Nozzle for hybrid engine

Abstract

The invention relates to a hybrid engine (10) for a projectile where the hybrid engine (10) is arranged with a propellant charge for a rocket engine (2) and a propellant charge for a base bleed unit (5) as well as a nozzle (7) and at least one opening (8), and where a valve (1) is arranged to close the opening (8) when the propellant charge for the base bleed unit (5) is combusted by means of moving the valve (1) when the propellant charge for the base bleed unit (5) is combusted. The invention further consists of a projectile arranged with a hybrid engine and a means for controlling a valve for a hybrid engine.

Description

NOZZLE FOR HYBRID ENGINETECHNICAL FIELD

[0001] The present invention relates to a hybrid engine for a projectile where the hybrid engine is arranged with a propellant charge for a rocket engine and a propellant charge for a base bleed unit as well as a nozzle and at least one opening and where a valve is arranged to close the opening when the propellant charge for the base bleed unit is combusted by means of moving the valve when the propellant charge for the base bleed unit is combusted. The invention further consists of a projectile arranged with a hybrid engine and a means for controlling a valve for a hybrid engine.BACKGROUND OF THE INVENTION, PROBLEM AREA AND KNOWN TECHNOLOGY

[0002] Several different methods of 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 exit velocity,2. Additional impulse - the projectile is provided with an energy source that gives an increased speed in the trajectory,3. Ballistic solution - causes the projectile to lose velocity more slowly after firing.

[0003] The first means - weapon solutions - based on the established values of muzzle energy and on ensuring that the maximum pressure in the ejection device is not exceeded for existing weapon solutions - only allows for a higher output velocity through the reduction of the projectile’s 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 warhead is reduced.

[0004] The second means - additional impulse - for example by arranging a rocket engine on the projectile - is suitable for rotationally stabilized projectiles and provides a good performance improvement. The main disadvantage are the increased cost that rocket engines entail, and the fact that the probability of hitting the target is diminished, as the rocket engine takes up space in the projectile and thus reduces the size of the warhead.

[0005] The third means of increasing the firing range - ballistic solution- is to reduce the aerodynamic resistance throughout the trajectory. This can be achieved in the following ways, either individually or in combination,- Undercalibration- Low resistance design- Base bleed unit

[0006] The first partial means, undercalibration, means that the projectile has a smaller diameter than the barrel, so it must be fitted with a driving mirror. A smaller projectile diameter results in a reduced effect on the target as the size of the warhead is reduced. The second partial mean - low-drag design - brings about aerodynamic adaptation, for example through the design of a rear cone. However, the design of a rear cone has other technical problems related to manufacture and, as in the previous case, the size of the warhead is reduced. The most established solution presently is the introduction of a base bleed unit, the third partial means, which improves the firing range without having too much of an impact on the space taken up by the warhead.

[0007] An important problem relates to increasing the firing range without this resulting in too great an impact on the projectile's ability to function.

[0008] Patent document US 4,637,572 describes a propellant unit comprising two valves for adjusting gas flow where the valves alternately open based on gas flow for controlling a projectile, such as a missile.

[0009] Patent document US 3,349,708 describes a rocket engine arranged in a projectile comprising several paths for the gas flow and includes a springloaded valve that opens and thus enables the ignition of a propellant during the ejection of the projectile. After ejection, the valve will close in order to direct gas generated by the propellant through a nozzle.

[0010] Patent document US 3,523,544 shows a valve solution for projectiles that are affected by accelerations, mainly in the radial direction when rotating the projectile. The valve opens and enables gas flow into the projectile.

[0011] A solution to the problem above and additional problems along with solutions are described below.THE INVENTION AND ITS PURPOSE

[0012] One purpose of the present invention is to solve the issues identified above relating to an improved hybrid engine comprising both base bleed functionality and rocket engine functionality for projectiles, comprising partly an impulse engine in the form of a rocket engine and partly a base bleed unit combined in a limited volume so as not to affect the projectile's ability to carry a load to a major extent.

[0013] Afurther purpose of the present invention is a hybrid engine for a projectile where the hybrid engine is arranged with a propellant charge for a rocket engine and a propellant charge for a base bleed unit as well as a nozzle and at least one opening and where a valve is arranged to close the opening when the propellant charge for the base bleed unit is combusted by means of moving the valve when the propellant charge for the base bleed unit is combusted.

[0014] According to further aspects for a hybrid engine according to the invention, the following applies: that the valve is designed with an abutment section and a closure component arranged perpendicular to the abutment section, and where the abutmentsection has the purpose of abutting against the drive charge for the base bleed unit and as the drive charge for the base bleed unit is combusted, move the valve to its second, closed, position and where the closure component is arranged to move to a closed position and close the opening. that the abutment section abuts the propellant charge for the base bleed unit, that the closing section of the valve is arranged in a groove arranged in a rear section of the hybrid engine. that a spacer is arranged between the rear section and propellant charge for rocket engine and propellant charge for base bleed unit and that the spacer is arranged with a groove to enable gas flow from the combustion of propellant charge for base bleed unit to be led out through an opening and that the spacer is arranged with a groove which the abutment section of the valve can move across. that the rear section of the hybrid engine is arranged with 4, 5, 6, 7, 8, 9, 10, 11 or 12 openings. that the propellant charge for the rocket engine and a propellant charge for the base bleed unit consist of a solid propellant, where said solid propellant is gunpowder. that the propellant charge for the base bleed unit is ignited by a base bleed igniter.

[0015] The invention further consists of a projectile outfitted with a hybrid engine including a rocket engine and a base bleed unit as per the above.

[0016] The invention further consists of a means for controlling a valve for a hybrid engine for a rotationally stabilized projectile where the hybrid engine, comprising at least one propellant charge for a rocket engine and at least one propellant charge for a base bleed unit, is arranged so that gas generated during combustion of the propellant charge for the base bleed unit is led out of the hybrid engine through a nozzle and at least one opening and where a valve is arranged so as to close the opening during the combustion of the propellant charge of the base bleed unit by means of an abutment section abuts the propellant charge of the base bleed unit so that the valve closes the openingwhen the propellant charge of the base bleed unit is combusted by the valve being moved by the rotating movement of the projectile, when the propellant charge for the base bleed unit is completely or partially combusted, and the valve has closed the opening, the propellant charge for the rocket engine is initiated after which the gas that is generated by means of the combustion of the rocket engine propellant is mainly led through the nozzle.LIST OF FIGURES

[0017] The invention will be described below by reference to the figures that are included there:Fig. 1a shows a hybrid engine in a cross-sectional view according to an embodiment of the invention.Fig. 1 b shows a magnified section of a hybrid engine in a cross-sectional view according to an embodiment of the invention.Fig. 2a shows a hybrid engine in a cross-sectional view according to an embodiment of the invention.Fig. 2b shows a magnified section of the hybrid engine in a cross-sectional view according to an embodiment of the invention.Fig 3 shows the rear section of the hybrid engine according to an embodiment of the invention.Fig. 4a shows the rear section of the hybrid engine according to one embodiment of the invention.Fig. 4b shows the rear section of the hybrid engine according to one embodiment of the invention.Fig. 4c shows the rear section of the hybrid engine according to one embodiment of the invention.DETAILED DESCRIPTION OF EMBODIMENT

[0018] The present invention shows a new and alternative design for base bleed valve for a hybrid engine for a projectile.

[0019] An ejection device, also termed a cannon, a howitzer, or a piece, in the sense of an artillery piece, has the goal of making use of a propellant for the purpose of firing a projectile. Preferably, a propellant, such as gunpowder, is initiated in one part of the cannon, oftentimes a chamber specifically adapted to the purpose. Initiation takes place by way of igniting the propellant, for instance by means of an ignition cartridge or an igniter in a munition device, which is initiated by means of striking. Other methods for igniting the propellant may include ignition of the propellant by means of laser energy or electric energy. The propellant burns at a high rate and results in large amounts of gas being produced, which creates a gas pressure in the chamber which propels the projectile out of the barrel of the firing device. The propellant has been adapted in order to generate a constant pressure on the projectile during the entire barrel procedure, to the greatest extent possible, as the projectile moves in the barrel, which results in the projectile leaving the muzzle of the barrel with high speed.

[0020] Projectiles, such as various types of grenades, generally include some form of warhead and some form of barrel which initiates the warhead. Fuzes can be of different types where contact fuzes are common for projectiles that are meant to burst when in contact with an object, timed fuzes when the projectile is meant to burst at a certain predetermined time and proximity fuzes when the projectile is meant to burst when an object comes within a certain distance from the projectile. The use of proximity fuzes is preferred when confronting flying vessels, while timed fuzes can be used when confronting a large number of various different objects. It is advantageous to combine various types of fuze functions in one and the same fuze, for instance in order for the projectile to burst after a certain time if it fails to detect any object, and so on.

[0021] It is advantageous for the warhead to comprise some type of explosive substance, as well as some type of shattering casing which encloses the explosive substance. Various types of propellants, such as fins, can furthermore be arranged in either the barrel or in their own subcomponent.

[0022] In order to stabilize the projectiles once the projectiles have left the barrel, the projectiles are preferably designed with rotation or with fins. In cases where the projectiles are designed with rotation, the projectiles are said to be rotationally stabilized and in cases where the projectiles are arranged with fins, the projectiles are said to be fin stabilized. Fin-stabilized projectiles should have no rotation, or very low rotation, when leaving the barrel.

[0023] To achieve rotation on the projectiles, the barrel is often designed with rifling, to which the projectile connects during the firing process. Rifling means that the barrel in a firearm, the barrel, is provided with spiral-shaped rifling. The opposite is a smooth-bore barrel. When the rifling engages the projectile during firing, it rotates along its longitudinal axis. Due to the rotation, minor irregularities or damage to the projectile will not cause a drift. Rotation is also necessary for an elongated (torpedo-shaped) projectile to maintain its direction after leaving the barrel and not start tumbling around. This is referred to as the projectile being rotation-stabilized. In smooth-bore weapons, only round (spherical) projectiles or fin-stabilized projectiles can be fired. An elongated projectile without fins will tumble as it leaves the muzzle.

[0024] Thus, rifling consists of grooves that are integrated into the track of the barrel, and the elevation in between is referred to as barriers. The rifling of fine- caliber firearms usually consists of four grooves that are turned to the right, while cannons, such as artillery pieces, have more grooves depending on the caliber of the launching device. In order for the rifling to be able to engage the projectile, the projectile must either be slightly larger than the diameter between the barriers, which is common for fine-caliber weapons, or be equipped with a special flange, called a belt, which has a slightly larger diameter than the barriers, which is common in projectiles with a diameter greater than 20 mm. The belt can be made out of plastic, composite material, or a soft metal, such as brass. The length of the barrel on which the groove rotates an entire revolution is called pitch and is usually the number of inches per revolution. Apitch of 1 :10 inches means that the projectile rotates a revolution of 10 inches. The corresponding pitch in millimeters is written 1 :254 mm. The pitch is adjusted so that the projectile obtains the initial rotational speed required for it to maintain the required stability throughout its trajectory from launch to target, i.e. without losing its stability and starting to tumble around.

[0025] Most barrels include rifling, and, by arranging projectiles with sliding belts, both rotation-stabilized and fin-stabilized projectiles can be launched with rifled barrels. Smooth-bore barrels are basically only used for weapon systems intended to armored combat vehicles, as the rotation of the projectile means that the directed explosive action, RSV, is less effective since the centrifugal force causes the beam from RSV to be spread out.

[0026] One method to increase the firing distance of artillery shells, as well as to reduce the firing time for anti-aircraft and armor projectiles, through gas flow in the rear of the projectile, is known as base bleed. This technique entails a fuel being combusted in the rear section of the projectile and thus generates a mass flow, essentially gaseous, which flows out, and is usually combusted, adjacent to the base plane / rear of the shell / projectile. The purpose of base bleed is primarily to reduce base drag and thus does not provide any driving force to the projectile. In the event that an additional impulse is desired for the projectile, the projectile should be arranged with a rocket engine which, during its combustion, generates a potent gas development which ideally should be led through a nozzle.

[0027] Figure 1 shows a cross-section of a hybrid engine 10 comprising a base bleed unit, comprising an opening 8, a propellant charge for base bleed unit 5 and a base bleed igniter 3, as well as a rocket engine, comprising a propellant charge for rocket engine 2, a rocket engine igniter 1 , a propellant support for the propellant charge for rocket engine 9 as well as an aerospike nozzle 7. The valve device 1 is arranged so as to be in a first open position, as shown in figure 1 a, when the propellant charge for the base bleed unit 5 has not yet been consumed, the opening 8 is open and enables the outflow of gas, and ina second closed position, when the propellant charge for base bleed unit 5 is consumed when the opening 8 is closed and prevents the outflow of gas.

[0028] Out of the inflowing combustion gases, which flow into the base bleed chamber 9, when the propellant is combusted in the ejection device, both the base bleed igniter 3 and the propellant charge for the base bleed unit 5 will be ignited. At a certain value of the pressure - the forcing pressure - the projectile will begin to move, whereby the belt, not shown in the figure, is pressed into grooves in the barrel. During the acceleration in the barrel, the propellant charge for the base bleed unit 5 will be pressed backwards and radially outwards during simultaneous shape change, which is why both design and choice of material of the propellant charge for base bleed unit 5 are important to ensure the functionality of the base bleed. Similarly, the propellant charge for the rocket engine 2 will be pushed backwards and radially during simultaneous shape change, which is why both the design and the choice of material of the propellant charge for rocket engine 2 are important to ensure the functionality of the rocket engine. The propellant charge for rocket engine 2 and / or the propellant charge for base bleed unit 5 can also be provided with a propellant support, for example made from a polymer, to improve the ability of the propellant charges to handle the axial and / or radial forces during launch. The design of the propellant support can also affect how the propellant charge for the rocket engine 2 and / or the propellant charge for the base bleed unit 5 is initiated, for example by delaying the initiation of the propellant charge for the rocket engine 2 and / or the propellant charge for the base bleed unit 5 until after the projectile has left the barrel or another suitable time.

[0029] 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 abuts the enclosure of the charge lengthwise. Thus, the load becomes hydrostatic as a result, even in this case.

[0030] During the passage through the muzzle, the pressure inside the base bleed chamber 9 will be of the same order of magnitude as the muzzle pressure, while the pressure outside the base bleed device and the rocket engine will quickly drop to atmospheric pressure. The base bleed device and the rocket engine will thereby be exposed to a high internal pressure and must be dimensioned with this in mind. Through the relatively large nozzle 7 and the nozzle 8, however, the pressure will be equalized very quickly. Due to the rapid pressure drop after the passage through the muzzle, the design is adapted so as to prevent the extinguishing of the propellant charge for base bleed unit 5. In addition, base bleed igniter 3 is adapted to bum even while exposed to strong pressure changes.

[0031] Figure 1 b shows an enlarged section of a hybrid engine 10 in a crosssection view, comprising at least one opening 8, drive charge for base bleed unit 5 and a drive charge for the rocket engine 2, valve device 1. The valve device is manufactured so as to have an L-like structure comprising abutment component 11 and a closure component 12. The purpose of the abutment component 11 is to abut the propellant charge for the base bleed unit 5 and as the propellant charge for base bleed unit 5 combusts, move the valve device 1 to its second, closed, position. The closure component 12 is arranged so as to move to a closed position and close the opening 8.

[0032] Figure 2a shows a cross-section view of a hybrid engine 10 comprising a base bleed unit, comprising at least one opening 8, which is closed by valve device 1 and a rocket engine, comprising a propellant charge for rocket engine 2 and nozzle 7. The propellant charge for base bleed unit 5 and the associated base bleed igniter 3 have been combusted and generated gas for the base bleed that flowed through both opening 8 and nozzle 7. The valve device 1 is arranged in a second closed position, when the propellant charge for the base bleed unit 5 is consumed, which means that the opening 8 is closed and prevents the outflow of gas.

[0033] Figure 2b shows an enlarged section of a hybrid engine 10 in a crosssection view, comprising at least one opening 8, drive charge for base bleed unit 5 is consumed and where the propellant charge for the rocket engine 2 is initiated, the valve device 1 is closed and seals the opening 8. The valve device is manufactured so as to have an L-like structure comprising abutment component 11 and a closure component 12. The valve device is moved to its second, closed position. The closure component 12 is moved to the closed position and has closed the opening 8, whereupon the gas flow from the propellant charge for the rocket engine 2 flows through nozzle 7 whereupon the projectile receives an additional impulse from the rocket engine

[0034] Figure 3 shows the rear section of the hybrid engine including the centrally located nozzle 7 and six (6) openings 8. Depending on the design and technical adaptation, the number of openings 8 may vary, but at least one opening 8 is arranged in the rear section.

[0035] Figure 4a shows the rear section on a projectile comprising the valve device 1 , designed so as to have an L-like structure comprising abutment component 11 and a closure component 12. The closure component 12 slides on a groove 21 arranged in the rear section 20.

[0036] The valve device is designed so as to have an L-like structure comprising abutment component 11 and a closure component 12. The closure component 12 slides on a track 21 arranged in the rear section 20. A spacer disk 30 is arranged against the rear section 20. The spacer disk 30 is arranged with a groove 31 to enable gas flow from the combustion of propellant charge for base bleed unit 5 to be led out through opening 8. As well as groove 32 which the abutment section 11 of the valve can move across. The spacer disk 30 is designed with spacers 33 which arrange a distance between the spacer disk 30 and the rear section 20 in order to enable gas flow from the propellant charge for the base bleed unit 5 to the opening 8 and to enable the valve 1 tobe operated in the groove 21 without external influence, such as influence from the gunpowder in the propellant charges due to the viscoelastic expansion.

[0037] Figure shows a rear section 20 of the projectile The valve device is designed so as to have an L-like structure comprising abutment component 11 which is designed so as to move along groove 32 on the spacer disk. The spacer disk 30 is also arranged with grooves 31 to guide the gas flow to openings on the rear section. Figure 4c shows half of the rear section of a hybrid engine with six openings and thus six valves and twelve grooves 31. The number of openings, valves and grooves can be changed depending on the application area.DESCRIPTION OF FUNCTIONS

[0038] A launching device is provided for firing, firing, projectiles with a propellant charge. The propellant charge, which can be gunpowder, for example, burns after initialization and generates a high pressure that propels the projectile out of a barrel. The projectile is arranged in the barrel by a method called hiring, it is common for a belt enclosing the projectile to be deformed relative to a groove arranged in the barrel which retains the projectile in the barrel. The propellant charge is arranged in what is often called a chamber in which the propellant charge is combusted during the generation of gases, gunpowder gases, which cause the projectile to move in the barrel. Preferably, a continuous / constant pressure is created in the chamber which also fills the barrel with pressurized gas behind the projectile as it moves towards the muzzle of the barrel. When the propellant charge is initiated, the base bleed igniter is also ignited and, in addition, if desired and arranged, the propellant charge for the base bleed unit. When the projectile leaves the muzzle of the barrel, a strong drop in pressure will affect the base bleed unit, which is why both the rocket engine igniter, potentially the base bleed igniter, the propellant charge for the base bleed unit and the propellant charge for the rocket engine have been adapted to cope with the pressure change.

[0039] At a certain time, for example immediately after the projectile has left the barrel, or in connection with the launch, the propellant charge for the base bleed unit 5 and / or the base bleed igniter 3 is initiated and generates a constant base bleed that flows out through the nozzle 7 and openings 8.

[0040] The propellant charge for the base bleed unit 5 combusts and moves the valve 1 so that the openings 8 are closed, the combustion time for the propellant charge for the base bleed unit 5 is thus preferably over 10 sec. Depending on the caliber of the projectile, the combustion time for the propellant charge for the base bleed unit can change, where medium caliber projectiles have a significantly shorter combustion time relative to coarse caliber projectiles.

[0041] Once the propellant charge 5 has been combusted, the propellant charge for rocket engine 2 is initiated. The propellant charge for rocket engine 2 often burns relatively quickly, for example between 5 sec and 20 sec, and thus creates an impulse on the projectile. The valve 1 is moved by the rotational forces which create a radial force acting on the valve 1 as the projectile rotates. The abutment section 11 on the valve 1 is prevented from moving by the propellant charge for the base bleed unit 5, but when the propellant charge for the base bleed unit 5 is combusted, the movement of the valve is made possible. The closure section 12 on the valve 1 closes opening 8 and thereby closes opening 8 for the gas bleed unit. When the propellant charge for the base bleed unit 5 is combusted, the propellant charge for the rocket engine 2 is initiated, which directly abuts the propellant charge for the base bleed unit 5. Preferably, the entire surface of the propellant charge on the base bleed unit 5 bums and thereby ignites the entire surface of the propellant charge for the rocket engine 2 when the entire propellant charge for the base bleed unit 5 is combusted. When the propulsion for the rocket engine 2 is initiated, a high gas pressure is created in the base bleed chamber 9 which is led out through the nozzle 7, the high gas pressure in the base bleed chamber 9 also contributes to the pressure on the closing section 12 of the valve 1 increasing and thus closing theopening 8 effectively. The propellant charge for the rocket engine 2 bums for a relatively short time and generates an additional impulse for the projectile.

[0042] Problems with firing projectiles arranged with a belt included the belt causing wear on the barrel as we as the seal between the projectile and the barrel loosening, thus enabling the entry of gunpowder gases, which affects the launch process, among other things by the fact that it results in the projectile launch speed, VO, varying between different projectiles depending on differences in the seal between the projectile and the barrel.

[0043] The combination of projectile length, weight, and design determines the rotational speed required to stabilize the projectile. In general, short projectiles with a high diameter (coarse caliber) require a lower rotational speed compared to long projectiles with a small diameter (fine caliber). Barrels can also be manufactured with progressively increasing pitch. Extremely long projectiles, such as dart ammunition, also called flechette, can be difficult to rotationally stabilize, which is why they are instead preferably fin stabilized.

[0044] For best performance, the barrel should have a pitch that is high enough for the projectile to have such a high rotational speed that the projectile is rotationally stabilized, but the pitch should not be so large that the rotational speed is much higher than is required to achieve rotational stabilization. Coarser projectiles lead to better stabilization when a higher momentum is achieved, while elongated projectiles have an aerodynamic pressure point with leverage, which results in lower stability.

[0045] Different forms of gunpowder are preferably used for the propellant charge for the launch device, the rocket engine igniter, the base bleed igniter, the propellant charge for the base bleed and the propellant charge for the rocket engine. Gunpowder is often divided into the groups of barrel gunpowder and rocket gunpowder, since two relatively different properties are required for each gunpowder. In a barrel, it is desirable to achieve high pressures (severalhundreds of MPa) for a short time (a few ms), while, for a rocket, it is rather desirable to obtain a reasonably constant pressure (tens of MPa) for a longer time (sec-min). From a chemical point of view, however, some rocket and barrel propellants are very similar. In order to evaluate the performance of a certain barrel gunpowder, one can rely on the specific force, which is often stated in MJ / kg, which is not the same as the gunpowder's energy content. A high-performance barrel powder has a high specific force. For rocket powder, one can instead rely on the corresponding measure of specific impulse, which is given in Ns / kg. A high-performance propellant has a high specific impulse.

[0046] The geometric shape of the powder is very important for the performance of the powder. The amount of gas produced when the gunpowder burns is proportional to the burning speed and the burning surface. The burning surface is dependent on the shape and porosity of the gunpowder, which means that the gunpowder can take on a different appearance depending on the intended manner of producing the gas. As a result, names such as sheet gunpowder, stick powder and multi-hole gunpowder can be observed in a propellant context.

[0047] Common military powders are, for example, nitrocellulose powder, NC powder, or single base powder, which is a solid substance produced by gelatinizing nitrocellulose with ethanol and ether. Another more historical name for this gunpowder is cotton gunpowder. The single-base gunpowder is somewhat sensitive to moisture, which can reduce the gunpowder's performance. Single-base powder is used in the ammunition for firearms and artillery pieces. Nitroglycerin gunpowder, NCGL gunpowder, or double-base gunpowder is a solid produced by gelatinizing nitrocellulose with nitroglycerin. The double-base gunpowder has more energy than the single-base gunpowder and less sensitive to moisture. A disadvantage of this type of gunpowder is that the combustion temperature is high, which contributes to barrel wear. Doublebase powder is used in the ammunition for, among other weaponry, tank guns and anti-aircraft pieces where high exit velocities are desired.

[0048] Nitroguanidine gunpowder or triple base gunpowder is a solid substance produced by mixing double-base gunpowder with nitroguanidine. Triple-base gunpowder is not sensitive to moisture and does not have as much energy as double-base gunpowder, but has the advantage that the barrel wear and muzzle flame are less than when using double-base gunpowder. The triple-base gunpowder is mainly used in ammunition for larger guns and artillery pieces. All the above-mentioned powders, which are based on nitrocellulose, are also called low-smoke powders, mainly due to the fact that the comparative powder was black powder, which generated extensive smoke development. Doublebase powder is used both as cannon powder and as rocket powder. Composite gunpowder is a solid substance that is produced by mixing an oxygen-rich salt with a binder and possibly also with an additional fuel such as a metal. The most common nowadays is to use ammonium perchlorate, AP, as an oxygen emitter, and to use a thermosetting plastic, polymer, as a binder, as well as a fuel. Aluminum is often also used in order to increase the specific impulse. The composite gunpowder can be made very high in energy and given a high specific impulse (over 2.600 Ns / kg). A disadvantage of the composite gunpowder of the type mentioned above is that it emits a clear streak of smoke, especially in moist air, and always when it contains aluminum. Composite gunpowder is used in rocket engines for, for example, missiles or launch rockets.

[0049] The propellant charge for the base bleed unit 5 and the propellant charge for the rocket engine 2 can each be made of different types of gunpowder but can also be made of the same type of gunpowder, but as a result of the valve closing the openings, the combustion process for the gunpowder can change after the propellant charge for the base bleed unit 5 is combusted and the propellant charge for the rocket engine 2 is initiated, for example by the pressure in the hybrid engine being altered. Thus, the propellant charge for the base bleed unit 5 and the propellant charge for the rocket engine 2 can be made of a homogeneous piece of gunpowder, of the same type of gunpowder but with different designs to change the burning rate, or of completely different types of gunpowder or of other combinations to achieve the desired functionality.EXAMPLES OF EMBODIMENTS

[0050] Examples of calibers for projectiles fitted with hybrid engine base bleed valve are 20 - 155mm but they can also be used for larger diameter projectiles although this is less common in current weapon systemsALTERNATIVE EMBODIMENTS

[0051] The invention is not limited to the embodiments specifically shown, but can be varied in different ways within the framework of the claims.

[0052] For instance, it is clear that the number, size, material, and shape of the elements included in the projectiles, as well as the details, are to be adapted according to the projectile(s) and projectile compositions, along with other construction-related properties, which are applicable to each individual case.

[0053] For instance, the projectile can be arranged so that it is capable of exploding, emitting shrapnel, catching fire, exerting a thermobaric effect, fighting fires, to be used as a training projectile, in light kits, in smoke kits, to exert electromagnetic effect, bring about electromagnetic disturbances or other loads and functions.

Claims

Claims1 . Hybrid engine (10) for a projectile, characterized in that the hybrid engine (10) is arranged with a propellant charge for a rocket engine (2) and a propellant charge for a base bleed unit (5) as well as a nozzle (7) and at least one opening (8), and where a valve (1 ) is arranged to close the opening (8) when the propellant charge for the base bleed unit (5) is combusted by means of moving the valve (1 ) when the propellant charge for the base bleed unit (5) is combusted.

2. Hybrid engine (10) for projectile according to claim 1 , characterized in that the valve (1 ) is designed with an abutment section (11 ) and a closure section (12) arranged perpendicular to the abutment section (11 ), and where the abutment section (11 ) has the purpose of abutting against the propellant charge for the base bleed unit (5) and as the drive charge for the base bleed unit (5) combusts, move valve (1 ) to its second, closed, position and where the closing section (12) is arranged to move to a closed position and close the opening (8).

3. Hybrid engine (10) for a projectile according to claim 2, characterized in that the abutment section (11 ) abuts against the propellant charge for the base bleed unit (5).

4. Hybrid engine (10) for a projectile according to one of claims 2 - 3, characterized in that the closing section (12) of the valve (1 ) is arranged in a groove (21 ) arranged in a rear section (20) of the hybrid engine (10).

5. Hybrid engine (10) for projectile according to one of the above claims, characterized in that a spacer disk (30) is arranged between the rear section (20) and the propellant charge for a rocket engine (2) and a propellant charge for the base bleed unit (5) and in that the spacer disk (30) is arranged with a groove (31 ) to enable gas flow from the combustion of the propellant charge for the base bleed unit (5) to be led out through an opening (8) and in thatthe spacer disk (30) is arranged with a groove (32) which the abutment section (11 ) of the valve (1 ) can move across.

6. Hybrid engine (10) for projectile according to one of claims 4 - 6, characterized in that the rear section (20) of the hybrid engine (10) is arranged with 4, 5, 6, 7, 8, 9, 10, 11 or 12 openings (8).

7. Hybrid engine (10) for a projectile according to one of the above claims, characterized in that the propellant charge for the rocket engine (2) and a propellant charge for the base bleed unit (5) consist of a solid propellant, where the solid propellant is gunpowder.

8. Hybrid engine (10) for projectile according to one of the above claims, characterized in that the propellant charge for the base bleed unit (5) is ignited by a base bleed igniter (3).

9. Projectile (100) arranged with hybrid engine (10) comprising a hybrid engine (10) according to any of claims 1 - 8.

10. Means for controlling a valve (1 ) for a hybrid engine (10) for a rotationally stabilized projectile, characterized in that the hybrid engine (10), including at least one propellant charge for a rocket engine (2) and at least one propellant charge for a base bleed unit (5), are arranged so that gas generated during combustion of propellant for the base bleed unit (5) is led out of the hybrid engine through a nozzle (7) and at least one opening (8) and where a valve (1 ) is arranged so as to close the opening (8) during combustion of the propellant charge of the base bleed unit (5) by an abutment section (11 ) arranged to the valve (1 ) abutting against the propellant charge of the base bleed unit (5) so that the valve (1 ) closes the opening (8) when the propellant charge of the base bleed unit (5) is combusted by the valve (1 ) being moved by the rotating motion of the projectile, then the propellant charge for the base bleed unit (5) completely or partially combusted, and valve (1 ) has closed theopening (8), the propellant charge for rocket engine (2) is initiated, after which the gas generated during the combustion of the propellant charge for rocket engine (2) is directed mainly through the nozzle (7).

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