EP2455704A2 - Missile with a skin having an ablation layer thereon - Google Patents

Abstract

A missile comprises an outer casing (12); an outer coating (14) in the form of an ablation layer (18) applied to the outer casing; a matrix material (24) disposed in the ablation layer and intended to at least partially decompose during a flight; and hollow glass bodies (26) embedded in the matrix material. The matrix material is a self-curing material, epoxy resin, polyester resin, elastomer, terpolymer elastomer, thermoplastic material or isocyanate. Independent claims are included for the following: (1) a matrix material comprising hollow glass bodies embedded as an ablation layer intended to be partially vaporized during a flight and forming an outer coating on an outer casing of a missile; and (2) producing a missile, involving providing an outer casing; providing an outer coating in the form of an ablation layer containing a matrix material intended to at least partially decompose during a flight and hollow glass bodies embedded in the matrix material; applying the ablation layer to the outer casing as a liquid material; and subsequently curing the liquid material.

Description

The invention relates to a missile having an outer shell and an outer coating applied thereto in the form of an ablation layer, which contains a matrix material intended for at least partial decomposition during a flight.

Air targets require fast missiles that are superior in maneuverability to their targets because of their high speed. Airspeeds over 1000 m / s are desirable here.

It is an object of the present invention to provide a missile that is reliably ready for use even after a flight at a speed above 1000 m / s.

This object is achieved by a missile of the type mentioned, in which according to the invention in the matrix material hollow glass body are embedded.

The invention is based on the consideration that in a flight in the atmosphere at high speed frictional heat is generated, through which the missile, in particular at its tip and at its tail, heats up. This phenomenon is known from space travel, in which, for example, space gliders are equipped with a heat shield. The thermal insulation effect of such a heat shield is achieved mainly by a pyrolysis resulting cooling boundary layer between the missile and the passing air of the atmosphere. The material of the heat shield gasifies and thus forms around the heat shield a gas layer, which serves as a cooling boundary layer.

Such a heat shield is usually placed as a plate-shaped material on the missile and connected thereto. With respect to missiles in the form of missiles, this approach has the disadvantage that the application is complicated and therefore expensive and the heat shield has a relatively large thickness in order to be able to be placed as a layer can.

In contrast to aerospace aircraft, the high-speed phase of an unmanned guided missile, in particular an anti-aircraft missile, lasts only a few seconds. The effect of heat is thus lower than, for example, in a space glider. However, the outer shell is thinner and sensitive electronic components are closer to the outer shell than a space glider. A critical temperature is therefore lower than in a space glider. The requirements for a heat shield with an ablation layer on an unmanned guided missile are therefore different insofar as it must provide only a short time against a relatively low heat, but the thermal shield within this time must be so good that the temperature of the underlying outer shell only slightly increases, for example by less than 50 K, in particular less than 30 K.

Due to the presence of glass hollow bodies in the matrix material of the ablation layer, a high thermal insulation can be achieved even with a very thin ablation layer, for example in the form of a lacquer layer, so that the missile can be provided with a very thin ablation layer which nevertheless achieves a sufficient thermal insulation effect. The thickness of the ablation layer is expediently below 1 mm, preferably below 0.7 mm, in particular below 0.5 mm. As a result, the weight of the missile can be kept low and its range high.

The missile is expediently an unmanned guided missile, in particular with a rocket engine, for example a missile intended for destroying targets with a destructive effect causing the destruction. Such a rocket may be a ground-to-air missile or an air-to-air missile, a rocket to combat aerial targets. The outer shell of the missile may be a metal shell that protects the interior components of the missile.

An ablation layer is characterized in that it is provided at an airspeed at which the missile is in regular operation, thermally decomposed. In the following, thermal decomposition can be understood to mean that material of the ablation layer at least partially changes from a solid to a gaseous state when the temperature increases. Expediently, the thermal decomposition of the ablation layer loses at least 1% of its weight per minute, in particular per second, with material changing from the solid state to the gaseous state. The above-mentioned amount of material advantageously relates only to the matrix material of the ablation layer. As outer coating is understood such a coating, which points radially outward. An interior coating that faces an interior is not an exterior coating in that sense.

The glass hollow bodies are expediently glass hollow spheres. These are at least substantially spherical glass bodies which form a cavity in their interior. The sphericity is achieved when the smallest outer diameter in any direction is not less than 50%, in particular 80%, of the largest outer diameter of the glass hollow sphere in a different direction. The cavity is expediently filled with gas, preferably at least 90%, in particular completely.

In an advantageous embodiment of the invention, at least 80% of the glass hollow bodies contained in the matrix material have an outer diameter of 12 μm ± 5 μm. As a result, a good thermal insulation effect can be achieved even with a thin ablation layer of less than 1 mm thickness. In this case, an average outer diameter of the glass hollow body, e.g. a not quite spherical glass hollow sphere, are considered.

A further advantageous embodiment of the invention provides that the hollow glass body make up at least 20% of the layer volume of the ablation layer. As a result, a good thermal insulation effect of the ablation layer can be achieved. With a volume fraction of the hollow glass body up to 65%, the ablation layer can still remain mechanically stable in such a way that it does not flake off even in the case of reasonable strokes.

The invention is also directed to a method for producing a missile with an outer shell, in which an outer coating in the form of an ablation layer is applied to the outer shell, which at least partially Decomposition during a flight provided matrix material. It is proposed that glass hollow spheres are embedded in the matrix material according to the invention.

A thin ablation layer is particularly easy to apply in the form of a paint, for example, applied with a brush or sprayed through a nozzle on the outer shell. Generally speaking, it is advantageous if the ablation layer is applied as a liquid material to the outer shell. In this respect, a liquid material is also understood to mean a viscous material that can be applied to the outer shell by spraying or spread as a layer. Appropriately, the initially liquid material is such that it is curable after application to the outer shell and in particular cures independently. The curing can be done by drying, vulcanization, by a chemical reaction of two different components or in other ways.

A matrix material is a material into which the hollow glass body can be embedded in such a way that it is held firmly by the matrix material in its position in the matrix material. Particularly advantageously, the matrix material is a lacquer.

Conveniently, the matrix material is a self-hardening material. The curing may be accomplished by the evaporation of a diluent, by vulcanization or as a chemical reaction, e.g. in a multi-component system.

Particularly advantageously, the matrix material contains an epoxy resin, whereby a simple application and an independent curing can be achieved. An epoxy resin can consist of polymers which harden from a liquid state into a solid state with the addition of a suitable hardener and form a thermosetting plastic.

Further advantageously, the matrix material contains a polyester resin, with which also a simple application and a self-curing can be achieved.

It is further possible and advantageous if the matrix material contains an elastomer. Particularly suitable is a terpolymeres elastomer, such as EPDM (ethylene-propylene-diene rubber).

A likewise suitable ablation layer can be achieved in that the matrix material contains a thermoplastic, PEEK (polyetheretherketone) being particularly suitable for its hardness and stability.

Also suitable are isocyanates, for example polyurethanes, which, however, are expediently not used as foam but as varnish.

The chemical composition of the matrix material is advantageously chosen so that the decomposition temperature of the matrix material is between 150 ° C and 250 ° C, in particular between 180 ° C and 220 ° C. Further, it is advantageous if the composition of matrix material and glass hollow bodies is selected so that the thickness of the ablation layer at an energy input of 1 MW / m ² within 20 s between 50 .mu.m and 500 .mu.m shrinks, in particular between 50 .mu.m and 200 .mu.m. This energy input is typical at velocities of antimissile missiles in lower air layers, so that within a typical approach of a missile the corresponding layer thickness is given off by gasification and thus forms the thermal protection layer.

A good thermal protection effect can also be achieved if the ablation layer loses 50 μm to 150 μm in thickness at a temperature of 200 ° C within 20 seconds.

The ablation layer need not be the only layer on the outer shell of the missile and may be attached to an underlying layer and / or below an overlying layer. Several layers underneath and / or above are also conceivable. A good mechanical resistance of the ablation layer can be achieved if it comprises a base layer and a cover layer applied thereto, which is free of glass hollow bodies. Due to the thermal insulation effect of the hollow glass body in the base layer with the glass hollow bodies, the heat transfer from the cover layer is delayed in the outer shell of the missile.

The mechanically stable cover layer can protect the underlying base layer and is expediently designed so that it also functions as an ablation layer, analogous to the base layer. In a high-speed flight of the missile first the cover layer and then the base layer is decomposed, both layers cool the outer shell by Ablationswirkung. The cover layer may be a lacquer layer, and it is in particular thinner than the base layer, for example, with a thickness of not more than 300 microns.

Further, it is advantageous if the material of the cover layer is kept at least substantially the same as the matrix material of the base layer, so that both layers have at least substantially the same ablation effect and thus the same cooling effect.

A particularly stable layer on the outer shell can be achieved if the ablation layer is applied to a primer layer, which in turn is applied to the outer shell. The primer layer is expediently formed from the same material as the matrix material of the ablation layer. If the ablation layer is coated with a further layer which is free of glass hollow bodies, an aerodynamically advantageous surface can be produced. Such a cover layer can also be understood as part of the ablation layer, since the cover layer is expediently likewise an ablation layer.

The invention is further directed to the use of a matrix material in which hollow glass bodies are embedded. It is proposed that the matrix material according to the invention be used as an ablation layer provided for at least partial evaporation during a flight and forming an outer coating on the outer shell of a missile.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing and the description contain numerous features in combination, which the skilled person expediently consider individually and will summarize meaningful further combinations.

Fig. 1

einen Flugkörper mit Außenhülle und Flügel, auf denen eine Ablationsschicht aufgebracht ist, und

Fig. 2

eine Schnittdarstellung durch die Spitze des Flugkörpers aus Fig. 1

Show it:

Fig. 1

a missile with outer shell and wings, on which an ablation layer is applied, and

Fig. 2

a sectional view through the tip of the missile Fig. 1

Fig. 1 shows a schematic representation of a missile 2 with a wing 6-bearing fuselage 4 and a hood 8, which forms the tip of the missile 2, and the a arranged under the hood 8 Dom 10 protects. The missile 2 is an unmanned missile in the form of an anti-aircraft missile for controlling air targets with an unillustrated active, which is provided for destroying the air target by blowing.

The hull 4 and the hood 8 form an outer shell of the missile 2, wherein the wings 6 can be optionally referred to as parts of the outer shell. On the outer shell several layers are applied, for example in the form of a paint, in Fig. 2 are shown.

Fig. 2 shows a section through the tip of the missile 2. Shown is an outer shell 12 made of metal and a coating 14 applied thereto. The coating 14 is also applied to the wings 6. It is composed of two layers 16, 18, wherein the layer 16 is a primer layer on the metallic outer shell 12. On this primer, the layer 18 is applied as an outer coating, which therefore points radially outward from the view of the outer shell 12 and is formed as Ablationsschicht. This ablation layer 18 comprises a base layer 20 and a cover layer 22 applied thereon.

The base layer 20 of the ablation layer 18 is formed from a matrix material 24 with glass hollow bodies 26 embedded therein, wherein both the layers 16 and 18 and the glass hollow bodies 26 are not drawn to scale, but are too thick or too large. The matrix material 24 is a self-hardening material in the form of an epoxy resin or a polyester resin, in which the hollow glass body 26 are firmly and immovably embedded after hardening of the matrix material 24. In a first exemplary embodiment, the cover layer 22 consists of the same material as the matrix material 24 and is applied to the base layer 20 in the form of a covering lacquer layer. The cover layer 22 is free of glass hollow bodies 26. The primer layer 16 is made of a different material than the matrix material 24.

While the primer layer 16 is about 200 .mu.m thick, the ablation layer 18 is about 700 .mu.m thick, with about 500 .mu.m on the base layer 20 and about 200 .mu.m on the cover layer 22. The glass hollow bodies 26 are hollow glass spheres with an average outer radius of 12 μm, 90% of the hollow glass body 26 having an outer diameter of 12 μm ± 3 μm. The glass hollow bodies 26 make up about 25% by volume of the base layer 20.

In a further embodiment, the primer layer 16 is made of the same material as the matrix material 24 of the base layer 20, whereas the cover layer 22 is made of a different material, eg, another lacquer to reduce the surface roughness caused by the base layer 20 bearing the glass hollow bodies 26 , For example, the primer layer 16 is a layer of paint called Seevenax (Seevenax is a registered trademark DE 841645 the company Mankiewicz Gebr. & Co. (GmbH & Co. KG), Hamburg) as an adhesion-promoting layer exist. On the primer layer 16, a plurality of layers Seevenax with 25 vol .-% glass hollow body 26 are applied as a base layer 20 until a layer thickness of 500 microns is reached. As cover layer 22, a topcoat is used, for example, Alexit Noridur 406 (Alexit is a registered trademark DE 61721 Mankiewicz Gebr. & Co. (GmbH & Co. KG), Hamburg; Noridur is a registered trademark DE 667526 the company Mankiewicz Gebr. & Co. (GmbH & Co. KG), Hamburg).

In order to produce the ablation layer 18, the matrix material 26 can be mixed with a diluent into which the glass hollow bodies 26 have previously been introduced. For this purpose, the thinner with the glass hollow bodies 26 are first stirred and then stirred together with the matrix material 24. For example, 1250 g of Seevenax, 250 g of hardener and 300 g of diluent are possible and advantageous, 50 g of glass hollow body 26 being stirred into 400 g of thinner.

A viscous mixture of not yet cured matrix material 24 and glass body coupons 26, also referred to as a liquid mixture can be applied to the primer layer 16 by means of a Sprühlackierungsgerät in several layers, wherein a layer initially hardens before a further layer is applied. After curing of the uppermost layer of the base layer 20, the cover layer 22 can then also be applied and cured by the device for spray application.

The base layer 20 thus obtained has a decomposition temperature of about 200 ° C and shrinks at an energy input of 1 MW / m ² within 20 s by about 70 microns. In this way, it forms a sufficient heat protection, so that the outer shell 12 is heated at this energy input within 20 s by not more than 30 ° C.

The ablation layer 18 can also be applied without a covering layer 22 and expediently covers at least the front part of the outer shell 12 of the missile 2, for example the outer shell 12 over a length of at least 10% of the entire missile 2. Expediently, the ablation layer 18 covers the entire fuselage 4 as an outer coating, whereby the wings can be coated by the Ablationsschicht.

LIST OF REFERENCE NUMBERS

2

missile

4

hull

6

wing

8th

cap

10

cathedral

12

outer shell

14

coating

16

primer layer

18

ablation

20

base layer

22

topcoat

24

matrix material

26

Hollow glassware

Claims (15)

A missile (2) having an outer shell (12) and an outer coating applied thereto in the form of an ablation layer (18) containing a matrix material (24) provided for at least partial decomposition during flight;
characterized,
that glass hollow bodies (26) are embedded in the matrix material (24). A missile (2) according to claim 1,
characterized,
hollow glass body that at least 80% of the matrix material (24) contained (26) having an outer diameter of 12 microns ± 5 microns. A missile (2) according to claim 1 or 2,
characterized,
that the hollow glass body (26) constitute at least 20% of the layer volume of the ablation layer (18). A missile (2) according to one of the preceding claims,
characterized,
that the matrix material (24) is a self-hardening material. A missile (2) according to one of the preceding claims,
characterized,
that the matrix material (24) contains an epoxy resin. A missile (2) according to one of the preceding claims,
characterized,
in that the matrix material (24) contains a polyester resin. A missile (2) according to one of the preceding claims,
characterized,
in that the matrix material (24) contains an elastomer, in particular a terpolymeric elastomer. A missile (2) according to one of the preceding claims,
characterized,
in that the matrix material (24) contains a thermoplastic. A missile (2) according to one of the preceding claims,
characterized,
that the matrix material (24) contains an isocyanate. A missile (2) according to one of the preceding claims,
characterized,
in that the ablation layer (18) has a decomposition temperature between 150 ° C and 250 ° C. A missile (2) according to one of the preceding claims,
characterized,
that the composition of matrix material (24) and glass hollow bodies (26) is selected so that the thickness of the ablation layer (18) at an energy input of 1 MW / m ² within 20 s between 50 .mu.m and 200 .mu.m shrinks. A missile (2) according to one of the preceding claims,
characterized,
in that the ablation layer (18) comprises a base layer (20) and a cover layer (22) applied thereon, which is free of glass hollow bodies (26). A missile (2) according to claim 12,
characterized,
that the material of the covering layer (22) is the same material as the matrix material (24). Use of a matrix material (24), in which glass hollow bodies (26) are embedded, as an ablation layer (18) provided for partially evaporating during a flight and forming an outer coating on the outer shell (12) of a missile (2). Method for producing a missile (2) with an outer shell (12), in which an outer coating in the form of an ablation layer (18) is applied to the outer shell (12), which contains a matrix material (24) provided for at least partial decomposition during flight , are embedded in the hollow glass body () 26, wherein the ablation layer (18) is applied as a liquid material on the outer shell (12) and then cured.

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