EP0404844B1 - Shell base for carrier missiles - Google Patents

Abstract

The base plate (23) of a shell base (20) for a carrier missile, with a cavity (26), for example for a parachute, on the side farther from the rear of the missile may be bent axially when the missile is fired. This results in radial constriction of the base envelope (22) and loss of contact between the guide strip (27) on the envelope (22) and the barrel of the weapon and frequently leads to escape of gas. To prevent the above-mentioned radial constriction in the region of the guide strip, the shell base (20) has a base plate (23) convex toward the rear of the missile. As a result of the convexity of the base plate (23), when the missile is fired a radial expansion occurs which ensures that the guide strip (27) remains gastight and transmits torsion even at high gas pressures.

Description

The invention relates to a floor for support floors, as defined in the preamble of claim 1.

Such a floor is known for example from DE 36 43 291. As tests have shown, such floors have an unfavorable deformation behavior. This leads to problems with sealing and with the swirl transmission through the guide band. The gas breakdown that is unavoidable at high gas pressures (loss of contact between the guide band and the pipe wall) leads to the opening and closing of the sealing gap while the pipe is passing through, thus stimulating the projectiles to vibrate and increasing pipe wear.

The cause of these sealing problems is that the axial force components attacking the rear of the projectile cause an axial deflection of the base plate, combined with a radial expansion of the front cover of the floor and a radial constriction of the rear floor or the rear guide band area. The radial deformation due to the axial force components during firing are superimposed on the radial deformations due to the simultaneously acting radial force components.

This overlay causes the resulting radial deformation of the floor of the floor.

The radially acting forces result on the one hand from the gas pressure which is present up to the rear edge of the guide belt and the guide belt pressure. These forces lead to a radial constriction of the floor covering over the entire length. If the result of the superimposition of both deformation states is a resulting radial constriction at the rear edge of the guide belt, there is a loss of contact between the guide belt and the tube. This exposed gap space fills with gas, which is synonymous with an increase in the radial force on the bottom shell. This results in a further enlargement of the radial constriction in the area of the guide belt and ultimately leads to complete gas breakdown.

Explosive projectiles are also known from US Pat. No. 4,327,643, the base plates of which are curved on the rear side. However, there is explosive in the interior of the storeys, so that the base plate cannot be deformed much in the axial and radial directions (if there were a cavity in the interior of the storeys, the floor of the storey would lack radial support from the explosive due to its thin walls and extreme curvature of the floor collapse under the gas pressure up to the guide band when firing).

The present invention has for its object to provide a floor of the type mentioned, in which a radial constriction in the guide band area is avoided.

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

The further subclaims represent particularly advantageous embodiments of the invention.

The invention is therefore based on the idea of correcting the deformation behavior during firing by means of a curved shape of the base in such a way that the axial bulging of the base also causes a radial expansion in the rear floor area. This shape-specific bottom deformation during firing ensures gas tightness and swirl transmission of the guide belt even at high gas pressures.

At this point, it should be pointed out once again that the idea of the invention, which is essential to the invention, cannot be deduced from US Pat. A corresponding radial constriction of the guide band should not be prevented there or does not occur at all because the projectile itself is filled with explosives up to the base plate.

In the following, more details and advantages of the invention will be described using exemplary embodiments and with the aid of figures.

Fig. 1a und 1b

schematisch den Querschnitt eines an sich bekannten Hohlbodens im Ruhezustand und beim Abschuß;

Fig. 2

den Querchnitt eines erfindungsgemäßen Hohlbodens;

Fig. 3a und 3b

den Querschnitt eines erfindungsgemäßen Kugelkalottenbodens im Ruhezustand und beim Abschuß;

Fig. 4

die Gegenüberstellung eines an sich bekannten Flachbodens mit einem Kugelkalottenboden;

Fig. 5

den Querschnitt eines erfindungsgemäßen Kegelbodens; und

Fig. 6

den Querschnitt eines Teiles eines Trägergeschosses mit erfindungsgemäßem Geschoßboden.

Show it:

1a and 1b

schematically the cross section of a hollow floor known per se at rest and when firing;

Fig. 2

the cross section of a hollow floor according to the invention;

3a and 3b

the cross section of a spherical cap bottom according to the invention in the idle state and when firing;

Fig. 4

the comparison of a flat bottom known per se with a spherical cap bottom;

Fig. 5

the cross section of a conical bottom according to the invention; and

Fig. 6

the cross section of a part of a supporting floor with floor floor according to the invention.

In Fig. 1a and 1b, 10 denotes the floor, which consists of a base shell 12 and a base plate 13. The bottom cover 12 has a conical rear part 14 (also referred to as a boat tail). The boat tail circumferential edge, that is to say the transition region from the conical rear part to the cylindrical base shell, is identified by 15.

On the side of the floor 10 facing away from the rear of the projectile there is a cavity 16 in which there are no parts axially supporting the base plate 13 and the base shell radially. In practice, parachutes of the submunition storeys are often arranged in this room. A guide band 17 is also applied to the base shell 12. For the sake of a better overview, the barrel walls of the weapon have not been shown in the figures.

In Fig. 1a, the floor 10 is shown in its rest position. As FIG. 1b shows, the forces acting on the rear of the projectile cause an axial deflection of the base plate 13, combined with a radial expansion in the front area of the base cover 12. At the same time, there is a radial constriction in the rear area of the base cover 12, supported by the guide band pressure and the radially acting gas pressure up to the trailing edge of the guide belt. This constriction causes the guide band 17 to lose its sealing function with respect to the combustion gases when fired at high gas pressures. A loss of contact at the trailing edge of the guide belt increases the radial application of force and increases the radial constriction of the bottom cover 12. A gas breakdown is then inevitable.

mit:

D =

Kaliber des Geschosses

t =

Wölbungstiefe

f =

Abstand der Führungsbandhinterkante vom äußeren Rand der Wölbung

g =

Abstand der Führungsbandhinterkante von der Boat-Tail-Kante

β =

maximaler Steigungswinkel.

Fig. 2 shows the cross section of a floor 20 according to the invention, which has a floor covering 22 and a floor plate 23. The conical rear part was designated 24, the boat tail circumferential edge 25, the parachute-receiving cavity 26 and the guide band 27. The trailing edge of the guide belt bears the reference number 28. The following relationships apply to the curvature of the base plate 23:

With:

D =

Bullet caliber

t =

Depth of curvature

f =

Distance of the trailing edge of the guide belt from the outer edge of the curvature

g =

Distance of the leading edge of the guide belt from the boat tail edge

β =

maximum pitch angle.

The distance between the edge region of the curvature and the inner edge of the boat tail is considerably smaller than the caliber D and essentially corresponds to the transition radii between the curvature and the boat tail. This area is neglected in the following FIGS. 3 to 6, i. H. the curvature connects directly to the inside of the boat tail.

In the following, a floor is described in more detail in which the curvature of the base plate has the shape of a spherical cap:

wobei R der Radius der Kugelkalotte ist.In Fig. 3a, the floor 30 of the invention is shown in the idle state. The floor covering of the floor is marked with 32, the bottom plate with 33, the conical rear part with 34 and the boat tail circumferential edge with 35. The parachute cavity, the guide band and the guide band trailing edge have the reference symbols 36, 37 or 37 'and 38 or 38'. Instead of the relationship (1), the curvature of the bottom plate 33 can also be described using the following relationship: $$\text{2/3 D ≦ R ≦ 3/2 D}$$

where R is the radius of the spherical cap.

It should also be noted that the following should apply to the distance x from the intersection of the elongated spherical cap 39 and the trailing edge 38 or 38 ': $$\text{x ≦ 1/10 D}$$

In this case, the intersection 39 can be both in front of and behind the trailing edge 38 or 38 ' lie. In Fig. 3a, the right half of the projectile shows an embodiment in which the guide band edge lies behind the intersection 39, while the left half of the storey floor shows an embodiment in which the guide band rear edge 38 'lies in front of the intersection 39.

In any case, the leading edge 38 or 38 'of the guide tape, seen in the flight direction, must lie in front of the circumferential edge of the boat tail 35 (g ≧ 0).

The effect of the curved bottom plate 33 when fired is shown in Fig. 3b. With the exception of part of the conical tail, there is a radial widening of the base shell 32. This ensures gas-tightness when fired, but also the swirl transmission of the guide band 37 or 37 '.

In Fig. 4 the relationships of a storey floor according to the invention (Fig. 4a)) and a conventional flat floor (Fig. 4b) are shown again. In both cases it is a bullet with a caliber D = 155 mm. Length of the floor, position and length of the guide bands 47 and 47 'are the same. The wall thickness W of the flat bottom is equal to the greatest wall thickness of the spherical cap bottom and is 30 mm. The radius R is equal to 130 mm. The first gas breakthrough occurred at 3600 bar for the flat bottom, while the gas breakthrough only occurred at 4500 bar for the spherical cap bottom.

5 shows a floor 50 with a conical base plate 53 as a further example. The bottom shell is designated 52, the conical rear section 54 and the boat tail circumferential edge 55. Similar to the dome bottom, the point of intersection of the bottom cone with the bottom cover 59 can be in front of or behind the trailing edge 58 or 58 '.

The following applies to the cone angle α of the base plate 53: $$\text{7 ° ≦ α ≦ 25 °}$$

The relationship (3) again applies to the distance x of the trailing edge of the guide belt from the intersection 59.

The present invention is particularly advantageous for artillery-carrying projectiles with a thin-walled projectile casing. Because the demand for maximum usable space limits the floor height and the thin wall of the projectile casing requires radial support of the projectile casing in the guide band area by the floor casing.

As a result of the limited floor length, you are usually forced to retract the rear edge of the guide belt to the circumference of the boat tail (g = 0) in order to be able to arrange the length of the guide belt required for swirl transmission at all on the stern or on the floor-supported area. In order to ensure the function of the entire guide belt at this position of the rear edge of the guide belt, a radial widening of the base coupled with a radial squeezing of the guide belt in this area is necessary. These requirements can be met with the floor of the invention.

In Fig. 6 a part of a carrier floor with a thin envelope is shown. The floor of the floor is designated by 60 and in turn consists of a floor covering 62 and a floor plate 63. The floor covering 62 has a conical rear part 64, the boat tail edge of which is designated 65.

Part of a two-part guide band 67 is seated on the bottom cover 62. The cavity for a parachute, not shown, is identified by 66. The thin shell 69 of the supporting floor is fastened to the floor 60. There are submunitions inside the main storey. The rear end of such a submunition was indicated by the reference number 70. In a practical exemplary embodiment, a spherical cap base was used as the base plate.

Reference symbol list

10th

Storey floor, hollow floor

12

Ground cover

13

Base plate

14

conical tail (boat tail)

15

Boat tail wrap edge

16

cavity

17th

Guide band

20th

Floor

22

Ground cover

23

Base plate

24th

conical tail section

25th

Boat tail wrap edge

26

cavity

27

Guide band

28

Trailing belt edge

30th

Floor

32

Ground cover

33

Base plate

34

conical tail section

35

Boat tail wrap edge

36

cavity

37

Guide band

37 '

Guide band

38

Trailing belt edge

38 '

Trailing belt edge

39

Intersection of the circle described by the radius with the ground envelope

43, 43 '

Base plate

45, 45 '

Boat tail wrap edge

47, 47 '

Guide band

48, 48 '

Trailing belt edge

50

Floor

52

Ground cover

53

Base plate

54

conical tail section

55

Boat tail wrap edge

57, 57 '

Guide band

58, 58 '

Trailing belt edge

59

Intersection of the bottom cone with the bottom cover

60

Floor

62

Ground cover

63

Base plate

64

conical tail section

65

Boat tail wrap edge

66

cavity

67

Guide band

68

Leading belt trailing edge

69

Bullet casing

70

Submunition storey

α

Cone angle

β

maximum pitch angle

D

caliber

f

Distance between the rear edge of the guide belt and the edge of the curvature

G

Distance between the leading edge of the guide belt and the boat tail edge

R

Radius of the spherical cap

t

Depth of curvature

w

Wall thickness of the floor slab

x

Distance of the trailing edge of the guide belt from the intersection of the floor covering with an extended spherical cap or floor cone

Claims (6)

1. Projectile base (10,20,30,50,60) for carrier projectiles of sub-ammunition (70), the projectile base (10,20,30,50,60) having a base casing (12,22,32,52,62) with a conical tail part (14,24,34,54,64) and a base plate (13,23,33,43,53,63) and a guide band (17,27,37,47,57,67) provided on the base casing (12,22,32,52,62), while on that side of the projectile base (10,20,30,50,60) which faces away from the tail of the projectile a hollow space (16,26,36,56,66) is provided in which no parts are mounted which support the base plate (13,23,33,43,53,63) or the base casing (12,22,32,52,62), the cover of the base plate (12,22,32,52,62) being selected to ensure that the base will resist the firing stresses, characterised by the fact that the projectile base (20,30,50,60) has a base plate (23,33,43',53,63) which is convex towards the tail of the projectile and that the convexity of the base plate is defined by the following equations: $$\text{1/20 D ≦ t ≦ 1/5 D}$$

   

   $$\text{1/20 D ≦ f ≦ 1/5 D}$$

   

   $$\text{g ≧ 0}$$

   

   $$\text{10° ≦ β ≦ 40°}$$

   

   wherein

   D =   calibre of projectile,

   t =   depth of convexity

   f =   distance of rear edge of the guide band from outer edge of convexity,

   g =   distance of rear edge of the guide band from the boat-tail-edge,

   β =   maximum gradient angle.
2. Projectile base in accordance with Claim 1, characterised by the fact that the convexity of the base plate (23,33,43',63) is constructed in the form of a spherical cap.
3. Projectile base in accordance with Claim 2, characterised by the fact that the radius (R) of the spherical cap is governed by the following equation: $$\text{2/3 D ≦ R ≦ D}$$

   
4. Projectile base in accordance with Claim 3, characterised by the fact that the distance x of the rear edge of the guide band (38,38',48,68) from the point of intersection (39) of the circle described by the radius (R) with the base casing (32,62) is governed by the equation $$\text{x ≦ 1/10 D,}$$

   

   while the point of intersection (39) may be situated either in front of or behind the rear edge of'the guide band (38,38',48',68).
5. Projectile base (10,20,30,50,60) for carrier projectiles of sub-ammunition (70), the projectile base (10,20,30,50,60) having a base casing (12,22,32,52,62) with a conical tail part (14,24,34,54,64) and a base plate (13,23,33,43,53,63) and a guide band (17,27,37,47,57,67) provided on the base casing (12,22,32,52,62), that side of the projectile base (10,20,30,50,60) which faces away from the tail of the projectile being provided with a hollow space (16,26,36,56,66) in which no parts are mounted which support the base plate (13,23,33,43,53,63) or the base casing (12,22,32,52,62), the cover of the base plate (12,22,32,52,62) being selected to ensure that the base will stand up to the firing stresses, characterised by the fact that the projectile base (20,30,50,60) has a base plate (22,33,43',53,63) convex in the direction of the tail of the projectile, the convexity of the base plate (53) being of conical construction and the cone angle α of the base plate (53) being governed by the equation $$\text{7° ≦ α ≦ 25°.}$$

   
6. Projectile base in accordance with Claim 5, characterised by the fact that the distance x of the rear edge of the guide band (58,58') from the point of intersection (59) of the prolonged base cone with the base casing (52) is governed by the equation $$\text{x ≦ 1/10 D,}$$

   

   while the point of intersection (59) of the base cone with the base casing (52) may be situated either in front of or behind the rear edge (58,58') of the guide band.

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