Hybrid engine

Abstract

The present invention relates to a hybrid engine 10 for a projectile, wherein a rocket engine having an annular nozzle 7 is arranged together with a base bleed unit having a circular nozzle 8, the circular nozzle 8 of the base bleed unit is positioned at the center of the annular nozzle 7 of the rocket engine, and the hybrid engine 10 is arranged together with a propellant charge 2 for the rocket engine and a propellant charge 5 for the base bleed unit. The present invention further relates to a projectile 100 equipped with a hybrid engine.

Description

Technical Field

[0001] The present invention relates to a hybrid engine for a projectile, in which a rocket engine having an annular nozzle is arranged together with a base bleed unit having a circular nozzle, the circular nozzle of the base bleed unit is arranged at the center of the annular nozzle of the rocket engine, and the hybrid engine is arranged together with a propellant charge for the rocket engine and a propellant charge for the base bleed unit. The present invention further relates to a projectile equipped with the hybrid engine.

Background Art

[0002] Some methods for increasing the range distance of a projectile launched from a firearm are known and can be divided into the following three groups. 1. Weapon-based solution - Increase the launch speed of the projectile. 2. Additional propulsion - An energy source is provided to the projectile to increase the flight trajectory speed. 3. Ballistics-based solution - Slow down the speed reduction of the projectile after launch.

[0003] The first means - the weapon-based solution - is based on ensuring that the maximum pressure of the solution by the existing weapon is not exceeded based on a established value of the muzzle energy, but only enables an increase in the output speed through a reduction in the weight of the projectile. However, in practice, a significant increase in the range distance can only be obtained when the cross-sectional area of the projectile is simultaneously reduced. As a result, the size of the warhead becomes smaller, and the impact of the projectile on the target also becomes smaller.

[0004] The second means - additional propulsion - is, for example, by arranging a rocket engine on the projectile, is suitable for a spin-stabilized projectile, and provides good performance improvement. The main drawbacks are the increased cost of the rocket engine and the fact that the rocket engine occupies the space of the projectile, resulting in a smaller warhead size and a reduced probability of hitting the target.

[0005] A third way to increase range is to reduce air resistance along the trajectory. This can be achieved individually or in combination in the following ways: - Undercalibration (reduced bore size) -Low resistance design - Base flow control

[0006] The first method, undercalibration, means that the diameter of the projectile is smaller than the barrel, requiring the installation of a drive mirror. A smaller projectile diameter results in a smaller projectile size, thus reducing its impact on the target. Low-drag designs result in aerodynamic adaptations, for example, through the design of a rear cone. However, the design of a rear cone presents another technical challenge in manufacturing, and, as in the previous case, results in a smaller projectile size. The most established solution currently is the introduction of a base bleed unit, which improves range without significantly impacting the effective area space.

[0007] Patent document CN113153580B describes a rocket engine having a composite nozzle with an outer movable nozzle and an inner fixed nozzle. The vectorized thrust can be varied via the outer movable nozzle. The described rocket engine shows that a common propellant charge is used by the rocket engine and there is no base bleed unit.

[0008] Patent document WO2021 / 074553Al describes a rocket engine with an aerospike-shaped nozzle. The described rocket engine is a hybrid design and includes a combination of solid and liquid propellants for the rocket engine. The described rocket engine does not include a base bleed unit. [Overview of the project] [Problems that the invention aims to solve]

[0009] The solutions to the above problems, and any further issues arising from those solutions, are described below.

[0010] One object of the present invention is to solve the problems identified above regarding an improved hybrid engine for projectiles, which comprises a portion of an impulse engine in the form of a rocket engine and a portion of a base bleed unit combined in a limited volume so as not to significantly affect the ability to carry the load of the projectile.

[0011] A further object of the present invention is a hybrid engine for a projectile, wherein a rocket engine having an annular nozzle is arranged together with a base bleed unit having a circular nozzle, and the circular nozzle of the base bleed unit is positioned at the center of the annular nozzle of the rocket engine, the hybrid engine being arranged with a rocket engine propellant charge and a base bleed unit propellant charge, the base bleed unit propellant charge forming a gas flow which is discharged through the circular nozzle, and the rocket engine propellant charge generating a gas flow which is discharged through the annular nozzle. The annular nozzle and the circular nozzle are arranged separately and no gas flow is generated between the different nozzles. The gas flow generated from the base bleed unit propellant cannot pass through the annular nozzle, and the gas flow generated from the rocket engine propellant cannot pass through the circular nozzle. [Means for solving the problem]

[0012] Further aspects of the hybrid engine according to the present invention include the following: The rocket engine nozzle must be of the aerospike type. The propellant charge for the rocket engine and the propellant charge for the base bleed unit consist of solid propellants, and these propellants are gunpowder. The annular nozzle of a rocket engine surrounds the base bleed unit along with the circular nozzle. The rocket engine propellant charge should be positioned together with the gunpowder support. Rocket engine propellant is ignited by a rocket engine igniter. The propellant charge for the base bleed unit is ignited by the base bleed igniter. The burn time of rocket engine propellant charge is between 5 and 20 seconds, depending on the caliber of the projectile. The burn time of the propellant charge for the base bleed unit should be longer than 10 seconds.

[0013] The present invention further comprises a launch vehicle equipped with a hybrid engine including a rocket engine and a base bleed unit, as described above. [Brief explanation of the drawing]

[0014] The present invention will be described below with reference to the figures included herein. [Figure 1] Figure 1 shows a cross-sectional view of a hybrid engine according to one embodiment of the present invention. [Figure 2] Figure 2 shows a cross-sectional view of a projectile according to one embodiment of the present invention. [Modes for carrying out the invention]

[0015] This invention presents a novel and alternative design for a hybrid engine for projectiles.

[0016] The firing device, also called a piece in the sense of a cannon, howitzer, or artillery gun, aims to use a propellant to fire a projectile. Preferably, a propellant such as gunpowder is ignited (initiated) in a chamber that is part of the cannon and is often specially adapted for that purpose. Ignition is effected, for example, by igniting the propellant with an ignition cartridge or igniter, and this ignition is initiated by impact. Other methods of igniting the propellant may include igniting the propellant by laser energy or electrical energy. The propellant burns at high speed, resulting in the generation of a large amount of gas, creating gas pressure within the chamber, and propelling the projectile from the barrel of the firing device. The projectile is adapted to generate as constant a pressure as possible on the projectile throughout the ejection process within the barrel as it moves through the barrel, and as a result, the projectile shoots out of the barrel of the cannon at high speed.

[0017] The projectile generally includes some form of warhead, such as various types of shells, and some form of barrel to initiate the warhead. There can be various types of fuses, in which case there is a contact fuse, which is common for projectiles that are to burst when they come into contact with an object, a time fuse when the projectile is to burst at a specific predetermined time, and a proximity fuse when the projectile is to burst when an object enters within a certain distance of the projectile. The use of a proximity fuse is preferred when confronting flying objects, but a time fuse can be used when confronting a large number of various objects. For example, it is advantageous to combine various types of fuse functions in one and the same fuse in order to cause it to burst after a certain time, such as when the projectile cannot detect an object.

[0018] The warhead advantageously has some type of explosive material and some type of rupture casing that encloses the explosive material. Various types of projectiles, such as fins, can further be arranged either on the barrel or on one of its own sub-components.

[0019] To stabilize the projectile, it is preferable that the projectile rotates or has fins once it leaves the barrel. If the projectile is designed to rotate, it is called a rotationally stabilized projectile, and if the projectile has fins, it is called a fin-stabilized projectile. A fin-stabilized projectile should have no rotation or very little rotation when it leaves the barrel.

[0020] To impart rotation to the projectile, barrels are often rifled, and the projectile comes into contact with this rifling upon firing. Rifling refers to the spiral rifling present in the barrel of a firearm. The opposite is a smoothbore barrel. When the rifling engages with the projectile upon firing, the projectile rotates along its longitudinal axis. This rotation prevents drift (deviation) even if there is slight irregularity or damage to the projectile. Rotation is also necessary to ensure that elongated (torpedo-shaped) projectiles maintain their direction after leaving the barrel and do not begin to tumble while rotating. These are called rotationally stabilized projectiles. In smoothbore weapons, only round (spherical) projectiles or finned projectiles can be fired. Elongated projectiles without fins tumble as they leave the muzzle.

[0021] Thus, rifling consists of grooves integrated with the barrel's trajectory, and the raised areas between them are called barriers. The rifling of small-caliber firearms usually consists of four right-handed grooves, but for large guns such as artillery shells, the number of grooves increases depending on the caliber of the launcher. To enable the rifling to engage with the projectile, the projectile must have a special flange called a belt that is slightly larger than the diameter between the barriers, which is common for small-caliber weapons, or slightly larger in diameter than the barrier that is common for projectiles with a diameter exceeding 20 mm. The belt can be made of plastic, composite materials, or a soft metal such as brass. The length of the groove in the direction of one rotation is called the pitch, which is usually the number of inches per rotation. A pitch of 1:10 inches means that the projectile rotates once in 10 inches. The corresponding pitch in millimeters is expressed as 1:254 mm. The pitch is adjusted so that the projectile obtains the initial rotational speed required to maintain the necessary stability over the trajectory from launch to the target, that is, so that it does not start to sway while rotating and losing stability.

[0022] Most barrels contain rifling, and by placing the projectile with a slide belt, both spin-stabilized projectiles and fin-stabilized projectiles can be launched from rifled barrels. Smoothbore barrels are basically only used in weapon systems for armored combat vehicles because the rotation of the projectile reduces the effect of the RSV as the beam from the directional blast action, RSV, diffuses due to centrifugal force.

[0023] One method of increasing the firing range of artillery shells and shortening the firing time of anti-aircraft guns and armored guns is known as base bleed, which involves the gas flow behind the projectile. This technique burns fuel at the rear of the projectile, generating a mass flow that is essentially gaseous, and this mass flow usually exits adjacent to the base surface / the rear of the shell / the projectile and is usually burned. The purpose of base bleed is mainly to reduce base drag and thus does not provide driving force to the projectile.

[0024] Figure 1 shows a cross-section of a hybrid engine 10 comprising a base bleed unit having a nozzle 8, a propellant charge 5 for the base bleed unit and a base bleed igniter 3, and a rocket engine having a rocket engine propellant charge 2, a rocket engine igniter 1, a propellant support 4 for the rocket engine propellant charge and an aerospike nozzle 7. An aerospike is a type of nozzle and, from a technical standpoint, is an inverted version of a conventional bell nozzle, and is therefore also called an inverted nozzle. An aerospike nozzle is an annular nozzle, that is, a nozzle consisting of an annular opening having an inner radius and an outer radius. Nozzle 8 is a conventional circular nozzle, that is, a nozzle shaped like a circular opening, such as a hole of a certain diameter, through which gas can flow.

[0025] When the propellant is burned in the launcher, the incoming combustion gases ignite both the base bleed igniter 3 and the base bleed unit propellant charge 5, as well as the rocket engine propellant charge 2 and the rocket engine igniter 1. At a certain pressure value—force pressure—the projectile begins to move, and a belt (not shown in the diagram) is pushed into the barrel groove. During acceleration in the barrel, the base bleed unit drive charge 5 is pushed backward while simultaneously changing shape; therefore, both the design and material selection of the base bleed unit drive charge 5 are important to ensure the functionality of the base bleed. Similarly, the rocket engine propellant charge 2 is pushed backward and radially while simultaneously changing shape; therefore, both the design and material selection of the rocket engine propellant charge 2 are important to ensure the functionality of the base bleed. The rocket engine propellant charge 2 may also be equipped with a propellant support, for example, made of polymer, to improve the propellant charge's ability to handle axial and / or radial forces during launch. The design of the gunpowder support 4 can influence how the rocket engine propellant charge 2 is ignited, for example, by delaying the ignition of the rocket engine propellant charge 2 until after the projectile has left the barrel.

[0026] Once the projectile leaves the barrel, its axial acceleration stops. Due to the viscoelastic properties of the gunpowder and the large centripetal acceleration caused by rotation, the charge not only returns to its original length but is also extended until it hits the front end. Therefore, even in this case, the load results in hydrostatic pressure.

[0027] While passing through the muzzle, the internal pressure of both the base bleed chamber and the rocket engine is approximately equal to the directional pressure, but the external pressure of the base bleed device and rocket engine quickly drops to atmospheric pressure. This exposes the base bleed device and rocket engine to high internal pressure, and their dimensions must be determined with this in mind. However, once passing through the relatively large nozzles 7 and 8, the pressure quickly equalizes. Due to the rapid pressure drop after passing through the muzzle, the propellant charge 5 for the base bleed unit is designed to prevent extinction. Furthermore, the base bleed igniter 3 is adapted to burn even when subjected to strong pressure changes. Similarly, the propellant charge 2 for the rocket engine and the rocket engine igniter 1 are adapted accordingly.

[0028] Figure 2 shows a projectile 100 equipped with a hybrid engine 10, an action unit 20, and a fuse 30. The fuse 30 can be adapted based on the function of the warhead and may be made from, for example, an impact fuse, a time fuse, and / or a proximity fuse. The warhead can also be adapted based on the area of ​​use of the projectile 100, and in most contexts this includes projectiles with explosives and shrapnel effects, although other forms of effects may also be relevant. Figure 2 shows that the hybrid engine 10 occupies relatively little space on the projectile and can be placed on most commonly known projectile variations.

[0029] [Description of Features] A launcher is provided for firing a projectile using a propellant charge. The propellant charge may be gunpowder, for example, which burns after initiation, generating high pressure to launch the projectile from the barrel. The projectile is positioned in the barrel by a method called hiring, and generally a belt surrounding the projectile deforms into a groove positioned in the barrel to hold the projectile in place. The propellant charge is placed in what is often called a chamber, which burns the propellant charge while gas, gunpowder gases, are generated, moving the projectile within the barrel. Preferably, a continuous / constant pressure is generated in the chamber behind the projectile as it moves toward the muzzle of the barrel, filling the barrel with pressurized gas as well. When the propellant charge is ignited, the rocket engine igniter and base bleed igniter are also ignited, and further, if desired, propellant charges for the base bleed unit and rocket engine are also ignited. When the projectile leaves the muzzle of the gun barrel, a strong pressure drop affects the rocket engine and base bleed unit. Therefore, the rocket engine igniter and base bleed igniter, as well as the propellant charges for both the base bleed unit and the rocket engine, are adapted to respond to the pressure change. At some point in time, for example, after the projectile has left the barrel, the rocket engine starts and provides thrust to the projectile. Simultaneously, the base bleed generator starts and produces a certain amount of base bleed. The rocket engine often burns for a relatively short time, such as 5 to 20 seconds, and as a result generates thrust for the projectile. However, it is desirable for the base bleed unit to burn for the entire time from when the projectile leaves the launcher until it reaches the target. The burn time of the base bleed unit is preferably 10 seconds or more. The burn time of the base bleed unit varies depending on the caliber of the projectile, with medium-caliber projectiles having a significantly shorter burn time than large-caliber projectiles.

[0030] Problems associated with firing propellant charges arranged on a belt include the fact that the belt wears down the barrel, and that the seal between the projectile and the barrel loosens, allowing gunpowder gases to enter, which in turn affects the firing process, particularly because the difference in the seal between the projectile and the barrel causes the projectile's rate of fire V0 to vary from projectile to projectile.

[0031] The combination of the projectile's length, weight, and design determines the rotational speed required to stabilize it. Generally, short projectiles with a large diameter (large caliber) require a lower rotational speed than long projectiles with a small diameter (small caliber). It is also possible to manufacture barrels with a gradually increasing pitch. Extremely long projectiles, such as darts also known as flechettes, can be difficult to stabilize rotationally, and therefore fin-stabilized designs are preferable.

[0032] For optimal performance, the barrel should have enough pitch to allow the projectile to achieve a high rotational speed that provides rotational stability, but the pitch should not be so large that the rotational speed is far higher than the speed required to achieve rotational stability. Large-caliber projectiles achieve better stability when higher momentum is attained, while elongated projectiles have leverage on aerodynamic pressure points, resulting in reduced stability.

[0033] Preferably, different forms of gunpowder are used for the propellant charge of the launcher, the rocket engine igniter, the base bleed igniter, the base bleed propellant charge, and the rocket engine propellant charge. Gunpowder is often divided into barrel propellant groups and rocket propellant groups because two relatively different properties are required of each type of gunpowder. In barrels, it is desirable to achieve high pressure (hundreds of MPa) in a short time (several milliseconds), while in rockets, it is rather desirable to achieve a moderately constant pressure (tens of MPa) for a long time (seconds / minutes). However, from a chemical standpoint, rocket propellants and barrel propellants are very similar. To evaluate the performance of a barrel propellant, one can often rely on the specific force, expressed in MJ / kg, but this is not the same as the energy content of the gunpowder. High-performance barrel propellants have a high specific force. For rocket propellants, one can instead rely on the specific impulse, expressed in Ns / kg. High-performance propellants have a high specific impulse.

[0034] The geometric shape of gunpowder is crucial to its performance. The amount of gas produced when gunpowder burns is proportional to the combustion rate and the combustion surface. The combustion surface depends on the shape and porosity of the gunpowder; in other words, gunpowder can have different appearances depending on the intended way in which it generates gas. As a result, names such as sheet gunpowder, stick gunpowder, and perforated gunpowder can be observed in the context of propellants.

[0035] Common military explosives include, for example, nitrocellulose explosives, NC explosives, or single-component explosives, which are solid substances produced by gelling nitrocellulose with ethanol and ether. A more historical name for this explosive is guncotton. Single-component explosives are somewhat susceptible to moisture, which can degrade their performance. Single-component explosives are used in ammunition for firearms and artillery. Nitroglycerin explosives, NCGL explosives, or two-component explosives are solids produced by gelling nitrocellulose with nitroglycerin. Two-component explosives have higher energy than single-component explosives and are more susceptible to moisture. A drawback of this type of explosive is its high combustion temperature, which contributes to barrel wear. Two-component explosives are used in ammunition for various weapons requiring high rates of fire, such as tank guns and anti-aircraft guns.

[0036] Nitroguanidine gunpowder, or ternary gunpowder, is a solid substance manufactured by mixing nitroguanidine with a two-component gunpowder. While ternary gunpowder is susceptible to moisture and lacks the energy of two-component gunpowder, it has the advantage of causing less barrel wear and muzzle flame compared to two-component gunpowder. Three-component gunpowder is primarily used in ammunition for large cannons and artillery. All of the above gunpowder, with nitrocellulose as the main component, are also called low-smoke gunpowder, mainly because the comparison was made against black powder, which produces widespread smoke. Two-component gunpowder is used in both artillery and rocket propellant. Compound gunpowder is a solid substance manufactured by mixing an oxygen-rich salt with a binder, and sometimes additional fuel such as metal. Currently, the most common uses are ammonium perchlorate (AP) as an oxygen-releasing agent, and thermosetting plastics or polymers as the binder, as well as the fuel. Aluminum is often used to increase specific impulse. Compound explosives can be manufactured to very high energies and can be given high specific impulses (2,600 Ns / kg or more). A drawback of the type of compound explosive described above is that it emits a distinct trail of smoke, especially in humid air, and always when aluminum is included. Compound explosives are used, for example, in rocket engines such as those in missiles or launch vehicles.

[0037] [Examples] Examples of calibers for projectiles equipped with hybrid engines range from 20 to 155 mm.

[0038] [Alternative Implementations] The present invention is not limited to the embodiments specifically described, and can be modified in various ways within the scope of the claims.

[0039] For example, it is clear that the number, size, material, and shape of the elements contained in the projectile, as well as the details, are applicable to each individual case, along with other structurally related characteristics, depending on the projectile and its composition.

[0040] For example, projectiles may be configured to explode, release fragments, ignite, exert a thermobaric effect, be used for firefighting, be used as training projectiles, exert electromagnetic effects in certification kits, in smoke kits, cause electromagnetic interference, and have other loads and functions.

Claims

1. A hybrid engine (10) for a projectile, wherein a rocket engine having an annular nozzle (7) is arranged together with a base bleed unit having a circular nozzle (8), the circular nozzle (8) of the base bleed unit is positioned at the center of the annular nozzle (7) of the rocket engine, the hybrid engine (10) is arranged together with a propellant charge (2) for the rocket engine and a propellant charge (5) for the base bleed unit, the propellant charge (5) for the base bleed unit forms a gas flow that is led out through the circular nozzle (8), and the propellant charge for the rocket engine forms a gas flow that is discharged through the annular nozzle (7).

2. The nozzle of the aforementioned rocket engine is of the aerospike type. A hybrid engine (10) for a projectile according to claim 1.

3. The rocket engine propellant charge (2) and the base bleed unit propellant charge (5) consist of solid propellant, and the solid propellant is gunpowder. A hybrid engine (10) for a projectile according to claim 1 or 2.

4. The rocket engine having an annular nozzle (7) surrounds the base bleed unit having a circular nozzle (8). A hybrid engine (10) for a projectile according to claim 3.

5. The rocket engine propellant charge (2) is arranged together with the explosive support (4). A hybrid engine (10) for a projectile according to any one of claims 1 to 4.

6. The rocket engine propellant charge (2) is ignited by the rocket engine igniter (1). A hybrid engine (10) for a projectile according to any one of claims 1 to 5.

7. The propellant charge (5) for the base bleed unit is ignited by the base bleed igniter (3). A hybrid engine (10) for a projectile according to any one of claims 1 to 6.

8. The burn time of the rocket engine propellant charge (2) is between 5 and 20 seconds, depending on the caliber of the projectile. A hybrid engine (10) for a projectile according to any one of claims 1 to 7.

9. The burning time of the propellant charge (2) for the base bleed unit is longer than 10 seconds. A hybrid engine (10) for a projectile according to any one of claims 1 to 8.

10. A launch vehicle (100) equipped with a hybrid engine (10) having a rocket engine and a base bleed unit according to any one of claims 1 to 9.

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