Patent Application
20120167796
1. Field of the Invention
The present invention relates to missiles. More specifically, the present invention relates to an integrated warhead and rocket motor.
2. Description of the Related Art
There is a constant demand in the defense industry for improved missile systems. Increased kinematic performance (increased speed, shorter time of flight, longer range) and improved lethality are particularly desirable for increasing warfighting ability.
Any improvements, however, must be made without changing any missile interfacing if the missile is to remain compatible with existing aircraft or launchers. Missile length, diameter, box size, and weight cannot be changed from existing parameters.
Missiles typically include a warhead and a rocket motor. The warhead usually includes an explosive fill that may be surrounded by a material designed to fragment into shrapnel upon detonation. The rocket motor typically includes a propellant that is burned within a combustion chamber at high pressure. Missile lethality is governed primarily by the amount of explosive in the warhead, while missile speed and range are governed primarily by the amount of propellant in the rocket motor. Since space on the missile is limited, it can be difficult to increase both the kinematic performance and lethality of a missile without increasing its size and weight.
Hence, a need exists in the art for an improved missile offering increased kinematic performance and improved lethality than conventional designs.
The need in the art is addressed by the integrated warhead and rocket motor subassembly of the present invention. The novel subassembly includes a warhead, a rocket motor, and a single bulkhead separating the warhead and the rocket motor. The bulkhead is adapted to handle both pressure loads from the rocket motor and missile carry loads transmitted through a hook and hangar assembly, which is bolted into the bulkhead. This novel design merges the forward pressure bulkhead of the rocket motor and the aft bulkhead of the warhead in a conventional missile design into a single bulkhead located beneath the missile attach point. This allows for an increase in propellant length in the rocket motor, thereby increasing the speed and range of the missile.
In an illustrative embodiment, the warhead section of the subassembly includes an explosive fill surrounded by a material adapted to form a plurality of fragments upon detonation. In a preferred embodiment, the fragments are pre-formed into small cubes that are 80 to 85 grain in weight, using a material having a density greater than 16 g/cc. This design allows the warhead to maintain or increase missile lethality as compared to current conventional missiles.
a is a simplified diagram of a conventional missile.
b is a simplified diagram of a missile designed in accordance with an illustrative embodiment of the present teachings.
a is a simplified schematic of the warhead and rocket motor of a conventional missile.
b is a simplified schematic of an integrated warhead and rocket motor subassembly designed in accordance with an illustrative embodiment of the present teachings.
Illustrative embodiments and exemplary applications will now be described with reference to the accompanying drawings to disclose the advantageous teachings of the present invention.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
The warhead 12 includes a cylindrical metal casing 16 that is filled with an explosive 18. The explosive fill 18 is disposed between a forward bulkhead 20 and an aft bulkhead 22, and may be surrounded by a material 28 (shown in
A hook and hangar assembly 26 is bolted into the aft bulkhead 22, which is a heavy structural steel plate on the aft end of the warhead 12, forward of the bolt hole pattern 24. The hook and hangar assembly 26 allows the missile 10 to be grabbed and held by a launcher. At this location, practically all of the weight of the missile is carried through this hook and hangar assembly 26. The aft bulkhead 22 should therefore be very strong to carry missile weight and bending loads during aircraft dynamic maneuvering as well as the ejection process for launching the missile 10.
The rocket motor 14 includes a cylindrical metal casing 30 that is filled with a propellant 32. The rocket motor 14 may also include an arm fire device (AFD) 34 for igniting the propellant 32. The forward end of the rocket motor 14 includes a bolt hole pattern 36 for attaching the rocket motor 14 to the bolt hole pattern 24 of the warhead 12 with bolts and nutplates.
The rocket motor 14 includes a pressure bulkhead 38, which is a heavy structural steel plate on the forward end of the rocket motor 14 for withstanding rocket motor pressure. The rocket motor 14, when operating, is a pressure vessel carrying several thousand pounds of pressure per square inch. The pressure bulkhead 38 is typically a dome which is optimally designed to handle the pressure loads of the motor operation. As in a typical pressure vessel, the pressure bulkhead 36 should be very thick and strong.
In a conventional missile, the warhead and rocket motor are typically manufactured as separate entities, often by different vendors. Each subassembly is usually purchased separately and shipped separately to the missile manufacturer, where the subassemblies are bolted together during final assembly. This is a labor intensive process involving a lot of paperwork for the assemblers, process engineers, material commodity managers, material program managers, responsible engineering authority, and supply chain.
The novel design of the present invention eliminates the bolted joint between the warhead and rocket motor, and merges the warhead and rocket motor into a single entity that can be manufactured by one vendor and shipped as a single unit, eliminating the need for increased touch labor by the missile manufacturer as well as the associated paperwork. In accordance with the present teachings, this is accomplished by merging the forward pressure bulkhead of the rocket motor with the aft bulkhead of the warhead into a single bulkhead placed beneath the hook and hangar assembly.
In a conventional missile design as shown in
a and 2b illustrate the design of the present invention.
b is a simplified schematic of an integrated warhead and rocket motor subassembly 60 designed in accordance with an illustrative embodiment of the present teachings.
The novel missile subassembly 60 includes a cylindrical metal casing 62, which is divided into two cavities 64 and 66 by a single bulkhead 56 located beneath the missile attach point (the hook and hangar assembly 26). The first cavity 64 holds the explosive fill 18 of the warhead 52 and the second cavity 66, which is aft of the first cavity 64, holds the propellant 32 of the rocket motor 54. The hook and hangar assembly 26 is bolted into the bulkhead 56. The bulkhead 56 is designed to handle pressure loads from the rocket motor 54 during operation, as well as missile carry loads transmitted through the hook and hangar 26.
By moving the pressure bulkhead 56 to beneath the hook and hangar 26 in accordance with the present teachings, the propellant length in the rocket motor 54 is increased as shown by arrow 70. This design may slightly decrease the explosive length in the warhead 52 as shown by arrow 72. In accordance with the present teachings, the warhead 52 uses a new discrete fragment size and material to maintain or increase the probability of kill for the warhead (as compared to current conventional warheads).
The warhead 52 includes a layer of material 80 surrounding the explosive fill 18 that is adapted to fragment into shrapnel upon detonation. In a preferred embodiment, the warhead 52 includes pre-formed discrete fragments made from a very dense material, preferably having a density greater than 16 grams/cc. In an illustrative embodiment, the fragments are made from tantalum (16.69 g/cc) or tungsten heavy alloy (17-18 g/cc). In the preferred embodiment, the fragments are formed into small cubes that are 80 to 85 grain in weight (this is much smaller than conventional fragments, which are typically about 112 grain). These design parameters allow a smaller warhead to maintain or increase missile lethality.
The missile subassembly 60 may also include an arm fire device 82 in the rocket motor cavity 66 attached to the bulkhead 56. Any wires coupled to the umbilical connection 84 may be slid into the warhead cavity 64. The component casing 62 may include a small hole for allowing wires in the warhead cavity 64 to pass through the casing 62 to the umbilical connection 84.
Thus, by merging the aft bulkhead of the warhead with the forward pressure bulkhead of the rocket motor into a single bulkhead beneath the missile attach point (the hook and hangar assembly), propellant length in the rocket motor is increased, thereby increasing the speed and range of the missile. Missile lethality is maintained or improved by using smaller and denser discrete fragments. In addition, by integrating the warhead and rocket motor into a single subassembly, missile cost may be reduced through the elimination of labor and associated paperwork for buying, receiving, and assembling two explosive components.
Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications and embodiments within the scope thereof. For example, while the invention has been described with reference to an AMRAAM missile design, the present teachings may also be applied to other types and sizes of missiles.
It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention.
Accordingly,
