JP2000161140A - Rocket motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To moderate the impact by the internal pressure rise after ignition with a simple structure without damaging the performance by providing a burnable combustion suppressing material on a part of the initial combusting surface of a solid propellant. SOLUTION: A rocket motor R comprises a substantially cylindrical motor case 1, a solid propellant 2 consisting of a mixture of fuel and oxidizer, which is charged therein through an insulator, a nozzle 3 provided on the tail thereof. The solid propellant 2 is molded into an inner surface combustion type having an inner hole 4 opened to the tail side, and an igniter 6 is mounted on the mirror plate part 5 on the head side of the motor case 1. A burnable combustion suppressing material 7 is provided on the initial combustion surface of the solid propellant 2, or the inside surface of the inner hole 4. The combustion suppressing material 7 is formed into a strip laid along the rocket machine axial direction by use of a material consisting of a synthetic rubber of the same kind as the binder of the solid propellant 2 as main component and carbon powder mixed thereto. The combustion suppressing material 7 is provided extending from the vicinity of the tip of the igniter 6 to the open end part on the tail side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocket motor using a solid propellant.

[0002]

2. Description of the Related Art Rocket motors are described, for example, in pages 641 and 642 of "Augmented Edition Aerospace Engineering Handbook" published by Maruzen on April 25, 1983.

A rocket motor has a motor case loaded with a solid propellant in which a fuel and an oxidant are mixed, and has a nozzle at the tail of the motor case. Then, the solid propellant is ignited by an igniter, and high-pressure combustion gas generated by combustion of the solid propellant is ejected from a nozzle to generate thrust. Such a rocket motor is usually designed so that it can exhibit the maximum performance by efficiently utilizing the pressure resistance performance of the motor case and reducing the amount of heat-resistant material by shortening the combustion time. I have.

[0004]

However, since the internal pressure of the above-mentioned rocket motor reaches a maximum value in a short time after ignition, an impact occurs due to this. For this reason, the load condition of each part on the rocket main body side becomes strict as a countermeasure against impact, which may lead to an increase in weight or an impact on the flying attitude due to the impact, and improvement of these problems has been desired. .

In order to reduce only the above-described impact, the initial internal pressure level can be reduced by increasing the throat diameter of the nozzle or changing the shape (grain shape) of the solid propellant. Although it is possible, in these cases, the performance of the rocket motor itself is greatly reduced, so that it has been difficult to adopt it.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and has a simple structure without impairing the performance.
It is an object of the present invention to provide a rocket motor that can reduce an impact due to a rise in internal pressure after ignition.

[0007]

According to a first aspect of the present invention, there is provided a rocket motor having a structure in which a part of an initial combustion surface of a solid propellant is provided with a burn-off suppressing material having a burning property.
According to a second aspect of the present invention, the combustion suppressor is configured to burn out in 0.5 to 1 second.
The main component is the same kind of synthetic rubber as the solid propellant binder,
A structure in which carbon powder is mixed with the mixture,
The solid propellant is molded into an inner combustion type having an inner hole, and a structure in which a band-shaped combustion suppressor is provided along the rocket machine axial direction on the inner peripheral surface of the inner hole.
Band-shaped combustion suppressors are provided at equal intervals in the circumferential direction of the inner hole, and the above-mentioned configuration is used as means for solving the problem.

[0008] In the second aspect of the present invention, the amount by which the burn-in suppressing material is burned in 0.5 to 1 second is defined as the amount in which the burn-in suppressing material is burned out in less than 0.5 second. This is because the time of the low pressure state obtained by combustion is too short, and the internal pressure may rise rapidly. If the amount is burned out in a time longer than 1 second, the low pressure state obtained by combustion of the combustion suppressing material This is because the time is too long and it takes too much time for the internal pressure to reach the maximum value, which may affect the performance of the rocket motor itself.

[0009]

In the rocket motor according to the first aspect of the present invention, the solid propellant is provided with a burn-in suppressing material on a part of the initial burning surface, and the area of the initial burning surface is reduced. When the solid propellant is ignited, the amount of combustion gas generated is suppressed only while the combustion suppressor is burning, and a rapid increase in the internal pressure is prevented.
Then, the burning surface of the solid propellant becomes the original size as the combustion suppressor burns out, the amount of combustion gas generated increases, and the internal pressure rises to the maximum value.

In the rocket motor according to the second aspect of the present invention, the combustion suppressor is burned in 0.5 to 1 second, so that the combustion time of the combustion suppressor is too short and the internal pressure rises rapidly. Such a situation is prevented, and a situation in which the combustion time of the combustion suppressor is too long and the internal pressure takes too long to reach the maximum value is also prevented.

In the rocket motor according to the third aspect of the present invention, since the main component of the same kind of synthetic rubber as the binder of the solid propellant and the mixture thereof with the carbon powder are used as the combustion suppressing material, The viscosity of the combustion suppressor to be applied to the propellant can be easily adjusted, and radiant heat can be blocked.

In the rocket motor according to the fourth aspect of the present invention, a band-shaped combustion suppressing material is provided on the inner peripheral surface of the inner hole of the solid propellant formed into the inner combustion type along the rocket machine axial direction. For example, when ignition is performed from the head side, the combustion of the initial propellant of the solid propellant and the combustion of the combustion suppressing material progress smoothly from the head side to the tail side, and the whole combustion becomes stable.

[0013] In the rocket motor according to the fifth aspect of the present invention, since the strip-shaped combustion suppressors are provided at equal intervals in the circumferential direction of the inner hole, the combustion of the initial combustion surface of the solid propellant and the combustion of the combustion suppressors are performed. Becomes uniform in the circumferential direction of the inner hole, and the entire combustion becomes more stable.

[0014]

According to the rocket motor according to the first aspect of the present invention, a sudden increase in the internal pressure after ignition can be achieved with a very simple structure by using a combustion suppressor provided on a part of the initial combustion surface of the solid propellant. Can be prevented, and the original combustion state can be obtained quickly with the burning of the combustion suppressing material.
It is possible to alleviate the impact caused by the increase in the internal pressure after ignition without impairing the performance of the rocket motor. In addition, the impact mitigation function reduces the load conditions and the like on the rocket body side, thereby contributing to a reduction in weight and the like, and can also eliminate situations that affect the rocket's flight attitude. . Furthermore, by selecting the material, shape and thickness of the combustion suppressor,
The internal pressure increase pattern after ignition can be easily controlled, and the degree of freedom in design can be increased.

According to the rocket motor according to the second aspect of the present invention, the same effect as that of the first aspect can be obtained, and in addition, the amount of the combustion suppressing material is set to be burned out in 0.5 to 1 second. In addition, the time of the low pressure state obtained by the combustion of the combustion suppressing material becomes appropriate, so that a sudden increase in internal pressure and impact can be prevented more reliably, and the performance of the rocket motor can be maintained well.

According to the rocket motor according to the third aspect of the present invention, the same effects as those of the first and second aspects can be obtained, and in addition, a synthetic rubber of the same type as the solid propellant binder is used as a main component. The use of a combustion suppressant mixed with carbon powder makes it easy to adjust the viscosity of the combustion suppressor for application to solid propellants, improving workability and providing a function to block radiant heat. Thus, the function of the combustion suppressing material can be enhanced.

According to the rocket motor of the fourth aspect of the present invention, the same effects as those of the first to fourth aspects can be obtained, and when the internal combustion type solid propellant is ignited from its head side. In addition, the solid propellant and the combustion suppressing material can be smoothly burned in the machine axis direction, and a stable combustion state can be obtained as a whole.

According to the rocket motor according to the fifth aspect of the present invention, the same effect as that of the fourth aspect can be obtained, and the strip-shaped combustion suppressors are provided at equal intervals in the circumferential direction of the inner hole. Thus, the solid propellant and the combustion suppressing material can be uniformly burned in the circumferential direction of the inner hole, and the combustion state can be further stabilized.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rocket motor R shown in FIG. 1 (a) is loaded with a solid propellant 2 in which a fuel and an oxidant are mixed, through an insulator (not shown) in a substantially cylindrical motor case 1. Nozzle 3 on the tail of the motor case 1.
It has. The solid propellant 2 is formed into an inner combustion type, and has an inner hole 4 opened on the tail side. Also,
An igniter 6 is provided on the head plate 5 on the head side of the motor case 1.
Is installed. The igniter 6 is provided so as to protrude into the inner hole 4 of the solid propellant 2 through the center of the end plate 5 and is electrically connected to an ignition device (not shown).

The rocket motor R is provided with a burn-out suppressing material 7 on the initial combustion surface of the solid propellant 2, that is, on the inner peripheral surface of the inner hole 4. The combustion suppressor 7 is formed in a belt shape along the rocket machine axial direction, and is provided from near the tip end of the igniter 6 to the open end on the tail side. In this embodiment, as shown in a development view of the inner hole 4 in FIG.
The number of the burn suppressing materials 7 is provided at equal intervals in the circumferential direction of the inner hole 4, and the amount is such that it burns out in 0.5 to 1 second as a whole.

The combustion suppressor 7 is mainly composed of a synthetic rubber of the same type as the binder of the solid propellant 2 for the purpose of adjusting the viscosity for improving workability with respect to the solid propellant and cutting off radiant heat. It is a mixture. In order to provide the combustion suppressing material 7 to the solid propellant 2, a method of applying the combustion suppressing material 7 to the solid propellant 2 after molding, a method of applying the combustion suppressing material 7 formed into a sheet to the solid propellant 2, and the like. Or a method in which the combustion suppressing material 7 is applied or pasted to a solid propellant molding core, and the solid propellant 2 is formed and the combustion suppressing material 7 is integrated.

In the rocket motor R having the above configuration, when ignition is performed by the igniter 6, the solid propellant 2 starts burning, and the combustion suppressing material 7 also starts burning. At this time, in the rocket motor R, since the area of the initial combustion surface of the solid propellant 2 is reduced by the amount of the combustion suppressing material 7,
Only during the combustion of the combustion suppressing material 7, the amount of generated combustion gas is suppressed and a low pressure state is established, so that a rapid increase in the internal pressure is prevented. Then, the burning surface of the solid propellant 2 becomes the original size as the combustion suppressor 7 is burned off, the amount of combustion gas generated increases, and the internal pressure rises to the maximum value.

As described above, in the rocket motor R, the shock caused by the increase of the internal pressure immediately after the ignition is reduced by the extremely simple structure using the combustion suppressing material 7, so that the original combustion state can be quickly obtained. The performance of the rocket motor R itself is not impaired at all.

In the rocket motor R, in the internal combustion type solid propellant 2 ignited from the head side by the igniter 6, the band-shaped combustion suppressing material 7 along the rocket machine axis direction is formed around the inner hole 4. Since the solid propellant 2 is provided at equal intervals in the direction, the combustion of the initial combustion surface of the solid propellant 2 and the combustion of the combustion suppressor 7 progress smoothly from the head side to the tail side, and are uniform in the circumferential direction of the inner hole 4. And the overall combustion state becomes more stable.

Here, using the test rocket motor T shown in FIG. 2 (a), a combustion test was performed with and without the combustion suppressing material.

The test rocket motor T comprises a motor case 1 comprising a first member 11 having a substantially cylindrical shape having a bottom and a second member 12 having a cylindrical shape connected to the first member 11.
A third member 13 forming the nozzle 3 is connected to the member 12. On the rocket head side (left side in FIG. 2) of the first member 11, an ignition device 15 for the inside thereof is provided. Third
The member 13 includes a fourth member 14 in which the throat portion 3a of the nozzle 3 is formed inside. Inside the motor case 1, an inner combustion type solid propellant 2 formed into a cylindrical shape is loaded via an insulator. This solid propellant 2 also burns from both end faces.

As an embodiment of the rocket motor according to the present invention, a combustion suppressor 7 is provided on the inner peripheral surface of the inner hole 4 of the solid propellant 2 as shown in FIG. Combustion control material 7
In the rocket, four belt-shaped ones are used along the axial direction of the rocket machine, and are provided at equal intervals in the circumferential direction of the inner hole 4. The rocket motor according to the embodiment includes the first and second embodiments in which the solid propellant 2 is formed and the combustion suppressor 7 are integrated with the solid propellant 2, and the third embodiment in which the solid propellant 2 is provided with the combustion suppressor 7. An example was used. Further, as a conventional example, a rocket motor having no combustion suppressing material 7 was prepared.

The solid propellant 2 has an axial length L1 of 287 mm, an outer diameter D1 of 165 mm, and an inner diameter D2.
Is 80 mm. The inner diameter D3 of the throat 3a of the nozzle 3 is 22.1 mm. Further, the combustion suppressing material 7
And the distance L3 between the combustion suppressors 7 were made substantially the same.

Then, combustion tests were performed on the rocket motors of the first to third embodiments and the conventional example, and the internal pressure of the motor case was measured. The results are shown in the graph of FIG.

As is apparent from the figure, in the conventional rocket motor shown by the dotted line, while the internal pressure sharply increases after ignition, the rocket of the first to third embodiments shown by the solid line. In the motor, only a slight difference occurs due to the difference in the construction of the combustion suppressor 7, and in each case, the sudden increase of the internal pressure is prevented by the combustion suppressor 7. It has reached the original maximum internal pressure similar to the example, and it has been confirmed that the effect of the combustion suppressing material 7 can be obtained without impairing the performance of the rocket motor itself.

In each of the above embodiments, the solid propellant 2 of the internal combustion type has an inner hole 4 having a circular cross section. can do. Also, in the case of the combustion suppressing material 7, a band-like material having a certain width has been exemplified. However, the shape, thickness, material, and the like can be appropriately selected, thereby easily increasing the internal pressure increase pattern after ignition. Can be controlled.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a) illustrating an embodiment of a rocket motor according to the present invention and a developed view (b) of an inner hole of a solid propellant.

FIG. 2 is a sectional view (a) illustrating a rocket motor for a combustion test and a developed view (b) of an inner hole of a solid propellant.

FIG. 3 is a graph (a) showing changes in the internal pressure of the motor case over time in a combustion test of each of the rocket motors of the first to third examples and the conventional example, and the range for one second after ignition is enlarged. It is a graph (b).

[Explanation of symbols]

 R Rocket motor 2 Solid propellant 4 Inner hole 7 Combustion suppressor

Continued on the front page (72) Inventor ▲ Taka ▼ Masahiro Nono 1-5-1-506, Kosugaya, Sakae-ku, Yokohama-shi, Kanagawa-ken (72) Inventor Takashi Seike 90 Address (72) The inventor Haruhito Antino 2 Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (5)

[Claims] 1. A rocket motor characterized in that a part of the initial combustion surface of a solid propellant is provided with a burnout suppressant having burnout properties. 2. The rocket motor according to claim 1, wherein the amount of the combustion suppressing material is such that the combustion suppressing material is burned off in 0.5 to 1 second. 3. The rocket motor according to claim 1, wherein the combustion suppressant is composed mainly of the same kind of synthetic rubber as the solid propellant binder, and is mixed with carbon powder. . 4. The solid propellant is formed into an internal combustion type having an inner hole, and a band-shaped combustion suppressor is provided on the inner peripheral surface of the inner hole along the axial direction of the rocket machine. A rocket motor according to any one of claims 1 to 4. 5. The rocket motor according to claim 5, wherein the band-shaped combustion suppressors are provided at equal intervals in a circumferential direction of the inner hole.