GB1578279A

GB1578279A - Method and apparatus for providing ground settling of the support plate of a shell thrower

Info

Publication number: GB1578279A
Application number: GB25479/77A
Authority: GB
Original assignee: Foerenade Fabriksverken AB
Current assignee: Foerenade Fabriksverken AB
Priority date: 1976-06-18
Filing date: 1977-06-17
Publication date: 1980-11-05
Also published as: NO144117C; SE7606985L; NO772134L; FI66249B; FI66249C; FI771916A; SE413698B; FR2355270A1; FR2355270B3; DE2726991A1; DE2726991C2; IL52285A; CH619040A5; NO144117B

Abstract

In order to fire the settling mortar shell, said shell is inserted into the barrel (1) of the mortar from above. When the firing pin (15) strikes the explosive capsule (14) of the mortar shell, the explosive charge (16) is detonated. This causes ignition of the powder charge (17), the sealing disc (18) bursting and burning or being pulverised. At the same time, there is strong recoil which is transmitted via the base (12) of the mortar shell and the base part (2) of the mortar to the base plate (4) which sinks further into the ground under this force. The explosion gases which flow out through the nozzle (13) have a very high speed. They are driven out through the barrel (1) of the mortar. They represent a flame which can be several metres long. Said flame is, however, not high enough to be able to observed from a long distance. It can also not be detected in the enemy radar. The casing 11 of the settling mortar shell can be pulled out of the barrel (1) by means of a suitable tool which is placed on the shoulder (19) of the nozzle (13). This settling mortar shell allows the base plate of a mortar to be settled without this being detectable by means of radar or similar means. <IMAGE>

Description

(54) METHOD AND APPARATUS FOR PROVIDING GROUND SETTLIMG OF THE SUPPORT PLATE OF A SHELL THROWER (71) We, FORENADE FABRIKSVERKEN, a Company owned by the Swedish Government, of 8 Tullgatan, S-631 87 Eskilstuna, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a method and an apparatus for providing a settling in the ground of the support plate of a shell thrower.

When shooting with a shell thrower a support plate for the shell thrower is put on the ground and is as far as possible pressed down into the ground, and the shell thrower is placed on said support plate. Since however the support plate "settles" when firing the first number of shots in that the support plate sinks somewhat down into the ground and/or is somewhat displaced in the horizontal direction the first shots give a strongly reduced accuracy in the shooting. Therefore some "settling shots" are fired, generally two or three shots, and during the firing thereof the bottom plate settles into the ground. Thereafter the real shooting can start.

In the future the movability of shell thrower units will be very high, and it can be calculated that settling shots, adjustment shooting and the real shooting must have been ended within two or three minutes, whereupon the units must change groups since they enemy by means of radar or other means may have succeeded in localizing the shell thrower within the lapse of said period of time.

Since the settling shots are normally considered ineffective it would be advantageous to be able to provide a settling of the support plate of the shell thrower without giving the enemy a possibility of localizing the shell thrower until the settling is already accomplished and the adjustment shooting and the real shooting has started.

Basis of the invention therefore is the problem to suggest a method and an apparatus for providing a ground settling of the support plate of a shell thrower without this being observable by means of radar or similar means.

According to the invention the said problem is solved by a method and a device, whereby one or several settling shots are fired in such a way that the settling shell or shells remain in the barrel of the shell thrower or are thrown out of the barrel such short distance that they cannot be observed optically from long distance, on radar or by similar means.

Further characteristics of the invention will be evident from the following detailed description in which reference will be made to the accompanying drawing. It is however to be understood that the following specification and the embodiment of the invention which is shown in the drawing is only an illustrating example and that different modifications may be presented within the scope of the appended claims.

In the drawing is diagrammatically and partly in an axial cross-section shown a shell thrower comprising a barrel 1 having a bottom piece 2 with a ball connection 3. For supporting the shell thrower on the ground there is a support plate 4 having a ball socket 5 for receiving the ball connection 3. On the underside the support plate 4 is formed with wings 6 intended to be pressed down into the ground and to prevent a side displacement of the support plate during the shooting. The support plate has a relatively large area so as to give a good support also in the vertical direction for the shell thrower after the support plate has settled in the ground. At the upper end the barrel 1 carries a couple of support legs 7 and a diagrammatically illustrated adjustment means 8 for the elevation and side correction of the shell thrower.

When mounting the shell thrower the support plate 4 is put on the ground and is by hand pressed as far as possible down into the ground.

Depending on the pressure forces appearing when shooting with the shell thrower the position of the support plate however is changed both in that the support plate can be displaced somewhat in the horizontal direction and that it sinks somewhat further down in the ground, for instance to the level 10, whereby the support plate can be supposed to have taken a stable position in which the shell thrower can be directed and the adjustment shooting and the real shooting can start.

In order to have the support plate settle in the ground and thereby be displaced from the ground position 9 to the ground position 10 one or more settling shots are fired, and in order to prevent the enemy from observing the said shooting a settling shell is used, which according to the invention is formed so that the shell remains in the barrel of the shell thrower when being fired or is thrown out of the barrel such short distance that it cannot be observed on the radar of the enemy or by other observation means.

The settling shell which in the drawing is shown in the shooting position in the shell thrower comprises a sleeve 11 the outer diameter of which substantially corresponds to the caliber of the barrel 1. At the lower end of the sleeve I 1 a bottom portion 12 is threaded which in the firing moment is supported on the bottom piece 2 of the shell thrower. In the upper part of the sleeve 11 is provided with or formed as a nozzle 13 the purpose of which is to increase the outflow speed of the combustion gases when shooting the settling shell thereby increasing the recoil pressure in the direction downwards which pressure is transmitted to the support plate 4 and provides a pressing down thereof in the aground. The nozzle 13 can be threaded in the sleeve 11 or can be formed integral therewith.

In the bottom portion 12 of the settling shell a detonating cap 14 is provided which when letting the shell down in the barrel hits a detonating pin 15 provided in the bottom piece 2 of the shell thrower. The bottom portion 12 of the settling shell carries a detonation charge 16 which in turn carries a powder charge 17 preferably comprising so called strips, and the powder charge 17 is on the top closed by a closing disc 18 which in the direction outwards is secured by a shoulder 19 at the lower edge of the nozzle 13.

The bottom portion 12 of the shell is preferably made of metal and the sleeve 11 and the nozzle 13 can be made of metal e.g. steel, aluminium or a metal alloy, a reinforced plastic or any other suitable material. Especially in the case when the settling shell is formed so as to remain in the barrel during the combustion of the powder charge there are no specific high demands on the strength of the sleeve 11 and therefore the sleeve can be made of a relatively simple and cheap material.

The closing disc 18 should be made of a material which breaks and is burnt or powdered when firing the shell, and as suitable materials can be mentioned wood fibre material, brittle plastic material, e.g. Bakelite (Registered Trade Mark) or similar, and preferably being a material which fractures at applied pressures of 100 bars or over.

When firing the settling shot the settling shell is in the conventional way let down in the barrel 1 of the shell thrower from the top, and when the detonation pin 15 hits the detonation cap 14 of the shell the detonation charge 16 is fired and the detonation charge 16 in turn fires the powder charge 17, whereby the closing disc 18 breaks and is burnt or powdered depending on the heat and pressure during the combustion of the powder charge. At the same time thereby appears a strong downwards recoil which over the bottom portion 12 of the shell and the bottom piece 2 of the shell thrower is transmitted to the support plate 4 which is thereby forced down in the ground.The combustion gases from the powder charge which have a very high speed when passing the nozzle 13 are ejected through the barrel of the shell thrower and give a flame which is some few meters high but which is not high enough to be observed from long distance and which can most important of all not be registered on the radar of the enemy.

The settling shell can be extracted by means of any suitable tool engaging the shoulder edge 19 ofthenozzle 13.

After the settling shots are fired the support plate 4 is supposed to have taken a stable position in the ground and after adjusting the shell thrower the shooting with live shells begins.

In an alternative embodiment of the invention the settling shell is on the outside thereof formed with one or more longitudinal or in spiral extending grooves which open at the underside of the bottom portion 12. When firing the settling shell the pressure is transmitted to the underside of the bottom portion 12 over the said grooves so that the shell is lifted and thrown out of the barrel 1. The grooves on the outside of the sleeve should be formed so that a relatively soft secondary pressure is built up at the underside of the bottom portion 12, whereby the shell is ejected from the barrel 1 by a relatively weak force and so that it is thrown out only some few meters. As an alternative to the grooves on the outside of the sleeve 11 the bottom portion 12 can be provided with one or more through bores to provide the ejection of the shell from the barrel 1. Also in this case the bores of the bottom portion 12 should be formed so that the shell is not brought to leave the barrel of the shell thrower until at the end of the pressure phase.

WHAT WE CLAIM IS: 1. Method for providing a ground settling of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. thrower. When mounting the shell thrower the support plate 4 is put on the ground and is by hand pressed as far as possible down into the ground. Depending on the pressure forces appearing when shooting with the shell thrower the position of the support plate however is changed both in that the support plate can be displaced somewhat in the horizontal direction and that it sinks somewhat further down in the ground, for instance to the level 10, whereby the support plate can be supposed to have taken a stable position in which the shell thrower can be directed and the adjustment shooting and the real shooting can start. In order to have the support plate settle in the ground and thereby be displaced from the ground position 9 to the ground position 10 one or more settling shots are fired, and in order to prevent the enemy from observing the said shooting a settling shell is used, which according to the invention is formed so that the shell remains in the barrel of the shell thrower when being fired or is thrown out of the barrel such short distance that it cannot be observed on the radar of the enemy or by other observation means. The settling shell which in the drawing is shown in the shooting position in the shell thrower comprises a sleeve 11 the outer diameter of which substantially corresponds to the caliber of the barrel 1. At the lower end of the sleeve I 1 a bottom portion 12 is threaded which in the firing moment is supported on the bottom piece 2 of the shell thrower. In the upper part of the sleeve 11 is provided with or formed as a nozzle 13 the purpose of which is to increase the outflow speed of the combustion gases when shooting the settling shell thereby increasing the recoil pressure in the direction downwards which pressure is transmitted to the support plate 4 and provides a pressing down thereof in the aground. The nozzle 13 can be threaded in the sleeve 11 or can be formed integral therewith. In the bottom portion 12 of the settling shell a detonating cap 14 is provided which when letting the shell down in the barrel hits a detonating pin 15 provided in the bottom piece 2 of the shell thrower. The bottom portion 12 of the settling shell carries a detonation charge 16 which in turn carries a powder charge 17 preferably comprising so called strips, and the powder charge 17 is on the top closed by a closing disc 18 which in the direction outwards is secured by a shoulder 19 at the lower edge of the nozzle 13. The bottom portion 12 of the shell is preferably made of metal and the sleeve 11 and the nozzle 13 can be made of metal e.g. steel, aluminium or a metal alloy, a reinforced plastic or any other suitable material. Especially in the case when the settling shell is formed so as to remain in the barrel during the combustion of the powder charge there are no specific high demands on the strength of the sleeve 11 and therefore the sleeve can be made of a relatively simple and cheap material. The closing disc 18 should be made of a material which breaks and is burnt or powdered when firing the shell, and as suitable materials can be mentioned wood fibre material, brittle plastic material, e.g. Bakelite (Registered Trade Mark) or similar, and preferably being a material which fractures at applied pressures of 100 bars or over. When firing the settling shot the settling shell is in the conventional way let down in the barrel 1 of the shell thrower from the top, and when the detonation pin 15 hits the detonation cap 14 of the shell the detonation charge 16 is fired and the detonation charge 16 in turn fires the powder charge 17, whereby the closing disc 18 breaks and is burnt or powdered depending on the heat and pressure during the combustion of the powder charge. At the same time thereby appears a strong downwards recoil which over the bottom portion 12 of the shell and the bottom piece 2 of the shell thrower is transmitted to the support plate 4 which is thereby forced down in the ground.The combustion gases from the powder charge which have a very high speed when passing the nozzle 13 are ejected through the barrel of the shell thrower and give a flame which is some few meters high but which is not high enough to be observed from long distance and which can most important of all not be registered on the radar of the enemy. The settling shell can be extracted by means of any suitable tool engaging the shoulder edge 19 ofthenozzle 13. After the settling shots are fired the support plate 4 is supposed to have taken a stable position in the ground and after adjusting the shell thrower the shooting with live shells begins. In an alternative embodiment of the invention the settling shell is on the outside thereof formed with one or more longitudinal or in spiral extending grooves which open at the underside of the bottom portion 12. When firing the settling shell the pressure is transmitted to the underside of the bottom portion 12 over the said grooves so that the shell is lifted and thrown out of the barrel 1. The grooves on the outside of the sleeve should be formed so that a relatively soft secondary pressure is built up at the underside of the bottom portion 12, whereby the shell is ejected from the barrel 1 by a relatively weak force and so that it is thrown out only some few meters. As an alternative to the grooves on the outside of the sleeve 11 the bottom portion 12 can be provided with one or more through bores to provide the ejection of the shell from the barrel 1.Also in this case the bores of the bottom portion 12 should be formed so that the shell is not brought to leave the barrel of the shell thrower until at the end of the pressure phase. WHAT WE CLAIM IS:

1. Method for providing a ground settling of

the support plate of a shell thrower, characterized in that one or more settling shots are fired by means of a settling shell in such a way that the settling shell during the firing remains in the barrel of the shell thrower or is ejected only a short distance from the barrel, whereby substantially only a flame of fire or some few meters height appears from the barrel.

2. A settling shell for carrying out the method of claim 1 ,said shell comprising a tubular casing open at one end and closed at the other by an end wall in which is mounted a detonating cap in a position to be detonated by the detonating pin of the shell thrower, a powder charge packed in said casing and sealed therein by a combustible or frangible closing disc retained within the tubular casing and spaced inwardly from said open end, wherein, in the open end of said casing, on the side of the closing disc remote from the powder charge is located a nozzle effective upon detonation of the shell to accelerate the gases leaving the shell casing and to increase the downward thrust on the support plate of the shell thrower.

3. A settling shell according to claim 2, wherein the tubular casing, rearwardly of said nozzle, towards the closed end, is provided with an inwardly directed abutment serving to retain in position said closing disc.

4. A settling shell according to claim 2 or 3, wherein said disc is constructed of wood fibre, or a synthetic plastics material having a brittleness that the disc is fractured at an applied pressure of 100 bars or over.

5. A settling shell according to any one of claims 24, wherein said casing is of steel, aluminium, a metal alloy, or reinforced plastic.

6. A settling shell according to any one of claims 2-5, wherein said nozzle is formed integrally with said casing.

7. A settling shell according to any one of claims 2-6, wherein the external surface of the shell casing is provided with one or more longitudinally extending or helical grooves, or said end cap is provided with one or more through bores, said grooves or bores being effective on detonation of the shell to transmit a secondary gas pressure to the underside of the closed end of the shell and thereby effect automatic ejection of the spent shell from the shell thrower.