1. Field of the Invention
The invention relates to retention and deployment systems for canards and more particularly to systems and methods for retaining and deploying canards and canard covers on a projectile.
2. Description of Related Art
During the launch of a projectile it is desired to have retractable canards which are retained within the projectile and subsequent to launch the canards unfold from within the projectile and extend into the airstream. Slots in the projectile housing are provided to accommodate deployment of the canards from within the projectile to the outside airstream. These slots increase drag on the projectile, reducing the range for the projectile launch, and expose the inner components to environmental conditions, such as electromagnetic interference. To solve these problems, slot covers can be used.
Existing mechanisms for canard cover ejection and canard deployment on launched projectiles are known in the art. In the past, mechanisms for canard deployment typically employ multiple pyrotechnics to eject the canard cover and additional spring-loaded mechanisms to deploy the canards. Using separate pyrotechnics and spring-loaded mechanisms to eject the covers and deploy the canards makes it difficult to synchronize the deployment of the canards, therein creating instability if one canard deploys before another, and increases the cost and the complexity of the deploying mechanism.
More recently, efforts have been made to deploy canards using a single pyrotechnic device, for example, as disclosed in U.S. Pat. No. 6,880,780 to Perry et al. (hereinafter, ‘Perry’). Perry discloses an apparatus using covers for controlled storage and deployment of the steering fins of a missile. The covers in Perry serve to prevent the fins from deployment while also providing an aerodynamic fairing. As part of the apparatus, Perry discloses rotatable latch arms for securing the covers. The disclosed rotatable latch arm includes parallel latch arm portions on opposite sides of the fin. The latch arm portions are joined together at only one end forming an open slot. The fins remain in the slot while being retained by the cover. But, when the cover is removed, the fins deploy. This design does not account for situations where the covers are accidentally ejected during or after launch, but before it is desired to have the canards released. When the covers are accidentally ejected and canards accidentally released, control over the projectile can be lost. In addition, to radially project the cover using the latch arm of Perry, a separate extending forward portion of the latch arm is positioned to contact an inwardly extending portion of the cover. This added geometry takes up additional space, adds complexity to manufacturing and uses more material, which adds weight and cost.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for systems and methods that allow for improved performance, and a retaining and deployment system that is easy to make, use and test. Therefore, it would be advantageous to provide systems and methods for retaining and deploying canards and canard covers that overcome the disadvantages associated with traditional canard retaining and deploying systems and methods and solves the challenges associated with such traditional systems and methods, such as accidental canard deployment. The present invention provides a solution to these problems.
The subject invention is directed to a new and useful system for retaining and deploying a plurality of canards and canard covers on a projectile. The system includes a projectile housing defining an interior chamber and a longitudinal axis, and a plurality of canards rotatably mounted to the housing. The plurality of canards are adapted for movement from a stowed position within the housing to a deployed position. The system further includes a plurality of canard covers. Each canard cover is adapted to conceal respective slots formed in the projectile housing and includes a hook element. The system also includes a bobbin and a plurality of rocker arms, the rocker arms rotatably mounted within the housing. The bobbin is movably disposed in the interior chamber of the housing along the longitudinal axis of the projectile housing and has first and second ends, and a retaining surface defined proximate the second end. Each rocker arm has a first arm end and a second arm end, with a canard retaining slot defined therebetween configured to secure a canard in the stowed position. The first arm end includes a latch element and the second arm end is positioned proximate the bobbin retaining surface. The system also includes a mechanism for driving the bobbin axially along the longitudinal axis, so as to deploy the plurality of canards and canard covers on the projectile.
Preferably, each rocker arm can be configured and adapted to rotate relative to a rocker arm rotation axis between a first and second position. Each latch element can include a cover retaining surface, wherein in the first position the cover retaining surface can be engaged with a corresponding internal surface of canard cover hook element and each second arm end can be engaged with the bobbin retaining surface. The cover retaining surface can be configured and adapted to retain the corresponding canard cover over its respective slot formed in the projectile housing. Each rocker arm can be forced to rotate relative to its respective rocker aim rotation axis into the second position, from the first position, when the bobbin is moved along the longitudinal axis relative to the projectile housing. During rotation from the first position to the second position, a cover ejection surface of the latch element of the rocker arm ejects the canard cover and the canard retaining slot releases the canards. In addition, in a preferred embodiment, a surface formed on each rocker arm proximate the second arm end is configured and adapted to mechanically push the associated canard into the deployed position when the rocker arm rotates relative to its respective rocker arm rotation axis.
In further accordance with certain embodiments, each of the canard cover hook elements has a caromed surface and an internal surface. Each of the canard covers also includes a main body section having forward and aft ends and a groove proximate the aft end. The groove is removably engaged with projectile housing, and the canard cover hook element, as previously described, is defined between the forward and aft ends, proximate the forward end. Each of the canard covers is configured to eliminate drag on the projectile housing.
In further accordance with certain embodiments, the mechanism for driving the bobbin can be a pyrotechnic component disposed within an axial bore formed within the first end of the bobbin. The pyrotechnic component can be configured and adapted to initiate a force on the bobbin which causes the bobbin to move along the longitudinal axis relative to the projectile housing. The axial movement of the bobbin can be translated into a force on the second arm end of each rocker arm causing the rotation of each rocker arm relative to a respective rocker arm rotation axis from it's the first position to the second position. The system can also include an absorber disposed proximate to the second end of the bobbin along the longitudinal axis, which is configured and adapted to reduce shock to the projectile housing during deployment. The absorber can be a crushable replaceable absorber.
Preferably, each canard can be configured and adapted to rotate about a respective fulcrum and in a respective plane passing through the longitudinal axis. The canards can be configured to be released and deployed simultaneously with one another. Also, the system can be disposed in a tip portion of the projectile housing. It is also envisioned that each canard can be locked along a respective transverse axis in the deployed position. Each canard can be configured to rotate through the respective slots described above, from the stowed position within the housing, into the deployed position.
The invention also provides a method for ejecting a plurality of canard covers and deploying a plurality of canards on a projectile. The method includes driving a bobbin disposed within an interior chamber formed in the projectile longitudinally so as to cause a plurality of rocker arms to rotate about a respective rocker arm axis. Each rocker arm defines a canard retaining slot configured to secure the canard in a stowed position. The rotation of the rocker arms causes the ejection of the plurality of canard covers and the subsequent mechanically timed release and deployment of the plurality of canards.
In further accordance with certain embodiments, the release and deployment of each of the canards can be simultaneous with one another.
These and other features of the systems and methods of the subject invention will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject invention appertains will readily understand how to make and use the systems and methods of the subject invention without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
These and other aspects of the subject invention will become more readily apparent to those having ordinary skill in the art from the following detailed description of the invention taken in conjunction with the drawings.
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject invention. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of the system for retaining and deploying a plurality of canards and canard covers on a projectile in accordance with the invention is shown in
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While shown in the exemplary context of having four canards 108 and corresponding canard covers 110, those skilled in the art will readily appreciate that any plurality of canards 108 and canard covers 110 can be used. In addition, those skilled in the art will readily appreciate that canard covers 110 and canards 108 can be placed in various locations on projectile housing 102, for example, canards can be disposed in or around a tip portion 101 of projectile housing 102. Those having skill in the art will also readily appreciate that the embodiments described herein can be used with any type of projectile requiring deployed canard or fin structures, for example, any control surface introduced to the air or fluid stream.
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Those skilled in the art will readily appreciate that drive mechanism 134 can be accessed through an end of projectile housing 102. This permits replacement of drive mechanism 134, therein allowing multiple deployment tests with minimum disassembly. In addition, those skilled in the art will readily appreciate that system 100 for retaining and deploying a plurality of canards and canard covers can be disposed in a small volume of tip portion 101 of projectile housing 102. This permits easier access and replacement with minimum disassembly.
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The invention also provides a method for ejecting a plurality of canard covers, e.g. canard cover 110, and deploying a plurality of canards, e.g. canards 108, on a projectile, e.g. projectile 102. The method includes driving a bobbin, e.g. bobbin 116, disposed within an interior chamber formed in the projectile longitudinally so as to cause a plurality of rocker arms, e.g. rocker arms 124, to rotate about a respective rocker arm axis, i.e. rocker arm rotation axis B. Each rocker arm defines a canard retaining slot, e.g. canard retaining slot 130, configured to secure the canard in a stowed position. The rotation of the rocker arms causes the ejection of the plurality of canard covers and the mechanically timed release and deployment of the plurality of canards. Those skilled in the art will appreciate that the release and deployment of the canards can be completed within milliseconds after initiating the mechanism to drive the bobbin, and that the release and deployment of each canard can be simultaneous with the release and deployment of the other canards. It is also envisioned that canards can be locked along a transverse axis D in the deployed position.
The methods and systems of the present invention, as described above and shown in the drawings, provide a system for retaining and deploying a plurality of canards and canard covers on a projectile with superior properties including increased synchronization of canard and canard cover deployment and canard retainment in case of accidental cover deployment. While the apparatus and methods of the subject invention have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the spirit and scope of the subject invention.