IL279912A - Multi stage missile - Google Patents

Description

MULTI STAGE MISSILE TECHNOLOGICAL FIELD The presently disclosed subject matter relates to multi stage missiles, in particular to two stage missiles.

BACKGROUND Small caliber type rockets (e.g. 122mm) are well known in the art and provide surface to surface ranges of well under 80km at relatively low unit costs.

Missiles having significantly greater range than such small caliber type rockets, and also having high accuracy, have unit costs that are conventionally far greater than unit costs of such small caliber type rockets (e.g. nominally 122mm diameter), typically at least one order of magnitude higher. A major contributor to such conventionally higher costs is the conventional design approach in which a new rocket design is provided based on a relatively larger diameter rocket propulsion system to provide the increased energy required for the increased range, while length to diameter (L/D) ratio is maintained at the same magnitude, or while the L/D ratio may be increased but conventionally still well below 35 for this ratio.

GENERAL DESCRIPTION According to a first aspect of the presently disclose subject matter there is provided an interstage module configured for coupling between a projectile and a booster stage of a multistage missile, the projectile comprising a projectile propulsion system, the interstage module configured for, responsive to initiation of decoupling of the booster stage from the projectile:enabling decoupling of the interstage module from the projectile under first predetermined conditions; andautonomously initiating operation of the projectile propulsion system under second predetermined conditions;and wherein the interstage module is configured for being in joined relationship with the booster stage at least during launch operation.

For example, said first predetermined conditions and/or said second predetermined conditions can be set up in the interstage module before launch from an external source, with the desired parameters being provided for example via a wire connection or via wireless connection from the external source. For example, immediately after launch the interstage module operates autonomously and independently of any other controller that may be carried by the multistage missile.

Alternatively, for example, said first predetermined conditions include a first time period after the booster stage terminates acceleration. For example, said first time period is greater than 2 seconds, or for example, said first time period is between zero seconds and 2 seconds.

Alternatively, for example, said second predetermined conditions include a second time period after the booster stage terminates acceleration.

Additionally or alternatively, for example, said second predetermined conditions include a second time period after initiation of decoupling of the interstage module from the projectile. Alternatively, for example, said second predetermined conditions include a second time period after launch of the multistage missile. ס - כ - Additionally or alternatively, for example, the interstage module configured for being integrally formed with the booster stage.

Additionally or alternatively, for example, the interstage module configured for being manufactured separately from the booster stage, and further configured for being affixed to the booster stage. For example, an aft projectile end of said the interstage module includes an aft threaded coupling portion, configured for mechanical coupling with a complementarily threaded portion comprised in a forward end of the booster stage. For example, said complementarily threaded portion corresponds to a threaded portion provided in a forward end of small caliber type rockets (e.g. nominally 122mm diameter) configured for coupling to a warhead of the small caliber type rockets (e.g. nominally 122mm diameter).

Additionally or alternatively, for example, the interstage module is mounted to the projectile via a coupling arrangement including a mechanical coupler and a forward pyrotechnic fastener arrangement, and wherein the coupling arrangement is configured for enabling separating the interstage module from the projectile responsive to operating the forward pyrotechnic fastener arrangement. For example, the interstage module comprises an interstage housing, and wherein the coupling arrangement includes fairing projecting forward from the interstage housing, the fairing comprising a forward fairing end configured for enabling mechanical coupling the interstage module to an aft end of the projectile, the fairing comprising a plurality of fairing petals each being affixed at an aft fairing end thereof to the interstage housing, wherein each adjacent pair of said fairing petals are separated from one another via a slit, each said slit extending aft from a forward fairing edge and aft of the forward pyrotechnic fastener arrangement. For example, the forward pyrotechnic fastener arrangement comprises a peripheral pyrotechnic device configured for providing mechanical contiguity between adjacent said petals at said slits, and a detonator for activating the peripheral pyrotechnic device. Additionally or alternatively, for example, said fairing petals are in peripheral arrangement with respect to interstage housing, and wherein said forward pyrotechnic fastener arrangement spans an internal periphery of each fairing petal and is configured for separating said aft fairing end including said interstage housing from said forward fairing end responsive to actuation of said forward pyrotechnic fastener arrangement. Additionally or alternatively, for example, said forward fairing end comprises an internally threaded portion configured for mechanical coupling with a complementarily externally threaded coupling portion provided on a projectile aft end of the projectile.

Additionally or alternatively, for example, the projectile propulsion system comprises an igniter for selectively initiating operation of the projectile propulsion system, and wherein the interstage module comprises a controller operatively connected to an electrical power supply and to the igniter via a lead. For example, the controller and the electrical power supply are housed in the interstage module. For example, said lead has slack to enable the controller to activate the ignitor via the lead after initiation of decoupling of the interstage module from the projectile. Additionally, for example, the controller and the electrical power supply are configured for being housed in the projectile, and wherein the controller is further configured for operating the forward pyrotechnic fastener arrangement housed in the interstage module, and wherein the controller and the electrical power supply are configured for remaining with the projectile after the interstage module decouples from the projectile. For example, the controller and the electrical power supply are configured for being removed from the projectile following operation of the projectile propulsion system under second predetermined conditions.

Additionally or alternatively, for example, the projectile comprises a plurality of fins that are deployable from a stowed configuration to a deployed configuration, and wherein the interstage module is further configured for:preventing deployment of the projectile fins while the interstage module is coupled to the projectile; andenabling deployment of the projectile fins once the interstage module is decoupled from the projectile.

For example, said fairing mechanically maintains the projectile fins in said stowed configuration until the interstage module is decoupled from the projectile.

According to a second aspect of the presently disclose subject matter there is provided a booster stage assembly for a projectile, comprising an interstage module as defined herein regarding the first aspect of the presently disclose subject matter, and a booster stage.

For example, the interstage module is integrally formed with the booster stage. Alternatively, for example, the interstage module is manufactured separately from the booster stage, and wherein the interstage module is affixed to the booster stage.

Additionally or alternatively, for example, the booster stage comprising a booster stage rocket motor and a plurality of booster stage fins, deployable from a stowed configuration to a deployed configuration.

Additionally or alternatively, for example, the booster stage has a length in the range of about 2.2m to 2.5m.

Additionally or alternatively, for example, the booster stage has an external diameter in the range 96mm to 163mm.

Additionally or alternatively, for example, the booster stage has an external diameter of 122mm.

Additionally or alternatively, for example, said booster stage is based on an aft portion of a small caliber type rocket system, in particular on small caliber type rocket propulsion system (e.g. nominally 122mm diameter).

According to a third aspect of the presently disclose subject matter there is provided a multistage missile comprising a projectile and a booster stage assembly, the booster stage assembly being as defined herein regarding the second aspect of the presently disclose subject matter.

For example, the projectile is based on a small caliber type rocket system, in particular on small caliber type rocket propulsion system (e.g. nominally 122mm diameter).

Additionally or alternatively, for example, the projectile comprises a projectile rocket motor and a plurality of projectile tins, deployable from a stowed configuration to a deployed configuration.

Additionally or alternatively, for example, an aft projectile end of said projectile includes an externally threaded coupling portion, configured for mechanical coupling with a complementarily internally threaded portion comprised in said interstage module.

Additionally or alternatively, for example, the projectile has a length in the range about 2.6m to about 3.2m.

Additionally or alternatively, for example, the projectile has a pre-launch diameter in the range 96mm to 163mm.

Additionally or alternatively, for example, the projectile has a pre-launch diameter of 122mm.

Additionally or alternatively, for example, the multistage missile has a length in the range 4.8m to 5.7m or in the range 4.4m to 5.7m.

Additionally or alternatively, for example, the multistage missile has a pre-launch diameter in the range 96mm to 163mm.

Additionally or alternatively, for example, the multistage missile has a length to pre-launch diameter ratio in the range 35 to 50.

Additionally or alternatively, for example, the projectile comprises a steering system in the form of an add-on Course Correction Kit unit.

According to a fourth aspect of the presently disclose subject matter there is provided a multistage missile comprising at least a projectile and a booster stage, the multistage missile having a longitudinal length and a pre-launch diameter, and wherein a ratio of said longitudinal length to said pre-launch diameter is not less than about 35.

For example, said ratio is in a range between about 35 and about 50.

Additionally or alternatively, for example, said ratio is any one of: 35, 36, 37, 38, 39, 40. 41,42, 43, 4, 45, 46, 47, 48, 49, 50.

Additionally or alternatively, for example, said pre-launch diameter is less than 150mm, optionally less than 125mm.

Additionally or alternatively, for example, said pre-launch diameter is about 122mm.

Additionally or alternatively, for example, the multistage missile comprises at least one set of fins, each fin being deployable from a stowed configuration to a deployed configuration, and wherein said pre-launch diameter corresponds to said fins being in the stowed configuration.

Additionally or alternatively, for example, each one of said projectile and said booster stage is based on a small caliber type rocket system, in particular on small caliber type rocket propulsion system (e.g. nominally 122mm diameter).

According to a fifth aspect of the presently disclose subject matter there is provided a method for operating a multistage missile, comprising: (i) providing the multistage missile, the multistage missile being as defined herein regarding the third aspect of the presently disclose subject matter; (ii) operating the booster stage to provide an initial acceleration to the multistage missile; (iii) decoupling of the interstage module from the projectile under said first predetermined conditions; (iv) initiating operation of the projectile propulsion system under said second predetermined conditions; and (v) operating the projectile to provide an additional acceleration stage and a subsequent coast phase.

A feature of at least one example of the presently disclosed subject matter is that a corresponding high accuracy weapon can be provided for use as a surface-to-surface missile or air-to-surface missile having a range above 80km or above 100km in a relatively inexpensive manner as compared with conventional systems of similar range and accuracy.

Another feature of at least one example of the presently disclosed subject matter is that a corresponding high accuracy missile for ranges exceeding 80 km or 100km can be provided in a cost-effective manner based on existing rocket engine technology.

Another feature of at least one example of the presently disclosed subject matter is that a novel approach is provided for designing and manufacturing longer range missiles by essentially using two relatively low-cost small caliber rocket propulsion systems (e.g. diameter 122 mm) longitudinally coupled via a novel interstage module, thereby creating a two stage missile configuration but with a non-conventional L/D ratio (for example, above 35). For example, such a novel approach can be implemented with relatively minor modifications of the original rocket propulsion systems interface and by providing the novel interstage module design.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig• ।is a side view of a multistage rocket according to an example of the presently disclosed subject matter. Fig. 2 is a side view of the example of Fig. 1, in which the fins of the booster stage are deployed. Fig. 3 is a side view of the example of Fig. 1, in which the projectile has decoupled from the booster stage. Fig. 4 is a perspective partial view of an aft section of the projectile of the example of Fig. 1. Fig. 5 is a perspective partial view of the interstage module and a forward section of the booster stage of the example of Fig. 1. Fig. 6 is a longitudinal cross-sectional side view of a portion of the example of the rocket of Fig. 1, including an aft section of the projectile, the interstage module and a forward section of the booster stage of the example of Fig. 1. taken along A-A; Fig. 6(a) shows a longitudinal cross-sectional side view of an alternative variation of the arrangement for retraining the fins of the projectile of the example of Fig. 6. Fig. 7 is a transverse cross-sectional side view of the example of Fig. 6, taken along B-B. Fig. 8 schematically illustrates a trajectory corresponding to one example of operating the example of Fig. 1. Fig. 9 schematically illustrates a trajectory corresponding to another example of operating the example of Fig. 1. Fig. 10 is a side view of an example of a steering system configured for use with the example of Fig. 1. Fig. 11 is a longitudinal cross-sectional side view of an alternative variation of the example of Fig. 6.

DETAILED DESCRIPTION Referring to Fig. 1 and Fig. 2, a multistage missile according to a first example of the presently disclosed subject matter is generally designated with reference numeral 10, and comprises a projectile 100. and a booster assembly 400, the booster assembly 45 comprising a booster stage 200 and an interstage module 300 joined thereto, the interstage module 300 being per se novel. The booster assembly 400 is interchangeably referred to herein as the first stage of the multistage missile 10. and the projectile 100 is interchangeably referred to herein as the second stage of the multistage missile 10.

In at least this example, the multistage missile 10 is configured for being steered at least for a portion of the trajectory and thus comprises a suitable steering system 500, as will become clearer herein. However, in alternative variations of this example, the multistage missile is not thus configured and omits such a steering system, and effectively operates as a multistage rocket.

As will become clearer herein, the booster stage 200 is configured for launching and accelerating the multistage missile 10 along a desired trajectory, while the projectile 100 is configured for enabling further acceleration thereof to reach a desired target, and thereby providing greater range than is possible by the projectile 100 in the absence of the booster assembly 400 or the booster stage 200.

In at least this example the projectile 100 is configured as a stand-alone vehicle, and is thus also capable of being operated - launched and optionally also steered to target - in the absence of the booster stage 200 or interstage module 300.

In at least this example the booster stage 200 is configured for enabling launching of the multistage missile 10, and for providing an initial acceleration for propelling the multistage missile 10 (and thus the projectile 100) along a desired trajectory, and comprises a suitable propulsion system 220 for so enabling. While at least in this example the propulsion system 220 comprises a solid fuel rocket motor and solid propellant accommodated within the external casing 210, in alternative variations of this example the propulsion system can instead or additionally include one or more liquid fuel rocket engines, for example.

-II- The booster stage 200 further comprises a plurality of fins 203 for stabilizing the missile 10, for example during the boost phase of the flight corresponding to the aforesaid initial acceleration, typically until the projectile 100 is separated from the booster stage 200.

In at least this example, the fins 203 are configured as wrap-around fins, being deployable from a respective stowed configuration (Fig. I) to a respective deployed configuration (Fig. 2). In the stowed configuration the fins 203 are wrapped around the periphery of the aft section 211 of the booster stage 200, providing a compact geometry, which can be useful for storage and/or for launching the missile 10 from a launch tube of internal diameter slightly greater than the maximum outer diameter DO of the missile 10. In the deployed configuration (as illustrated in Fig. 2) the fins 203 are projecting outwardly, generally radially with respect to the longitudinal axis AB of the booster stage 200. In alternative variations of this example, different stabilizing systems that also provide a compact geometry in the stowed configuration can be used - for example, planar fins that unfold longitudinally, for example similar to conventional S13 rocket launched from a flying platform.

In yet other alternative variations of this example, different stabilizing systems can be used, for example fixed fins.

The interstage module 300 is connected to a forward end 208 of the booster stage 200, and the interstage module 300 is configured for enabling the projectile 100 to be releasably mounted thereto, as will be disclosed in more detail herein.

In at least this example, the booster stage 200 is based on a small caliber type rocket, in particular the propulsion system thereof, (e.g. nominally 122mm diameter), which is already developed and mass-produced.

For example, the booster stage 200 can include at least a part of such a small caliber type rocket (e.g. nominally 122mm diameter), in particular on small caliber type rocket propulsion system thereof, suitably modified if necessary to allow for the incorporation of the interstage module 300, enabling the mounting of, and subsequently to the selective separation of, the projectile 100. In such examples, the unit cost of each booster stage 200 can be comparatively low, as compared with the unit cost of a booster stage that is developed specifically for use with the projectile 100. As will become clearer below, this feature of utilizing a small caliber type rocket propulsion system (e.g. nominally 122mm diameter) design for providing the booster stage 200 can contribute to minimizing the economic unit cost of each missile 10, so that in at least some examples, such a unit cost can be comparable to, i.e., at least within the same order of magnitude as, and for example not more than two times the unit costs of small caliber type rockets (e.g. nominally 122mm diameter).

Small caliber type rockets (e.g. nominally 122mm diameter) are well known in the art and can be defined as a MLRS (multiple launch rocket system) class of rockets that are mass produced as rockets that have a relative low economic unit cost.

An example of such a small caliber type rocket propulsion system (e.g., nominally 122mm diameter) on which the booster stage 200 can be based, is the 9M521 rocket, produced in Russia, or other variations of such small caliber type rockets (e.g., nominally 122mm diameter) produced in other countries, and typically launched from a BM-launch vehicle that includes a multiple rocket launcher.

Another example of such a small caliber type rocket propulsion system (e.g., nominally 122mm diameter) on which the booster stage 200 can be based, is the S-rocket, produced in Russia, and typically launched from a 5-tube pod launcher carried by aerial platforms such as Sukhoi Su-24 or helicopters such as Mil Mi-24.

In at least this example, the booster assembly 400 - i.e., the booster stage 2including the interstage module 300 affixed thereto - has an external diameter 1)2 in the range about 96mm to about 163mm, typically 122mm (with the fins 203 in the stowed positions), longitudinal length L2 of about 2.2m to 2.5m, take-off weight of about 50Kg.

In at least this example, and referring also to Fig. 3, the projectile 100 is configured for providing an additional acceleration for propelling the projectile 100 along the desired trajectory, after separation from the booster stage 200 and interstage module 300, and the projectile 100 comprises a suitable projectile propulsion system 120 for this purpose. In at least in this example the propulsion system 120 comprises a solid fuel rocket motor and solid propellant accommodated within the external casing 110.

In at least this example, and referring also to Fig. 4, the projectile propulsion system 120 also comprises an igniter 125 for selectively initiating operation of the projectile propulsion system 120. As will become clearer herein, the interstage module 300 is configured for initiating operation of igniter 125 and thus of the projectile propulsion system 120.

The projectile 100 further comprises a plurality of fins 103 for stabilizing the projectile 100, for example during the additional boost phase (corresponding to the aforesaid additional acceleration) and/or coast phase (corresponding to after termination of the aforesaid additional acceleration, typically ballistic) of the flight, and until the projectile 100 reaches the target. In this example, the fins 103 are configured as wrap- around fins, being deployable from a respective stowed configuration to a respective deployed configuration. In the stowed configuration the fins are wrapped around the periphery of the aft section 111 of the projectile 100, providing a compact geometry, which can be useful for storage and/or for launching the missile 10 from a launch tube of internal diameter slightly greater than the maximum outer diameter DO of the missile 10. In the deployed configuration (as illustrated in Fig. 3 for example) the fins 103 are projecting outwardly, generally radially with respect to the longitudinal axis AA of the projectile 100. In alternative variations of this example, different stabilizing systems can be used, for example fixed fins.

In at least this example, the forward end 108 of the projectile 100 comprises a suitable warhead 140.

As will become clearer herein, the aft end 118 of the projectile 100 is configured for enabling the projectile 100 to be releasably mounted to the interstage module 300.

In at least this example, the projectile 100 is also based on a small caliber type rocket propulsion system (e.g., nominally 122mm diameter), which as mentioned above is already developed and mass-produced. For example, the projectile 100 can comprise such a small caliber type rocket propulsion system (e.g., nominally 122mm diameter), in at least this example suitably modified to enable coupling to the interstage module 300, and for selective separation of the projectile 100 from the booster stage 200 via the interstage module 300. As mentioned above, small caliber type rockets (e.g., nominally 122mm diameter) are well known in the art and can be defined as a MFRS (multiple launch rocket system) class of rockets that are mass produced as rockets that have a relatively low economic unit cost.

Some variants of such small caliber type rockets (e.g., nominally 122mm diameter) have a ground-to-ground range of about 12km, while others have a 20km range. Other variants of such small caliber type rockets (e.g., nominally 122mm diameter) have range of about 40km.

An example of such a small caliber type rocket propulsion system (e.g., nominally 122mm diameter) on which the projectile 100can be based, is the 9M521 rocket, produced in Russia, or other variations of such small caliber type rockets (e.g., nominally 122mm diameter) produced in other countries, and which is typically launched from a BM-21 launch vehicle that includes a multiple rocket launcher.

Another example of such a small caliber type rocket propulsion system (e.g., nominally 122mm diameter) on which the projectile 100can be based, is the S-13 rocket, produced in Russia, and typically launched from a 5-tube pod launcher carried by aerial platforms such as Sukhoi Su-24 or helicopters such as Mil Mi-24.

In at least this example, the projectile 100has an external diameter 1)1in the range about 96mm to about 163mm, for example nominally 122mm, longitudinal length LI of 2.6m to 3.2m, take-off weight of about 70Kg to about 75Kg, including a payload (warhead) weight of about 19Kg. By "nominally 122mm" is meant that the projectile has a caliber of 122mm. and the actual diameter can be within ±1 mm of 122mm in practice.

In at least this example, and as disclosed above, the multistage missile 10is configured for being steered at least for a portion of the trajectory and thus comprises steering system 500.

In at least this example, and referring to Fig. 10, the steering system 500comprises a so-called add-on Course Correction Kit (also generically known as a "C2K" unit).

Such C2K add-on units are conventionally configured for converting a standard artillery rocket to a precise guided rocket, and the C2K unit is configured for correcting the otherwise ballistic trajectory of the original rocket.

Examples of C2K units are well known in the art, and can be added to any suitable 122mm diameter rocket, replacing the original fuse using the same mechanical interface.

Typically, such C2K units operate based on GPS data and 2D correction of the ballistic trajectory of the converted rocket, minimizing the dispersion of the rocket in the range and deflection.

In at least this example, the steering system 500. in the form of a C2K unit, comprises a bearing section 510, a steering section 520, an avionic section 530, and an aerodynamic skirt 550.

The bearing section 510 is configured provide the steering system 500 with the capability to control the inertial roll rate of the steering system 500 relative to roll of the projectile 100 and de-couple aerodynamic roll plane interactions. The bearing section 5is located at the aft of the steering section 520 and the avionic section 530. and has a direct interface with the projectile 100. In addition, bearing section 510 incorporates a Safe & Arm unit and the detonators for the warhead.

The steering section 520 comprises a set of (typically 4) fins 513, and servo actuators to control the aerodynamic fins 523. The four-fin configuration ensures a full two-dimensional divert capability (range and deflection). A GPS antenna is mounted along the outer surface of the steering section 520. The fins 523 are configured for deploying from a stowed position to a deployed position.

The avionics section 530 integrates all required airborne electronic components including an INS+GPS unit. In addition, the avionics section 530 includes a power supply for the steering system 500. The power supply is typically based on military grade lithium batteries, chosen to provide a wide operating temperature range.

The aerodynamic skirt 550 is attached to the bearing section 510 at the aft end of the steering system 500. The aerodynamic skirt 550 is configured for preserving the aerodynamic contour of the projectile 100, reducing aerodynamic drag and ensuring minimal loss of range.

It is to be noted that the interstage module 300 is configured for being in joined relationship with the booster stage 200 at least during launch operation, i.e., at least from launch of the missile 10 and until the projectile 100 separates from the booster stage assembly 400.

Referring also to Fig. 5, the interstage module 300 is configured for being integrally affixed to the booster stage 200 to provide the booster assembly 400. In other words, the interstage module 300 can be manufactured integrally with the manufacture of the booster stage 200. However, in alternative variations of this example, the interstage module 300 can be manufactured as a separate unit, and then affixed to the booster stage 200, to provide the booster assembly 400. In at least this example the interstage module 300 can be affixed to the booster stage 200 by configuring an aft part of the interstage module 300 with a threaded interface, for enabling the interstage module 300 to be threaded to a complementarily threaded forward portion of the booster stage 200. At least some small caliber type rockets (e.g. nominally 122mm diameter) are conventionally configured with a rocket motor section that is affixed to the warhead section via a threaded forward section of the rocket motor section, and such an arrangement can be used for affixing interstage module 300 to the threaded forward portion of the booster stage 200. in particular in examples where the booster stage 200 is based on the rocket motor stage of a small caliber type rocket (e.g. nominally 122mm diameter).

In any case, and according to an aspect of the presently disclosed subject matter, the interstage module 300 is configured for coupling together the projectile 100 and the booster stage 200, i.e. for coupling together the projectile 100 and the booster assembly 400, to thereby provide the multistage missile 10, which at least in this example is a two- stage missile. The interstage module 300 is further configured for selective decoupling the projectile 100 from the booster assembly 400. In particular, and, responsive to initiation of decoupling operation for effectively enabling decoupling of the booster stage 200 from the projectile 100. the interstage module 300 is further configured for: enabling decoupling of the interstage module 300 (together with the booster stage 200 that is affixed to the interstage module 300. i.e., for enabling decoupling of the booster assembly 400) from the projectile 100 under first predetermined conditions; andautonomously initiating operation of the projectile propulsion system 120 under second predetermined conditions.

It is to be noted that by "autonomously initiating operation of the projectile propulsion system 120" is meant that the interstage module 300 initiates operation of the projectile propulsion system 120 independently of any other controller that may be comprised in the multistage missile 10, for example that may be comprised in the projectile 100 itself. In practice the interstage module 300 can be set up before launch with the desired parameters regarding the first predetermined conditions and the said second predetermined conditions, for example from an external source, for example via a wire connection or via wireless connection from the external source, but immediately after launch the interstage module 300 operates autonomously and independently of any other said controller that may be carried by the missile 10.

It is also to be noted that this autonomous feature allows for relatively simple retrofitting of a suitable conventional projectile with a booster assembly without the need to replace or significantly modify the control unit of the conventional projectile.

As will become clearer herein, in at least some examples the step of initiating operation of the projectile propulsion system 120 under second predetermined conditions can be concurrent with or just after (i.e., no more than about 2 seconds after) the step of decoupling of the interstage module 300 from the projectile 100 under said first predetermined conditions.

However, and also as will become clearer herein, in at least some other examples the step of initiating operation of the projectile propulsion system 120 under second predetermined conditions can occur at a significant time after (i.e., more than about seconds after) the step of decoupling of the interstage module 300 from the projectile 1under said first predetermined conditions.

Referring also to Fig. 6, in at least this example the interstage module 3comprises an electrical power supply 320 and electrical wiring 315 coupling the electrical power supply 320 to the igniter 125 of projectile 100. For example, such an electrical power supply 320 can include a suitable battery.

The interstage module 300 comprises an interstage housing 310 accommodating a controller 350, operatively coupled to the power supply 320 and ignitor 125 via wiring 315. The interstage module 300. in particular the controller 350. is configured for providing an ignition pulse or signal to the ignitor 125 from the electrical power supply 320. responsive to said second predetermined conditions, to thereby initiate operation of the projectile propulsion system 120.

In examples in which the step of initiating operation of the projectile propulsion system 120 under second predetermined conditions is concurrent with or is just after (i.e., no more than about 2 seconds after) the step of decoupling of the interstage module 3from the projectile 100 under said first predetermined conditions, the wiring 315 to the ignitor 125 can incorporate some slack to enable the electrical connection between the ignitor 125 and the power supply to be maintained even though the interstage module 3has been decoupled and may have begun to distance itself from the projectile 100.

In any case, the interstage module 300 (and thus with the booster stage 200 - the booster assembly 400) is mounted to the projectile 100 via a coupling arrangement 360. The coupling arrangement 360 includes a mechanical coupler 365 and a forward pyrotechnic fastener arrangement 380. The coupling arrangement 360 is configured for separating the interstage module 300 (and thus effectively also the second stage 200) from the projectile 100 responsive to the forward pyrotechnic fastener arrangement 380 being activated.

Referring in particular to Fig. 5 and Fig. 6, the mechanical coupler 365 includes a fairing 370 projecting forward from interstage housing 310. The fairing 370 comprises a forward fairing end 370A having a forward fairing edge 370E. The forward fairing end 370A is configured for enabling mechanical coupling of the interstage module 300 to an aft end 118 of the projectile 100, as will become clearer herein.

The fairing 370 comprises a plurality of longitudinally projecting fairing petals 372, in this example three fairing petals 372. Each fairing petal 372 is essentially fixedly attached at a respective aft fairing end thereof to the interstage housing 310. The fairing petals 372 are in peripheral arrangement with respect to interstage housing 310.

The fairing petals 372 of each adjacent pair of fairing petals 372 are separated from one another via a respective slit 373, and thus in this example there are three slits 373. Each slit 373 extends aft from the forward fairing edge 370E. aft of the forward pyrotechnic fastener arrangement 380. and up to the interstage housing 310.

The mechanical coupler 365 includes a stiffening rib 366. comprising three rib portions 366A, each rib portion being affixed to an inside of a respective petal 372. Thus, each adjacent pair of rib portions 366A are separated from one another via a respective slit 373. In at least this example the stiffening rib 366. in particular the three rib portions 366A,have an L-shaped cross-section, providing, together with the inside of the petals 372A,a U-shaped ring facing aft.

In at least this example, the forward pyrotechnic fastener arrangement 380 comprises a peripheral pyrotechnic device 382configured for providing mechanical contiguity between adjacent said petals at said slits 373.

The peripheral pyrotechnic device 382is at least partially accommodated in the U-shaped ring formed between the stiffening rib 366and the fairing 372.

Thus, the forward pyrotechnic fastener arrangement 380spans an internal periphery of the fairing 370including the inside of each petal 372extending circumferentially from one side 372Aof the petal facing a slit 373,to the other side 372A of the petal facing the other slit 373.Optionally, the forward pyrotechnic fastener arrangement 380spans also spans the width of each said slit 373.The forward pyrotechnic fastener arrangement 380is thus located longitudinally between a forward end 372Aof each petal, and an aft end 372B of each petal 372.

The forward pyrotechnic fastener arrangement 380further comprises a detonator 385operatively connected to the controller 350via actuation line 316.

The forward pyrotechnic fastener arrangement 380is configured for separating the aft petal ends 372Bincluding said interstage housing 310from the forward petal ends 372Aresponsive to actuation of the forward pyrotechnic fastener arrangement 380.

The inside surface of the fairing 372.in particular the inside surface of the forward petal ends 372A,is configured for enabling coupling of the interstage module 300,and thus the booster stage 200,to the projectile 100.In at least this example, the inside surface of the fairing 372,in particular the inside surface of the forward petal ends 372A,are threaded 372T.

Furthermore, the aft end 118of the projectile 100is configured for enabling coupling of the interstage module 300.and thus the booster stage 200.to the projectile 100,and in at least this example the aft projectile end 1 18includes coupling portion 119, configured for mechanical coupling with fairing 372.For this purpose the coupling portion 119is externally threaded 119Tcomplementarily with respect to the internally threaded inside surfaces of the forward petal ends 372A.

Thus, the projectile 100 is coupled to the booster stage 200 via the interstage module 300, by essentially screwing the aft projectile end 118 in the fairing 372 via threads 119T and 372T.

To decouple the projectile 100 from via the interstage module 300, and thus from the booster stage 200, the forward pyrotechnic fastener arrangement 380 is activated by the controller 350 via line 316 and detonator 385, thereby separating the forward petal ends 372A from the aft petal ends 372B including said interstage housing 310 and thus the booster stage 200. At that point, since the forward petal ends 372A are separated by the respective slits 373, there is nothing holding them together and fall off the aft end 1of the projectile 100, as illustrated in Fig. 3.

For example, the aforesaid first predetermined condition can include a first time period after the booster stage 200 terminates acceleration. For example, in some examples such a first time period can be nominally zero seconds, while in other examples such a first time period can be a few seconds, for example up to 25 seconds. Alternatively, for example, the first predetermined conditions can include a first time period after launch of the multistage missile.

For example, the aforesaid second predetermined condition can include a second time period after the interstage module 300 is decoupled from the projectile 100. For example, in some examples such a second time period can be between zero and about second, while in other examples such a first time period can be more than one second, for example a few seconds, for example up to 25 seconds. Alternatively, for example, the second predetermined conditions can include a second time period after launch of the multistage missile. Alternatively, for example, the second predetermined conditions can include a second time period after the first conditions are met.

According to an aspect of the presently disclosed subject matter, and in at least this example, the interstage module 300 is further configured alternately for:preventing deployment of the projectile aft fins 103 while the interstage module 300 is coupled to the projectile 100; andenabling deployment of the projectile aft fins 103 once the interstage module 300 is decoupled from the projectile 100.

In at least this example, the fairing 372 mechanically maintains the fins 103 in the stowed configuration until the interstage module 300 (and thus the booster stage 200) is decoupled from the projectile 100.

Referring in particular to Fig. 4 and Fig. 7, the fins 103 are rotatable mounted to aft section 111 of the projectile 100. just forward of aft end 118, via hinge elements 107, and spring loaded to bias the fins 103 to the deployed position in the absence of a suitable restraining force.

The fins 103 are further configured with mechanical stops 109, which in this example are in the form of tabs that project aft from the trailing edges 101 of the fins 103. The stops 109 are shaped to be also projecting radially inwards with respect to the fins 103 in the stowed configuration.

In at least this example, the aft end 118 is configured with a plurality of circumferentially spaced recesses 119, each recess corresponding to one said stop 109. Each recess 119 has a shape and size such as to allow a corresponding stop 109 to be accommodated therein, and to be mechanically locked in place when the aft end 118 is screwed into the fairing 372, i.e., when the projectile 100 is coupled to the interstage module 300 and thus to the booster stage 200, as best seen in Fig. 6.

In alternative variations of this example, and as illustrated in Fig. 6(a), the trailing edge of each fin 103 can instead comprises a mechanical stop 103S also in the form of a tab that projects in an aft direction but concurrently does not project radially inward with respect to the fin 103 in the stowed configuration. In such an example, the internally threaded portion 372T on the inside of fairing 720 does not extend forward to the edge 370E. Rather, a forewardmost portion 372X of the fairing 720. extending aft from the edge 720E is recessed radially with respect to the internally threaded portion 372T to provide a radial gap sufficient to accommodate the mechanical stop 103 therein in the stowed configuration, and to be mechanically locked in place when the aft end 118 is screwed into the fairing 372. i.e., when the projectile 100 is coupled to the interstage module 300 and thus to the booster stage 200.

Once the forward pyrotechnic fastener arrangement 380 is operated to separate the forward petal ends 372A from the aft petal ends 372B including said interstage housing 310. the forward petal ends 372A are no longer mechanically held with respect to one another and fall off the aft end 118, terminating the restraining force on the fins 103. The unrestrained fins 103 are thus able to spring open to the deployed position.

It is to be noted that in alternative variations of this example, the interstage module 300 is not configured for preventing deployment of the projectile aft fins 103 while the interstage module 300 is coupled to the projectile 100. Thus, as soon as the missile leaves the launch tube the projectile aft fins 103 are automatically deployed in a similar manner to the fins 203 of the booster stage 200. In such as case, the fins 103 can be deployed as soon as the forward part of the missile including the projectile 100 clears the launch tube, while the aft fins 203 are deployed a little later when the whole of the missile has cleared the launch tube. In such an example, the fins 103 can be close to the center of gravity of the missile 10, and thus are not as effective in providing stability as the fins 203, and moreover add drag to the missile during the initial acceleration stage. However, in such an example, the slits 373 can be omitted, as well as the stops 109 and recesses 119.

Referring to Fig. 11, in alternative variations of the above examples in which the step of initiating operation of the projectile propulsion system 120 under second predetermined conditions is significantly after (i.e., more than about 2 seconds after) the step of decoupling of the interstage module 300 from the projectile 100 under said first predetermined conditions, the interstage module 300 comprises, instead of controller 3and power supply 320, controller 350A and power supply 320A. In this example, the controller 350A and power supply 320A are initially affixed to the projectile 100 so that after decoupling of the interstage module 300 from the projectile 100 the controller 350A and power supply 320A remain with the projectile 100 rather than with the interstage module 300 itself. In this example the controller 350A is operatively connected to detonator 385 via line 316A, and line 316A is configured for breaking on detonation of the forward pyrotechnic fastener arrangement 380. The controller 350A is also operatively connected to ignitor 125 via line 315A, and the controller 350A is also configured for providing an ignition pulse or signal (at any desired time after the interstage module 300 has decoupled from the projectile 100) to the ignitor 125 from the electrical power supply 320A, to thereby initiate operation of the projectile propulsion system 120. Furthermore, in such examples, responsive to autonomously carrying out the step of initiating decoupling of the interstage module 300 from the projectile 100 under said first predetermined conditions the controller 350A autonomously sends a suitable activating signal to activate the ignitor 125 at the appropriate said second conditions, for example after a certain period of time has elapsed. Once the projectile propulsion system 120 is ignited, the controller 350A and power supply 320A are ejected from the projectile 100 via the exhaust plume of the projectile propulsion system 120. for example. Optionally, a membrane can be provided at the aft end of the projectile propulsion system 120.

In at least a first example according to the presently disclosed subject matter, the multistage missile 10 can be operated as follows.

In the first example, the multistage missile 10 is configured for example for a surface to surface mission, and is surfaced launched, for example from a suitable launch tube, on the ground, on a ground vehicle, or on a sea surface vessel, for example. Such a launch tube can be similar to launch tubes used for launching conventional small caliber type rockets (e.g. nominally 122mm diameter), though longer in axial length to take account of the longer longitudinal length L0 of the missile 10 as compared with conventional small caliber type rockets (e.g. nominally 122mm diameter).

Launch of the missile 10 can be initiated in a similar manner to a conventional small caliber type rocket (e.g., nominally 122mm diameter). For example, an electrical pulse is applied to the propulsion system 220 of the booster stage 200.

The booster stage 200 provides a first acceleration phase, enabling the missile to accelerate to a suitable first cut-off velocity at which point acceleration is terminated. Such a first cut-off velocity can be in the range 500m/s to about 1500m/s. Concurrent with the missile 10 exiting the launch tube, the fins 203 of the booster stage 2automatically deploy.

Referring to Fig. 8, during the first acceleration stage the missile 10 also reaches a first altitude Hl and a first range RI.

At the aforesaid corresponding first predetermined condition, the interstage module 300 (together with the booster stage 200 that is affixed to the interstage module 300, i.e., the booster assembly 400) is decoupled from the projectile 100, and at the aforesaid corresponding second predetermined condition operation of the projectile propulsion system 120 is initiated.

For example, the first predetermined conditions can include a delay of less than seconds after the first cut-off of the booster stage propulsion system at which time the controller activates the forward pyrotechnic fastener arrangement 380,thereby decoupling the interstage module 300together with the booster stage 200from the projectile 100.The forward petal ends 372Afall off the aft end 118,terminating the restraining force on the fins 103,which are thus able to spring open to the respective deployed position.

For example, the second predetermined conditions can include a time delay of seconds after decoupling of the interstage module 300 from the projectile 100 is initiated, after which operation of the projectile propulsion system 120 is initiated.

Once the projectile propulsion system 120is activated, the projectile 100enters a second acceleration phase, enabling the projectile 100to accelerate to a suitable second cut-off velocity at which point acceleration is terminated. Such a second cut-off velocity can be in the range 1500m/s to about 1800m/s. Referring again to Fig. 8, during the second acceleration stage the projectile 100 also reaches a second altitude H2 and a second range R2.

Thereafter the projectile 100 continues along a coasting phase, reaching a ground target at third range R3.

For example, the first altitude Hlcan be about 2km, the second altitude H2can be about 5km, the third range R3 can be about 80km.

In at least a second example according to the presently disclosed subject matter, the multistage missile 10can be operated as follows.

In the second example, the multistage missile 10 is configured for example for an air to surface mission, and is air launched, for example from a carrier aircraft at an altitude HO,via a suitable launch tube, for example a 5-tube pod launcher. Such a launch tube can be similar to launch tubes used for launching conventional small caliber type rockets (e.g., nominally 122mm diameter) in aircraft, though longer in axial length to take account of the longer longitudinal length of the missile 10 as compared with conventional small caliber type rockets (e.g., nominally 122mm diameter).

Launch of the missile 10can be initiated in a similar manner to a conventional small caliber type rocket (e.g., nominally 122mm diameter) from an aircraft. For example, an electrical pulse is applied to the propulsion system of the booster stage 200.

The booster stage 200provides a first acceleration phase, enabling the missile 10 to accelerate to a suitable first cut-off velocity at which point acceleration is terminated. Such a first cut-off velocity can be in the range 700 m/s to about 800 m/s, assuming that the carrier aircraft is travelling at velocity of about 250 m/s.

Concurrent with the missile 10exiting the launch tube, the fins 203of the booster stage 200automatically deploy.

Referring to Fig. 9, during the first acceleration stage the missile 10 also reaches a first altitude Hl*,typically about the same initial altitude HOas from where the missile was launched or higher than initial altitude HO,and reaches a first range RI'.

At the aforesaid corresponding first predetermined condition, decoupling of the interstage module 300(together with the booster stage 200that is affixed to the interstage module 300,i.e., the booster assembly 400)from the projectile 100is initiated, and at the aforesaid corresponding second predetermined condition operation of the projectile propulsion system 120is initiated.

For example, the first predetermined conditions can include a delay of 0 seconds after the first cut-off velocity is attained or after the booster stage propulsion system 220 cuts out, at which time the controller activates the forward pyrotechnic fastener arrangement 380,thereby decoupling the interstage module 300together with the booster stage 200from the projectile 100.The forward petal ends 372Afall off the aft end 118, terminating the restraining force on the fins 103, which are thus able to spring open to the respective deployed position. In other words, decoupling of the interstage module 300 (together with the booster stage 200that is affixed to the interstage module 300,i.e. the booster assembly 400)from the projectile 100is initiated concurrent with termination of the first acceleration.

For example, the second predetermined conditions can include a time delay of more than 2 seconds after the decoupling operation is initiated.

Once the projectile propulsion system 120is activated, the projectile 100enters a second acceleration phase, enabling the projectile 100to accelerate to a suitable second cut-off velocity at which point acceleration is terminated. Such a second cut-off velocity can be in the range 1600 m/s to about 1800 m/s. Referring again to Fig. 9, during the second acceleration stage the projectile 100also reaches a second altitude H2‘, and reaches a second range R2'.

Thereafter the projectile 100continues along a coasting phase, reaching a ground target at third range R3‘.

For example, the first altitude Hl'can be about 7km, the second altitude H2'can be about 9km, and the third range R3* can be about 200km.

In at least this example, the projectile 100 has a maximum external diameter DI, corresponding to the fins 103 being in the respective stowed configuration. Furthermore, in at least this example, the booster stage 200 has a maximum external diameter D2, corresponding to the fins 203 being in the respective stowed configuration.

According to an aspect of the presently disclosed subject matter, and referring in particular to Fig. 1 and Fig. 3, maximum external diameter DIof the projectile 100is equal to or less than the maximum external diameter 1)2of the booster stage 200,and furthermore maximum external diameter D2 defines the maximum diameter DO of the missile 10.

The maximum diameter DOis also referred to herein as a pre-launch diameter, and corresponds to said fins 203and 103each being in the respective stowed configuration.

In at least this example, the projectile 100has a longitudinal length LI,and the booster stage 200including the interstage module 300has a longitudinal length L2.As best seen in Fig. 6, there is a longitudinal overlap between the projectile 100and the interstage module 300in the missile 10,and thus the longitudinal length L0of the missile 10is slightly less than the sum of longitudinal length LIand longitudinal length L2. - ר 1 - In at least this example, the maximum diameter DO is in the range about 96mm to about 163mm, typically 122mm.

In at least this example, the longitudinal length LO is in the range about 4.4m to about 5.7m. or in the range 4.8m to 5.7m.

According to an aspect of the presently disclosed subject matter, the ratio ROoflongitudinal length LO to maximum diameter DO of the missile 10 is not less than about 35. For example, the ratio RO can be in the range between about 35 and about 50, for example about 45. In at least one example, the ratio RO can be in the range between about and about 50, for example about 45, for a maximum diameter DOof the missile 10less 10than 150mm, for example less than 125mm, for example about 122mm.

In the method claims that follow, alphanumeric characters and Roman numerals used to designate claim steps are provided for convenience only and do not imply any particular order of performing the steps.

Finally, it should be noted that the word "comprising" as used throughout the 15appended claims is to be interpreted to mean "including but not limited to".

While there has been shown and disclosed examples in accordance with the presently disclosed subject matter, it will be appreciated that many changes may be made therein without departing from the scope of the presently disclosed subject matter as set out in the claims.

Claims (49)

-28 - CLAIMS:

1. An interstage module configured for coupling between a projectile and a booster stage of a multistage missile, the projectile comprising a projectile propulsion system, the interstage module configured for, responsive to initiation of decoupling of the booster stage from the projectile:enabling decoupling of the interstage module from the projectile under first predetermined conditions; andautonomously initiating operation of the projectile propulsion system under second predetermined conditions;and wherein the interstage module is configured for being in joined relationship with the booster stage at least during launch operation.

2. The interstage module according to claim 1, wherein said first predetermined conditions include a first time period after the booster stage terminates acceleration.

3. The interstage module according to claim 2, wherein said first time period is greater than 2 seconds.

4. The interstage module according to claim 2, wherein said first time period is between zero seconds and 2 seconds.

5. The interstage module according to claim 1. wherein said second predetermined conditions include a second time period after the booster stage terminates acceleration.

6. The interstage module according to any one of claims 1 to 5, wherein said second predetermined conditions include a second time period after initiation of decoupling of the interstage module from the projectile.

7. The interstage module according to any one of claims 1 to 5, wherein said second predetermined conditions include a second time period after launch of the multistage missile. ־ 29 -

8. The interstage module according to any one of claims 1 to 7, the interstage module configured for being integrally formed with the booster stage.

9. The interstage module according to any one of claims 1 to 7, the interstage module configured for being manufactured separately from the booster stage, and further configured for being affixed to the booster stage.

10. The interstage module according to claim 9, wherein an aft projectile end of said the interstage module includes an aft threaded coupling portion, configured for mechanical coupling with a complementarily threaded portion comprised in a forward end of the booster stage.

11. The interstage module according to claim 10, wherein said complementarily threaded portion corresponds to a threaded portion provided in a forward end of a small caliber type rocket propulsion system originally configured for coupling to a warhead of the corresponding small caliber type rocket.

12. The interstage module according to any one of claims 1 to 11, wherein the interstage module is mounted to the projectile via a coupling arrangement including a mechanical coupler and a forward pyrotechnic fastener arrangement, and wherein the coupling arrangement is configured for enabling separating the interstage module from the projectile responsive to operating the forward pyrotechnic fastener arrangement.

13. The interstage module according to claim 12, wherein the interstage module comprises an interstage housing, and wherein the coupling arrangement includes fairing projecting forward from the interstage housing, the fairing comprising a forward fairing end configured for enabling mechanical coupling the interstage module to an aft end of the projectile, the fairing comprising a plurality of fairing petals each being affixed at an aft fairing end thereof to the interstage housing, wherein each adjacent pair of said fairing petals are separated from one another via a slit, each said slit extending aft from a forward fairing edge and aft of the forward pyrotechnic fastener arrangement. -30-

14. The interstage module according to claim 13, wherein the forward pyrotechnic fastener arrangement comprises a peripheral pyrotechnic device configured for providing mechanical contiguity between adjacent said petals at said slits, and a detonator for activating the peripheral pyrotechnic device.

15. The interstage module according to any one of claims 13 to 14, wherein said fairing petals are in peripheral arrangement with respect to interstage housing, and wherein said forward pyrotechnic fastener arrangement spans an internal periphery of each fairing petal and is configured for separating said aft fairing end including said interstage housing from said forward fairing end responsive to actuation of said forward pyrotechnic fastener arrangement.

16. The interstage module according to any one of claims 12 to 15, wherein said forward fairing end comprises an internally threaded portion configured for mechanical coupling with a complementarily externally threaded coupling portion provided on a projectile aft end of the projectile.

17. The interstage module according to any one of claims 1 to 16, wherein the projectile propulsion system comprises an igniter for selectively initiating operation of the projectile propulsion system, and wherein the interstage module comprises a controller operatively connected to an electrical power supply and to the igniter via a lead.

18. The interstage module according to claim 17, wherein the controller and the electrical power supply are housed in the interstage module.

19. The interstage module according to claim 18, wherein said lead has slack to enable the controller to activate the ignitor via the lead after initiation of decoupling of the interstage module from the projectile.

20. The interstage module according to claim 17, wherein the controller and the electrical power supply are configured for being housed in the projectile, and wherein the controller is further configured for operating the forward pyrotechnic fastener arrangement housed in the interstage module, and wherein the controller and the electrical -31 - power supply are configured for remaining with the projectile after the interstage module decouples from the projectile.

21. The interstage module according to claim 20, wherein the controller and the electrical power supply are configured for being removed from the projectile following operation of the projectile propulsion system under second predetermined conditions.

22. The interstage module according to any one of claims 1 to 21, wherein the projectile comprises a plurality of fins that are deployable from a stowed configuration to a deployed configuration, and wherein the interstage module is further configured for:preventing deployment of the projectile fins while the interstage module is coupled to the projectile; andenabling deployment of the projectile fins once the interstage module is decoupled from the projectile.

23. The interstage module according to claim 22, wherein said fairing mechanically maintains the projectile fins in said stowed configuration until the interstage module is decoupled from the projectile.

24. A booster stage assembly for a projectile, comprising an interstage module as defined in any one of claims 1 to 23, and a booster stage.

25. The booster stage assembly according to claim 24, wherein the interstage module is integrally formed with the booster stage.

26. The booster stage assembly according to claim 24, wherein the interstage module is manufactured separately from the booster stage, and wherein the interstage module is affixed to the booster stage.

27. The booster stage assembly according to any one of claims 24 to 26. the booster stage comprising a booster stage rocket motor and a plurality of booster stage fins, deployable from a stowed configuration to a deployed configuration -32-

28. I'he booster stage assembly according to any one of claims 24 to 27, the booster stage having a length in the range of about 2.2m to 2.5m.

29. I'he booster stage assembly according to any one of claims 24 to 28, the booster stage having an external diameter in the range 96mm to 163mm.

30. The booster stage assembly according to any one of claims 24 to 29, the booster stage having an external diameter of 122mm.

31. The booster stage assembly according to any one of claims 24 to 30, wherein said booster stage is based on an aft portion of a small caliber type rocket propulsion system.

32. A multistage missile comprising a projectile and a booster stage assembly, the booster stage assembly being as defined in any one of claims 24 to 31.

33. The multistage missile according to claim 32, wherein the projectile is based on a small caliber type rocket system.

34. The multistage missile according to any one of claims 32 to 33, wherein the projectile comprises a projectile rocket motor and a plurality of projectile fins, deployable from a stowed configuration to a deployed configuration.

35. The multistage missile according to any one of claims 32 to 34, wherein an aft projectile end of said projectile includes an externally threaded coupling portion, configured for mechanical coupling with a complementarily internally threaded portion comprised in said interstage module.

36. The multistage missile according to any one of claims 32 to 35, the projectile having a length in the range about 2.6m to about 3.2m.

37. The multistage missile according to any one of claims 32 to 36, the projectile having a pre-launch diameter in the range 96mm to 163mm. - 33 -

38. The multistage missile according to any one of claims 32 to 37, the projectile having a pre-launch diameter of 122mm.

39. The multistage missile according to any one of claims 32 to 38, the multistage missile having a length in the range 4.4m to 5.7m.

40. The multistage missile according to any one of claims 32 to 39, the multistage missile having a pre-launch diameter in the range 96mm to 163mm.

41. The multistage missile according to any one of claims 32 to 40, the multistage missile having a length to pre-launch diameter ratio in the range 35 to 50.

42. The multistage missile according to any one of claims 32 to 41, wherein the projectile comprises a steering system in the form of an add-on Course Correction Kit unit.

43. A multistage missile comprising at least a projectile and a booster stage, the multistage missile having a longitudinal length and a pre-launch diameter, and wherein a ratio of said longitudinal length to said pre-launch diameter is not less than about 35.

44. The multistage missile according to claim 43, wherein said ratio is in a range between about 35 and about 50.

45. The multistage missile according to any one of claims 43 to 44, wherein said ratio is any one of: 35, 36, 37, 38. 39, 40, 41.42. 43, 4, 45. 46, 47, 48, 49, 50.

46. The multistage missile according to any one of claims 43 to 45, wherein said pre- launch diameter is less than 150mm, optionally less than 125mm.

47. The multistage missile according to any one of claims 43 to 46, wherein said pre-launch diameter is about 122mm. -34-

48. The multistage missile according to any one of claims 43 to 47, comprising at least one set of fins, each fin being deployable from a stowed configuration to a deployed configuration, and wherein said pre-launch diameter corresponds to said fins being in the stowed configuration.

49. The multistage missile according to any one of claims 43 to 48, wherein each one of said projectile and said booster stage is based on a small caliber type rocket propulsion system. 10 50.A method for operating a multistage missile, comprising: (i) providing the multistage missile, the multistage missile being as defined in any one of claims 32 to 42; (ii) operating the booster stage to provide an initial acceleration to the multistage missile; 15 (iii) decoupling of the interstage module from the projectile under said firstpredetermined conditions; (iv) initiating operation of the projectile propulsion system under said second predetermined conditions; and (v) operating the projectile to provide an additional acceleration stage and a subsequent coast phase. For the Applicants, REINHOLD COHN AND PARTNERS By: