Patent Grant
8445823
The following disclosure relates generally to guided munitions and, more particularly, to embodiments of guided munition systems including combustive dome covers, which combust after deployment to reduce or eliminate the production of debris.
Guided missiles, rockets, and other munitions are typically equipped with a homing guidance system referred to as a “seeker.” The seeker includes one or more sensors, which detect electromagnetic radiation emitted by or reflected from a designated target. Guidance electronics included within the seeker utilize the data generated by the seeker sensors, often in conjunction with data provided by other onboard systems (e.g., a global positioning system and/or an inertial navigational system), to determine the manner in which one or more flight control surfaces (e.g., wings, canards, thrust vector control vanes, etc.) should be manipulated to provide aerodynamic guidance to the munition during flight. A nose-mounted seeker dome physically protects the seeker sensors while allowing the transmission of electromagnetic radiation to the sensors during flight of the guided munition.
Multi-munition launch units, such as multi-tube launchers and rocket pods, allow the transport and independently-controlled launch of multiple (e.g., typically seven to nineteen) munitions. When a guided munition is utilized in conjunction with a multi-munition launch unit, the seeker dome of the guided munition may be exposed to rocket exhaust generated during launch of neighboring munitions. If exposure between the seeker dome and rocket exhaust occurs, harsh chemicals, soot, and other debris may deposit over the outer surface of the seeker dome (referred to herein as “dome contamination”). Dome contamination can block, attenuate, or otherwise interfere with the transmission of electromagnetic signals through the seeker dome and thereby negatively impact the guidance functionalities of the guided munition. Other possible sources of dome contamination include airborne water droplets (e.g., rain droplets); insect matter; and, in implementations wherein the guided munition is containerized, rocket exhaust produced by the guided munition's own rocket motor.
A dome cover can be positioned over the exterior of a seeker dome to physically shield the dome from rocket exhaust and other possible sources of contamination. When utilized, such dome covers must necessarily be removed or destroyed prior to seeker operation. Various deployment systems (e.g., actuators and timing electronics) have been developed to either eject a dome cover (if fabricated from a non-frangible material) or initiate fracture of a dome cover (if fabricated from a frangible material) at a desired time of deployment. Conventionally-known dome cover deployment system are, however, limited in certain respects. As one notable limitation, conventionally-known dome cover deployment systems often produce sizable, high energy debris upon dome deployment. Such debris can increase the likelihood of foreign object damage to nearby objects, including the platform or vehicle from which the guided munition is launched. As a specific example, debris created by conventionally-known dome cover deployment systems can increase the likelihood of foreign object damage to a rotary wing aircraft equipped with a rocket pod or other multi-munition launch unit from which the guided munition is launched. The production of debris during dome cover deployment may also be undesirable in instances wherein the munition is launched over a runway, which typically must be cleared of sizable debris prior to aircraft takeoff and landing.
It is thus desirable to provide embodiments of a guided munition system including a dome cover that produces little to no sizable debris upon deployment to reduce the likelihood of foreign object damage. It would also be desirable if embodiments of the dome cover were capable of self-deploying during munition flight at a predetermined munition airspeed without the aid of timing electronics or other control devices. It would also be desirable if, in certain embodiments, the dome cover could be deployed immediately prior to munition launch to enable prelaunch target verification by the munition's seeker (commonly referred to as “lock-on before launch”). Finally, it would be desirable to provide embodiments of a method for equipping a guided munition with a combustive dome cover. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying Drawings and this Background.
Embodiments of a guided munition system are provided. In one embodiment, the guided munition system includes a guided munition, which has a munition body and a seeker dome coupled thereto, and a combustive dome cover disposed over the seeker dome. The combustive dome cover is configured to uncover the seeker dome at a predetermined time of deployment and to combust when so deployed to minimize the production of debris.
Embodiments of a combustive dome cover are also provided. In one embodiment, the combustive dome cover includes an inner combustive liner, which is configured to ignite when exposed to a predetermined ignition temperature, and an outer inert layer, which is disposed over the inner combustive liner and configured to combust in conjunction with the inner combustive liner after ignition thereof.
Embodiments of a method for equipping a guided munition with a combustive dome cover are further provided. The method includes the steps of fabricating a combustive dome cover configured to combust when exposed to a predetermined ignition temperature, coupling a heating feature to the combustive dome cover, and positioning the combustive dome cover over a seeker dome included within the guided munition.
At least one example of the present invention will hereinafter be described in conjunction with the following figures, wherein like numerals denote like elements, and:
The following Detailed Description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding Background or the following Detailed Description.
As generically illustrated in
Seeker dome 20 is transmissive to one or more bandwidths of electromagnetic radiation emitted by or reflected from a designated target and detectable by EM radiation sensors 24. Seeker dome 20 will typically be transmissive to one or more of the visible, near infrared, midwave infrared, long wave infrared, and/or millimeter-wave radio frequency bandwidths. Seeker dome 20 can be formed from any material, currently known or later developed, that allows the transmission of EM signals through dome 20 within the desired sensor bandwidth(s) and that possesses sufficient structural strength to remain intact during munition handling, launch, and flight. By way of non-limiting example, seeker dome 20 may be formed from diamond, sapphire, zinc sulfide (ZnS), yttrium oxide (Y2O3) aluminum oxynitride (AlON), Spinel (MgAl2O4), magnesium fluoride (MgF2), composite optical ceramics, or similar materials. Although by no means limited to a particular geometry, seeker dome 20 will typically be either hemispherical or ogival in shape.
EM radiation sensors 24 are configured to receive electromagnetic radiation through seeker dome 20 and emitted from or reflected from a designated target to support passive guidance, semi-active guidance, or active guidance functionalities of guided munition 12. EM radiation sensors 24 may comprise any number of electromagnetic radiation detection devices suitable for performing this purpose by detecting radiation within any given frequency band of the electromagnetic spectrum; e.g., within ultraviolet, visible, near-infrared, mid-infrared, far-infrared, microwave, and/or radio wave frequencies. As a non-exhaustive list of examples, EM radiation sensors 24 may include one or more visible spectrum, semi-active laser, infrared, and/or millimeter wave detection devices. For example, in implementations wherein guided munition 12 assumes the form of a laser guided rocket, EM radiation sensors 24 may include at least one semi-active laser sensor. In embodiments wherein seeker 18 assumes the form of a dual- or tri-mode seeker, EM radiation sensors 24 may also include a millimeter wave radar sensor and/or an uncooled imaging infrared sensor.
Combustive dome cover 14 may be fabricated as a unitary piece or monolithic body. Alternatively, combustive dome cover 14 may be assembled from two or more individual cover pieces. In embodiments wherein combustive dome cover 14 is comprised of multiple pieces, it is preferred that the dome cover pieces are detachably joined so as to promote the subsequent separation or decoupling of the dome cover pieces at a desired time of deployment, typically either during an early phase of munition flight or immediately prior to munition launch. With respect to the exemplary embodiment illustrated in
As noted above, cover pieces 24 and 26 are preferably joined together so as to enable the separation of tubular shroud 24, 26 during flight of guided munition 12 or immediately prior to the launch thereof. In one implementation, cover pieces 24 and 26 are joined together by one or more retainer bands 40, which extend at least partially around an outer circumferential surface of tubular shroud 24, 26 to maintain cover pieces 24 and 26 in an assembled stated. If desired, and as shown most clearly in
The radial separation force initiating the release of retainer bands 40 can be generated by a mechanical or pyrotechnic means, such as by one or more separation charges disposed between the cover pieces. However, in a preferred embodiment, the radial separation force initiating release of retainer bands 40 is derived from aerodynamic forces acting on combustive dome cover 14 during munition flight. For example, as shown in
As addressed in the foregoing section entitled “Background,” it is desirable to minimize or eliminate the production of sizable, high-energy debris upon dome cover deployment to decrease the likelihood of foreign object damage to nearby objects, as well to the vehicle or platform from which the guided munition is launched. In this regard, combustive dome cover 14, and specifically cover pieces 24 and 26, are configured to combust during or immediately after dome cover deployment to minimize or eliminate the production of dome cover debris. In preferred embodiments, combustive cover 14 undergoes a deflagration process (i.e., a rapid, subsonic combustion) upon ignition. It should be noted that deflagration is properly distinguished from detonation, which is characterized by supersonic combustion propagating through shock wave compression. Combustion of dome cover 14 reduces cover 14 to gaseous and particulate reaction byproducts, such as ash. Such reaction byproducts pose little to no risk of foreign object damage to nearby objects (e.g., the engine or rotor of a rotary wing aircraft) and are consequently referred to herein as “low-FOD reaction byproducts.” Although it is generally preferred that dome cover 14 disintegrates substantially completely as a result of combustion, especially in embodiments wherein guided munition system 10 is deployed onboard an aircraft, this is not necessary in all embodiments; in certain embodiments, such as when guided munition system 10 is deployed onboard a ground-based vehicle, combustion of dome cover 14 may result in partial disintegration or break-up of cover 14 and may yield larger debris.
The body of combustive dome cover 14 may be formed as a single layer, homogenous structure. This notwithstanding, it is generally preferred that the body of combustive dome cover 14 is formed as a multi-layer structure, which includes a readily-ignitable inner combustive liner and at least one outer thermally insulative layer. For example, as shown in detail
Inner combustive liner 56 may be formed from any material or materials that, when exposed to a predetermined ignition temperature (or otherwise has applied thereto sufficient total energy to surpass the ignition threshold), ignite and rapidly combust to initiate break-up of combustive dome cover 14 in an abbreviated time frame (e.g., on the order of a few fractions of a second). In a similar manner, outer inert layer 58 may likewise be formed from any material or materials that undergoes rapid combustion when exposed to the high temperatures generated during combustion of inner combustive liner 56. In many cases, outer inert layer 58 and inner combustive liner 56 may contain or be fabricated from similar base materials, but differ in composition. In a preferred embodiment, inner combustive liner 56 comprises a combustive fiber matrix that contains at least one highly flammable compound, such as nitrocellulose (also commonly referred to as “cellulose nitrate” or “guncotton”). Outer inert layer 58 may likewise comprise a combustive fiber matrix that is substantially free of the highly flammable compound or compounds (e.g., nitrocellulose) contained within liner 56 or that has a significantly lower concentration thereof. Stated differently, in a preferred embodiment, inner combustive liner 56 may comprise a relatively energetic nitrocellulose-containing material having a sufficient nitrogen group density to initiate and accelerate a rapid combustive process, while outer inert layer 58 may comprise a lower energy or non-energetic nitrocellulose-containing having the minimal nitrogen group density required to sustain combustion. Additional materials (e.g., resins) may be added to inner combustive liner 56 and outer inert layer 58, as appropriate, to optimize the rigidity and durability of combustive dome cover 14. The thickness and specific composition of inner combustive liner 56 and of outer inert layer 58 will vary amongst different embodiments in relation to the desired ignition temperature of inner combustive liner 56, to the desired thermal insulation provided by outer inert layer 58, and other such design parameters. Although shown in
While embodiments combustive dome cover 14 may not include an outer ablative coating, the provision of an outer ablative coating, such as outer ablative coating 60, is useful for providing additional thermal insulation of inner combustive liner 56. Any one of a number of different conventionally-known, thermally-insulative ablative materials can be utilized as outer ablative coating 60, including various silicone-based coatings. Notably, the application and reapplication of outer ablative coating 60 can easily be performed by military personnel operating in-field utilizing, for example, an ablative kit. Thus, if significant material loss of the original ablative coating should occur due to, for example, repeated exposure to rocket exhaust gas during the launch of neighboring munitions, additional ablative material can be applied over outer inert layer 58 to restore outer ablative coating 60 to a desired thickness. Suitable silicone ablative kits are commercially available from the Dow Corning Corporation headquartered in Midland, Mich.
Guided munition system 10 further conveniently includes at least one heating feature thermally coupled to combustive dome cover 14 and, specifically, to inner combustive liner 56, which generates a sufficient heat quantity at the desired time of deployment to ignite liner 56 and, thus, initiate combustion of dome cover 14. In certain embodiments, the heating feature may assume the form of an aerodynamic heating structure, which projects from the body of dome cover 14 to generate heat during munition flight and auto-ignite dome cover 14. In such embodiments, the heating feature (or features) can be integrally formed with dome cover 14, and dome cover 14 may be formed a unitary or single-piece body. An example of a combustive dome cover including such an aerodynamic heating structure is described below in conjunction with
Referring once again to
The foregoing has thus provided an exemplary embodiment wherein guided munition system 10 employed an ignition device 64 actuated by the separation of multi-piece dome cover 14. In the above-described exemplary embodiment, separation of multi-piece dome cover 14 was driven primarily by drag forces acting on dome cover 14 and, specifically, on the blunt face of leading wall 36. In further embodiments, detonation of ignition device 64 may be passively triggered utilizing a drag-actuated ignition device (e.g., a relatively small pull-actuated explosive device), and separation of dome cover 14 may be augmented by or entirely driven by combustion of inner combustive liner 56 (
In a preferred embodiment, radial bore 70 is covered or plugged to prevent the inflow of hot exhaust gases into bore 70 and to inner combustive liner 56. As illustrated in
The foregoing has thus described multiple exemplary embodiments of a guided munition system including a combustive dome cover that rapidly combusts pursuant to dome cover deployment to minimize the production of debris. In the above-described exemplary embodiments, deployment of the combustive dome cover occurred during munition flight and was passively initiated without the usage of timing electronics or other electronic control devices. Advantageously, inflight deployment of the combustive dome cover allows the dome cover to remain in place over the seeker dome, and thus shield the seeker dome from contamination, through launch and an initial stage of munition flight. This advantage notwithstanding, in certain instances, it may be desired to actively initiate the deployment and the corresponding combustion of the dome cover immediately prior to munition launch. In particular, by deploying the combustive dome cover prior to munition launch, the munition seeker can perform prelaunch target acquisition and verification (commonly referred to as “lock-on before launch”). In such embodiments, a signal-actuated ignition device (e.g., a squib) may be embedded within the combustive dome cover and triggered by an ignition signal generated by a source external to the guided munition system, such as by an aircraft carrying the guided munition (described more fully below in conjunction with
Although in the foregoing example, the ignition signal initiating the detonation of squib 80 was generated by a source external to guided munition system 10, this need not always be the case. As indicated in
As previously noted, in still further embodiments, combustive dome cover may include one or more aerodynamic heating structures, which provide localized heating the combustive dome cover during munition flight to bring about auto-ignition of the combustive dome cover at a desired airspeed. Further emphasizing this point,
The foregoing has thus provided multiple exemplary embodiments of a guided munition system including a combustive dome cover is configured to uncover a seeker dome at a predetermined time of deployment and to combust to minimize the production of debris when so deployed to reduce the likelihood of foreign object damage. In some of the above-described exemplary embodiments, the combustive dome cover self-deploys during munition flight (e.g., in response to drag forces acting on a drag-generating member or initiating separation of a multi-piece cover) at a predetermined airspeed without the aid of timing electronics or other control devices. Furthermore, in at least some of the above-described exemplary embodiment, the combustive dome cover is able to be deployed immediately prior to munition launch (e.g., via transmission of an ignition signal to a signal-actuated squib) to enable prelaunch target verification by the munition's seeker (referred to as “lock-on before launch”). In a more general sense, the foregoing has also provided a method for equipping a guided munition with a combustive dome cover. In one embodiment, the method includes the steps of fabricating a combustive dome cover configured to combust when exposed to a predetermined ignition temperature, coupling a heating feature to the combustive dome cover, and positioning the combustive dome cover over a seeker dome included within the guided munition.
While the foregoing has specifically described embodiments of a guided munition system including an ignition device that generates heat to ignite the inner combustive liner of a combustive dome cover, it will be appreciated that the ignition device may assume any form suitable for igniting the combustive dome cover by applying sufficient total reaction energy thereto, whether or not the ignition device generates heat directly, and including various types of chemical and electrical ignition devices. For example, in certain embodiments, the ignition device may expose the inner combustive liner to a chemical agent (e.g., an accelerant or acid) at a desired juncture by, for example, rupture of a vile containing the chemical agent to ignite the combustive dome cover; e.g., such a vile could be ruptured by the separation of a multi-part dome cover, such as dome cover 14 described above in conjunction with
While at least one exemplary embodiment has been presented in the foregoing Detailed Description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing Detailed Description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set-forth in the appended Claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20120104149 A1 | May 2012 | US |
