Fuse with reversible airbrake

Abstract

A fuse is provided with a reversible airbrake intended for a projectile, wherein the airbrake is arranged such that errors which occur in the flight path of the projectile can be corrected by performing one or more extensions and retractions of the airbrake. The airbrake includes at least two braking surfaces symmetrically arranged each behind a respective protective device arranged on the casing surface of the fuse, wherein the brake surfaces can be extended and retracted in a rotational direction behind the at least two protective devices via a twist shaft arranged centrally in the fuse.

Claims

1. A fuse with a reversible airbrake, comprising a casing having a casing surface, protective devices arranged on the casing surface, and a reversible airbrake intended for a projectile, wherein the airbrake comprises at least one brake disc, the at least one brake disc comprising at least two brake surfaces arranged on a brake ring, the at least two brake surfaces being in a form of radially protruding parts on a periphery of the brake ring, the radially protruding parts being evenly distributed around the casing surface and arranged each behind a respective protective device of the protective devices in order to reduce the air resistance of the brake surfaces behind, wherein the brake surfaces are rotationally movable about a longitudinal axis of the fuse between a retracted position behind the respective protective devices and an extended position and, when retracted to the retracted position, the brake surfaces are concealed behind the respective protective devices when viewed from a front end of the fuse.

2. The fuse with a reversible airbrake according to claim 1, comprising three to ten brake surfaces evenly distributed around the casing surface.

3. The fuse with a reversible airbrake according to claim 1, wherein the brake surfaces are arranged successively in pairs behind the respective protective devices, the respective protective devices defining a rear plane and being evenly distributed on and around the casing surface, wherein the arranged brake surfaces are formed by a front brake surface arranged closest to the rear plane and a rear brake surface arranged behind the front brake surface in a direction away from the frontend.

4. The fuse with a reversible airbrake according to claim 3, comprising one or more rear brake surfaces.

5. The fuse with a reversible airbrake according to claim 1, wherein the brake surfaces are formed with a cross-section which corresponds to the cross-section of the respective protective device, so that in the retracted position, the brake surfaces are concealed behind the protective devices when viewed from the front.

6. The fuse with a reversible airbrake according to claim 1, wherein the brake surfaces are formed with a rectangular, circular, fin-shaped or arcuate cross-section.

7. The fuse with a reversible airbrake according to claim 1, wherein the respective protective devices define a rear plane, and the at least one brake disc includes a front brake ring arranged closest to the rear plane and one or more rear brake rings arranged behind the front brake ring in a direction away from the front end, the brake surfaces are evenly distributed on the front brake ring and the one or more rear brake rings.

8. A method of controlling the longitudinal spread of a projectile comprising an existing path-correcting fuse, the method comprising replacing the existing path-correcting fuse with a fuse comprising a reversible airbrake according to claim 1.

9. A projectile comprising a fuse according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is now described as an example with reference to the attached drawings in which:

(2) FIG. 1 shows a perspective view of a fuse with reversible brake surfaces in the inactivated, retracted position (a) behind protective devices, and a fuse with brake surfaces in the activated, extended position (b) behind the protective devices.

(3) FIG. 2 shows a perspective view of the brake surfaces arranged on brake rings behind a fuse with protective devices (a), and an embodiment with a fixed front brake disc (b) as a protective device.

DETAILED DESCRIPTION

(4) Before the invention is described in detail, it should be understood that this invention is not restricted to specific materials or configurations described herein. The configurations and materials may vary, for example in number, size, material and form of the elements contained in the proposed projectile, and details may be adapted according to the projectile type or types, the weapon system and/or other design properties which arise in the circumstances.

(5) It should also be understood that the terminology applied herein is used merely to describe specific embodiments and is not intended to restrict the scope of the present invention which is limited only by the attached claims.

(6) A reversible airbrake means an airbrake which can be extended and retracted, i.e. the braking effect can be increased or reduced by controlling the size of the brake surface. This allows correction of deviations in the flight path of the projectile, which reduces the longitudinal spread for example on artillery firing. Optimally, the airbrake can be extended and retracted several times during a flight of a projectile, which is possible with the present invention since the braking surfaces move in the rotational direction.

(7) The present invention will now be described in more detail with reference to the attached figures which show exemplary embodiments of the invention.

(8) FIG. 1 shows an embodiment of a projectile 2 with a reversible airbrake 1 according to the present invention. The front part 2 of the projectile body is screwed onto the rear part of the fuse 3. The front part of the fuse 3 is protected by a cone/truncated cone 30, the sides of which are called the casing surface 4. The airbrake 1 is in the retracted or non-braking position. The airbrake 1 comprises extendable and retractable brake surfaces 8, 8′ which in this embodiment consist of or comprise a front plate 8 and a rear plate 8′. These plates (8, 8′) are arranged in twistable fashion on the casing surface 4 of the fuse 3 of the projectile 2. The brake surfaces 8, 8′ are arranged behind a protective device 5 which in this embodiment is wedge-shaped. The number of wedges is here four, which are evenly distributed on and around the casing surface 4 of the fuse 3. The protective devices 5 reduce the air resistance of the brake plates 8, 8′ of the airbrake 1 during the flight of the projectile 2. In this way, sideways radial movements of the brake surfaces 8, 8′ are possible, which means that the brake effect can be controlled/regulated both ways, i.e. an increased or reduced angle of the brake surfaces 8, 8′ gives a greater or lesser braking effect. In one embodiment, the respective brake surfaces 8, 8′ may be driven both ways, i.e. both clockwise and counterclockwise. In other embodiments, they can only be driven one way. There may be one, two, three or multiple brake surfaces which are arranged behind each other and extended one after another in one direction only, in the manner of a fan. The brake surfaces then become gradually larger or smaller on one side of the respective protective device 5, depending on whether the brake surfaces 8, 8′ are angled out or in, and on how many of them are angled out or in. The brake surfaces can be controlled radially sideways in both directions, so the braking effect can be amplified or weakened under control. The movement is stepped or continuous. The extension X-X corresponds to the longitudinal axis of the projectile or the line of symmetry, and the present brake surfaces (8, 8′) are extendable and retractable radially sideways behind said protective devices (5) (wind protection), i.e. along the casing surface (4) perpendicularly to the longitudinal axis of the fuse or projectile. The brake surfaces 8, 8′ of the airbrake 1 are arranged behind and directly adjacent to the rear plane of the protective devices 5. The protective devices 5 are formed such that their cross-section corresponds to the cross-section of the brake surfaces 8, 8′, but other forms may also occur, such as for example fin-shaped, rectangular or arcuate. In this embodiment, the wedges 5 extend axially from the casing surface 4 of the fuse 3, from the rear part of the fuse 3 in the direction towards the nose part of the fuse 3. The airbrake 1 contains eight brake surfaces 8, 8′ arranged in pairs behind the rear plane of the four wedges 5. Each of the pairs of brake surfaces 8, 8′ is formed by a front brake surface 8 arranged closest to the rear plane of the wedge 5, and a rear brake surface 8′ arranged behind the front brake surface 8. The number of brake surfaces fitted behind a protective device is not limited in the invention, since certain embodiments have multiple brake surfaces arranged behind each other. The pairs of brake surfaces 8, 8′ are formed such that when retracted, in the inactivated position, they are concealed behind the rear plane of the respective wedge 5 when viewed from the front.

(9) FIG. 1b shows the same embodiment of the airbrake as FIG. 1a but in the extended braking position. On extension of the brake surfaces 8, 8′, the front brake surface 8 of the two paired brake surfaces 8, 8′ is twisted counterclockwise around the symmetry line of the projectile 1, so that it appears on the left side of the wedge 5 when viewed from the front. The other brake surface 8′ is twisted in the opposite direction, rotationally clockwise, so that it appears on the right side of the wedge 5 when viewed from the front. In other embodiments, they may be controllable in the same way or in opposite ways, or both ways.

(10) FIG. 2a shows an embodiment of the brake discs 6,6′. The airbrake 1 in this embodiment comprises two similar brake discs 6, 6′ arranged in twistable fashion, namely a front brake disc 6 and a rear brake disc 6′. In this embodiment, the brake discs consist of or comprise a brake ring 7, 7′ on which the brake surfaces 8, 8′ are arranged.

(11) A front brake disc 6, 6′ according to the present invention comprises or consists here of brake surfaces 8, 8′ arranged on a brake ring 7, 7′.

(12) The front brake disc 6 is arranged closest to the rear plane of the wind protection 5, and the rear brake disc 6′ is arranged behind the front brake disc 6. In this embodiment, the front brake disc 6 contains four evenly distributed brake surfaces 8, and the rear brake disc 6′ comprises four evenly distributed brake surfaces 8′. The brake surfaces 8, 8′ in this embodiment are integrated with the brake rings 6, 6′ in the form of radially protruding parts on the periphery of the brake rings 6, 6′.

(13) The number of brake surfaces 8 is at least two. The number of brake surfaces 8 may vary, on condition that they are symmetrically balanced around the body 2 of the projectile. The size of the brake surfaces may also vary, since sometimes it is more suitable to have several small brake surfaces 8, 8′ which can be extended one after the other, and sometimes fewer large brake surfaces 8, 8′, wherein the number or shape of these is not limited in the present invention.

(14) The rotation of the brake discs 6, 6′ is driven in one embodiment for example by ring gears. The ring gears may be driven for example by a two-way gear arrangement coupled to a twist shaft which is centrally arranged in the fuse 3 and driven by a battery-powered electric motor. On activation and extension of the airbrake 1, the respective brake discs 6, 6′ are twisted simultaneously, via the gear arrangement and twist shaft, respectively counterclockwise and clockwise through a given distance in the rotational direction.

(15) On deactivation and retraction of the airbrake, the respective brake disc 6, 6′ is twisted correspondingly in the opposite rotational direction. In another embodiment of the airbrake as a discontinuously variable, on and off brake, the brake discs 6, 6′ are twisted instantaneously between two end positions, from fully retracted brake surfaces 8, 8′ to fully extended brake surfaces 8, 8′, or from fully extended brake surfaces 8, 8′ to fully retracted brake surfaces 8, 8′. The position of the brake surfaces 8, 8′ is controllable, which means that their position and braking effect can be determined. One or more battery-powered solenoids may be used instead of an electric motor to drive the twist shaft (not shown). The use of solenoids means a cheaper solution than an electric motor, and the projectile would also be lighter with the solenoid solution. Alternatively, the inner parts of the brake discs 6, 6′ are formed with drive cogs.

(16) For frictionless rotation of the brake discs 6, 6, a plain bearing may be provided, or one or more ball bearings between the brake discs 6, 6′.

(17) In a further embodiment of the airbrake 1 as a continuously variable brake for selective control of a projectile, the brake discs 6, 6′ are instead twisted in stages through short distances for successive correction of the projectile flight path during its travel to the target. Control takes place via satellite navigation. For example, the twist distances are calculated by a programmable control computer, based on collected data from measurement and image sensors arranged in the projectile, for example on speed, direction and position of projectile relative to the target.

(18) FIG. 2b shows a further embodiment of said airbrake 1. In this embodiment, the protective device is formed by the first brake surface 8 which is fixedly mounted on the fuse 3, such that the first brake surface 8 is not controllable or is in the inactive position. Behind the first brake surface 8 is at least one controllable brake surface (8′) as described above.

(19) An airbrake 1 according to said principle may be formed either as a continuously variable brake or as a discontinuously variable, on and off brake.

(20) For the present embodiment to work, the rotation centre must not be moved from the symmetry axis.

(21) In yet another embodiment (not shown) intended for selective control of several projectiles simultaneously against different targets, the fuse or projectile also comprises a satellite-navigated unit for remote-controlled programming by a programmable control computer.

(22) The protective devices 5 however generate an air resistance, but this is acceptable taking into account the improved controllability provided by a reversible airbrake 1 which can be extended and retracted.

(23) To summarise, the present invention solves the problem of the effect of centripetal acceleration on the airbrake on extension and retraction, because the airbrake is formed with twistably arranged brake surfaces 8, 8′. On extension and retraction of the brake surfaces 8, 8′, these are twisted in a rotational direction behind the respective protective device 5, which also allows path corrections in the later part of the flight path towards a target. With real-time control.