retain the string ends therein (these are known as Legal or Treasury tags).

Instead of using a Treasury tag as illustrated it may be possible to use some other form of continuous loop, for instance formed from a length of synthetic cord whose ends have been fused together or a loop formed by stamping it from a sheet of suitable material, e.g. synthetic plastics sheet.

Each link 1 7 is attached to its eye 11 by passing one end of the loop through the eye 11 and then feeding said end back through the bight left by the remainder of the loop to form cinching knot 20. The other end of the loop 1 7 is then folded back on itself to form a pair of loops 25, 26 through which the end 1 6 of the elastic 1 5 is inserted whereby a self-tightening clove-hitch or cinching knot 21 tightly grips the elastic end 1 6 and indeed grips it more tightly on extension of the elastic.

It will be seen that with the illustrated arrangement, due to the pivoting of the eyes 11, the elastic can no longer become twisted in use because any twisting results in the eyes being rotated by the twisted elastic thereby untwisting it. Also the use of the link members or loops 1 7 allows the elastic ends 16 to be quickly and simply attached to the frame by inserting them into loops 15, 26. Thus there is no longer any need as in the prior art to push the elastic ends 1 6 through holes in the forks and knot the free ends to prevent them pulling back through in use so time is saved.

Claims (11)

1. A method of attaching the ends of an elastic member of a catapult to a catapult frame, comprising releasably attaching each end of said elastic member, either directly or indirectly, to a respective anchor member, each of said anchor members being mounted in a respective arm of the catapult frame for rotation about an axis perpendicular to the length of said arm, said axes being mutually parallel.

2. A catapult including an elastic member having each of its ends attached, directly or indirectly, to a respective anchor member, each of said anchor members being mounted on a respective arm of a catapult frame for rotation about an axis perpendicular to the length of said arm, said axes being mutually parallel.

3. A method in accordance with claim 1 or a catapult in accordance with claim 2 wherein each said anchor member has a shank provided at one end thereof with an eye and having at the other end thereof a bead rotatably received in a stepped transverse bore in a said arm, said bore having a wider portion rotatably receiving said bead and a shank portion through which said shank extends to said eye.

4. A method or catapult in accordance with claim 3 wherein said wider portion of said stepped bore contains a bearing cup receiving said bead.

5. A method or catapult in accordance with claim 4 wherein said bearing cup is formed of brass, a polyacetal or nylon.

6. A method or catapult in accordance with any one of the preceding claims wherein each said end of said elastic material is attached to the eye of a respective said anchor by an endless link of flexible, inextensible material knotted about said eye and said end.

7. A method or catapult in accordance with claim 6 wherein said link is formed of a string or cord of natural or synthetic material.

8. A method or catapult in accordance with claim 7 wherein the ends of a length of said string or cord are connected together by a metal sleeve crimped thereon to form said link.

9. A method or catapult in accordance with claim 6 wherein said link is stamped from a sheet of plastics material.

10. A catapult substantially as herein described with reference to the accompanying drawings.

11. A method of attaching the ends of an elastic member of a catapult to a catapult frame, substantially as herein described with reference to the accompanying drawings.