IL314183B2 - Long range artillery projectile with auxiliary energetic material for rear casing ejection - Google Patents

Description

- 1 – 314183/3 LONG RANGE ARTILLERY PROJECTILE WITH AUXILIARY ENERGETIC MATERIAL FOR REAR CASING EJECTION TECHNOLOGICAL FIELDThe present disclosure relates to the field of artillery projectiles, and more specifically, but not exclusively, to long-range 155 mm artillery projectiles. BACKGROUND OF THE INVENTIONArtillery projectiles are projectiles which payload contains explosives, an incendiary, or other chemical fillings. One common caliber for artillery projectiles is a diameter of 155 mm. These projectiles are standard ammunition for field guns and howitzers, with a range of up to approximately 40 km. Various technologies have been employed to extend the range of 155 mm projectiles. Generally, these technologies fall into one of two categories: technologies reducing base drag, and technologies incorporating an internal motor. With respect to reducing drag, modifications such as a "boat tail" (a slight taper toward the back of the projectile) or fins have been utilized to help reduce air resistance. A "base bleed" mechanism is used to release a small amount of gas behind the projectile during flight, to thereby reduce the base drag that is generated as air wraps behind the projectile. Fig. 1A illustrates an exemplary embodiment of a prior art artillery projectile with a base bleed (the M1128 projectile). Projectile 1 includes body 2, rotating band 3, obturating band 4, payload 5, fuze 6, and supplementary charge 7. All of these components are standard features of an artillery projectile. In addition, a base bleed mechanism is configured at the rear of artillery projectile 1 and includes igniter assembly and base bleed propellant grain 9. The base bleed propellant grain is typically a propellant, such as ammonium perchlorate/hydroxy terminated polybutadiene (AP/HTPB). The igniter assembly 8 is a pyrotechnic composition such as magnesium/polytetrafluoroethylene (Mg/PTFE). When the projectile 1 is fired, the pyrotechnic composition ignites, thereby causing ignition of the solid propellant when the projectile is already airborne. The burning of the solid propellant generates gas exhaust at the rear of the artillery projectile. The exhaust gas reduces the drag of the projectile by approximately 20-30%. 30 - 2 – 314183/3With respect to the use of internal motors, conventional 155 mm projectiles are fired using external propelling charges, which burn in the gun following firing. Some projectiles, called "rocket-assisted projectiles", incorporate additional rocket motor within the projectile. Fig. 1B illustrates a cross section of a typical prior art rocket assisted projectile 10 (the M549). Projectile 10 includes fuze 11, payload 12, insulator 13, rotating band 14, and obturating band 15, which are standard components, as discussed. The projectile 10 further includes a rocket grain 16 and a delay fuse 17. When the projectile is fired, the propellant gases ignite the delay fuze 17, which burns for approximately seconds and then sets off the rocket igniter to initiate the rocket motor, which burns rocket grain 16 for approximately three seconds. This additional thrust augments the velocity and consequently, the range of the projectile 10. In this configuration, the rocket fuel includes an oxidizer, and the auxiliary rocket is thus airless. In alternative configurations (not shown), the auxiliary rocket is a jet engine - a form of airbreathing motor that utilizes forward motion of the projectile to provide air to the fuel in the motor for combustion. Using combinations of technologies such as those described has enabled significant improvement in projectile range. Nevertheless, each improvement has its own limitations and drawbacks, including ratio of power to weight, and cost of the internal motors of rocket assisted projectiles, especially for jet engine motors. Accordingly, it is desirable to consider alternative mechanisms for extending a projectile’s range. SUMMARY OF THE INVENTIONThe present disclosure introduces a novel long-range artillery projectile. The artillery projectile of the invention comprises an expulsion unit that is positioned within a body of the projectile and configured to cause pressure-mediated separation of a front projectile from a rear casing of the projectile, causing ejection of the rear casing and forward acceleration of the front projectile. Advantageously, the expulsion unit may be provided in long-range rocket-assisted artillery equipped with a base bleed unit to further increase both the speed and the flight distance of the projectile. The " long-range artillery projectile " according to the invention may have a structure typical of such projectiles, exemplified by the non-limiting 155 mm projectiles. The projectile may comprise a cartridge or a rear casing comprising a base charge and a front-end projectile that is seated securely at the top of the rear casing. The rear casing is - 3 – 314183/3typically free of any payload and is initially used to permit ejection of the projectile from the weapon barrel. Following separation, the rear casing has no function. Projectiles of the invention are not cluster munitions or flare munitions. The expulsion unit of the invention may be provided in the rear casing of the projectile, or at the front end of the projectile, as further discussed below. According to its broadest aspect, a long-range rocket-assisted artillery projectile is disclosed; the artillery projectile comprising an internal rocket engine, an expulsion unit and optionally a base bleed unit, wherein the expulsion unit is configured to induce or pressure-induce mid-flight separation of the projectile rear end part (rear casing) from the front-end part (the projectile, or bullet), and forward accelerate the front end part. As used herein, " separation " encompasses detachment of the rear casing from the front projectile, wherein said detachment is caused by an increased pressure in the projectile. Within the context of the present invention, separation of the two parts of the projectile is enabled by generation and compression of gases within the expulsion unit, which causes the expulsion unit to timely drive the separation of the two parts. As noted herein, the separation occurs mid-flight or after the projectile has left the barrel of the weapon. Separation is not intended to occur prior to exiting the barrel. The term "mid-flight" does not refer to any specific distance along the flight path; rather to any time point along the flight path, after the projectile has left the barrel of a weapon. The separation time is not limited to any distance from the weapon or from the target. The " expulsion unit " may be provided in a form of an encasing or an enclosure or a compartment within the projectile, wherein the encasing or enclosure may comprise or be equipped or be provided with an energetic material such as propellant, that is caused to ignite at a predetermined time following firing of the projectile. The ignition of the energetic material in the expulsion unit causes increasingly higher pressures in the unit. The ignition of the energetic material in the expulsion unit may be independently timed from the moment of firing of the projectile and independent of the operation of any other functional feature or component that may be present in the projectile (such as a rocket engine or a base bleed). Alternatively, the ignition of the energetic material may be timed after or prior to ignition or operation of any one functional feature of component that may - 4 – 314183/3be present in the projectile. In such an alternative configuration, the expulsion unit may not contain an energetic material, as further explained hereinbelow. In a first aspect, there is provided an artillery projectile comprising rocket engine, an expulsion unit and optionally a base bleed unit, wherein the expulsion unit is configured to cause mid-flight separation of the projectile rear end part (rear casing) from a front end part, and thereby forward accelerate the front end part. In some embodiments, a base bleed unit is absent, or the projectile is free of a base bleed. In some embodiments, a base bleed is present. In some embodiments, the expulsion unit is in a form of an encasing or a chamber, optionally containing an energetic material. In some embodiments, the expulsion unit comprises an energetic material ignitable to generate gases within the expulsion unit to increase pressure within the projectile and cause the separation. In some embodiments, the expulsion unit comprises an ignitor configured for timed ignition of the energetic material. In some embodiments, ignition of the energetic material is timed from a moment of firing of the projectile or timed in accordance with ignition or operation of any component included in the projectile. In some embodiments, the expulsion unit comprises or includes an energetic material. The ignition of the energetic material generates gases within the expulsion unit that increase pressure within the projectile and cause backward ejection of the rear casing and forward acceleration of the projectile. The expulsion unit may be provided within either part of the projectile, namely at the rear casing - in which case the expulsion unit will be separated from the front projectile end; or may be provided within the front projectile end - in which case it will remain with the front-end following separation. For the purpose of reducing weight of the front end of the projectile, allowing increased acceleration, speed and distance of flight, the expulsion unit will typically be formed part of the rear end of the projectile. The energetic material may be selected from black powder; solid pyrotechnic compositions; zinc–sulfur propellants comprising powdered zinc metal and powdered sulfur; candy propellants comprising potassium nitrate and a sugar fuel such as dextrose, sorbitol or sucrose; composite propellants comprising e.g., ammonium-nitrate-based or ammonium-perchlorate-based composites; polyurethane-bound aluminum solid fuel; - 5 – 314183/3nitrocellulose/nitroglycerin double base propellant with ammonium perchlorate and powdered aluminum; C6H6N6(NO2)6 CL-20 nitroamine; and others. In some embodiments, the energetic material is black powder. The ignition of the expulsion unit comprising the energetic material may be achieved by an ignitor and may be timed from the moment of firing of the projectile or may be timed in accordance with the ignition or operation of any one element or component included in the projectile, e.g., a rocket engine or a base bleed unit. In some embodiments, the projectile comprises an internal rocket engine, the expulsion unit and a base bleed unit, wherein the expulsion unit is positioned forward to the base bleed unit (and at the back of the rocket engine). In such a configuration, the energetic material is caused to ignite within a time period from the firing of the projectile, or within a time period from the ignition of the base bleed, or within a time period from the time the base bleed becomes inoperable or ceases to burn; or may be ignited directly by the base bleed. Where the expulsion unit comprises an energetic material, the expulsion unit and the rocket engine may be operable as independent units within the projectile casing. The ignition of the energetic material may occur prior to ignition of the rocket engine and may trigger same. In other words, the energetic material may be ignited independently and prior to the ignition of the rocket engine. The timing of ignition of the energetic material of the expulsion unit may be within a time period from the firing of the projectile, or within a time period from the ignition of the base bleed (if present). The ignition of the rocket engine may follow once the expulsion unit has caused the rear and front ends of the projectile to separate. However, in some configurations, the expulsion unit may be provided free of any energetic material. In such configurations, the expulsion unit may be configured with the rocket engine to direct gases generated during the ignition of the rocket engine into the expulsion unit. The gases are collected in the chamber to cause an increase in the gas pressure within the projectile and bring about ignition of the expulsion unit that separates the front and rear ends of the projectile. Thus, where the projectile is provided with a rocket engine and an expulsion unit, the expulsion unit may be: 1- configured with an energetic material that is timed to ignite prior to ignition of the rocket engine, causing separation of the front and rear ends of the - 6 – 314183/3projectile; subsequently, the rocket engine ignites to forward accelerate the projectile; or 2- dependent on the ignition of the rocket engine, whereby gases generated by the operation of the rocket engine collect within the expulsion unit to cause an increase in pressure and separation of the front and rear ends of the projectile; thereby reducing weight and allowing the projectile to accelerate. In such a configuration, the expulsion unit may be provided free of any energetic material. However, to further increase or speed up separation of the front and the rear ends, the expulsion unit may still contain an amount of the energetic material. In additional configurations of a projectile of the invention, the projectile comprises a base bleed unit that is provided at a rear end of the projectile, a rocket engine provided at a front end of the projectile and an expulsion unit that is provided between the base bleed unit and the rocket engine. In such a so-called full configuration, the expulsion unit may or may not comprise an energetic material, as described herein, and may operate in any operation sequence with the base bleed unit and the rocket engine. In a first operation sequence, upon leaving the barrel of a weapon, the base bleed mechanism operates to reduce drag of the projectile. When the projectile reaches a predetermined time of flight or reduction of speed, or at any time after the base bleed has become inoperable, or initiated by the base bleed, the energetic material in the expulsion unit ignites to generate sufficient gas pressure to cause ejection of the rear end of the projectile and forward acceleration of the front end. Subsequently, or timed from the point of separation, the rocket engine may ignite and propel the projectile to its destination at a higher speed. In a second operation sequence, upon leaving the barrel of a weapon, the base bleed mechanism operates to reduce drag of the projectile. When the projectile reaches a predetermined time of flight or reduction of speed, or at any time after the base bleed has become inoperable, or initiated by the base bleed, the energetic material in the expulsion unit ignites to generate sufficient gas pressure in the projectile. Prior to causing separation of the rear and forward ends of the projectile, the expulsion unit may cause ignition of the rocket engine and subsequent separation of the front and rear ends. - 7 – 314183/3In a further operation sequence, upon leaving the barrel of a weapon, the base bleed mechanism operates to reduce drag of the projectile. When the projectile reaches a predetermined time of flight or reduction of speed, or at any time after the base bleed has become inoperable, or initiated by the base bleed, the rocket engine ignites to generate gases that are directed to and trapped or contained in the expulsion unit. An increase in the gas pressure within the expulsion unit causes ejection of the rear end of the projectile. Other and alternative operation sequences may also be relevant. As further detailed below, the addition of the expulsion unit, as disclosed herein, improves the speed of the projectile, by adding 50 to 150 m/sec in such a way to increase the distance/range it is capable of achieving. Using the projectile having the structure described herein and the methods disclosed herein, it is possible to launch the projectile to ranges of 75 km or longer. These ranges have previously been achieved only by using more costly and accordingly less practical engines, such as ramjet engines. By contrast, the disclosed projectile is able to achieve the desired range using any conventional rocket engine. The invention thus provides a long-range artillery projectile comprising a separable front end and a rear end, a rocket engine provided in the front end and an expulsion unit configured and operable to generate pressure within the projectile to thereby cause separation of the projectile front end from the rear end. In some embodiments, the projectile comprises a base bleed unit. In some embodiments, the expulsion unit comprises an energetic material, e.g., a prepollent. In some embodiments, the long-range artillery projectile comprises a separable front end and a rear end, an internal rocket engine provided in the front end of the projectile, a base bleed unit provided in the rear end of the projectile and an expulsion unit positioned forward of the base bleed unit, wherein the expulsion unit comprises an energetic material configured and operable to ignite and generate pressure within the projectile to thereby cause separation of the projectile front end from the rear end. In some embodiments, the energetic material is caused to ignite within a time period from the firing of the projectile, or within a time period from the ignition of the base bleed, or within a time period from the time the base bleed becomes inoperable. In some embodiments, the energetic material is ignited by the base bleed. - 8 – 314183/3In some embodiments, the long-range artillery projectile comprises a separable front end and a rear end, a rocket engine provided in the front end of the projectile and an expulsion unit positioned at the back of the rocket engine, wherein the expulsion unit comprises an energetic material configured and operable to ignite and generate pressure within the projectile, prior to ignition of the rocket engine, wherein the pressure causes separation of the projectile front end from the rear end. In some embodiments, the long-range artillery projectile comprises a separable front end and a rear end, a rocket engine provided in the front end of the projectile and an expulsion unit positioned at the back of the rocket engine, wherein the rocket engine is configured to ignite and generate gases, wherein said gases are collected within the expulsion unit and cause an increase in pressure within the projectile, to thereby cause separation of the projectile front end from the rear end, and wherein the expulsion unit optionally comprises an energetic material. In some embodiments, the expulsion unit is free of any energetic material. In some embodiments, the projectile includes: -a rocket engine configured to burn a fuel stored therein to thereby generate thrust, the engine being surrounded by an internal engine casing; -a rear casing configured around the engine casing; -a base bleed unit within the rear casing; and -an expulsion unit configured between the engine casing and the base bleed unit, i.e., provided in the rear casing. In some embodiments, the projectile may include a delay ignitor for the expulsion unit, which may optionally be configured within the base bleed unit. The delay ignitor for expulsion unit may be ignited by an ignitor of the base bleed unit, or by an independent ignitor member. In some embodiments, the delay ignitor for the expulsion unit may be configured to ignite the energetic material at a predetermined time following launch of the projectile. The predetermined time may be set to ensure that the energetic material does not ignite before the base bleed has terminated. The rocket engine may be any rocket engine known in the art. The engine may include a delay ignitor that is ignited by the ignition of the expulsion unit, or which is timed to ignite after a certain predetermined time following inactivation of the base bleed - 9 – 314183/3or from the ignition of the expulsion unit. In some embodiments, the engine may be ignited at a predetermined time after the energetic material has been ignited. Both the rocket engine and the base bleed unit may be selected amongst those known in the art. The selection of a proper or a suitable engine and base bleed unit is by no way limiting the projectiles of the invention. The rocket engine used may be selected from solid-propellant engines, hybrid-propellant engines, monopropellant engines, bipropellant engines, gas-gas engines, dual mode propulsion engines, tripropellant engines, air-augmented engines, turborocket engines, resistojet engines, arcjet engines, variable specific impulse magnetoplasma engine, pulsed plasma thrusters and others. Non-limiting examples of rocket engines include RD-0410 nuclear rocket engine, J58 jet engine, Rolls-Royce/Snecma Olympus engines, turbojet with reheat (Concorde) engine, Pratt & Whitney F119 engine, RD-0750 rocket engine, RD-0146 rocket engine, Rocketdyne RS-25 rocket engine, RD-180 rocket engine, RD-170 rocket engine, F-(Saturn V first stage) engine, NK-33 rocket engine, Merlin 1D rocket engine, and others. In some embodiments, the projectile may be a 155 mm projectile. The invention further provides a 155 mm artillery projectile, the projectile comprising a rocket engine casing surrounding a rocket engine, and a rear casing configured around the engine casing, wherein the rear casing comprises a base bleed unit and an expulsion unit configured between the engine casing and the base bleed unit, and wherein: (i) the expulsion unit comprises an energetic material configured and operable to ignite and generate gas-derived pressure within the projectile, prior to ignition of the rocket engine, wherein the pressure causes ejection of the rear casing; or wherein (ii) the rocket engine is configured to ignite and generate gases, wherein said gases are collected within the expulsion unit and cause an increase in pressure within the projectile, to thereby cause ejection of the rear casing. According to a further aspect, a method of firing a long-range artillery projectile according to the invention is disclosed. The method comprises launching the artillery projectile of the invention; burning mid-flight the energetic material of the expulsion unit, to thereby eject the rear casing; and generating thrust with the rocket engine until the artillery projectile reaches its target. - 10 – 314183/3The invention further provides a method comprising launching the artillery projectile of the invention; generating thrust with the rocket engine and causing gases generated by the engine to collect within the expulsion unit, to thereby eject the rear casing of the projectile. The invention further provides a method comprising launching the artillery projectile of the invention; during a first flight stage, operating the base bleed unit; in a second flight stage, burning mid-flight the energetic material of the expulsion unit, to thereby eject the rear casing; and in a third flight stage, generating thrust with the rocket engine until the artillery projectile reaches its target. The method of firing a long-range artillery projectile comprises an internal engine casing surrounding a rocket engine, and a rear casing configured around the internal engine casing, wherein the rear casing comprises a base bleed unit and an expulsion unit configured between the rocket engine casing and the base bleed unit, the method comprising launching the artillery projectile; during a first flight stage, operating the base bleed unit; in a second flight stage, burning mid-flight the energetic material in the expulsion unit, to thereby eject the rear casing; and in a third flight stage, generating thrust with the rocket engine until the artillery projectile reaches its target. In some implementations according to the second aspect, the method includes igniting the energetic material with a delay ignitor configured within the base bleed unit. Alternatively, the method includes igniting the energetic material with an ignitor associated with the expulsion unit. The invention provides the following configurations of artillery projectiles according to the invention, wherein the projectiles are not cluster munitions or flare munitions: 1. an artillery projectile comprising a rocket engine and an expulsion unit, as disclosed herein; and 2. an artillery projectile comprising a rocket engine, an expulsion unit and a base bleed unit, as disclosed herein. The invention further provides: An artillery projectile comprising rocket engine, an expulsion unit and optionally a base bleed unit, wherein the expulsion unit is configured to cause mid-flight separation - 11 – 314183/3of the projectile rear end part (rear casing) from a front end part, and thereby forward accelerate the front end part. In some configurations of a projectile of the invention, the expulsion unit is in a form of an encasing or a chamber, optionally containing an energetic material. In some configurations of a projectile of the invention, the expulsion unit comprises an energetic material ignitable to generate gases within the expulsion unit to increase pressure within the projectile and cause the separation. In some configurations of a projectile of the invention, the expulsion unit comprises an ignitor configured for timed ignition of the energetic material. In some configurations of a projectile of the invention, ignition of the energetic material is timed from a moment of firing of the projectile or timed in accordance with ignition or operation of any component included in the projectile. In some configurations of a projectile of the invention, the projectile is free of a base bleed unit. In some configurations of a projectile of the invention, the projectile comprises a base bleed unit. In some configurations of a projectile of the invention, the expulsion unit is positioned forward to the base bleed unit. In some configurations of a projectile of the invention, the expulsion unit is positioned rearward of the rocket engine. In some configurations of a projectile of the invention, the projectile comprises a base bleed unit, the expulsion unit is positioned between the base bleed unit and the rocket engine. In some configurations of a projectile of the invention, ignition of the energetic material is timed from the firing of the projectile, or within a time period from ignition of the base bleed, or within a time period from the time the base bleed becomes inoperable or ceases to burn. In some configurations of a projectile of the invention, ignition of the energetic material is by the base bleed. In some configurations of a projectile of the invention, the expulsion unit is positioned rearward of the rocket engine, and wherein the expulsion unit optionally comprises an energetic material. - 12 – 314183/3In some configurations of a projectile of the invention, the expulsion unit comprises an energetic material, and the expulsion unit is operated independently of the rocket engine. In some configurations of a projectile of the invention, ignition of the expulsion unit energetic material occurs prior to ignition of the rocket engine. In some configurations of a projectile of the invention, the expulsion unit energetic material is ignited independently and prior to ignition of the rocket engine. In some configurations of a projectile of the invention, timing of ignition of the energetic material is within a time period from the firing of the projectile, or within a time period from ignition of the base bleed. In some configurations of a projectile of the invention, ignition of the rocket engine follows separation of the rear casing from the front end of the projectile. In some configurations of a projectile of the invention, the expulsion unit is configured with the rocket engine to direct gases generated during ignition of the rocket engine into the expulsion unit. In some configurations of a projectile of the invention, the expulsion unit is free of an energetic material. In some configurations of a projectile of the invention, the gases generated during ignition of the rocket engine are collected in the expulsion unit to cause an increase in the gas pressure within the projectile, leading to separation of the front end from the rear casing of the projectile. The projectile according to claim 1, the expulsion unit being: -configured with an energetic material timed to ignite prior to ignition of the rocket engine, causing separation of the front end of the projectile from the rear casing of the projectile; subsequently, the rocket engine ignites to forward accelerate the front part of the projectile; or -dependent on the ignition of the rocket engine, whereby gases generated by operation of the rocket engine collect within the expulsion unit to cause an increase in pressure and separation of the front end from the rear casing. In some configurations of a projectile of the invention, the projectile comprising a rocket engine casing surrounding the rocket engine, and a rear casing configured around the engine casing, wherein the rear casing comprises the base bleed unit and the expulsion - 13 – 314183/3unit, the expulsion unit is configured between the engine casing and the base bleed unit, and wherein: the expulsion unit comprises an energetic material configured and operable to ignite and generate gas-derived pressure within the projectile, prior to ignition of the rocket engine, wherein the pressure causes ejection of the rear casing; or wherein the rocket engine is configured to ignite and generate gases, wherein said gases are collected within the expulsion unit and cause an increase in pressure within the projectile, to thereby cause ejection of the rear casing. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1A-Billustrate a prior art artillery projectile with a base bleed mechanism (1A) and an artillery projectile with rocket-assisted propulsion; Fig. 2illustrates a cross-section of a long-range artillery projectile, according to embodiments of the present disclosure; Figs. 3A-3D illustrate stages of operation of the artillery projectile of Fig. 2 , according to embodiments of the present disclosure; Fig. 4 illustrates steps in a method of firing a long-range artillery projectile, according to embodiments of the present disclosure. Fig. 5 illustrates a flight path of a projectile according to the invention. DETAILED DESCRIPTION OF EMBODIMENTS OF THE DISCLOSURE Figs. 1A-B illustrate a projectile according to the state of the art. Fig. 2 schematically illustrates artillery projectile 100. Artillery projectile 100 is illustrated with an emphasis on the components that are unique to the present embodiments, such that the absence or lack of description of various components from the illustrated projectile (e.g., rotating band, obturating band, fins, air intake vents, or exhaust vents) should not be interpreted as evidence of their absence. As seen in Fig. 2 , projectile 100 includes a fuze 102 and a payload 104. The fuze 102 and payload 104 may be conventional components. Internal engine 106 is rearward of the payload 104 and separated from the payload by insulator 105. Engine 106 includes, among other parts, a delay ignitor 110 and a rocket propellant 107. Engine 106 is enclosed by internal engine casing 108. Engine 106 may be any engine suitable for inclusion in an artillery projectile, including an airless engine and - 14 – 314183/3(with suitable modifications from the embodiment illustrated in Fig. 2 ) a ramjet, pulsejet or any other engine. An expulsion unit 114 is configured rearward of the engine 106. The energetic material contained in the expulsion unit is ignited with a delay ignitor 116. Rear casing 112 wraps around the expulsion unit 114 and the internal engine 106. Putting it differently, the front end of the projectile, including the elements 102, 104, 105, 106, 107, and 108 is sealingly positioned within the rear casing 112. The rear casing 1may be made of any suitable casing for an artillery projectile, such as steel. At a rear portion of the rear casing 112 is a base bleed unit 120. The base bleed unit 120 includes ignitor 122 and a propellant 124. The base bleed mechanism 120 operates in most respects like a standard base bleed unit. One difference between a standard base bleed unit and the base bleed unit used in accordance with the present disclosure may be that igniter 122 may also be connected to delay ignitor 116 for the expulsion unit, and optionally delay ignitor 118 for the internal engine, so that the ignitor is also configured to initiate operation of those components, as will be discussed further herein. Figs. 3A-3D illustrate different stages of operation of the artillery projectile 100, and Fig. 4 illustrates steps in a method of operation 200 of artillery projectile 1including a rocket engine and a base bleed, in accordance with the full configuration. It should be noted that certain components of projectile 100 are depicted slightly differently in Figs. 3A-3D compared to their depiction in Fig. 2 . As the depiction of the projectile is schematic, these differences are not significant. At step 201 of Fig. 4 , the artillery projectile is launched. When the projectile is launched, the projectile appears substantially as illustrated in Fig. 3A . At step 202 of Fig. 4 , the base bleed system is initiated with the ignitor 122, to thereby generate exhaust gas behind the artillery projectile, and reduce drag of the projectile during flight. Referring to Fig. 3B and step 203 of Fig. 4 , the energetic material of the expulsion unit is burned. For example, the expulsion unit is connected to delay ignitor 116, which is initiated by the igniter 122 of the base bleed 120. Theoretically, the delay ignitor 116 may be initiated directly by the firing of projectile 100, without being initiated by ignitor 122. - 15 – 314183/3 The burning of the energetic material of the expulsion unit is illustrated schematically in Fig. 3B . As the front part of the artillery projectile accelerates in a forward direction, along arrow 140, the energetic material, e.g., propellant, of the expulsion unit 114 burns, as illustrated with burst 144. The propellant burst 144 further forward accelerates the front part of the projectile, while the rear portion of the projectile 100 is dislodged backwards in a direction 142. In Fig. 3B , the rear casing 112 has partially displaced from the engine casing 108. Referring now to Fig. 3C and step 204 of Fig. 4 , the internal engine 106 is ignited. The ignition of the internal engine 106 may proceed through lighting of delay ignitor 110, via delay ignitor 118, as shown in Fig. 2 . Alternatively, delay ignitor 110 is ignited by the burning of the expulsion unit. Regardless, once the internal engine is ignited, exhaust 1of the internal engine propels the front end or bullet end forward. At this point, rear casing 112 has disengaged completely from the engine/rear casing. Referring now to Fig. 3D , and to step 205 in Fig. 4 , the projectile 100 with its decreased diameter (lower drag) continues to move forward, powered by the remaining velocity, until it reaches its target. In advantageous embodiments, the range of the artillery projectile may be 75-km or greater. This distance may be particularly met when the projectile is shot from a 52-caliber gun. A 52 caliber means that the length of the barrel is 52 times the 155 mm bore, or approximately 8.06 meters. A gun with a smaller caliber (e.g., 39/45 caliber) may also shoot the artillery projectile at extremely long distance as compared to conventional artillery projectiles, although not as far as the 52-caliber gun. Fig. 5 demonstrates a flight path of a projectile of the invention along a path P, from shooting position S1. Once the projectile leaves the barrel of the weapon, the base bleed unit is ignited, reducing drag of the projectile. The base bleed continues to burn for a period of about 20 seconds as the projectile travels along the path P. At position Salong the path, the base bleed turns off or is terminated, at which point S2, the ignitor of the expulsion unit may ignite the propellent of the expulsion unit. The propellant may be timed to ignite at point S2 or at a time point or position S3, or at any time point between S2 and S3. The time period between S2 and S3 may be between zero seconds to 10-30 seconds. According to other configurations, any time period may be preselected. - 16 – 314183/3 At point S3, the propellant of the expulsion unit explodes or burns to cause separation between the rear casing of the projectile and its front end. Alternatively, in configurations wherein the expulsion unit is not provided with a propellant, at position S2 or at a time point or position S3, or at any time point between S2 and S3, ignition of rocket engine generates gases that collect in the expulsion unit, thereby increasing pressure within the expulsion unit, causing separation between the rear casing and the front end of the projectile. As flight of the projectile continues through point S3, the expulsion unit causes ignition of the rocket engine. Alternatively, the rocket engine may be ignited at point Sto further accelerate the projectile forward through point S5 over ballistic path S6. The engine may be ignited immediately following separation of the rear casing or at any time thereafter. Typically, the time difference between point S3 and S4 may be between zero and 20-30 seconds.

Claims (13)

1. - 17 - 314183/

2. CLAIMS: 1. An artillery projectile comprising a rocket engine, an expulsion unit, a rear casinghaving a region arranged around a casing of the rocket engine; and a base bleed unit, wherein the expulsion unit is provided between the base bleed and the rocket engine and is configured to timely drive a mid-flight ejection of the rear casing from a front-end part of the projectile, and further increase speed of the front-end part, wherein the mid-flight ejection comprises ignition of an energetic material present in the expulsion unit prior to ignition of the rocket engine, or wherein, in an expulsion unit free of an energetic material, the mid-flight ejection comprises ignition of the rocket engine prior to the ejection, whereby gases generated by ignition and operation of the rocket engine collect within the expulsion unit, causing an increase in pressure and ejection of the rear casing. 2. The projectile according to claim 1, wherein the expulsion unit is in a form of anencasing or a chamber containing an energetic material.

3. The projectile according to claim 1 or 2, wherein the expulsion unit comprises an ignitor configured for timed ignition of the energetic material.

4. The projectile according to claim 3, wherein ignition of the energetic material istimed from a moment of firing of the projectile or timed in accordance with ignition or operation of a component included in the projectile.

5. The projectile according to claim 3, wherein ignition of the energetic material is timed from the firing of the projectile, or is within a time period from ignition of the base bleed, or is after the base bleed becomes inoperable or ceases to burn.

6. The projectile according to claim 1, wherein ignition of the energetic material isby the base bleed.

7. The projectile according to claim 1, wherein the expulsion unit comprises an energetic material, and the expulsion unit is operated independently of the rocket engine.

8. The projectile according to claim 7, wherein ignition of the expulsion unitenergetic material occurs prior to ignition of the rocket engine.

9. The projectile according to any one of claims 6 to 8, wherein ignition of the rocketengine follows separation of the rear casing from the front end of the projectile.

10. The projectile according to claim 1, wherein the expulsion unit is free of anenergetic material. - 18 - 314183/

11. An artillery projectile comprising a rocket engine, an expulsion unit, a rear casinghaving a region arranged around a casing of the rocket engine; and a base bleed unit, wherein the expulsion unit is provided between the base bleed and the rocket engine and comprises an energetic material ignitable to timely drive a mid-flight ejection of the rear casing from a front-end part of the projectile, and further increase speed of the front-end part; wherein ignition of the energetic material is timed from the firing of the projectile, or is within a time period from ignition of the base bleed, or is within a time period from the time the base bleed becomes inoperable or ceases to burn.

12. The projectile according to claim 11, wherein the ignition of the energetic materialis within a time period from ignition of the base bleed.

13. The projectile according to claim 11, wherein the ignition of the energetic materialis after the base bleed becomes inoperable or ceases to burn. 15