JPH03507Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a nozzleless rocket motor that provides stable flight.

[Conventional technology]

Most rocket motors have a nozzle on the combustion gas exhaust side of the chamber in which the propellant is loaded, and this type is used from small to large models. However, among relatively small rocket motors, there are also known nozzle-less rocket motors that do not have a nozzle. This nozzleless rocket motor can be used, for example, as a rope projector for marine rescue and overhead line work.

The nozzleless rocket motor is also disclosed in AIA Paper "AIAA", 1312 (1984), and has been known for a long time. Its cross section is shown in FIG. The nozzleless rocket motor is
The propellant 21 is loaded into the chamber 20, and the propellant 2
The rear end surface 23 of the chamber 20 is configured to be in the same plane as the rear end surface 24 of the chamber 20 .

[Problem that the invention attempts to solve]

The flow of gas and the state of the combustion surface during operation of this nozzleless rocket motor are shown in FIG. The combustion of the propellant 21 is not uniform over each cross-sectional circumference of the bore 27, such as due to turbulence in the gas flow over the combustion surface 26. As a result, the rate of regression of the combustion surface becomes non-uniform, and the cross-sectional shape of each inner hole 27 becomes asymmetrical with respect to the central axis 28 of the rocket motor. As a result, the rear end surface 23 of the propellant 21
The cross-sectional shape of the inner hole is also asymmetrical with respect to the center axis 28 of the rocket motor, and the direction (thrust direction) 30 of the gas ejected from the rear end surface of the propellant 21, that is, the rear end surface 24 of the chamber, coincides with the center axis 28 of the rocket motor. do not. Therefore, there was a problem that the flight path of the rocket motor became unstable.

The present invention solves the above-mentioned problems of conventional nozzle-less rocket motors and provides a nozzle-less rocket motor that provides stable flight.

[Means for solving problems]

A nozzleless rocket motor of the present invention for solving the above problems will be explained with reference to FIG. 1 corresponding to an embodiment. As shown in the figure, the nozzleless rocket motor of the present invention has a propellant 3 loaded in a cylindrical chamber 1, and the cylinder of the chamber 1 extends from the rear end surface 4 into which the propellant 3 is loaded. has been done.

[Effect]

As shown in FIG. 2, the cross-sectional shape of the inner hole 7 of the propellant 3 is not necessarily symmetrical with respect to the central axis 11 of the rocket motor. Therefore, the direction 10 of the gas ejected from the rear end surface 4 of the propellant 3 does not coincide with the central axis 11 of the rocket motor. However, the high-temperature, high-pressure gas ejected from the rear end surface 4 of the propellant 3 expands while moving from the position of the propellant rear end surface 4 to the position of the chamber rear end surface 5 via the extension part 8 of the chamber 1, and its cross-sectional diameter When becomes equal to the inner diameter of the chamber (point A in FIG. 2), the direction is then directed toward the center axis 11 of the rocket motor. As a result, the thrust direction of the rocket motor coincides with the direction of the gas ejected from the chamber rear end surface 5, that is, the central axis 11, regardless of the direction of the ejected gas at the position of the propellant rear end surface 4. Therefore, it flies stably.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a sectional view showing an example of the nozzleless rocket motor of the present invention. As shown in the figure, a mirror plate 2 is attached to a cylindrical chamber 1 by means such as welding. The materials used for the chamber 1 and the end plate 2 include those used in conventional rocket motors, such as metals such as iron, FRP (fiber reinforced plastics), and ceramics. A propellant 3 is filled in the chamber 1 . At this time, the chamber 1 further extends from the rear end surface 4 of the propellant 3 loaded. That is, the propellant is not filled to the full extent to the rear end surface 5 of the chamber 1, but is left in the middle, thereby forming an extended portion 8 that is not filled with the propellant 3.

The length L of this extension portion 8 is determined by the pressure at the position of the propellant rear end face 4 and the inner diameter of the chamber 1. It is sufficient to measure the degree of expansion of the gas ejected from the propellant rear end face 4, and extend it to a position where its cross-sectional diameter is equal to the chamber inner diameter. If the inner diameter of the chamber is D, it is generally preferable that L is in the range of 0.5D to 4D. If it is shorter than 0.5D, the flight stability tends to decrease, and if it is longer than 4D, the flight stability will not change, so it is useless.

The propellant 3 loaded in the chamber can be, for example, a composite propellant, a double base propellant, a modified propellant of these propellants, etc.
It is not particularly limited to the type. Also, the combustion type is not particularly limited, and internal combustion, end-face combustion, a combination of the two, etc. can be used.

The type of propellant, its combustion type, etc. can be determined as appropriate in relation to the required performance. To load the propellant 3 into the chamber 1, a propellant slurry is poured into the chamber 1 to a predetermined position, and then the slurry is hardened. The propellant may be pre-hardened externally, an adhesive may be applied to its outer surface, and the adhesive may be cured after being loaded into the chamber 1 to a predetermined position. In order to prevent the inner surface of the chamber extension 8 from being corroded by the combustion gas, an adhesive may be applied to the inner surface in advance to prevent the inner surface from being directly exposed to the combustion gas.

The above nozzleless rocket motor operates as follows. An igniter (not shown) is inserted into the propellant rear end face side or end plate side, and the propellant 3 is ignited by igniting the igniter. Second
As shown in the figure, the propellant 3 burns sequentially from the inner hole surface 6, but the cross section of the inner hole 7 is not perfectly circular due to the influence of slight differences in burning speed. Therefore, the gas flow direction 10 corresponds to the rear end surface 4 of the propellant 3.
When it ejects from the chamber, it is not fixed, but when it is defined by the extension part 8 and ejects from the rear end face 5 of the chamber, it coincides with the central axis 11. Therefore, the rocket motor flies as planned and stably.

A nozzleless rocket motor to which the present invention is applied was prototyped with the following specifications, and a flight test was conducted.
After treating the inner surface of a steel chamber 1 with an inner diameter of 30 mm and a length of 350 mm, a composite propellant slurry is poured in and hardened in the usual manner to form a propellant 3 with a length of 300 mm, an outer diameter of 30 mm, and an inner diameter at the front end. (End plate 2 side)
We prototyped a nozzle-less rocket motor (see Figure 3) with a diameter of 17mm and a diameter of 10mm at the rear end. That is, in this nozzleless rocket motor, the extended portion 8 of the chamber is 50 mm (L≈1.7D). A normal igniter was inserted into this nozzleless rocket motor from the rear end of the chamber, and a flight test was conducted at an angle of incidence of 30°.
As a result of the flight test, the horizontal reach reached 300m, which was almost in line with the predicted value. The horizontal displacement of the point of fall was 5 m.

On the other hand, a conventional nozzleless rocket motor was prototyped as described below, and the same combustion tests as above were conducted. A steel chamber 1 with an inner diameter of 30 mm and a length of 300 mm was similarly treated and loaded with propellant. At this time, the rear end surface of the chamber and the rear end surface of the propellant were arranged to be on the same plane. There is therefore no chamber extension (see Figure 4). As a result of conducting the same flight test as above for this nozzleless rocket motor, the horizontal reach distance was approximately 230 m, which was approximately 76% of the predicted value.
The lateral deviation was 41m.

[Effect of idea]

As explained above, the nozzleless rocket motor of the present invention has much superior flight stability and is highly reliable compared to conventional nozzleless rocket motors. Furthermore, since the structure is simple, it is also economically advantageous.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an embodiment of the nozzleless rocket motor of the present invention, Fig. 2 is a cross-sectional view showing the situation during operation, Fig. 3 is a cross-sectional view of a prototype, and Fig. 4 is a conventional nozzle. FIG. 5 is a cross-sectional view of the non-rocket motor, showing its operating state. 1... Chamber, 2... End plate, 3... Propellant,
4...Propellant rear end surface, 5...Chamber rear end surface, 6
...Propellant inner hole surface, 7... Propellant inner hole, 8...
...Extension portion, 10...Gas flow direction, 11...
central axis.

Claims (1)

[Scope of utility model registration request] 1. A nozzle-less rocket motor in which a propellant is loaded into a cylindrical chamber, characterized in that the cylinder of the chamber is extended from a rear end surface into which the propellant is loaded.