Patent Application
20130092790
1. Field of the Invention
The invention is in the field of air vehicles launched from launchers, such as powered or unpowered projectiles launched from gun tubes, launch tubes, or other launchers, with end features that could interfere with deployed surfaces of the air vehicles.
2. Description of the Related Art
Air vehicles launched from launch tubes, gun tubes, or other launchers often have fins that are used in flight to stabilize the vehicle, as well as for other purposes. The fins are stowed during launch, in order to allow the air vehicle to fit in the launcher.
Pressurized gases produced for propulsion during launch may get underneath the fins during the launch process. Near the mouth of the launcher there may be a muzzle brake or other openings which redirect pressure that is inside the launcher, for instance to reduce recoil. The pressurized gasses trapped underneath the fins may tend to push the fins outward, which is undesirable, as contact between the fins and the walls of the launcher may damage the fins and/or the launcher, and/or may adversely affect trajectory of the air vehicle.
If the launcher is rifled, so that the air vehicle spins about its longitudinal axis as part of the launch process, centrifugal forces may urge the fins outward prior to the vehicle exiting the launcher. Again premature deployment of fins would be undesirable.
In view of the above, it would be desirable to easily control fin deployment. Management of fin deployment may be accomplished by control of roll rate, internal pressurization, and fin moments of inertia, but such control puts restraint on performance.
A launcher-fired air vehicle has a release mechanism for releasing fins from a stowed configuration. The release mechanism is ejected from a cavity in the fuselage when the vehicle reaches a low-pressure region of the launcher where a muzzle brake is located. The release mechanism includes a pin with a length selected so that it releases the fins after a delay, preventing the fins from beginning deployment while still in the launcher in such a way that would cause the fins to contact the wall or walls of the launcher.
According to an aspect of an invention, an air vehicle launched from a launcher includes: a fuselage; fins coupled to the fuselage, wherein the fins deploy from an initial stowed configuration in the launcher to a deployed configuration in flight; a release mechanism that releases the fins from the stowed configuration, wherein the release mechanism includes a longitudinally oriented pin in a cavity in the fuselage; and a valve that selectively lets pressurized gasses into the cavity through the valve.
According to a further aspect of the invention, a method of launching an air vehicle from a launcher includes: using pressurized gasses to move the air vehicle within the launcher; when an aft end of the air vehicle reaches openings near the muzzle of the launcher, beginning movement of a release mechanism for releasing the fins of the air vehicle; and after a delay following the beginning movement of the release mechanism, using movement of the release mechanism to release a restraint that keeps fins of the air vehicle from deploying.
To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
The annexed drawings, which are not necessarily to scale, show various aspects of the invention.
An air vehicle that is launched from inside a launcher, includes a release mechanism for releasing fins of the vehicle from a stowed condition to a deployed condition. The release mechanism includes a pin that is located within a cavity in the fuselage of the air vehicle. Pressurized gasses are used within the launcher to provide a force to accelerate the air vehicle and expel it from the launcher. The same pressurized gasses initially fill the cavity in the fuselage. The launcher includes a reduced-pressure portion, wherein the internal gas pressure behind the air vehicle, within the launcher, is reduced by openings, such as from a muzzle brake. When the air vehicle passes into the reduced-pressure portion of the launcher, the gas pressure behind the air vehicle is reduced. This causes the pressurized gas within the cavity to drive the release mechanism backwards relative to the air vehicle, out of the cavity. Once the release mechanism has moved back far enough, the pin clears the vehicle, and the fins are released to begin deployment from the stowed condition. The length of the pin may be used to control the timing of the fin deployment, the delay between the initial movement of the release mechanism out of the cavity, and when the fins are released. The mechanism provides a simple, inexpensive, and reliable way to control timing of fin deployment, to prevent fins from deploying early and contacting the side(s) of the launcher, for example.
The fins 14 are mechanically restrained by a restraint 18 in order to keep the fins 14 in the stowed condition during launch of the air vehicle 10 from a launcher, such as a launch tube. The restraint 18 may include a band or cable 20 that is wrapped around the fuselage 12.
With reference now in addition to
As described in greater detail below, the release mechanism 24 is detached from the fuselage 12 by pressure forces. As pressurized gasses build up in the launcher behind the air vehicle 10, the pressurized gasses also enter the cavity 34. Eventually the aft end of the air vehicle 10 reaches a low-pressure region at the end of the launcher, a region where a muzzle brake is located or where there are other openings in the barrel of the launcher. When the aft end of the air vehicle 10 passes into this low-pressure region, there is an imbalance of pressure forces on the base 30 of the release mechanism 24, since the pressure from the high-pressure gasses still inside the cavity 34 are greater than the pressure pushing from the outside of the base 30. This imbalance of pressure forces pushes the release mechanism longitudinally back relative to the fuselage 12, causing the release mechanism 24 to be expelled from the cavity 34.
The pin 28 may be made long enough in a longitudinal direction to delay the release of the restraint 18 for some time after the movement of the release mechanism 24 begins. The length of the pin 28 may be chosen such that the restraint 18 is released only after the air vehicle 12 has exited the launcher. Alternatively, the length of the pin 28 may be selected such that the restraint is released while part of the air vehicle 10 is still in the launcher, with the timing selected such that the fins 14 do not contact the side walls of the launcher.
With reference to
The base 30 has a cup shape, with a ridge 54 around a perimeter of the base 30. The cup shape facilitates expulsion of the release mechanism 24 from the cavity 34 by capturing and better utilizing the high-pressure gasses pressing against the middle part of the base 30. The base 30 may cover substantially all of an aft-facing opening of the cavity 34 (
As discussed earlier, the pin 28 has a length 58 that is selected to control the timing of the release of the restraint 18 (
Many variations are possible for the embodiments described above. The valve 44 may have a variety of alternate configurations as part of the release mechanism 24 that is expelled from the cavity 34 (
The release mechanism 24 has many advantages over other ways of controlling timing for the release of the fins 14 (or other devices). The mechanism is a simple, inexpensive, reliable, and repeatable way to control timing.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.
