Patent Grant
7398721
The invention relates to missile launchers, and more particularly to cold-gas missile launchers.
A canisterized missile is typically launched using the missile's own booster—so called “hot launch.” When the booster fires, a plume of high-temperature (i.e., in excess of 5000° F.), high-velocity exhaust gas is generated. Since the plume is quite erosive (e.g., due to its high velocity and sometimes the presence of metallic particulates, etc.), direct exposure to it adversely affects the missile, the missile canister, other launch structures, and the surrounding environs (e.g., deck of a ship, etc.).
As a consequence, most missile-launch systems include an exhaust-gas management system, which directs the booster plume away from the missile, launch structure, etc. But to survive the plume's extreme conditions, the launch structure, as well as the exhaust-gas management system itself, must incorporate thermal- and erosion-protection materials.
The exhaust-gas management system and thermal- and erosion-protection materials necessarily add weight, cost and complexity to the launching system. Furthermore, heating of the launch structure and deck that results from hot launch creates a residual thermal signature. This signature is readily detectable by various sensors, and therefore potentially compromises the survivability of the missile launcher and, indeed, the ship or vehicle that supports it.
To address the problems of hot launch, “cold launch” systems have been developed. In a cold launch, the missile's booster is not used to eject the missile from the missile canister; rather, some other means, which does not generate the high temperatures or the erosive flow of a missile plume, is used. After the missile clears the canister, the missile's booster fires, with minimal impact on the launch structure, etc.
Existing cold launch systems have a variety of drawbacks. One drawback is that most cold launch system include a substantial number of additional components. Another drawback is that in some cold launch systems, the missile is exposed to high-pressure gas from a gas generator (that provides the pressure for launch).
The present invention is a cold-gas munitions launch system that avoids some of the costs and disadvantages of the prior art.
A cold-gas munitions launch system in accordance with the illustrative embodiment of the present invention includes a munitions canister, a gas generator, and a sled. The sled supports a munition.
The sled, which seals against the inside of the canister, is spaced a distance from the aft end of the canister. In the illustrative embodiment, the gas generator is located at the extreme aft end of the canister, partially within a hemispherical-shape closure. In some embodiments, there is small gap or plenum between the gas generator and the sled prior to launch.
When the gas generator ignites, it produces gas, which drives the sled forward. As the sled moves, a plenum is created (or enlarged in embodiments in which it is present at pre-launch). The plenum is defined by the hemispherical-shape closure at the aft end, the inside walls of the canister, and the hemispherical-shape bottom of the sled. The gas is retained within the plenum since the sled seals against the inside wall of the canister. The plenum expands as the sled advances with the canister.
The plenum continues to receive gas and expand by driving the sled forward. Near the end of it's travel, the sled passes vents in the canister. The vents open to release the gas contained within the plenum. As the sled reaches the end of the canister, the munition is launched by its own inertia, at a velocity that is within the range of about 3 to 9 g.
After the munition clears the canister, and more particularly at a distance of about 150 feet therefrom, the munition's booster is ignited. This substantially decreases the impact that the plume has on the launch system, deck, etc., thereby eliminating the need for an exhaust-gas management system.
In the illustrative embodiment, system 100 includes canister 102, sled 112, and gas generator 118, arranged as shown. Canister 102 contains munition 124. As used in this specification, the term “munition(s)” means any canistered projectile that includes a booster, such as any of a variety of missiles, airborne tagging systems, etc.
In the Figures, canister 102 is depicted in a horizontal position. It is to be understood that, during an actual launch, canister 102 will be partially upright (i.e., inclined), but not fully vertical. A fully vertical launch position is avoided so that if the missile fails to fire after it's ejected from canister 102, it will not fall back onto system 100.
With continued reference to
Prior to launch, sled 112 is coupled to aft end 108 of canister 102, such as by explosive bolts 117. The aft or rear-facing surface of sled 112 is shaped to maximize pressure load; in the illustrative embodiment, it has a hemispherical shape. The forward-facing surface of sled 112 is flat and supports munition 124. The munition is also supported, along its length, by a plurality of movable, collapsible rail “cars” 120 that move along the inner surface of canister 102. The munition is coupled to sled 112 by explosive bolts (not depicted) or some other means.
In preparation for launch, sled 112 must decouple from canister 102, and munition 124 must decouple from the sled, which is the purpose for the explosive bolts. In some alternative embodiments, combined active/passive restraint mechanisms can be used for reversibly securing sled 112 to canister 102 and munition 124 to sled 112, such as the mechanism disclosed in applicant's co-pending U.S. patent application Ser. No. 11/091,233. This case is incorporated by reference herein.
In the illustrative embodiment, gas generator 118 is disposed within canister 102, aft of sled 112. In the illustrative embodiment, gas generator 118 is disposed partially within aft hemispherical closure 110. The gas generator provides the driving force to launch munition 124. More particularly, gas generator 118 supplies gas at a rate and pressure that is sufficient to accelerate sled 112 and munition 124 to a launch velocity of between about 3 to about 9 g (i.e., about 96 to about 288 ft/s). The specific output requirement of the gas generator, in terms of pressure and flow rate, is a function of the weight of munition, which can vary widely as a function of munition type.
Plenum 226 is defined between seal 224 and bottom surface 114 of sled 112. Sled 112 is suitably sealed against the inner wall of canister 102, so that plenum 226 is capable of retaining gas that is delivered by gas generator 118. This enables pressure to build within the plenum, which drives sled 112 and munition 124 forward. It is notable that the plenum enlarges as sled 112 advances.
Often, munition 124 will have a larger diameter at its tail than its nose. As consequence, as sled 112 and munition 124 advance through canister 102, rail cars 120 collapse against the inner wall of the canister to facilitate passage of the munition.
In the illustrative embodiment, cold-gas munitions launch system 100 includes an internally-located gas generator (i.e., gas generator 118). In some alternative embodiments, gas is sourced externally and delivered to aft end 108 via appropriate tubing, etc., (not depicted).
Operations 402 and 404 recite releasing the sled from the canister and releasing the munition from the sled, respectively. These operations have been described previously, and can be implemented, for example, with active mechanisms (e.g., explosive bolts, etc.) or combined active/passive mechanisms.
Operation 406 recites accelerating the sled through the canister by pressurizing a region of the canister behind said sled. As previously described, pressurization can be performed by a captive gas generator, as in the illustrative embodiment, or by externally-sourced gas.
Operation 408 recites venting gas from the canister. In some embodiments, this is done “automatically” as the sled passes vents that are disposed near the forward end of the canister.
Operation 410 recites firing the booster on the munition after it exits the canister. This operation is performed when the munition has traveled at least about 150 feet away from the forward end of the canister. This is done using the munitions own inertia, as imparted by the energy in the pressurized gas.
It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that a particular feature, structure, material, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the present invention, but not necessarily all embodiments. Furthermore, it is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.
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| Number | Date | Country |
|---|---|---|
| 2-296600 | Jul 1990 | JP |
