SE546345C2 - HYBRID ENGINE FOR PROJECTILE - Google Patents

Abstract

The invention relates to a hybrid engine (10) for a projectile where a rocket engine with a ring-shaped nozzle (7) is arranged together with a base flow assembly with a circular nozzle (8) where the circular nozzle (8) on the base flow assembly is arranged centered in the ring-shaped nozzle (7) on the rocket engine and that the hybrid engine (10) is arranged with a propellant charge for the rocket engine (2) and a propellant charge for the base flow assembly (5). The invention further relates to a projectile (100) arranged with a hybrid engine.

Description

The present invention relates to a hybrid engine for a projectile where a rocket engine with an annular nozzle is arranged together with a base flow assembly with a circular nozzle where the circular nozzle on the base flow assembly is arranged centered in the annular nozzle on the rocket engine and the hybrid engine is arranged with a propellant charge for the rocket engine and a propellant charge for the base flow assembly.

The invention further relates to a projectile equipped with a hybrid motor.

BACKGROUND OF THE INVENTION, PROBLEM AREA AND PRIOR ART A number of different methods for increasing the range of projectiles fired from firearms are known and can be divided into three groups: 1. weapon solution - the projectile is given a higher initial velocity, 2. additional impulse - the projectile is provided with an energy source that provides an increased velocity in the trajectory, 3. ballistic solution - causes the projectile to lose velocity more slowly after firing.

The first possibility - weapon solutions - based on the fact that established values for muzzle energy and that maximum pressure may not be exceeded for existing weapon solutions, a higher muzzle velocity can only be achieved by reducing the projectile weight, in practice, however, a significant increase in the firing range is only obtained if the cross-sectional area of the projectile is simultaneously reduced. This in turn reduces the effect that the projectile can have on the target as the size of the impact part is reduced.

The second option - additional impulse - for example by arranging a rocket motor on the projectile - is suitable for rotationally stabilized projectiles and provides a good performance improvement. The disadvantage is primarily the increased cost that the rocket motor entails but also a reduced possibility of impact on the target as the rocket motor takes up space in the projectile and thereby reduces the size of the impactor.

Filed with the Swedish Patent and Trade Mark Office in 2023 -ÛZ- l E The third possibility of increasing the firing range is to reduce the aerodynamic resistance in the trajectory. This can be achieved in the following ways, either individually or in combination, - Undercalibration - Low-resistance design - Base flow assembly The first method, undercalibration, means that the projectile has a smaller diameter than the barrel, which is why it must be equipped with a driving mirror. A smaller diameter of the projectile means reduced effect on the target as the size of the impact part is reduced. Low-resistance design involves aerodynamic adaptation, for example by implementing a tail cone. However, implementing a tail cone has other manufacturing problems and again that the size of the impact part is reduced. The most established solution at present is the introduction of a base flow assembly that positively affects the firing range without having too much of an impact on the space of the impact part.

Patent document CN 113153580 B describes a rocket engine comprising a combined nozzle with an outer movably arranged nozzle and an inner fixedly mounted nozzle. Through the outer movably arranged nozzle, a changed vectorized thrust can be realized. The described rocket engine is demonstrates that a common propellant charge is used by the rocket engine and demonstrates no base flow assembly.

Patent document WO 2021/074553 A1 describes a rocket engine arranged with a nozzle in the form of an aerospike design. The described rocket engine is of a hybrid design comprising a combination of solid and liquid propellant for the rocket engine. The described rocket engine does not comprise a base flow assembly.

Solution to the above problem and additional problems with solution are described below.

IHKOm nu Pareni- och registreringsverket 3 zuza -nz-THE INVENTION AND ITS PURPOSE An object of the present invention is to solve the above-identified problems related to an improved hybrid engine for projectiles comprising partly an impulse engine in the form of a rocket engine and partly a base flow assembly combined in a limited volume so as not to affect the projectile's ability to carry a load to any great extent.

A further object of the present invention is a hybrid engine for a projectile where a rocket engine with an annular nozzle is arranged together with a base flow assembly with a circular nozzle where the circular nozzle on the base flow assembly is arranged centered in the annular nozzle on the rocket engine and that the hybrid engine is arranged with a propellant charge for the rocket engine and a propellant charge for the base flow assembly. According to further aspects of a hybrid engine according to the invention; that the nozzle for the rocket engine is of the aerospike type. that the propellant charge for the rocket engine and a propellant charge for the base flow assembly consist of a solid propellant and where the propellant is gunpowder. that the rocket engine with an annular nozzle surrounds the base flow assembly with a circular nozzle. that the propellant charge for the rocket engine is arranged with a gunpowder support. that the propellant charge for the rocket engine is ignited by a rocket engine igniter. that the propellant charge for the basic flux assembly is ignited by a basic flux igniter. that the burning time for the propellant charge for the rocket motor is between 5 sec - 20 sec depending on the caliber of the projectile. that the burning time for the propellant charge for the basic flux assembly is greater than 10 sec.

Filed with the Patent and Registration Office 4 2023 ~ÛZ-The invention further comprises a projectile arranged with a hybrid engine comprising a rocket engine and a base flow assembly as above.

IIIHUIII Llll FCILBHL* UUH Registration Office 2023 -ÛZ- 1LIST OF FIGURES The invention will be described in more detail below with reference to the attached figures, in which: Fig. 1 shows a hybrid engine in a cross-sectional view according to an embodiment of the invention.

Fig. 2 shows a projectile in a cross-sectional view according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention shows a new and alternative design of a hybrid engine for a projectile.

A launcher, also called a cannon, howitzer, or piece, such as an artillery piece, is intended to fire a projectile by means of a propellant. Preferably, a propellant, such as gunpowder, is initiated in a part of the cannon, often a chamber specially adapted for this. Initiation takes place by igniting the propellant, for example with a primer or a igniter in an ammunition unit, which is initiated by impact. Other methods for igniting the propellant can be by laser or electrical energy igniting the propellant. The propellant burns at high speed and with a large gas evolution, which creates a gas pressure in the chamber that drives the projectile out of the firing barrel of the launcher. The propellant is adapted to generate, to the greatest extent possible, a constant pressure on the projectile during the entire course of the barrel, as the projectile moves in the firing barrel, which creates a high velocity on the projectile when the projectile leaves the muzzle.

Projectiles, such as various types of grenades, in most cases include some form of action part and some form of fuse that initiates the action part. Fuses can be of different types, where impact is common for projectiles that are intended to explode upon contact with an object, time fuses when the projectile is intended to explode at a certain predetermined time, and zone fuses when the projectile is intended to explode when an object comes within a certain distance of the projectile. Zone fuses are preferably used when combating aircraft, while time fuses and impact fuses can be used when combating a large number of different objects. It is advantageous to combine different types of fuse function in the same fuse, so that if a fuse with zone fuse function does not detect any object, the projectile explodes after a certain time, etc.

The action part preferably comprises some form of explosive and some form of fragmentation casing that encloses the explosive. Furthermore, various forms of control means, such as fins, can be arranged, either in the fuse or in a separate sub-component.

In order to stabilize the projectiles after they have left the barrel, the projectiles are preferably provided with rotation or fins. In the case that the projectiles are provided with rotation, the projectiles are said to be rotation-stabilized, and in the case that the projectiles are provided with fins, the projectiles are said to be fin-stabilized. Fin-stabilized projectiles should have no rotation or very low rotation when they leave the barrel.

To achieve rotation on the projectiles, rifling is often arranged in the barrel to which the projectile connects during the firing process. Rifling means that the barrel of a firearm, the barrel, is provided with spiral grooves. The opposite is a smooth-bore barrel. When the rifling enters the projectile during firing, it rotates along its longitudinal axis. Through the rotation, minor irregularities or damage to the projectile will not cause a drift. Rotation is also necessary for an oblong (torpedo-shaped) projectile to maintain its direction after it leaves the barrel and not start to tumble around, this is called the projectile being rotationally stabilized. In smooth-bore weapons, only round (spherical) projectiles or fin-stabilized projectiles can be fired. An oblong projectile without fins will tumble when it leaves the muzzle.

Rifles are thus grooves arranged in the bore of the barrel, and the elevation between them is called ridges. Usually, the rifling of small-caliber firearms consists of four right-handed ridges, while cannons, such as artillery pieces, have a larger number of ridges depending on the caliber of the firing device. In order for the rifling to engage the projectile, the projectile must either be slightly larger than the diameter between the ridges, which is common for small-caliber weapons, or be provided with a special flange, called a girdle, which has a slightly larger diameter than the ridges, which is common in projectiles with a diameter of greater than 20 mm. The girdle can be made of plastic, composite material or a soft metal, such as brass. The length of the barrel on which the rifling turns one full turn is called the pitch and is usually stated in inches per revolution. A pitch of 1:10 inches means that the projectile rotates one revolution of 10 inches. The corresponding pitch in millimeters is written as 1:254 mm. The pitch is adjusted so that the projectile receives the initial rotational speed required for it to maintain the required stability throughout its entire trajectory from launch to target, that is, without losing its stability and starting to tumble around.

Most barrels include rifling and by arranging projectiles with sliding belts, both rotationally stabilized and fin-stabilized projectiles can be fired with rifled barrels. Smooth-bore barrels are in principle only used for weapon systems intended to combat armored combat vehicles as the rotation of the projectile means that the directed explosive effect, RSV, works less well because centrifugal force causes the jet from the RSV to spread out.

A way to increase the firing range of artillery shells, and to reduce the firing time of anti-aircraft and anti-tank projectiles, by means of a gas flow in the rear of the projectile, is known as base bleed. This technique involves burning a fuel in the rear of the projectile, thereby generating a mass flow, essentially gaseous, which flows out and usually burns out in connection with the base plane/stern of the shell/projectile. The purpose of base bleed is primarily to reduce the base resistance and thus does not provide any propulsion to the projectile.

Figure 1 shows a hybrid engine 10 in cross-section comprising a base flow assembly, comprising a nozzle 8, propellant charge for base flow assembly 5 and a base flow igniter 3, and a rocket engine, comprising a propellant charge for rocket engine 2, rocket engine igniter 1, propellant support for rocket engine propellant charge 4 and aerospike nozzle 7. Aerospike is a type of nozzle that can also be called an inverted nozzle since the nozzle, from a technical perspective, consists of several conventional bell nozzles that have been turned inside out.

From the incoming combustion gases when the propellant is burned in the launcher, both the base flux igniter 3 and the propellant charge for the base flux assembly 5 will be ignited, and the propellant charge for the rocket motor 2 and the rocket motor igniter 1 will also be ignited. At a certain pressure value - the forcing pressure - the projectile will begin to move, whereby the belt, not shown in the figure, is pressed into the rifling on the firing barrel. During acceleration in the firing barrel, the propellant charge for the base flux assembly 5 will be pressed backwards while simultaneously changing shape, which is why both the design and choice of material of the propellant charge for the base flux assembly 5 are important in ensuring the functionality of the base flux. In the same way, the propellant charge for the rocket motor 2 will be pressed rearward and radially while simultaneously changing shape, which is why both the design and choice of material of the propellant charge for the rocket motor 2 are important to ensure the functionality of the base flow. The propellant charge for the rocket motor 2 can also be provided with a powder support, for example made of a polymer, to improve the propellant charge's ability to handle the axial and/or radial forces during launch. The design of the powder support 4 can also affect how the propellant charge for the rocket motor 2 is initiated, for example by delaying the initiation of the propellant charge for the rocket motor 2 until after the projectile has left the fire tube.

When the projectile leaves the barrel, the axial acceleration ceases. Due to the viscoelastic properties of the gunpowder and the large centripetal acceleration due to the rotation, the charge not only returns to its original length, but will be extended until it rests against the front end. In this case too, the load will consequently be hydrostatic.

When passing through the orifice, the pressure inside both the base flow assembly and the rocket motor will be of the same order of magnitude as the orifice pressure, while the pressure outside the base flow assembly and the rocket motor will quickly drop to atmospheric pressure. The base flow assembly and the rocket motor will then be exposed to a high internal pressure and must be dimensioned with this in mind. However, due to the relatively large nozzles 7 and 8, the pressure will very quickly equalize. Due to the rapid pressure drop after passing through the orifice, the design is adapted to avoid the combustion of the propellant charge for the base flow assembly 5 being extinguished, and the base flow igniter 3 is also adapted to burn even under severe pressure changes. In the same way, the propellant charge for the rocket motor 2 and the rocket motor igniter are adapted. Figure 2 shows a projectile 100 arranged with a hybrid motor 10, action part 20 and a fuse 30. The fuse 30 can be adapted based on the function of the action part and can, for example, be made of a striker tube, a timer tube and/or a zone tube. The action part can also be adapted based on the areas of use of the projectile 100 but in most cases includes explosives and a fragmentation casing, but other forms of action may also be relevant. Figure 2 illustrates that the hybrid motor 10 takes up relatively little space on the projectile and can be arranged for most generally known projectile variants.

Filed with the Swedish Patent and Registration Office 2023 -ÛZ- 1FUNCTIONAL DESCRIPTION A firing device is arranged to fire, shoot, projectiles with a propellant charge. The propellant charge, which may be gunpowder for example, is combusted after initiation and generates a high pressure that drives the projectile out of a gun barrel. The projectile is arranged in the gun barrel by a process called insertion, commonly occurring is that a belt surrounding the projectile is deformed against a rifling arranged in the gun barrel that retains the projectile in the gun barrel. The propellant charge is arranged in what is often called a chamber in which the propellant charge is combusted while generating gases, gunpowder gases, which cause the projectile to move in the gun barrel. Preferably, a continuous/constant pressure is created in the chamber which also fills the firing tube with pressurized gas behind the projectile as it moves towards the muzzle. When the propellant charge is initiated, the rocket motor igniter and the base flux igniter are also ignited and, if desired and planned, the propellant charge for the base flux assembly and the propellant charge for the rocket motor. When the projectile leaves the muzzle, a strong pressure drop will affect the rocket motor and the base flux assembly, which is why both the rocket motor igniter, the base flux igniter, the propellant charge for the base flux assembly and the propellant charge for the rocket motor are adapted to cope with the pressure change. At a certain point in time, for example immediately after the projectile leaves the firing tube, the rocket motor is initiated and gives the projectile an impulse. At the same time, the base flux assembly is initiated and generates a constant base flux. The rocket motor often burns relatively quickly, for example between 5 seconds and 20 seconds, thereby creating an impulse on the projectile. However, the basic flux assembly preferably burns during the entire journey of the projectile from the launcher to the target, the burning time for the basic flux assembly is thus preferably over 10 seconds. Depending on the caliber of the projectile, the burning time can change for the basic flux assembly, where medium-caliber projectiles have a significantly shorter burning time compared to large-caliber projectiles.

Problems with firing projectiles equipped with a belt are partly that the belt wears on the barrel and partly that the seal between projectile and barrel can become loose and thus allow gunpowder gases to pass, which affects the firing process, among other things, because the projectile's firing speed, V0, can vary between different projectiles depending on the varied seal between projectile and barrel.

The combination of the projectile's length, weight, and design determines the rotational speed required to stabilize the projectile. In general, short projectiles with a large diameter (coarse caliber) require a lower rotational speed compared to long projectiles with a small diameter (fine caliber). Fire tubes can also be manufactured with progressively increasing pitch. Extremely long projectiles, such as arrow ammunition, also called flechette, can be difficult to rotationally stabilize, which is why they are preferably fin-stabilized instead.

For best performance, the barrel should have a pitch that is high enough to give the projectile a high enough rotational speed to be rotationally stabilized, but the pitch should not be so high that the rotational speed is much higher than what is required to achieve rotational stabilization. Thicker projectiles provide better stabilization as a higher angular momentum is achieved, while long, narrow projectiles provide an aerodynamic pressure point with leverage, which results in lower stability.

For both the propellant charge for the launcher, the rocket motor igniter, the base flux igniter, the propellant charge for the base flux and the propellant charge for the rocket motor, different forms of gunpowder are preferably used. Gunpowder is divided into the groups of gunpowder and rocket powder, as two relatively different properties are required for each gunpowder. In a gunpowder, high pressures (several hundred MPa) are desired for a short time (a few ms), while for a rocket, a fairly constant pressure (tens of MPa) is desired for a longer time (sec-min). From a chemical point of view, however, some rocket and gunpowder powders are very similar. A measure for evaluating the performance of a gunpowder is the specific work value, force, which is often stated in MJ/kg, which is not the same as the energy content of the gunpowder. A gunpowder with high performance has a high specific work value. The equivalent for rocket powder is the measure of specific impulse, which is stated in Ns/kg. A rocket powder with high performance has a high specific impulse.

The geometric shape of the powder is very important for the performance of the powder. The amount of gas produced when the powder burns is proportional to the burning rate and the burning surface. The burning surface depends on the shape and porosity of the powder, which means that the powder can look different depending on the way in which gas production is desired. This means that terms such as leaf powder, rod powder and multi-hole powder appear in the context of propellants.

Common military powders include nitrocellulose powder, NC powder, or single-base powder, which is a solid produced by gelatinizing nitrocellulose with ethanol and ether. Another more historical name for this powder is cotton powder. Single-base powder is somewhat sensitive to moisture, which can reduce the performance of the powder. Single-base powder is used in ammunition for firearms and artillery pieces. Nitroglycerin powder, NCGL powder, or double-base powder is a solid produced by gelatinizing nitrocellulose with nitroglycerin. Double-base powder is more energetic than single-base powder and less sensitive to moisture. A disadvantage of this type of powder is that the combustion temperature is high, which contributes to barrel wear. Double-base powder is used in ammunition for, among other things, tank guns and anti-aircraft guns where high muzzle velocities are desired.

Nitroguanidine powder or triple base powder is a solid substance that is produced by mixing double base powder with nitroguanidine. Triple base powder is not sensitive to temperature and is not as energetic as double base powder, but has the advantages that barrel wear and muzzle flame are less than when using double base powder. Triple base powder is mainly used in ammunition for larger cannons and pieces. All of the above-mentioned powders, which are based on nitrocellulose, are also called smokeless powders, mainly because the comparative powder was black powder, which generated extensive smoke development. Double base powder is used both as cannon powder and as rocket powder. Composite powder is a solid substance that is produced by mixing an oxygen-rich salt with a binder and possibly also an additional fuel such as a metal. The most common today is to use ammonium perchlorate, AP, as an oxygen donor and a thermosetting plastic, polymer, as a binder and also fuel, and often also, to increase the specific impulse, aluminum. The composite powder can be made very energy-rich and given a high specific impulse (over 2,600 Ns/kg). A disadvantage of the composite powder of the above type is that it emits a clearing smoke trail, especially in humid air, and always when it contains aluminum.

Composite propellants are used in rocket engines for, for example, missiles or launch vehicles.

EXAMPLES Examples of calibers for projectiles equipped with a hybrid motor are 20 - 155 mm.

ALTERNATIVE EMBODIMENTS The invention is not limited to the embodiments specifically shown but can be varied in various ways within the scope of the claims.

It is understood, for example, that the number, size, material and shape of the elements and details included in the projectiles are adapted to the barrel(s), projectile and projectile assemblies and other design features that currently exist. filed with the Patent and Registration Office 12 2023 ~oz- is The projectile can, for example, be arranged for explosive effect, fragmentation effect, incendiary effect, thermobaric effect, firefighting, training projectiles, lighting sets, smoke sets, electromagnetic effect, electromagnetic interference or other loads and functions.

Claims (1)

1. Filed with the Patent and Trademark Office in 2023 -UZ- 1Hybrid engine (10) for projectiles, characterized in that a rocket engine with an annular nozzle (7) is arranged together with a base flow assembly with a circular nozzle (8), where the circular nozzle (8) on the base flow assembly is arranged centered in the annular nozzle (7) on the rocket engine, and that the hybrid engine (10) is arranged with a propellant charge for the rocket engine (2) and a propellant charge for the base flow assembly (5). Hybrid engine (10) for projectiles according to any of the above claims, characterized in that the nozzle for the rocket engine is of the aerospike type. Hybrid engine (10) for projectile according to any of the above claims, characterized in that the propellant charge for rocket engine (2) and a propellant charge for base flow assembly (5) consist of a solid propellant and where the solid propellant is gunpowder. Hybrid engine (10) for projectile according to claim 3, characterized in that the rocket engine with annular nozzle (7) surrounds the base flow assembly with a circular nozzle (8). Hybrid engine (10) for projectile according to any of the above claims, characterized in that the propellant charge for rocket engine (2) is arranged with a gunpowder support (4). Hybrid engine (10) for projectile according to any of the above claims, characterized in that the propellant charge for rocket engine (2) is ignited by a rocket engine igniter (1). Hybrid engine (10) for projectile according to any of the above claims, characterized in that the propellant charge for the base flux assembly (5) is ignited by a base flux igniter (3). Hybrid engine (10) for projectile according to any of the above claims, characterized in that the combustion time for the propellant charge for the rocket motor (2) is between 5 sec - 20 sec depending on the caliber of the projectile. Hybrid engine (10) for projectile according to any of the above claims, characterized in that the combustion time for the propellant charge for the base flux assembly (2) is greater than 10 sec. Projectile (100) provided with a hybrid engine (10) comprising a rocket motor and a base flux assembly according to any of claims 1 - 9.