Rocket launch system

Abstract

To provide a rocket launch system that floats a hybrid rocket low in danger of explosion etc., up to the stratosphere with a floating body and launches it from the stratosphere.SOLUTION: A rocket launch system includes a floating body which floats in the stratosphere, a rocket supported by the floating body and launched from the floating body, and an attitude control device controlling the attitude of the rocket supported by the floating body, wherein the rocket comprises a fairing part loaded with a satellite or cargo and a rocket engine part generating propulsion power, and the rocket engine part is a hybrid rocket which generates the propulsion power by letting a liquid oxidizer react with solid fuel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rocket launch system that launches a rocket from the stratosphere. [Background technology]

[0002] Space development is currently experiencing rapid growth. For example, the global space industry market is worth about 40 trillion yen, and is predicted to reach 120-160 trillion yen by 2040. In such space development, the development of rockets to carry objects (hereinafter referred to as "payload") into space is important. Rockets are classified into solid fuel rockets, liquid fuel rockets, and hybrid rockets depending on the type of fuel that provides propulsion.

[0003] Solid fuel rockets use solid fuel and solid oxidizer as propellants. Solid fuel rockets have excellent combustion properties because the fuel and oxidizer are in the same phase, and the solid fuel has a high packing density, making it easy to obtain large thrust. On the other hand, the fuel used in solid fuel rockets is a type of explosive, so it is difficult to handle during storage and transportation. Therefore, careful management is required during the production, storage, and transportation of solid fuel.

[0004] Liquid fuel rockets use liquid fuel and liquid oxidizer as propellants. Liquid fuel rockets generate thrust by mixing liquid fuel and liquid oxidizer in a sprayed state and burning them. Like solid fuel rockets, the propellant in liquid fuel rockets is of the same phase, so it has excellent combustion properties and is easy to obtain a high specific impulse. However, with typical high-performance propellants, the fuel and oxidizer must be kept stable at low or extremely low temperatures. In addition, since both the fuel and oxidizer are liquid and easily mixed, there is a risk of explosion. In addition, the structure of the rocket is more complex than that of a solid fuel rocket, which makes it difficult to design and manufacture, and tends to be expensive.

[0005] Hybrid rockets mainly use solid fuel and liquid or gaseous oxidizer as propellants. Because the fuel and oxidizer are in different phases, they do not mix and burn easily, making it difficult to obtain large thrust compared to solid fuel rockets and liquid fuel rockets. On the other hand, because the solid fuel and liquid oxidizer are stored separately, it is easier to manage the propellant compared to solid fuel rockets and liquid fuel rockets, and there is no risk of the solid fuel and oxidizer reacting unintentionally, making them safer. In particular, hybrid rockets that use polymers as solid fuel are particularly easy to manage during manufacture, storage, and transportation.

[0006] In addition, in the hybrid rocket described in Patent Document 1, it is described that the solid fuel containing tetra-ol glycidyl azide polymer increases combustibility through self-heating decomposition, making it possible to reduce the size of the combustion gas generation chamber and combustion chamber. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special express bulletin number 2020-7960 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, hybrid rockets have been developed as low-cost, small-scale chemical combustion systems. Hybrid rockets are expected to be used in the private sector because of their simple structure, which keeps costs down and their high safety. However, they have issues with low combustion efficiency and low thrust, and have not been put to practical use very often. For example, even with a hybrid rocket such as that in Patent Document 1, it is difficult to build a rocket launch system that can reach outer space from the ground using conventional technology. Thus, although hybrid rockets have many advantages, it is difficult to obtain large propulsive force, and there is a problem that it is difficult to put them to practical use for launching into outer space. [Means for solving the problem]

[0009] In response to the above-mentioned problems, the inventors of the present invention have discovered that the problem of low thrust can be solved by lifting the rocket up to the stratosphere using a float and then launching it from the stratosphere, thereby reducing air resistance.

[0010] However, when launching a rocket, there is a possibility that part of the rocket may separate or that part or all of the rocket may fall into the sea or on land due to flight trouble, etc. Therefore, in order to ensure safety on sea or on land, it is necessary to coordinate with stakeholders such as fishermen and landowners and to launch the rocket at limited times and places, and such coordination requires a lot of time and cost.

[0011] Despite this, when launching a rocket from the stratosphere, if the rocket fuel explodes due to malfunction of a device or instrument, parts of the rocket or floating body casing may fly in all directions and fall, causing damage over a wide area. If such a case is assumed, the above-mentioned adjustments become difficult, and there is a problem that the rocket launch will always be carried out with the possibility of causing serious damage if the rocket launch fails. Furthermore, there is a problem that the rocket's propellant, etc. may cause marine pollution.

[0012] (1) Based on the above-mentioned findings and problems, the rocket launch system of the present invention includes a float that floats in the stratosphere, a rocket supported on the float and launched from the float, and an attitude control device that controls the attitude of the rocket supported on the float, wherein the rocket has a fairing section for carrying a satellite or cargo, and a rocket engine section for generating thrust, and the rocket engine section is a hybrid rocket that generates thrust by reacting a liquid oxidizer with a solid fuel.

[0013] According to this rocket launch system, since the air resistance of the rocket launched from the stratosphere is reduced, it is easy to launch the satellite or cargo mounted on the fairing into any orbit even with low thrust, and since the hybrid rocket is a rocket with low risk of explosion, it is possible to prevent the fuel from exploding during the rocket launch and causing widespread damage. In addition, since the fuel of the hybrid rocket is solid, even if it falls, it remains in mass and there is no pollution, and the oxidizer also evaporates, so it does not pollute the sea.

[0014] Furthermore, the rocket is not a manned spacecraft, but is for cargo transportation with the fairing and rocket engine sections separated. Therefore, the rocket does not have a life support system or crew habitation module to carry human crew members into space, and is specialized for transporting unmanned payloads such as satellites and scientific instruments. This frees the rocket from design constraints related to crew safety and comfort, allowing it to optimize payload capacity and launch efficiency, reducing design and operation costs compared to manned spacecraft, giving it an advantage especially in commercial space development.

[0015] (2) In the rocket launch system of (1) above, the solid fuel may be a polymer material. In this way, a rocket engine with high thrust can be constructed, which is easy to burn even in the stratosphere, where temperatures can reach as low as -50°C, while reducing the risk of explosion. In addition, the specific impulse per unit amount of fuel is increased, which allows the overall fuel of the rocket to be reduced, and the weight of the rocket can also be reduced.

[0016] (3) In the rocket launch system of (1) above, the liquid oxidizer may be non-toxic, such as liquid oxygen, nitrous oxide, hydrogen peroxide, hydroxylammonium nitrate, etc. In this case, by reacting with the solid fuel, which is a polymeric material such as a low-melting-point thermoplastic resin, good combustion occurs, and a rocket engine with high thrust can be constructed.

[0017] (4) In the rocket launch system of (1) above, the liquid oxidizer may be pressurized by a pressurizing mechanism such as a turbo pump to react with the solid fuel. In this way, the reaction between the liquid oxidizer and the solid fuel is promoted even in the stratosphere, where temperatures can reach as low as -50°C, making it possible to configure a rocket engine with high thrust.

[0018] (5) In the rocket launch system of (1) above, the stratosphere to which the levitation body floats during rocket launch may be at an altitude of 20km to 50km. This allows the levitation body to be safely lifted to the launch altitude, reduces the risk of explosion, and prevents widespread damage. Furthermore, the air resistance of the rocket is reduced, making it easier to launch the rocket and payload into any orbit even if the specific impulse is low. Effect of the Invention

[0019] According to the present invention, even a rocket with low thrust can be launched into a desired orbit, thereby realizing a low-cost rocket launch system. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is an image diagram showing an example of how the rocket launch system according to an embodiment of the present invention is used. [Diagram 2] 1 is a schematic diagram of a rocket according to an embodiment of the present invention. [Diagram 3] FIG. 1 is a schematic diagram illustrating a rocket launch system according to an embodiment of the present invention. [Figure 4] 4 is a schematic diagram showing an engine section of a rocket mounted on the rocket launch system shown in FIG. 3. [Diagram 5] 13 is a simulation result assuming the launch of a 5 kN hybrid rocket using the rocket system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

[0022] 1 to 4, a rocket launch system S according to the present invention includes a float 1 that floats in the stratosphere, a rocket 2 that is supported by the float 1 and launched from the float 1, and an attitude control device 3 that controls the attitude of the rocket 2 supported by the float 1. The rocket 2 is a hybrid rocket that generates propulsive force by reacting a liquid oxidizer with a solid fuel.

[0023] As shown in FIG. 1, in the rocket launch system S, a rocket 2 is supported on a float 1, and after the float 1 is launched into the stratosphere at an altitude of about 30 km, the rocket 2 is launched into the air. The launched rocket 2 reaches outer space at an altitude of 100 km, and then launches a small satellite weighing 100 kg or less into a satellite orbit at an altitude of 500 km. In this way, the rocket launch system S can launch a payload into any orbit at any time. Note that, although a three-stage rocket is illustrated in FIG. 1, the rocket is not limited to this.

[0024] As is well known, the stratosphere is the layer located above the troposphere, which is the lowest part of the atmosphere closest to the earth's surface. The boundary between the troposphere and the stratosphere is called the (tropopause) tropopause or the tropotropic station. The higher the temperature of the earth's surface, the higher the height of the tropopause, and the lower the height of the tropopause. The height of the tropopause is about 17 km at the equator, about 10 km at both poles, and at mid-latitudes it varies depending on the season but is about 10-odd km. The rate at which temperature drops with height in the troposphere is called the temperature lapse rate, and the average rate is roughly 0.6°C / 100m.

[0025] In the stratosphere, the lowest part of the stratosphere, located above the troposphere, has a nearly constant temperature, but above the lowest part, the temperature rises with height from about 20km to about 50km above the earth's surface. In the stratosphere, water vapor generated from the oceans and other sources does not rise above the tropopause. Also, unlike the troposphere, the temperature is higher the higher up in the atmosphere, so convection is less likely to occur, and there are no associated weather changes, making it stable.

[0026] Above the stratosphere there is a layer called the mesosphere, which is located at an altitude of about 50 to 80 km above the earth's surface and has a temperature of approximately -80°C to -90°C. The atmospheric composition up to this mesosphere is almost the same as that of ordinary air. In this specification, the area above the mesosphere, 100 km above the earth's surface, is considered outer space.

[0027] 2, the rocket 2 includes a fairing section 26 and a rocket engine section 27. In this embodiment, the rocket 2 is a so-called cargo rocket that loads a satellite or cargo onto the fairing section.

[0028] In this embodiment, the rocket engine section 27 has a first stage engine section 28 and a second stage engine section 29, and both the first stage engine section 28 and the second stage engine section 29 are hybrid rockets that generate thrust by reacting liquid oxidizer with solid fuel.

[0029] The fairing section 26 of the rocket 2 is located at the tip of the rocket and protects the payload from air resistance and heat associated with passing through the atmosphere during launch. A satellite or cargo is safely placed inside the fairing section 26 as a payload, and after reaching outer space, the fairing section 26 is separated from the rocket engine section 27 when it is no longer needed. This separation process is carried out after it is confirmed that the payload has reached the designated orbit, and provides the space necessary for the deployment of the satellite or cargo.

[0030] The first stage engine section 28 is the primary propulsion section responsible for the launch and initial ascent phase of the rocket and is required to provide a large amount of thrust. This stage uses a combination of liquid oxidizer and solid fuel to form a hybrid rocket engine, as described below. Hybrid engines combine the efficiency of liquid fuel engines with the simplicity of solid fuel engines, allowing for safer and more reliable operation.

[0031] The second stage engine section 29 is intended for propulsion in space and precise orbital insertion of the payload. This stage uses more precisely controlled engines to make the fine adjustments necessary to precisely place the payload in the desired orbit. The second stage engine section 29 is designed to be lighter and more efficient than the first stage engine section 28. This stage also employs a hybrid rocket engine, improving operational flexibility and efficiency.

[0032] Rocket 2 is not a manned spacecraft, but is purely intended for cargo transportation. Therefore, Rocket 2 does not have a life support system or crew habitation module to carry human crew into space, and is specialized for transporting unmanned payloads such as satellites and scientific instruments. This frees Rocket 2 from design constraints related to crew safety and comfort, allowing it to optimize payload capacity and launch efficiency. Rocket 2 also has reduced design and operating costs compared to manned spacecraft, giving it an advantage especially in commercial space development.

[0033] As shown in FIG. 3, the float 1 is a so-called balloon that can rise into the sky. In this embodiment, the float 1 is a single gas balloon using helium or hydrogen as the buoyancy gas. However, the float 1 may be a hot air balloon, a hybrid thermal and gas balloon, or may include multiple balloons. In this embodiment, the float 1 floats unmanned to an altitude of about 30 km from the Earth's surface, which is the stratosphere. The latitude and longitude when the float 1 launches the rocket 2 are selected each time based on the launch conditions (payload and launch destination), and are optimal.

[0034] When the rocket 2 is launched from the float 1, in the stratosphere at an altitude of about 30 km, the temperature is low at about -50°C, the air pressure is about 10 hPa (1 / 100 of that near the earth's surface), and the air resistance is about 1 / 20. By launching the rocket 2 under such conditions, the thrust of the rocket 2 according to this embodiment can be reduced by 1 / 3 to 1 / 2 compared to the thrust of a rocket launched from the earth's surface. This allows the rocket engine system to be 2 / 3 the size.

[0035] The rocket engine section 27 is a hybrid rocket engine that generates thrust by reacting a liquid oxidizer with a solid fuel.

[0036] In a hybrid rocket engine, the phases of the solid fuel and liquid oxidizer are different, so mixing and combustion do not occur easily, and it is easier to manage the propellant than the conventional solid fuel rocket engines and liquid fuel rocket engines. In other words, since the fuel is solid and the oxidizer is liquid, the fuel and oxidizer do not naturally mix together, the risk of explosion is extremely low, and it is easy to manage during storage and transportation.

[0037] As shown in Fig. 4, the rocket engine section 27 according to this embodiment includes an oxidizer storage chamber 21 that stores a liquid oxidizer, a combustion chamber 22 that holds solid fuel and causes it to react with the liquid oxidizer, a turbo pump 23 that sends the liquid oxidizer to the combustion chamber 22, a conventionally well-known ignition device 24 that ignites the solid fuel, and a nozzle 25 that ejects the combustion gas generated by the combustion of the liquid oxidizer and the solid fuel. Note that while Fig. 4 shows a first stage engine 28, a second stage engine 29 has a similar configuration.

[0038] The turbo pump 23 draws in the liquid oxidizer in the oxidizer storage chamber 21, pressurizes it, and supplies it to the combustion chamber 22 at a high pressure. The turbo pump 23 according to this embodiment has a configuration that separates the liquid phase and the gas phase of the gas-liquid multiphase flow inside the pump. This allows smooth reactions such as combustion of the liquid oxidizer and solid fuel even if the rocket is in an environment where the temperature is low, about -50°C, and the atmospheric pressure is about 10 hPa.

[0039] The nozzle 25 is connected to the combustion chamber 22, and can generate thrust for the rocket 2 by ejecting high-temperature, high-pressure gas produced by mixing and burning the solid fuel and liquid oxidizer.

[0040] The liquid oxidizer to be used may be, for example, nitrous oxide (NO) having a high vapor pressure, or a non-toxic material such as liquid oxygen, hydrogen peroxide, or hydroxylammonium nitrate. Nitrous oxide (NO) is chemically stable, inexpensive, and easy to procure. The oxidizer storage chamber 21 is made of a corrosion-resistant material such as aluminum or stainless steel.

[0041] In this embodiment, the solid fuel is a low melting point thermoplastic resin that melts at least at 120°C and has fluidity. The solid fuel according to this embodiment is mainly composed of paraffin oil, and contains styrene-based elastomer resin, xylene resin, and melting aid (fatty acid). The solid fuel has an elastic modulus (mN / mm^2) of 37 to 620. It is desirable that the solid fuel has a high combustion regression rate and a low viscosity in a molten state. It is also desirable that the solid fuel has high elasticity and adhesiveness. The solid fuel is formed into a cylindrical shape and is contained in the combustion chamber. However, it may have other shapes such as those used in tandem multi-stage impinging jet type hybrid rockets.

[0042] When the rocket 2 is launched, liquid oxidizer pressurized by a turbo pump 23 is introduced into a combustion chamber 22 filled with solid fuel. Solid fuel does not ignite naturally, but is ignited by applying heat with an ignition device 24. A flame is formed on the surface of the ignited solid fuel. In the combustion chamber 22, the solid fuel decomposes or melts due to the heat, generating fuel gas, and the introduced liquid oxidizer also evaporates due to the heat, turning into oxidizing gas.

[0043] When the vaporized solid and liquid fuels are mixed together through convection and diffusion, a chemical reaction occurs and a diffusion flame is generated. After that, the heat of the diffusion flame promotes the vaporization of new fuel and oxidizer, and the chemical reaction continues to occur and the flame is maintained. This phenomenon is called boundary layer combustion because the diffusion flame occurs within the "boundary layer" that is formed when the oxidizer flows along the fuel surface and adheres to the solid surface.

[0044] Generally, the thrust of a rocket 2 is determined primarily by the engine's combustion regression rate. The combustion regression rate of a hybrid engine is determined by the amount of solid fuel vaporized, the heat required for the fuel to rise to its vaporization temperature, the heat of vaporization (latent heat) of the fuel material, and the amount of heat added from the outside. In the case of boundary layer combustion such as in a hybrid rocket, the distance between the diffusion flame and the solid fuel is about a few mm.

[0045] In solid and liquid fuel rockets, the distance between the flame and the solid fuel is a few micrometers, and in hybrid rockets, the amount of heat transferred to the fuel is smaller than in solid and liquid fuel rockets, making it difficult to melt and gasify the fuel, and ultimately resulting in lower thrust.

[0046] In the hybrid rocket launch system S according to the present invention, the thrust of the hybrid rocket is lower than that of a solid fuel rocket or a liquid fuel rocket. However, since the hybrid rocket is launched in a state where it is floated up to the stratosphere by the float 1, the air pressure is lower than that at the earth's surface, at approximately 10 hPa (1 / 100 of that near the earth's surface), and the air resistance is approximately 1 / 20. As a result, compared to a solid fuel rocket or a liquid fuel rocket that carries a payload from the earth's surface to an orbit in outer space, the hybrid rocket rocket 2 can carry the same weight of payload to the same orbit by launching it from the stratosphere, even though it has a lower thrust.

[0047] As shown in FIG. 5, a simulation was performed assuming the launch of a 5 kN hybrid rocket in a rocket launch system according to an embodiment of the present invention. In the case of a ground launch (altitude 0 km), the reached altitude was 26.4 km, whereas in the case of an air launch (altitude 30 km), the reached altitude was 107.08 km, meaning that the rocket could reach outer space.

[0048] The attitude control device 3 controls the attitude of the rocket 2 supported by the float 1. For example, the attitude control device 3 includes a suspended body 31 (see FIG. 3) suspended by a wire or the like from the bottom of the float 1, a housing 32 connected to the bottom end of the suspended body 31, a gimbal (not shown) provided inside the housing 32, and a flywheel (not shown) supported by the gimbal. The flywheel has a spindle motor and rotates by the power of the spindle motor. The gimbal has a drive device and tilts the rotation axis of the spinning flywheel with one, two or three degrees of freedom by using the power of the drive device.

[0049] The attitude control device 3 also includes a control unit, a position detection unit, an altitude detection unit, an attitude detection unit, a temperature detection unit, a wind speed detection unit, a wind direction detection unit, an output detection unit, and a wireless communication device.

[0050] The position detection unit may be, for example, an inertial navigation system or a satellite navigation system. The position detection unit detects the latitude and longitude of the floating body 1 and outputs the detected latitude and longitude to the control unit. The altitude detection unit is, for example, a barometric altimeter or a radio altimeter. The altitude detection unit detects the altitude of the floating body 1 and outputs the detected altitude to the control unit. Note that the position detection unit may detect the altitude.

[0051] The attitude detection unit is, for example, a gyro sensor. The attitude detection unit detects the orientation and attitude of the attitude control device 3, and therefore the orientation and attitude of the rocket 2, and outputs the detected orientation and attitude to the control unit. The temperature detection unit is, for example, a thermocouple or a thermistor. The temperature detection unit detects the air temperature around the levitation body 1 and the attitude control device 3, and outputs the detected air temperature to the control unit.

[0052] The wind speed detection unit detects the wind speed around the float 1 and the attitude control device 3, and outputs the detected wind speed to the control unit. The wind direction detection unit detects the wind direction around the float 1 and the attitude control device 3, and outputs the detected wind direction to the control unit. The output detection unit detects the output of the rocket 2 engine, and outputs the detected output to the control unit. The wireless communication device performs wireless communication with control equipment on the ground.

[0053] The control unit monitors the detection values ​​of the position detection unit, altitude detection unit, attitude detection unit, temperature detection unit, wind speed detection unit, wind direction detection unit, and output detection unit. Furthermore, the control unit transfers the detection values ​​of the position detection unit, altitude detection unit, attitude detection unit, temperature detection unit, wind speed detection unit, wind direction detection unit, and output detection unit to the wireless communication device, and causes the wireless communication device to transmit the detection values ​​to the ground control device. Furthermore, when the wireless communication device receives an operation signal transmitted from the ground control device, the operation signal is transferred from the wireless communication device to the control unit, and the control unit controls the attitude control device 3, the rocket 2 holder, and the rocket 2 according to the operation signal.

[0054] The rocket 2 has been described as being roughly cylindrical and pencil-shaped, but the rocket launched from the stratosphere is not limited to being cylindrical, and may be other shapes such as an onion or mushroom shape.

[0055] Although the embodiments of the present invention have been described above, the present invention is not limited to these descriptions. Any modifications to the above-described embodiments made by a person skilled in the art are also included within the scope of the present invention as long as they include the characteristics of the present invention. [Industrial Applicability]

[0056] The present invention can be used in launching rockets. [Explanation of symbols]

[0057] S Rocket Launch System 1. Floating body 2. Rocket 3. Rocket Launcher 21 Liquid Oxidizer Containment Chamber 22 Combustion chamber 23 Turbo Pump 24 Ignition system 25 Nozzles 26 Fairing section 27 Rocket Engine Section 28 First Stage Engine 29 Second Stage Engine 31 Hanging body 32 Case

Claims

1. A floating body that floats in the stratosphere; A rocket supported on the float and launched from the float; and an attitude control device for controlling the attitude of the rocket supported by the levitation body, The rocket includes a fairing section for carrying a satellite or a cargo, and a rocket engine section for generating thrust. A launch system, wherein the rocket engine section is a hybrid rocket that generates thrust by reacting a liquid oxidizer with a solid fuel.

2. 10. The rocket launch system of claim 1, wherein the rocket engine section comprises a first stage engine section and a second stage engine section, the first engine section and the second stage engine section being a hybrid rocket.

3. 3. The rocket launch system of claim 1 or 2, wherein the float is a balloon.

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