FR2573446A1 - Towing cable of braided fibres for aerial target - has varying cross=sectional area - Google Patents

Abstract

A towing cable for an aerial target has a tubular or rectangular sheath of braided fibres, and is made of sections of different cross-sectional areas composed of different numbers of fibre bundles held together by fibres extending over more than one section. The fibres may be synthetic. The cross-sectional area of the cable pref. decreases from the aircraft end to the target end. A method of making the cable by cutting some of the fibres as they are braided is also claimed.

Description

 "Towing cable in particular for aerial target and its manufacturing process".

 The towing of an aerial target is ensured by a braided cable connecting the target to the towing aircraft. For flight safety reasons, the cable can be between 1000 and 1500 meters long.

In the take-off phase of the towing aircraft, the cable is coiled and thus forms an assembly which is bulky and heavy given its great length. Due to the size, the weight of the cable and the need to also house the target under the towing plane, it is necessary to use planes having one or more bulky containers and, consequently, having characteristics and possibilities different evolution of the planes having to practice the tests of shooting on the target

 The object of the present invention is to provide a towing cable which, at equal length, is lighter and less bulky and can be accommodated under an aircraft having characteristics similar to those of aircraft carrying out fire tests.

 To this end, this cable, of the type constituted by a sheath formed by braiding bundles of synthetic son and having a rectangular tubular section, is composed of sections which, having different sections from the end of attachment to the aircraft to the hooking end to the target, are differentiated by the number of bundles of wires constituting them and are interconnected by bundles extending at least over two successive sections.

 This cable combines, with the advantages coming from its rectangular tubular section, allowing it to carry out dense coils, without lost intervals as with cables of circular section, a gain in volume and weight coming from the variations in cross section of its last sections. Compared to a cable with cores, of circular section and of the same length, it provides a gain in volume of the order of 35% while having a higher resistance.

 In one embodiment, the sections have sections which decrease from the hooking end to the aircraft to the end of hooking to the target and are composed of bundles of wires whose number decreases.

 Thus, the cable has a maximum section in the immediate vicinity of the aircraft, that is to say in its zone undergoing a very large tensile force during the release of the target.

 The invention also relates to the method of manufacturing this cable consisting, during the braiding of the sheath constituting it, by means of a braiding machine, and after the running of each of the first nl sections to cut certain bundles of wires by balancing the peripheral distribution of the remaining beams.

 I1 emerges from the above that the cable can be manufactured by a traditional machine with an arrangement of the operating conditions thereof.

 The invention will be better understood with the aid of the description which follows with reference to the appended diagrammatic drawing representing, by way of nonlimiting examples, an embodiment of this cable composed of three sections of equal length and illustrating its phases Manufacturing.

FIG. 1 is a schematic plan view from above showing the cable in the position of use for towing a target behind an aircraft,
FIG. 2 is a side elevation view showing, on a reduced scale, its various sections,
FIG. 3 is a partial side view of the braiding machine ensuring the manufacture of the cable,
Figures 4, 5 and 6 are schematic plan views from above showing the distribution, on the braiding machine, of the spindles delivering the bundles of wires during the various phases of cable manufacturing.

 In FIG. 1, (2) designates a towing cable whose front end is hooked to a towing aircraft (3) and whose rear end is hooked to a target (4).

 According to the invention, this cable is composed of several sections and, for example, in this embodiment, of three sections respectively (2a, 2b, 2c). These sections have equal lengths (1) but may have different lengths.

 In known manner, this cable constituted by a tubular braid formed by the interweaving of bundles of synthetic wires, (5) in FIG. 3, is produced by a braiding machine. In the embodiment shown, this machine comprises a chassis (6), shown in FIG. 3, on which are mounted free in rotation twelve wheels with ouches (7) each pivoting about a vertical axis, but in direction reverse from one wheel to another, as represented by the arrows (8) in FIGS. 4 to 6. Each of the twelve wheels (7) comprises four openings (7a) each capable of cooperating successively with the twenty four spindles (fl to f24).

Each of these is connected in rotation to a coil (9) carrying the winding of a bundle of wires (5). The ouches wheels (7) are associated with guide ramps and internal and external toothed ramps cooperating with the spindles and so that the odd spindles (fl, f3, f5, ..., f23) rotate on them- same in one direction, for example in the direction of the arrow (10) in FIGS. 4 to 6, and that the even spindles (f2, f4, ..., f24) rotate in the opposite direction in the direction of the arrows (12 ) of the same figures. When the loom is in operation, the different bundles of wires (5) unwinding from the reels (9) driven by the bundles (fl, ..., f24) form the tubular braid shown in (2) in FIG. 3.

 According to the invention, for the manufacture of the first section, the loom has the traditional configuration shown in FIG. 4, that is to say implements twenty four beams (fl to f24) driving the twenty four coils (9). When a braid length corresponding to the length (1) of the first section (2a) of cable has been produced, the braiding machine is stopped and certain spindles, namely eight spindles, are removed. In order not to disturb the manufacture of the braid, the spindles removed are taken from different places in the crown formed by the wheels with ouches (7) and by half in the series of even spindles rotating in one direction and by half in the series of odd spindles rotating in the opposite direction. As shown in Figure 5, in dashed lines, the deleted spindles are those referenced (f5, f6, fll, f12, f17, f18, f23, f24). The wire bundles (5) corresponding to the suppressed spindles are sectioned. This operation is completed by a reduction of the mesh to the centimeter of the braid, so as to reduce its cross section. The loom is then restarted and makes it possible to manufacture the second section (2b).

 When a length (I) of this section (2b) has been manufactured, the loom is again stopped and, as shown in FIG. 6, eight other spindles, namely those shown in dashed lines, are deleted ( fl, f2, f9, f10, f13, f14, f21, f22). In order not to disturb the balancing of the braiding operation but also to obtain sufficient resistance, the four spindles (fll, f12, f23, f24) which were removed for the second of the second section are also replaced. (2b). As before, the bundles of wires unwinding from the reels put back in place are introduced into the braid during training. Likewise, the mesh is reduced to the centimeter of the sheath, so as to reduce its section.

 This manufacturing process which is described above, in the case of its application to the manufacture of a braid composed of twenty four bundles of wires can, without departing from the scope of the invention, be applied to the manufacture of braid comprising a number of different beams, provided that at the same time that spindles are removed, care is taken to balance these spindles, which is within the reach of the Honne of Art.

 The cable thus formed, is therefore composed of different sections of braided sheath forming a continuous cable and each formed respectively by twenty four bundles, sixteen bundles and twelve bundles of synthetic son. It should be noted that if some of these bundles extend over the entire length of the cable, for example those delivered by the spindles (f3, f4, f7, f8, f15, f16, f19, f20) appearing in solid lines at the FIG. 6, the other beams extend only over two successive sections and even over a single section for the beams coming from the time zones (fll, f12, f23, f24).

 Finally, this manufacturing method described above in the case of its application to the constitution of a towing cable with decreasing section can also be used to manufacture a cable having, over all or part of its length, decreasing sections and each of its ends of sections of larger section.

Claims (4)

 1. Towing cable in particular for aerial target, of the type constituted by a sheath (2) formed by braiding bundles (5) of synthetic wires and having a tubular and rectangular cross section characterized in that it is composed of sections ( 2a, 2b, 2c) which, having different sections from the aircraft attachment end (3) to the target attachment end (4), differ in the number of beams (5) son constituting and are interconnected by bundles extending at least over two successive sections.  2. Cable according to claim 1 characterized in that the sections have sections which decrease from the hooking end to the plane to the hooking end to the target and are composed of bundles of wires whose number is decreasing.  3. A method of manufacturing the cable according to any one of claims 1 and 2 characterized in that it consists, during braiding of the sheath (2) constituting it, by means of a braiding machine, and after scrolling of each of the first nl sections (2a, 2b), to cut certain bundles (f5, f6, fll, f12, ...) of wires by balancing the peripheral distribution of the remaining bundles.  4. Method according to claim 3 characterized in that the cutting of the beams is ensured with the machine stopped and followed by a reduction of the mesh on the sheath.