TECHNICAL FIELD
The present invention relates to controlling the flight path of rockets, missiles, and other flying projectiles. In particular, the invention relates to a small fast diverter for use with a projectile for steering the projectile in flight by ejecting a mass in response to a signal from a trajectory control system.
BACKGROUND
Missiles and projectiles historically have been guided by canting exhaust nozzles, moving fins or firing thrusters. Depending on the size and speed of the missile or projectile, most of these operate relatively slowly, re-directing the trajectory of the platform in small increments.
As the size of the missile or projectile becomes smaller and faster, many conventional divert or attitude control systems become too large and slow to provide sufficient trajectory change. For projectiles or missiles traveling at very high velocity or supersonic speeds and spinning, small rocket motors have been used to create side thrust to the body. These thrusters have limited impulse and fire over several milliseconds which results in “smearing” the thrust vector if the missile or projectile body is rotating.
Known devices provide divert impulses to a rotating projectile or missile using small slugs of high density metal that are released from the spinning body. These small slugs are released by generating a high pressure force, shearing pins or other retention mechanisms. These known devices must be sufficiently robust to withstand high internal pressure which adds weight and volume. The use of a propellant or pyrotechnic for the pressure generating medium limits the reaction time to milliseconds.
A conventional missile or projectile includes a matrix or array of thrusters or slug diverters. As each thruster or diverter is fired, the original trajectory of the missile or projectile is altered. The reaction time of these thrusters or diverters is slow, there are fewer opportunities to make one or more trajectory changes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a missile or projectile with a matrix or array of thrusters or slug diverters in accordance with an embodiment of the present disclosure.
FIGS. 2A and 2B show a slug including a release mechanism and a slug mass 200 in accordance with an embodiment of the present disclosure.
FIG. 3A is a cross-sectional view showing a release mechanism before being coupled to a slug mass in accordance with an embodiment of the present disclosure.
FIG. 3B is a cross-sectional view showing the bolt body of the release mechanism shown in FIG. 3A.
FIG. 4 is a cross-sectional view showing an explosive charge in accordance with the present disclosure.
FIG. 5A is a cross-sectional view showing a squib assembly in accordance with the present disclosure.
FIG. 5B is a cross-sectional view showing the header subassembly of the squib assembly shown in FIG. 5A.
FIG. 6 is a cross-sectional view showing a slug mass in accordance with an embodiment of the present disclosure.
FIG. 7A shows a cross-sectional view of a diverter array with a single layer of slugs in accordance with an embodiment of the present disclosure.
FIG. 7B shows a cross-sectional view of a diverter array with two layers of slugs in accordance with an embodiment of the present disclosure.
FIG. 7C is a perspective view showing a diverter array including a plurality of angularly offset layers of slugs in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
A. Overview
Embodiments according to the present disclosure include various projectile diverters for improving slug ejection reaction time. Additionally, thrust may be improved, especially for very high velocity projectiles spinning at extreme spin rates, at least in part because the retention mechanisms of the projectile diverters contribute to the mass of the slugs that are ejected.
At least some embodiments according to the present disclosure may include a large number of projectile diverters in a small volume to provide a broad selection of projectile diversion control. Additionally, these projectile diverters are immune to high axial acceleration spin rates and adjacent pyrotechnic shocks.
At least some embodiments according to the present disclosure may include metal slugs or high density masses that are released at a precise rotational angle to provide radial impulse. The slugs or masses may be deployed individually, simultaneous or sequentially to affect the desired trajectory alteration of a projectile in flight. Because higher projectile spin rates increase the centrifugal force acting on the slugs or masses; accordingly, very strong mechanisms are required to attach the slugs or masses to the projectile prior to release.
At least some embodiments according to the present disclosure may include an explosive bolt release mechanism that provides retention while in extreme G-force environments, and also releases the slugs or masses within microseconds of a FIRE command. The explosive bolt may be configured to occupy little volume and be protected from adjacent slugs and have a pre-determined separation plane.
In at least some embodiments of the present disclosure, slug or mass release can be consistently predicted because the separation plane of the explosive bolt includes a groove that can be adjusted within demonstrated margins without changing the internal components of the release mechanisms. The slug or mass has an inside diameter that provides a clearance between it and the explosive bolt. This clearance allows the explosive bolt to expand without transmitting pyro shock to adjacent slugs or projectile structure, thereby also providing 360 degree protection from adjacent slugs and explosive bolts.
According to at least some embodiments of the present disclosure, when a projectile or missile is launched, the acceleration loads are normal to the longitudinal axis of the explosive bolt release mechanism and do not tend to move or displace the release mechanism internals. When the projectile begins to spin, the centrifugal force pulls on the slugs or masses, thereby tensioning the bolt. When release is initiated, the explosive charge severs the bolt by shock wave interaction rather than by pressure.
B. Embodiments of Projectile Diverter Release Mechanisms
FIG. 1 illustrates a missile or projectile 10 with a matrix or array 20 of thruster or diverter slugs 30 in accordance with an embodiment of the present disclosure. The intended trajectory of the projectile 10 as shown in FIG. 1 is in a direction D1; however, the projectile 10 is traveling is in a direction D2. To divert the projectile 10 from the direction D2 to the direction D1, a trajectory control system 12 releases one or more slugs 30 from the array 20. As the slugs 30 is released, the trajectory of the projectile 10 is altered.
FIGS. 2A and 2B show one of the slugs 30 with a release mechanism 100 and a slug mass 200 in accordance with the present disclosure. Each release mechanism 100 retains a corresponding slug mass 200 in an unactuated configuration of the slug 30 (FIG. 2A) and releases the slug mass 200 in an actuated configuration of the slug 30 (FIG. 2B). The trajectory control system 12 issues a FIRE command and the slug 30 transitions within microseconds, e.g., in less than 100 microseconds or approximately 50 microseconds, from the unactuated configuration (FIG. 2A) to the actuated configuration of the slug 30 (FIG. 2B).
The slug mass 200 may be coupled to the release mechanism 100 by a threaded connection or another suitable mechanical connection. According to one embodiment, the release mechanism 100 includes a first set of screw threads 102 that cooperatively engage a second set of screw threads 202 on the slug mass 200.
FIG. 3A is a cross-sectional view showing the release mechanism 100 before being coupled to the slug mass 200. The release mechanism 100 includes a bolt body 110, an explosive charge 130, and a squib assembly 150.
The bolt body 110 extends along a longitudinal axis L-L between a first end 112a and a second end 112b. The first set of screw threads 102 is disposed on an outer surface 114 of the bolt body 110 proximate the first end 112a and a third set of screw threads 104 is disposed on the outer surface 114 proximate the second end 112b. The third set of screw threads 104 provides a coupling between the slug 30 and a fourth set of screw threads (not shown) on the projectile 10.
The outer surface 114 of the bolt body 110 may include a shoulder 116 and a groove 118. The shoulder 116 may provide a limit stop for the slug mass 200 with respect to the bolt body 110. In particular, the shoulder 116 may contiguously engage a corresponding boss 204 provided on an inner surface 204a of the slug mass 200 (FIG. 6). Accordingly, an outside diameter of the third set of screw threads 104 is smaller than the inside diameter of the boss 204 to permit the slug mass 200 to freely slide over the second end 112b. According to one embodiment, a threadable coupling between the slug mass 200 and the bolt body 110 is complete when boss 204 on the slug mass 200 contiguously engages the shoulder 116 on the bolt body 110.
The groove 118 provides a pre-determined separation plane X-X between the first end 112a and the second end 112b of the bolt body 110. The geometry and location of the groove 118 are selected to minimize the amount of the explosive charge 130 that is needed to cause separation. In particular, the depth and location along the longitudinal axis L-L of the groove 118 may be selected based on the tested structural properties of an individual batch of bolt bodies 110. Accordingly, the same explosive charge 130 may be used consistently and the groove 118 varied to achieve the desired separation in the actuated configuration of the slug 30 (FIG. 2B). Further, the first end 112a of the bolt body 110 remains coupled to and adds additional mass to the slug mass 200 in the actuated configuration of the slug 30 (FIG. 2B).
Referring to FIG. 3B, an end face 120 of the bolt body is provided at the second end 112b of the bolt body 110. The end face 120 couples the outer surface 114 of the bolt body 110 to an inner surface 122 of the bolt body 110. The inner surface 122 cinctures a passageway 122a extending along the longitudinal axis L-L and including three sections I, II and III. Section I is proximate to the end face 120 and has the largest cross-sectional area transverse to the longitudinal axis L-L. Section III terminates at a closed end 124 of the passageway 122a and has the smallest cross-sectional area transverse to the longitudinal axis L-L. Section III is also provided proximate to the separation plane X-X. Section II of the passageway 122a is disposed between and couples Sections I and III. Section II may include a cross-sectional area transverse to the longitudinal axis L-L that is greater than section III and smaller than section I.
The outer surface 114 of the bolt body 110 may also include a fitting recess 128 at the first end 112a of the bolt body 110. The fitting recess 128 may receive a torque applying tool (not shown) that may be used, e.g., for turning the slug 30 so that the third set of screw threads 104 couples to the fourth set of screw threads (not shown) on the projectile 10. The recess fitting 128 may include, for example, a slot to receive a flat blade screwdriver, a hexagonal hole to receive an Allen wrench, or another configuration suitable to receiving a correspondingly shaped tool.
The bolt body 110 may be fabricated from high-strength stainless steel. For example, the bolt body 110 may include Inconel 718 or another material having an ultimate tensile strength of approximately 180,000 to 220,000 pounds-per square-inch (psi), a minimum yield strength of approximately 160,000 psi, and a hardness of approximately 40-46 (Rockwell C).
FIG. 4 is a cross-sectional view showing the explosive charge 130 in accordance with the present disclosure. The explosive charge 130 includes a secondary explosive material 132 and a primary explosive material 134. The secondary explosive material 132, which can include, e.g., Tetryl or “CH6” (2,4,6-trinitrophenyl-methylnitramine), is pressed directly into section III of the passageway 122a at high pressure, e.g., approximately 15,000 psi, and uniform density, e.g., approximately 1.6 grams-per-cubic centimeter. Pressing the secondary explosive material 132 into the bolt body 110 results in maximum coupling of the explosive with the separation plane X-X, thereby minimizing the total quantity of the secondary explosive material 132 required to separate the bolt body 110. The primary explosive material 134 can include Lead Azide. The primary explosive material 134 can be pressed into a loading sleeve 136 for safety. The loading sleeve 136 including the primary explosive material 134 pressed into a bore 138 can be inserted into the passageway 122a so that a leading end 140a of the loading sleeve 136 is proximate the secondary explosive material 132 in section III and a trailing end 140b is disposed in section II. The loading sleeve 136 accordingly includes a first portion 142 having an outside diameter that corresponds to the inside diameter in section III and a second portion 144 having an outside diameter that corresponds to the inside diameter in section II. The bore 138 is approximately constant throughout the first portion 142 and the second portion 144 so that the volume of the primary explosive material 134 that is loaded into the loading sleeve 136 remains consistent. The loading sleeve 136 may slide in the passageway 122a to permit the primary explosive material 134 to contiguously engage the secondary explosive material 134; however, a ledge formed on the inner surface 122 between sections II and III constrains the movement of the loading sleeve 136 toward the first end 112a of the bolt body 110.
FIG. 5A is a cross-sectional view showing the squib assembly 150 in accordance with the present disclosure. The squib assembly 150 includes a header subassembly 152, a heating element 170, an ignition charge 176, a charge cup 180, and an inert material 190, which can provide an insulator between the ignition charge 176 and the primary explosive material 134 for safety.
Referring additionally to FIG. 5B, the header subassembly 152 includes a header body 154, a pair of electrically conductive pins 162, and a sealing material 168. The header body 154 extends along the longitudinal axis L-L between an output end 156a and an input end 156b. An interior surface 158 of the header body 154 cinctures a cavity 158a that includes an enlarged portion 160a at the output end 156a, a sealing portion 160b, a corona ring 160c, and an entrance portion 160d at the inlet end 156b. The enlarged portion 160a is sized to receive the charge cup 180. Disposed inside the charge cup 180 are the heating element 170, the ignition charge 176, and the inert material 190, which may include an insulator disk 190a and/or diatomaceous earth. The enlarged portion 160a also receives ends of the pins 162. The sealing portion 160b of the cavity 158a cinctures the sealing material 168 and bulges 164 on the pins 162. The sealing material 168 may include a bead of glass, e.g., Corning 9010 or 9013, fused around the bulges 164 to (1) prevent the pins 162 from being expelled from the header body 154; (2) provide a hermetic seal between the header body 154 and the pins 162; and (3) electrically insulate the header body 154 and the pins 162. The corona ring 160c separates the sealing portion 160b and the entrance portion 160d. The corona ring 160c defines an aperture 166 through which the pins 162 extend, but through which the sealing material 168 does not extend. Accordingly, an air gap 166a is formed between the corona ring 160c and the pins 162 and provides a means to prevent an electrostatic discharge from inadvertently sending an electrical charge to the heating element 170. The entrance portion 160d may radially diverge from the corona ring 160c to the inlet end 156b.
The header body 154 can include stainless steel for welding compatibility with the bolt body 110. This provides a solid attachment for the squib assembly 150 to the bolt body 110, as well as provides a hermetic seal to protect the contents in the passageway 122a and to provide a long shelf and service life.
The squib assembly 150 receives the FIRE signal from the trajectory control system 12. Upon receiving the FIRE signal, the heating element 170, which may include a Thin Film Bridge (TFB), heats rapidly setting off the ignition charge 176. According to one embodiment, the ignition charge 176 includes potassium dinitrobenzofuroxan or “KDNBF” (potassium 4,6 dinitro-7 hydroxy-7 hydro-benzofuroxan). The ignition charge 176 may also be pressed in the body at high pressure to mitigate movement in high G-force environments. The squib assembly 150 is fabricated separately from the bolt body 110 and can therefore be acceptance tested separately from the bolt body 110. The output of the squib assembly 150 reacts at detonation velocity, e.g., approximately 6,000 to 8,000 meters-per-second, so that the total function time is very short, e.g., 50 to 100 microseconds.
FIG. 6 is a cross-sectional view showing a slug mass 200 in accordance with an embodiment of the present disclosure. The inner surface 204a of the slug mass 200 may include the second set of screw threads 202 and the boss 204. According to one embodiment of the present disclosure, there is a radial clearance between the outer surface 114 of the bolt body 110 and the boss 204 on the slug mass 200 in the unactuated configuration of the slug 30 (FIG. 2A). This clearance allows the bolt body 110 to expand when the explosive charge 130 is ignited without transmitting pyro shock to adjacent slugs 30 or other structure of the projectile 10. Additionally, the slug mass 200 also provides 360 degree protection from adjacent slugs 30 and release mechanisms 100.
C. Implementations of Projectile Diverter Release Mechanisms
FIG. 7A shows a cross-sectional view of the projectile 10 with a single layer of slugs 30 (two slugs 30 are shown in FIG. 7). According to one embodiment of the present disclosure, the projectile is a 2.25-inch diameter gun fired projectile. It should be apparent from the description above, however, that the diverter would be useful on many types of projectiles.
FIGS. 7B and 7C show that plural layers of slugs 30 can also be used in a projectile 10. For example, the projectile 10 shown in FIG. 1 includes three layers of slugs 30 in the array 20. FIG. 7B shows two layers of slugs 30, and FIG. 7C shows that the layers in the array 20 can be angularly offset to reduce the axial thickness of the array 20 along a longitudinal axis A-A of the projectile 10. A central chase 14 can be used for running a control bus or individual wires (not shown) between the trajectory control system 12 and individual slugs 30.
As shown in FIGS. 7A and 7B, the longitudinal axes L-L of the slugs 30 are approximately perpendicular to the longitudinal axis A-A of the projectile 10, such that the ejection of a slug mass 200 will produce a lateral reaction force on the projectile 10 and thereby divert the projectile to its intended trajectory.
D. Methods for Using Projectile Diverter Release Mechanisms
If the intended trajectory of the projectile 10 is in a direction D1, but the projectile 10 is traveling is in a direction D2, one or more slugs 30 from the array 20 can be released to divert the projectile 10 toward direction D1. The trajectory control system 12 issues a FIRE command and the slug(s) 30 transition within microseconds, e.g., in less than 100 microseconds or approximately 50 microseconds, from the unactuated configuration (FIG. 2A) to the actuated configuration of the slug 30 (FIG. 2B). Upon receiving the FIRE signal, the heating element 170 heats rapidly setting off the ignition charge 176. In turn, the ignition charge 176 detonates the primary explosive material 134, which detonates the secondary explosive material 132. The output of the squib assembly 150 reacts at detonation velocity, e.g., approximately 6,000 to 8,000 meters-per-second, so that the total time between the trajectory control system 12 issuing the FIRE command and the slug mass 200 being ejected is very short, e.g., 50 to 100 microseconds. As each slug 30 is released, the trajectory of the projectile 10 is altered toward the intended trajectory.
E. Alternative Embodiments or Features
From the foregoing, it will be appreciated that specific embodiments of the disclosure have been described herein for purposes of illustration, but that various modifications can be made without deviating from the spirit and scope of the disclosure. For example, it may be desirable to have from one to 64 or more slugs on a projectile. Additionally, it may be desirable to orient the longitudinal axes of the slugs obliquely and/or tangentially with respect to the longitudinal axis of a projectile. Moreover, specific elements of any of the foregoing embodiments can be combined or substituted for elements in other embodiments. Furthermore, while advantages associated with certain embodiments of the disclosure have been described in the context of these embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, embodiments of the disclosure are not limited except as by the appended claims.
Patent Application
20110204177
