EP0096847B1 - Chaff dispensing device - Google Patents

Description

The invention relates to a device for distributing dipoles which are arranged to be ejected in a sleeve in the form of sections of the same length, the sections each consisting of bundled and centripetal-biased dipoles in an envelope.

From DE-OS 3 015 719, dipole sections of different lengths are arranged in sections in a sleeve. The dipole sections can be ejected from the sleeve via a piston, the piston being drivable by a gas pressure-generating charge.

GB-PS 834 596 discloses sections of dipoles bundled by loose, thin paper, which are arranged in a sleeve made of reinforced paper. In addition, it is known to insert a section of the paper directly enveloping the dipoles as a tail in the mass of the dipoles, for example in the radial direction.

In the case of an extraordinarily large number of dipoles bundled in a circle, it is finally known to arrange a section of the sheathing in the form of a tail in the interior of the bundle as a tail. Due to the tail, the mass of the dipoles is present in approximately two equal subsets. This roughly doubles the area of attack for the air flow to form a cloud.

From US-A-3 023 703 it is known for a rocket to provide sections of dipole packets of equal length, the dipoles being arranged in an envelope and being centripetal biased. These sections are ejected radially from the missile. The sheath consists of two slightly overlapping foils directly adjacent to the dipoles and a holding tape that can be cut open. All dipole sections are provided with the films described above. When the sections are ejected, they open at the same time, so that the time-delayed release of the dipoles required for a relatively large dipole cloud is not present.

For dipole sections arranged in a sleeve, for rapid and large cloud formation, it is necessary that the dipole sections can be ejected relatively easily and quickly and that the individual dipoles separate independently of one another after leaving the pipe mouth in order to achieve a radar to form relevant cloud. In addition to the use of this effect in the emergency services for signal generation, the measure for deceiving target-seeking radar devices in aircraft and missiles is important.

The object of the invention is to provide a structurally simple, inexpensive dipole arrangement for an ejection sleeve, which can be ejected from the sleeve in a short time and quickly generates a large-area and homogeneous cloud after the ejection.

This object is achieved by the features according to the invention of the characterizing part of claim 1.

Advantageous developments of the invention are specified in the subclaims.

The metal foil slides very well on the highly polished inner surface of the sleeve, so that the energy required to eject the sections from the sleeve can be measured relatively small. On the other hand, with a standardized discharge charge compared to the prior art, the discharge width of the sections is increased by approx. 30%. This is advantageous for the diameter of the cloud when ejecting from the aircraft and for the distance and height of the cloud above the ejection location for earth-based ejection, since the sections cover a relatively large distance at high average speed during the detachment of the dipoles.

The dipoles pretensioned in the sections act as a drive spring for the metal foil surrounding the section, so that a time-delayed release of the dipoles is achieved depending on the number of turns of the metal foil.

The section with a low number of turns releases the dipoles earlier than the section with a higher number of turns.

With the sleeve arranged stationary, a radar-relevant cloud with a diameter of approx. 4 m is reached when there is no wind, at a wind force of 3 m a cloud is approx. 4 m high with a diameter of 3 m and a length of approx. 40 m.

When the dipole arrangement is ejected from an aircraft, a radar-relevant cloud is reached which is approximately 50% larger than the side view area of an aircraft, such as the F-104G Starfighter. The diameter of the cloud is also larger than the largest cross section of a fighter plane. This provides an all-round repellent against ground-based and air-based defense devices with homing radar.

According to claim 2 it is achieved that the section lying at the mouth of the sleeve has an envelope with a number of turns of 1.2 to 0.75, which initiates cloud formation immediately after the ejection. The deflection time for the opposing radar is therefore very short, since the cloud surface detected by the radar as the target arises much earlier than according to the prior art. A cloud that is 70% formed is sufficient to deflect the radar from the aircraft.

According to claim 3, the section arranged at the mouth of the sleeve can be without a cover in order to increase the formation of the cloud with respect to its radar-relevant intensities.

Claim 4 covers in a simple manner a frequency spectrum which is evenly present per unit area of the finished cloud. The decisive factor here is that the cutting length is selected so that the dipoles assigned to the highest frequency cover about one square meter of the finished cloud in a radar-relevant manner. Those dipoles of a section that not enough in themselves to cover one square meter of the finished cloud, are supplemented by corresponding dipoles of other sections to meet the above condition. A good distribution of the dipoles both in the longitudinal direction of the cloud and in the transverse direction is achieved in that the dipoles of different lengths form the structure in the manner of a network by swirling.

According to claim 5, it is ensured that, in addition to the low friction when the sections are ejected from the sleeve, the unwinding of the metal foil from the bundled dipoles takes place rapidly due to the low friction between the turns of the foil or the dipoles and the foil. Nest formation due to dipoles sticking together in large numbers is thereby reliably avoided.

An inexpensive metal foil can be found in claim 6.

The one-piece metal foil according to claim 7 ensures that after ejection from the sleeve - due to the radially expanding dipoles - the only plastically deformable metal foil only needs to increase its winding radius until the number of turns <1 and a sufficiently large distance (window ) is reached between the two ends of the film. Because of this window, dipoles are detached from the section (package) by the air flow and, on the other hand, the film itself is removed from the package. As a result, the parcel can unfold unhindered into a partial cloud due to the clamping force still present in the parcel and the air flowing out. The number of partial clouds of a minimum of 10 pieces and a maximum of approximately 25 pieces then results in the actual cloud by overlapping.

• Fig. 1 ein Flugzeug und aus separaten Dipol-Anordnungen gebildete Wolken,
• Fig. 2 eine Dipol-Anordnung mit Hülse,
• Fig. 3 eine Einzelheit 111 nach Fig. 2,
• Fig. 4 eine weitere Dipol-Anordnung mit Hülse,
• Fig. 5 eine Einzelheit V nach Fig. 4,
• Fig. 6 einen einzelnen Dipol-Abschnitt.

Embodiments of the invention are shown in the drawing. It shows:

• 1 shows an aircraft and clouds formed from separate dipole arrangements,
• 2 shows a dipole arrangement with a sleeve,
• 3 shows a detail 111 according to FIG. 2,
• 4 shows a further dipole arrangement with a sleeve,
• 5 shows a detail V according to FIG. 4,
• Fig. 6 shows a single dipole section.

1, a radar grid of an opposing radar with the stop lines 1 to 4 is specified. The grid 5 is approx. 21 m. Between the rest lines 1 and 2 there is an aircraft 6, which has emitted dipoles 10 to 12 at two intervals in accordance with the arrow 7, thereby forming the radar-relevant clouds 8, 9 lying between the rest lines 2 to 4. Comparing the areas of aircraft 6 and cloud 8 or 9, cloud 8 or 9 is approximately 30% larger than the area of the aircraft shown.

The stop lines 1 to 4 correspond to a conventional radar with a pulse width of 200 µs at a predetermined target distance. The speed of the aircraft is 300 m / s. The output sequence of dipole arrangements is 100 m / s.

2, a dipole arrangement 13 consists of a sleeve 14 with a square inner cross section, dipole sections 15 to 24, a piston 25 and a cover 26. The inner surfaces 27 of the sleeve 14 are highly polished. The individual dipoles 10 to 12 usually consist of aluminum-coated glass threads. These glass threads are stranded in the longitudinal direction of the sleeve 14, the length of the dipoles 10 to 12 corresponds to the length of the individual sections 15 to 24.

In accordance with the diagram plotted over the sleeve 14, the number of turns for a covering made of thin, double-sided smooth (polished) aluminum foil with a thickness of approximately 0.1 mm are plotted on the ordinate 28.

A curve 40 determined by empirical values allows the number of turns of the foils 31 to 39 to be determined for each individual dipole section 16 to 24. Thus the number of turns for the dipole section 16 = 1.2, for the section 24 = 4.2 and for the section 21 = 2.6 (FIG. 3). The section 15 at the mouth 45 of the sleeve 14 has no casing. Here, the dipoles 10 are arranged as a package section 15 “naked” in the sleeve 14.

3 shows how the start 41 of the film 35 is offset from the end 42 when the number of turns of the film 36 = 2.6. The film 36 is detached from FIG. 2 and is drawn at a distance between the turns for the sake of better illustration. In reality, the turns of the film 36 are close together. The contact pressure between the windings of the film is achieved by inserting the individual dipole sections 16 to 24 into the sleeve 14. This is because the sections 16 to 24 have larger dimensions in the circumferential direction before insertion into the sleeve 14 than the inner cross section of the sleeve 14. To insert the sections 16 to 24 into the sleeve, the sections 16 to 24 which have already been wrapped are therefore made using a suitable device pressed into the sleeve 14. The section 15 is pressed as the last part of the sections 16 to 24 into the sleeve, so that their dipoles 10 are also biased centripetal.

The mode of operation of the device according to FIGS. 2 and 3 is that the piston 25, which is driven in the direction of the mouth 45, lifts the cover 26 from the mouth 45 via the sections 16 to 24. Then the "naked" section 15 is ejected first. The centripetal-biased dipoles 10 diverge in the radial direction and, after they have left the mouth 45, are swirled by the inflowing air.

This process is repeated in the following sections 16 to 24, the start of the swirling being delayed in accordance with the different number of turns of the metal foils in the sections 16 to 24.

In section 16 with a number of turns = 1.2, the compressed dipoles 10 act as a spring element. This spring element acts in the radial direction in that the dipole assembly expands radially. As a result, they act on the metal foil 31 and reduce the number of turns until the metal foil 31 releases the dipoles on the circumference. Only then does the swirling of the dipoles 10 by the attacking air flow begin. The wound metal foil 31 is also removed from the dipoles.

Due to the increasing number of turns of the metal foils 31 to 39 in the direction of the piston 25, a correspondingly increasing delay for the start of swirling of the dipoles 10 is achieved. According to the FIG., This leads to an elongated dipole cloud 8 or 9, which is considerably larger in diameter 100, height 110 and length 120 than the corresponding mass of the aircraft 6.

The long dipole sections 15 to 24, which are designed differently in accordance with the required frequency band and are arranged approximately at intervals in the sleeve 14, ensure that the cloud 8 or 9 has the required frequency spectrum with each surface unit.

4, dipole sections 46 to 52 of a dipole arrangement 44 are configured as packets of the same length. The section 46 lying at the mouth 45 of the sleeve 14 is only partially wrapped with metal foil 56 in accordance with the number of turns = 0.75. This means that 25% of the package surface lies directly against the inner surface 27 of the sleeve 14, while 75% of the surface is covered by the metal foil 56.

In order to achieve a required frequency spectrum, the dipole sections 47, 49, 51 - with dipoles lying in the longitudinal direction of the sleeve 14 - are cut transversely to the longitudinal axis of the sleeve 14 (section line 54). The cut (depth of cut 53) through the metal foil and the dipoles is carried out in such a way that the dipoles 12 (each section 47, 49, 51) with the shortest length (subset 65) cover about one square meter of cloud surface with regard to radar in terms of their number.

This also ensures that the same number of dipoles 11 (subset 66) meet the aforementioned condition. The remaining subset 67 of the dipoles 10 does not - seen by itself - result in a relevant radar area of one square meter. However, this subset 67 is supplemented by the adjacent dipoles 10 of sections 48 and 50.

5, the depth of cut is designated 53 and the cut line 54. The cut is carried out by means of a suitable device before the sections 46 to 52 are filled into the sleeve 14 through the enveloping metal foil and the relevant dipoles. The non-cut dipoles 10 then result in the subset 67. The curve 70 indicated in the upper part of FIG. 4 is defined analogously to FIG. The curve 70 indicates the number of turns of the metal foil in relation to the respective sections 46 to 52.

The mode of operation of the dipole arrangement according to FIG. 4 corresponds to the function described for FIGS. 3 and 4.

Due to the partial wrapping, number of turns = 0.75 of section 46, after it has been ejected in the direction of arrow 7 (FIG. 1) in the same way as described in FIG. 2, the swirling of the dipoles begins immediately, but only on that of film 56 uncovered surface. Only after the film 56 has been removed is the complete dissolution of the section 46 possible. The swirling of the dipoles 10 is therefore stretched in time by the metal foil 56.

In sections 47, 49 and 51, in which each section has dipoles 10 to 12 of different lengths, the metal foil is pulled up to a number of turns <1 after ejection from sleeve 14 due to the radial pressure of dipoles 10 to 12, to the extent that until the inflowing air has loosened the film and loosens and distributes the dipoles.

In the case of a sleeve with a square inner cross section, the inner edge length of which is 22 mm and which is provided with the described dipole sections in the axial direction over a length of approximately 180 mm and with approximately 400,000 dipoles per section, a single dipole was used - Arranging a radar-relevant cloud with maximum dimensions of approx. 16 m in length, 4.5 m in height and 4.5 m in diameter when ejecting an aircraft with a flight speed of V = 300 m / s.

In the arrangements according to FIGS. 2 to 5, the dipoles 10 to 12 of all sections lie in the axial direction of the sleeve 14. In addition, with all sections, with the exception of sections 47, 49 and 51, the dipoles of the sections are transverse to the longitudinal direction to arrange the sleeve 14. Furthermore, a circular cross-section can also be used instead of the square inner cross-section of the sleeve 14.

All sections 15 to 24 and 46 to 52 contain dipoles 10 and 10, 11, 12 which act as “spring elements”.

6, a dipole section 70 has dipoles 10 and a metal foil 71. The film 71 is provided with an integral air brake 72. The air brake 72 consists of two braking surfaces 73, 74. The braking surfaces are determined by edges 75, 76 of the film 71.

The air brake 72 is folded in the sleeve 14 accordingly, so that it supports the unwinding of the film 71 from the section 70 after the ejection by the air flowing in the direction of arrow 77. The essential idea of this solution is that the twice-bent end of the film 71 creates a very effective air brake.

The start of the unwinding process is accelerated. The duration of the unwinding process is not significantly accelerated, however, since a free film end, similar to a “flag”, already acts as a brake due to the air vortex. This air brake 72 saves space and therefore does not influence the number of dipoles 10 in section 70.

The measure described above can also be used for the incised sections 47, 49, 51.

Claims (8)

1. Apparatus for the distribution of dipoles which are arranged ejectably in an ejection sleeve (14) in the form of several portions (15-24, 46-52), in which respect the individual portions consist respectively of bunched, and centripetally biassed dipoles in a sheathing (36), characterised in that the portions (15-24; 46-52) are of different length and the sheathing thereof consists of thin metal foil (31-39; 56-62) which is smooth on both sides, the number of turns of which decreases considered in the ejection direction and the sleeve (14) is provided with a polished inner surface and an ejection mouth (45).

2. Apparatus according to Claim 1, characterised in that the numbers of turns of the sheath- ings amount to 4.2-1.2, or respectively 4.5 up to 0.75.

3. Apparatus according to claim 1, characterised in that a portion (15) without a sheathing, but with centripetally biassed dipoles (10) is arranged at the mouth (45) of the sleeve (14) and portions (16-24) having a sheathing (31-39) lie subsequently.

4. Apparatus according to claims 1 and 2, characterised in that in accordance with the predetermined frequency spectrum, in the portions (47-52) with dipoles (10) of the same length, by incisions (54) transversely to the longitudinal axis of the sleeve (14), beside dipoles of the same length also dipoles (11, 12) of different length are contained; and the depth of cut (53) is dependent upon the required number of the dipoles for the highest frequency surface-area unit.

5. Apparatus according to claim 1, characterised in that the metal foil (31-39; 56-62) is only plastically deformable and has mirror-finished surfaces on both sides.

6. Apparatus according to claim 1, characterised in that the metal foil (31-39) consists of aluminium and is about 0.1 mm thick.

7. Apparatus according to claim 1, characterised in that the metal foil per portion (16-24; 46-52) is in one piece.

8. Apparatus according to claim 1, characterised in that an air brake (72) through two edges (75, 76) lying transversely to the winding direction (77) is provided at the free end (42) of the metal foil (71).

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