JPH06147798A - Base bleed bullet - Google Patents

Abstract

PURPOSE:To reduce both the weight and the volume of a base bleed bullet as compared with those of a conventional base bleed bullet and to provide a high hitting accuracy by providing a plurality of windows at equal intervals in a circumferential direction at a hollow cylindrical member having the same diameter as that of a rear end of a shell member for forming a gas supply chamber. CONSTITUTION:A cylindrical shell member 13 for forming a gas supply chamber 15 is mounted at a bottom 16 of a bullet, gas is supplied via a gas supply agent A to be charged in the chamber 15 to the rear of the bottom 16 to reduce a bullet bottom resistance. In such a base bleed bullet 30, the member 13 has a plurality of windows 9 at equal intervals in a circumferential direction. Thus, the used quantity of the agent can be largely reduced, and hence the volume of the gas supply chamber can be also largely decreased. As a result, the weight of the bullet can be reduced, and its volume and particularly its axial length can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to artillery shells used in artillery, and more particularly to base bleed shells therein.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional shell. This shell 1 is used, for example, as described below. Bullet bottom 2
A bag-shaped propellant is loaded between the gun and the barrel closing machine (not shown), and the number of the bags is increased or decreased depending on the range. Three
Indicates a fuze. Ignition of the propellant produces high-temperature, high-pressure gas, and this gas pressure fires a shell. In addition,
The closing machine is a cylindrical steel ingot which is screwed into the breech ring to close the breech.

The velocity of the shell fired from the gun is highest at the time of leaving the muzzle, and thereafter, the velocity decreases due to the drag force proportional to the square of the velocity, and the velocity drops to the ground. In order to extend the range, it is necessary to reduce the air resistance of the cannonball, and as a result, it has a pointed bullet shape as shown in FIG. The greatest drag factor in such bullet-shaped shells is the bottom resistance (base drag). This is because the projectiles fly at high speed, resulting in decompression in the rear area of the bottom of the projectile, which causes a force acting in the direction opposite to the flight direction to act.

In order to make the low pressure region behind the bottom of the bullet equal to the ambient pressure, gas is supplied to the rear of the bottom of the bullet to reduce the resistance of the bullet. An example of a base bleed bullet is shown in FIG. This base bleed bullet 20 has a cylindrical outer shell member 4 attached to a bullet bottom 2 ′, and the outer shell member 4 forms a gas supply chamber 8. The outer shell member 4 has a base 4a on one end side,
A gas outlet 6 is formed in the center of the base 4a. A gas supply agent 5 is annularly loaded in the gas supply chamber 8,
An ignition charge 7 is arranged at the center thereof and fixed to the bottom 2 '.

Next, the operation of the base bleed bullet will be described. When the base bleed bullet 20 is loaded into the barrel (not shown) and the propellant (not shown) is ignited, the propellant generates high-temperature and high-pressure gas, and this gas pressure causes the base bleed bullet 20 to move inside the barrel. Move forward at high speed. At this time, the ignition charge 7 in the gas supply chamber is ignited by the heat and pressure of the propellant to ignite the gas supply agent 5. The base bleed bullet 20 separated from the barrel flies while ejecting high-temperature gas supplied by the gas supply agent 5 from the outlet 6. This supply gas acts to prevent a pressure drop behind the bottom of the bullet. By this method, it was possible to reduce the base resistance of the base bleed bullet, and as a result, it was possible to extend the range by nearly 20%.

[0006]

The above-mentioned conventional base-bleed ammunition has a structure in which a gas supply agent is added to the conventional ammunition, and therefore the weight and volume of the conventional ammunition must be increased. was there.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to reduce both the weight and the volume of the conventional base bleed bullet. The aim is to provide a base bleed bullet that is both accurate and highly accurate.

[0008]

In the base bleed bullet of the present invention, a cylindrical outer shell member forming a gas supply chamber is attached to the bottom of the bullet, and a gas supply agent loaded in the gas supply chamber is provided to the rear of the bottom of the bullet. In a base bleed bullet that supplies gas to reduce bottom resistance, the outer shell member has a hollow cylindrical member having the same diameter as the outer shell member at the rear end, and the cylindrical member is circumferentially equidistant. It is characterized by having a plurality of windows at intervals.

If the amount of the gas supply agent used for the base bleed bullet can be reduced, the base bleed bullet can be made smaller and lighter. Therefore, the present inventor has focused on the composition. As the gas supply agent used for the base bleed ammunition, generally, a composite explosive capable of self-sustaining and stable combustion under low pressure is used. Its composition is 9 by weight percent
It consists of 0% solid oxidizer and 10% fuel / binder. Therefore, the objective can be achieved by reducing the amount of the oxidizer which makes up 90% of the total weight.

In order to reduce the amount of the oxidizing agent, the outer shell member is provided with a hollow cylindrical member having the same diameter as the outer shell member at the rear end according to the present invention, and the cylindrical member has a plurality of windows at equal intervals in the circumferential direction. Is achieved by having

With the above structure, it is possible to reduce the amount of the oxidizer, and consequently, the size and weight of the base bleed bullet can be reduced, and the amount of the oxidizer can be reduced by the oxygen in the air taken in through the window based on the above structure. Can be supplemented with.

The composition of the gas supply agent A used for the base bleed bullet of the present invention and the composition of the gas supply agent B used for the conventional base bleed bullet are shown in Table 1 (the numbers are weight percents). ).

[0013]

[Table 1]

A metallocene combustion catalyst is added to the gas supply agent A used in the base bleed bullet of the present invention in order to make the combustion rate equal to that of the gas supply agent B used in the conventional base bleed bullet. . Although butadiene rubber is used as the combustion and binder, other rubber or resin may be used as long as it has mechanical strength that satisfies the required value. Further, although ammonium perchlorate is used as the oxidant, other perchlorates or nitrates can be used as long as the burning rate satisfies the required value.

Compared with the gas supply agent B, the gas supply agent A has a significantly smaller amount of the oxidizing agent, that is, ammonium perchlorate. Therefore, it is in a state of oxygen deficiency, and when it is burned, a gas with a small amount generated and a low combustion temperature is generated. However, in the base bleed bullet according to the present invention, it is possible to increase the combustion temperature and increase the gas generation amount by taking in oxygen in the air from the window of the cylindrical member during flight. This increased hot gas
It flows out to the rear of the bottom of the bullet and acts to reduce the resistance of the bullet in a base bleed bullet during high-speed flight.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view of a base bleed bullet according to the present invention. In the base bleed bullet 30, a cylindrical outer shell member 13 is attached to a bullet bottom portion 16. The outer shell member 13 has a dimension reduced in the axial direction as compared with the outer shell member in the conventional base bleed bullet. A gas outlet 14 is formed in the center of the base 13a of the outer shell member 13.

A gas supply chamber 15 is formed by the outer shell member 13. The volume of the gas supply chamber 15 is reduced by the axial reduction of the outer shell member 13. In the gas supply chamber 15, the above-mentioned gas supply agent, that is, butadiene rubber 37%, ammonium perchlorate 60%,
Further, the gas supply agent A composed of 3% of combustion catalyst is annularly charged, and the ignition charge 12 is fixed to the bullet bottom 16 at the center thereof.

The outer shell member 13 has a hollow cylindrical member 17 at its rear end. The cylindrical member 17 has both ends open and an outer diameter of the same size as the outer diameter of the outer shell member 13. One end of the cylindrical member 17 is fitted to a circumferential step 18 formed at the rear end of the outer shell member and is fixed to the step 18, and the other end is fitted to the gas outlet 10. Are configured.
Further, the cylindrical member 17 has three windows 9 formed at equal intervals in the circumferential direction. Each window 9 has a long rectangular shape in the axial direction, and is formed in the peripheral wall portion of the cylindrical member 17 at intervals of 120 °.

Next, the operation of the base bleed bullet 30 will be described.

A propellant charge is loaded between the shell bottom 16 and a barrel closure (not shown), and a high temperature, high pressure gas is generated by ignition of the propellant charge. A base bleed bullet is fired by the gas pressure of the generated gas, and the base bleed bullet advances at high speed in the barrel. At this time, the ignition charge 1 in the gas supply chamber 15
2 is the gas supply agent A which is ignited by the heat and pressure of the propellant.
Light up. The base bleed bullet released from the barrel flies while letting out low-temperature gas generated by the gas supply agent from the outlet 14. This outflow gas mixes with the air sucked through the window 9 of the cylindrical member, re-combusts to become a high-temperature gas, increases the amount of gas, and flows out from the gas outlet 10. This outflow gas prevents a pressure drop behind the bottom of the bullet, reducing the resistance of the base bleed bullet during high-speed flight.

As described above, in the base bleed bullet according to the present invention, air is taken in through the window of the cylindrical member during flight, and the air causes the gas supply agent to reburn the excessive fuel gas to increase the outflow gas amount. Can be made. In this way, the amount of the reduced amount of the oxidant can be supplemented by oxygen in the air, so that the amount of the gas supply agent used can be reduced to one-third or less of that in the conventional case.

In order to investigate the aerodynamic properties of the base bleed bullet of the present invention, a wind tunnel experiment was conducted using a model. Two models were used for comparison. That is, with respect to the base bleed bullet shown in FIG. 1, the test was performed for a model with a window opened: Model I and a model without a window: Model II.
The result is shown in FIG. The horizontal axis represents the angle of attack θ, and the vertical axis represents the moment coefficient Cm. The moment coefficient is a dimensionless coefficient used for moments, similar to the force coefficient, the drag coefficient, and the thrust coefficient.
The result of the model I with the window opened is shown by a curve I, and the result of the model II without the window is shown by a curve II. In the model II, even if the angle of attack θ is changed, the moment coefficient Cm changes only slightly. On the other hand, in the model I, the moment coefficient Cm increases as the angle of attack θ changes. This means that if the base bleed projectile is eccentric during flight, the window according to this configuration acts to suppress the eccentricity, so that the base bleed projectile naturally returns to its flight path. This results in an improved accuracy of the shell.

[0024]

Since the present invention is configured as described above, the amount of the gas supply agent used can be greatly reduced, for example, to one-third or less of that in the conventional case. Along with this, the volume of the gas supply chamber can be greatly reduced. as a result,
It is possible to reduce the weight of the base bleed bullet and also to reduce its volume, particularly the axial length.

Further, according to the present invention, it is possible to realize a base bleed bullet with improved accuracy of hit.

Since the outer shell member is provided with the hollow cylindrical member with the window having the same diameter as this outer shell member, the structure is simple, the number of parts is small, the manufacturing is easy, and the cost is low. Is also advantageous.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a base bleed bullet of the present invention.

FIG. 2 is a partial sectional view of a conventional base bleed bullet.

FIG. 3 is a partial sectional view of a conventional shell.

FIG. 4 is a diagram showing the results of model I and model II wind tunnel experiments.

[Explanation of symbols]

 9 Window 10 Gas Outlet 12 Ignition Charge 13 Outer Shell Member 14 Outlet 15 Gas Supply Chamber 16 Bullet Bottom 17 Cylindrical Member A Gas Supply Agent

Claims (1)

[Claims] 1. A cylindrical outer shell member forming a gas supply chamber is attached to the bottom of a bullet, and a gas supply agent loaded in the gas supply chamber supplies gas to the rear of the bottom of the bullet to reduce the resistance of the bullet. In the base bleed bullet described above, the outer shell member includes a hollow cylindrical member having the same diameter as the outer shell member at the rear end portion, and the cylindrical member has a plurality of windows at equal intervals in the circumferential direction. A base bleed bullet.