AU2003242677B2

AU2003242677B2 - Smoke projectile

Info

Publication number: AU2003242677B2
Application number: AU2003242677A
Authority: AU
Inventors: Christian Koch Ernst; Thorsten Kothe; Josef Schneider
Original assignee: Diehl Munitionssysteme GmbH and Co KG
Current assignee: Diehl Defence GmbH and Co KG
Priority date: 2002-06-14
Filing date: 2003-06-12
Publication date: 2009-03-26
Anticipated expiration: 2023-06-12
Also published as: US20060060103A1; DE50301814D1; ZA200410264B; WO2003106913A1; AU2003242677A1; IL165732A0; EP1514072B1; BR0311793B1; BR0311793A; IL165732A; DE10226507A1; EP1514072A1; MY134363A

Description

1 DP 1847 WO WB/GA/bu Diehl Munitionssysteme GmbH Co KG, D-90552 R1thenbach Fog projectile The invention concerns a fog projectile having an active charge comprising a pyrotechnic active material for producing an aerosol which emits in the infrared and which is impenetrable in the visual.

Armoured and unarmoured vehicles are protected by means of aerosol curtains from discovery, detection and target tracking and thus from the threat of missiles.

DE 199 14 097 Al describes a suitable pyrotechnic active material for producing an aerosol which is strongly emissive in the infrared and impenetrable in the visible. That active material develops a protective camouflage fog or mist which, besides impenetrability in the visible range, also permits long-duration cover in the infrared range. As its main constituents that active material contains red phosphorus, an alkali metal nitrate or a mixture of alkali metal nitrates while as secondary constituents it contains at least one transition metal or a metallic compound or alloy thereof, at least one metalloid and a binder.

As the threatening missiles approach at flight speeds of 200 to 600 m/s, a fog screening effect must take place very rapidly, after they have been identified. Known projectiles however deploy their action only after a flight time and time delay of for example 2 s. In that time the vehicle is unprotected.

DE 29 08 217 C2 describes a unit charge for fog concealment of vehicles, having a casing filled with fog bodies. The fog bodies are in the form of cylindrical flat discs with an open central hole, which are disposed one upon the other. The fog bodies are ejected without an enclosure from the casing. The arrangement does not provide for fading out of the line of sight in the infrared range.

Therefore, it would be advantageous to provide a fog projectile of a simple structure, which is so designed that rapid fading of the line of sight in the infrared radiation range and in the visual radiation range occurs upon discharge in a spatial angle.

SUMMARY OF THE INVENTION According to the invention, there is provided a fog projectile having an active charge including a pyrotechnic active material for producing, after firing and discharging the active charge from a projector barrel, an aerosol which emits in the infrared radiation range and which is impenetrable in the visual radiation range, wherein the active charge is a hollow-cylinder stack which includes a plurality of layers of hollow-cylinder segments forming a hollow space in the interior of the active charge stack, and wherein the hollow-cylinder stack together with a firing and discharge charge is held in an enclosure which is arranged to hold together, in an initial phase of flight of the fog projectile, the hollow-cylinder stack after firing the hollow-cylinder segments by way of the hollow space and after discharging the active charge from the projector barrel, and wherein the enclosure further is arranged to burn away, after said initial phase of flight of the fog projectile, by way of the fired hollow-cylinder segments, such that the flow of air acting on the hollowcylinder stack during the flight gets into the stack of hollow-cylinder segments, whereby the fired hollow-cylinder segments are driven apart.

In one embodiment the active charge stack consisting of the hollow-cylinder segments is discharged or expelled, held by an enclosure or sheathing, from a projector barrel, whereby aerodynamic stability is guaranteed in the initial phase of the flight. That ensures that the stack does not already deploy immediately at the vehicle. It is only after some metres of flight, for example 5m to 10 m, that the fired hollow-cylinder segments break the enclosure or sheathing open. Due to the resulting absence of aerodynamic cladding the flow of air acting thereon gets into the stack of the hollow-cylinder segments. As a result the segments are immediately driven apart, which results in the burning hollow-cylinder segments fanning out over a large area, in a wide spatial angle. That provides an aerosol fog or mist distributions very quickly, for example within 0.25 s, which conceals the vehicle both in relation to missiles approaching horizontally and also in gliding flight, in the 03/03/09,va 14584 p2speci.2 00 I infrared radiation range and in the visual radiation range. In the vehicle therefore o there is a period of time which is long in comparison with the state of the art to Z perform travel maneuvers to evade the moment of impact, as calculated in the vehicle, of the approaching missile.

BRIEF DESCRIPTION OF THE FIGURES SAdvantageous configurations are set forth in the appendant claims and the NO description hereinafter. In the drawing: Figure 1 shows a fog projectile with a plurality of layers of hollow-cylinder segments in an enclosure or sheathing; S 10 Figure 2a is a plan view of a layer of four hollow-cylinder segments; Figure 2b shows a side view in the direction of the arrows IIb-IIb in Figure 2a; Figure 3a shows a plan view of a single hollow-cylinder segment; Figure 3b shows a perspective view of a single hollow-cylinder segment; Figure 4 shows an apertured disc of the enclosure or sheathing; Figure 5 shows a foil of the enclosure or sheathing, unwound; Figure 6 shows the fog projectile in a discharge device; Figure 7 shows an aerosol fog produced by the fog projective; and Figure 8 shows a time diagram of the development of the effect of the aerosol fog.

DETAILED DESCRIPTION OF THE EMBODIMENTS A fog projectile 1 comprises a hollow-cylindrical active charge 2, a firing charge 3 and an enclosure or sheathing 4 (see Figure The active charge 2 is a stack comprising a plurality of layers 5 of hollow-cylinder segments 6. Each layer is composed of a plurality of hollow-cylinder segments 6. There is a hollow space 7 in the interior of the active charge stack.

As shown in Figures 2a and 2b each layer 5 is formed by four hollowcylinder segments 6, wherein the segment angle a is 900 and the individual hollowcylinder segments 6 bear against each other. The segment angle a can also be smaller than 90', in which case then there are correspondingly more hollow-cylinder segments 6 in a layer.

06/ 11/08,va 14584 p2-3aspeci,3 -3a-

O

C The diameter d of the hollow space 7 is 1/6 D, wherein D is the outside Sdiameter of the active charge stack (see Figure I and Figures 2a and 2b).

SThe active charge stack 2 is of a height H which is for example 20 h, wherein h is the height of a hollow-cylinder segment (see Figures 1, 2b and 3b).

The height h is preferably 1/15 D.

The hollow-cylinder segments 6 are compressed from a pyrotechnic active N material which produces an aerosol which is emitting and damping in the infrared Sradiation range and which is impenetrable in the visual. An active material of that kind is described in DE 199 14 097 Al. As main constituents it has red phosphorus, S 10 an alkali metal nitrate or a mixture of alkali metal nitrates and as secondary constituents it has at least one 06/ 11/08,va 14584 p2-3aspcci,4 4 transition metal, or a metal-rich compound or alloy thereof and at least one metalloid and a binder.

The firing charge 3 which serves to fire the hollow-cylinder segments 6 by way of the hollow space 7 and which can serve as a discharge charge is a pyrotechnic firing composition which contains: to 80% by mass of black powder, 0 to 20% of an organic binder, 0 to 2 0 of a metal powder from the group of the metals magnesium, aluminium, boron, zirconium and titanium, and 0 to 20% of a burning moderator based on a transition metal compound such as CuO, K[Fe 2

(CN)

6 5

H

5 2 Fe).

The enclosure or sheathing 4 has a combustible foil 8 which for example comprises a paper saturated with paraffin. The foil 8 initially holds together the active charge stack 2 consisting of the hollow-cylinder segments 6. The foil 8 encloses the active charge stack 2 at the top side and at its periphery U, corresponding to the diameter D, over the entire height H. Figure 5 shows the foil 8 in the unwound condition. The foil 8 is connected to a disc 9 which bears against the underside of the active charge 2.

The disc 9 comprises a pressed fibre material and has a central opening 10. The diameter dl of the opening 10 is the diameter d (see Figure 1 and Figure 4).

The described fog projectile can be inserted into a metallic projector barrel 11 (see Figure Figure 6 shows the arrangement in the pulledapart condition. Arranged at the bottom 12 of the barrel 11 is an electrical firing element 13 whose electrical contacts 14 can be closed by way of a suitable switching device in the vehicle. The firing element 13 upon initiation fires the firing charge 3 which can act at the same time as the ejection charge.

When firing takes place the hollow-cylinder segments 6 are fired and the fog projectile 1 is ejected. In the region of between about 5 and 10 m after the beginning of gas development of ejection, the hollow-cylinder segments 6 remain held together by the foil 8. After the foil 8 burns away,

A

about 5 to 10 m after leaving the vehicle-mounted barrel 11, the active charge stack 2 fans out, with the hollow-cylinder segments 6 separating, and the individual hollow-cylinder segments 6, after a distance S at a spacing from the vehicle F to be protected, develop a fog curtain N which screens the vehicle F both in relation to a missile K1 which is threatening in a condition of gliding flight and a missile K2 which is attacking in horizontal flight (see Figure 7).

Development of the protective fog N is effected for example within 0.25s after the vehicle F has identified and evaluated the threat posed by the missiles K1 and K2.

Figure 8 shows a comparison of known operative times and the operative time which can be achieved by the projectile according to the invention. At the time tO the vehicle F identifies the threat posed by an approaching missile and thus triggers discharge of the camouflage fog device, which then takes place at the moment tl. The time t4 is the time at which, according to the calculation of the vehicle F, the threatening projectile impacts.

In accordance with the state of the art fog generation W which counteracts the missile threat is achieved in accordance with the line a at the moment t3 whereas the active level achieved with the described device is already achieved in accordance with the line b at the time t2. It will be seen in this respect that the period of time between t3 and t4 is substantially shorter than the period of the time between t2 and t4. This means that, between t2 and t4, the vehicle under threat has available a substantially longer period of time for travel manoeuvres to evade the threat, than in the state of the art in which only the time between t3 and t4 is available for evasive travel manoeuvres.

00

O

CN Throughout this specification and the claims which follow, unless the context o requires otherwise, the word "comprise", and variations such as "comprises" and Z "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

NO The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form or suggestion that the prior art forms part Sof the common general knowledge in Australia.

S 06/11/08,va 14584

Claims

1. A fog projectile having an active charge including a pyrotechnic active material for producing, after firing and discharging the active charge from a projector barrel, an aerosol which emits in the infrared radiation range and which is impenetrable in the visual radiation range, wherein the active charge is a hollow- cylinder stack which includes a plurality of layers of hollow-cylinder segments forming a hollow space in the interior of the active charge stack, and wherein the hollow-cylinder stack together with a firing and discharge charge is held in an enclosure which is arranged to hold together, in an initial phase of flight of the fog projectile, the hollow-cylinder stack after firing the hollow-cylinder segments by way of the hollow space and after discharging the active charge from the projector barrel, and wherein the enclosure further is arranged to burn away, after said initial phase of flight of the fog projectile, by way of the fired hollow- cylinder segments, such that the flow of air acting on the hollow-cylinder stack during the flight gets into the stack of hollow-cylinder segments, whereby the fired hollow-cylinder segments are driven apart.

2. A fog projectile according to claim 1 wherein the firing charge forms the lowermost layer of the stack.

3. A fog projectile according to any one of the preceding claims wherein the enclosure includes a foil and a disc arranged beneath the stack.

4. A fog projectile according to any one of the preceding claims wherein the foil of the enclosure encloses the active charge at the periphery and at the top side.

A fog projective according to any one of the preceding claims wherein the foil includes a paper saturated with paraffin.

6. A fog projectile according to any one of the preceding claims wherein the disc of the enclosure is a disc of pressed fibre material. 03/03/09.va 14384 claims,6 00 O C

7. A fog projectile according to any one of the preceding claims wherein the disc of Sthe enclosure has an opening therethrough.

8. A fog projectile according to any one of the preceding claims wherein an electrical firing element projects into the firing charge. NO

9. A fog projectile according to any one of the preceding claims wherein the dimensioning is such that the enclosure breaks open about 5 metres to about Smetres along its trajectory. CI A fog projectile substantially as hereinbefore described with reference to the drawings. 06/11/08,va 14584 claims,7