Method and apparatus for stowing and deploying control surfaces of a guided air vehicle

Apparatus for stowing and deploying a plurality of control surfaces of a guided air vehicle comprises: a housing including: a plurality of slotted openings along an outside surface thereof; and a corresponding plurality of cavities within the housing, each cavity extending to the outside surface of the housing through the slotted opening corresponding thereto and configured to accommodate span wise stowage of a corresponding control surface of the plurality, and each cavity having a section including an angled ledge and side wall support surface to accommodate stowage of the corresponding control surface in a span wise canted position with respect to the corresponding slotted opening. A method of operating comprises the steps of: folding each control surface of the plurality edge wise through the corresponding slotted opening and into the corresponding cavity within the housing; moving each folded control surface into a stowage section of the corresponding cavity to edge wise mis-align each folded control surface from the corresponding slotted opening; moving each control surface in the corresponding cavity from the corresponding stowage section into edge wise alignment with the corresponding slotted opening; and deploying each control surface edge wise aligned with the corresponding slotted opening from the cavity through the corresponding slotted opening to a deployed position.

BACKGROUND OF THE INVENTION

The present invention relates to guided air vehicles with control surfaces, in general, and more particularly, to method and apparatus for stowing and deploying the control surfaces of the guided air vehicle.

Guided air vehicles such as missiles, smart bombs, smart munitions, projectiles and bullets, for example, utilize control surfaces, such as fins, canards and wings, for example, to guide their trajectory along a desired flight path. Such air vehicles, especially those launched from manned or unmanned aircraft or ground craft, require that their control surfaces be stowed within or partially within the body of the air vehicle during storage and transportation, and also during launch in order to: (1) minimize potential damage; (2) allow the air vehicle to fit physically in the launch apparatus; and (3) minimize the effects of aerodynamic forces acting upon the control surfaces during launch. Once the air vehicle is in flight, the control surfaces may be deployed to their desired positions for guiding the vehicle. In many instances, control surface deployment is controlled by an on-board processor to allow completion of the air vehicle mission in accordance with a desired target strategy.

Many different apparatus have been developed for stowing and deploying the control surfaces of an air vehicle including: electromechanical, solenoids, pyrotechnic gas generators and retractors, and mechanical apparatus such as no-backs and inefficient transmissions, for example. Depending upon the circumstances and operating environments, some apparatus were found to be inappropriate for the given task; others were found not to work; and still others were found to be too expensive to implement. In addition, deployment apparatus using pyrotechnic devices or other similar devices have significant drawbacks of: not being indestructibly testable since they operate on a single shot basis, and of inducing significant shock to the supporting structure.

Accordingly, there is a need for method and apparatus for stowing and deploying control surfaces of a guided air vehicle that overcome the drawbacks and limitations of the conventional apparatus and are simpler and more cost effective. The present invention is intended to provide such apparatus and method that satisfy these needs.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, apparatus for stowing and deploying a plurality of control surfaces of a guided air vehicle comprises: a housing including: a plurality of slotted openings along an outside surface thereof; and a corresponding plurality of cavities within the housing, each cavity extending to the outside surface of the housing through the slotted opening corresponding thereto and configured to accommodate span wise stowage of a corresponding control surface of the plurality, and each cavity having a section including an angled ledge and side wall support surface to accommodate stowage of the corresponding control surface in a span wise canted position with respect to the corresponding slotted opening.

In accordance with another aspect of the present invention, a method of stowing and deploying a plurality of control surfaces of a guided air vehicle comprises the steps of: folding each control surface of the plurality edge wise through a corresponding slotted opening disposed along an outside surface of a housing and into a corresponding cavity within the housing; moving each folded control surface into a stowage section of the corresponding cavity to edge wise mis-align each folded control surface from the corresponding slotted opening; moving each control surface in the corresponding cavity from the corresponding stowage section into edge wise alignment with the corresponding slotted opening; and deploying each control surface edge wise aligned with the corresponding slotted opening from the cavity through the corresponding slotted opening to a deployed position.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A and 1Bare side and sectional top views, respectively, of a control unit10containing a plurality of control surfaces suitable for embodying the broad principles of the present invention. The control unit10may be disposed in a guided air vehicle (GAV) in such a manner that the plurality of control surfaces protrude through the outer shell of the GAV when deployed in order to guide the GAV during flight as will be better understood from the description found herein below. In the exemplary embodiment depicted inFIGS. 1A and 1B, there are four control surfaces12,14,16and18which are shown in their deployed positions. In this embodiment, the four control surfaces are disposed about the circumference of a cylindrically shaped metal housing20, approximately 90° apart. Each of the control surfaces12,14,16and18which may be made of Titanium or steel, for example, are beveled width wise at an angle away from a center line along the span thereof to render knifed leading and trailing span edges. Thus, each control surface appears sideways in the shape of an elongated diamond as shown by the side view of surface14inFIG. 1A. Note that the material and shape of the control surfaces12,14,16and18are described herein by way of example and that other materials and shapes may be used just as well without deviating from the broad principles of the present invention.

The metallic housing20includes vertical slotted openings22,24,26and28through which the control surfaces12,14,16and18, respectively, may be folded into cavities of the housing20and stowed away as will become more evident from the description found herein below. In the present embodiment, the housing20may be made of Titanium, steel, aluminum or high performance plastics and may be partitioned into two stages—a bottom stage30and a top stage32, for ease in the assembly of parts. For example, electrical actuating motors for each of the control surfaces may be seated in cavities on the top surface of the bottom stage30and protrude upward beyond the top surface. In addition, the bottom stage30contains in cut out cavities thereof drive gear trains and shafts mechanically coupling the actuator motors to their respective control surfaces. Exemplary shafts34and36are shown coupled to control surfaces12and16, respectively, inFIG. 1A. An assembly of motor controller electronics and one or more power sources, such as batteries, for example, may be also disposed in cut out cavities of the bottom stage30and connected through wiring to power and control the actuator motors.

Once the motors, gear trains, shafts, batteries and electronic assembly are secured in place in and on the bottom stage30, then the top stage32may be placed on top of the bottom stage30in a position which aligns the respective slotted openings of the two stages30and32. The top stage32has cavities cut from the bottom surface thereof which match the configurations of the control surface actuator motors which protrude up from the bottom stage30so as to fit over and cover them. The top stage32sits on and around a circumferential edge seal40of the bottom stage30. A long screw42may be disposed up through stage30, screwed into a threaded metal hole in stage32and tightened to secure the two stages30and32together around the edge seal40. An electrical connector44may be secured to an aperture at the bottom of the bottom stage30to permit electrical connections of command signals from a command processor of the GAV to couple to the motor controller electronics of the unit10.

Disposed on top of the top stage32is a circular retaining cap or disk50which may be made of a plastic material, for example. The disk50includes slots52,54,56and58around the circumference of its side surface, approximately 90° apart. In a zero degrees (0°) position state, the disk50is positioned with respect to the top stage32so that the slots52,54,56and58align respectively with the slotted openings22,24,26and28. A screw60secures the disk50to the top stage32and acts as a pivot point for a rotation of the disk50. Grooves corresponding to the control surfaces12,14,16and18are cut into the bottom of the retaining disk50. These groves extend radially from around the pivot point out to the slots52,54,56and58to accommodate the tips of the control surfaces when folded into the housing20. Clearance is retained between the retaining disk50and top stage32circumferentially along a circular edge62to permit a substantially free rotation of disk50with respect to the top stage32, the effects of such rotation being explained in greater detail in the description below.

In the present embodiment, the control surfaces12,14,16, and18may be folded manually through their respective slotted openings22,24,26and28into the housing20. Generally, when deployed, each of the control surfaces are locked into their deployed positions by a latch mechanism, for example. So, when it is time to rotate each control surface into the housing20, the latch mechanism is unlatched and each control surface is rotated about an axis70into the housing20to the 0° position or ready to deploy state (seeFIGS. 3A and 3B). Alternatively, the motor controller of the electronics assembly in the bottom stage30may be pre-programmed to operate the control surface actuator motors through a sequence of operations to fold the control surfaces into the housing20.

In either case, the motor controller is pre-programmed to operate the actuator motors through a sequence of operations to simultaneously stow them in place from the 0° position. The motor controller is also pre-programmed to operate the actuator motors through a sequence of operations, as directed by commands from the command processor of the GAV, for example, to move the control surfaces from the stowed state to the ready to deploy state, and then, to deploy the control surfaces from the housing20. In the present embodiment, the operations of the plurality of motor actuators are synchronized substantially. However, it is understood that this need not be the case. Generally, during testing of the unit10, the control surfaces12,14,16and18are controlled through various operations. Once successful testing is completed, the control surfaces are folded up into the housing20and stowed away therein for storage, transportation and launch. Generally, thereafter, the control surfaces will not be deployed again until commanded to do so after launch and during flight of the GAV.

Once the control surfaces are stowed away in the housing20, the unit10may be disposed within a guided air vehicle (GAV) at a position along the length thereof dependent on whether the control surfaces are to be applied as fins, wings or canards. For example, if the control surfaces are to act as fins, then the unit10is disposed at the rear end of the GAV in such a manner to align the slots22,24,26and28with corresponding slots in the skin or shell of the GAV so that when deployed the control surfaces will protrude through the skin at the rear end of the GAV and act as guiding fins thereof. Accordingly, if the control surfaces are to act as canards, then the unit10is disposed at the front end of the GAV in such a manner to align the slots22,24,26and28with corresponding slots in the skin or shell of the GAV so that when deployed the control surfaces will protrude through the skin at the front end of the GAV and act as guiding canards thereof.

A block diagram functional schematic of the motor controller, control surface actuator motors and corresponding gear trains suitable for use in the embodiment ofFIGS. 1A and 1Bis shown inFIG. 2. Referring toFIG. 2, a common motor controller80is electrically coupled to actuator motors82,84,86and88which respectively correspond to control surfaces12,14,16and18. Each of the motors82,84,86and88are mechanically coupled to its respective control surface shaft through a corresponding gear train92,94,96and98. In the present embodiment, the motors and associated gear trains may be made intentionally inefficient to reduce movement of the control surfaces when in a static position. One or more batteries100may be coupled to the electrical motors82,84,86and88and electronic controller80to provide operational electric power thereto.

As noted above, when the controller80receives a command via connector44, it responds by controlling the motors82,84,86and88through the proper sequence of operations. The motors82,84,86and88, in turn, move the corresponding control surfaces12,14,16and18to their desired positions simultaneously via the respectively corresponding gear train and shaft mechanically linked thereto. For example, if the motor controller80is commanded to fold the control surfaces into the housing20, it controls the motors82,84,86and88to rotate the control surfaces about their respective axes70until each control surface12,14,16and18passes through its corresponding slotted opening22,24,26and28and is contained within their respective cavities of the housing20as shown in theFIGS. 3A and 3Bwhich are side and sectional top views of unit10.

Referring toFIGS. 3A and 3B, the control surfaces12,14,16and18are folded respectively through slotted openings22,24,26and28into cavities102,104,106and108cut into the housing20. During folding of the control surfaces, the retaining disk50is in the 0° position and the tips of the control surfaces pass through retainer slots52,54,56and58and into the corresponding grooves thereof. Once the step of folding the control surfaces12,14,16and18into their respective housing cavities102,104,106and108is complete, the motor controller80may be commanded to execute a sequence of pre-programmed operations to control the motors82,84,86and88to simultaneously rotate and cant the control surfaces12,14,16and18into a stowed position as shown inFIGS. 4A and 4Bwhich are side and sectional top views of unit10.

Referring toFIGS. 4A and 4B, the cavities102,104,106and108are cut out from the housing20to each include an angled ledge112,114,116and118, respectively, and an angled side wall support surface122,124,126and128, respectively, to accommodate stowage of the respectively corresponding control surfaces12,14,16and18.FIG. 5is a cut-away illustration of the housing20showing the stowed control surfaces12,14,16and18in their cavities102,104,106and108resting behind their respective angled ledges112,114,116and118and along their angled side wall support surfaces122,124,126and128. In the present embodiment, the control surfaces12,14,16and18are controlled simultaneously to their stowed positions by rotating their respective shafts counterclockwise approximately 2.5°, for example, from the 0° position around an axis130perpendicular to the page as shown inFIG. 4A.

The rotational motion of a control surface about axis130to and from a stowed position is achieved in the present embodiment by a pinion gear, which is part of the corresponding actuator motor, driving a spur gear that is part of a ball screw or lead screw. A nut of the ball screw or lead screw has a link attached to it via a pin configuration. An opposite end of the link is attached to an arm using the pin configuration. The arm is integral to an output shaft to which the control surface is assembled using a pin that permits the control surface to pivot about axis70from the ready to deploy position (seeFIGS. 3A and 3B) to the deployed position (seeFIGS. 1A and 1B).

Note that as the control surfaces are simultaneously rotated about their respective axes130to their canted or stowed positions behind their respective angled ledges and against their respective angled sidewall supports, the tips of the control surfaces which are disposed into grooves of the retaining disk50cause the retaining disk50along with the slots52,54,56and58to rotate along with them. Accordingly, when in the control surfaces12,14,16and18are in their stowed positions, the corresponding slots52,54,56and58are offset from their 0° position and no longer aligned with their corresponding slotted openings22,24,26and28as shown inFIGS. 4A and 4B. The combination of the offset slots52,54,56and58, the angled ledges112,114,116and118and the angled supporting sidewalls122,124,126and128prevent the control surfaces12,14,16and18from being unintentionally forced out from the housing20as will become better understood from the following description.

During the control surface stowage and launch, the control surfaces are folded within the structure10and are canted or stowed over to their respective control surface side-wall supports. In this stowed position, the control surfaces are located behind their respective angled ledges. Upon launch of the GAV, forces act on the control surfaces to force them against their respective control-surface side-wall supports. If the launch produces a GAV spin, the spin acts to force the control surfaces against their respective control-surface side-wall supports, and in addition, acts to force the trailing edge of the control surface against their respective angled ledges caused by a radial centripetal force. The angled ledges prevent the control surfaces from backdriving or rotating toward their respective control surface slotted opening.

In high-g applications of a GAV such as a cannon or gun launch, special considerations have to be given to the balloting (side-slap) and set-back (primary launch thrust) forces exerted on the control surfaces of unit10. The forces developed during high-g acceleration are such that prior anti-backdrive features may be overcome, possibly resulting in a premature deployment. As shown in the illustration of the present embodiment inFIGS. 6A and 6B, when a balloting force or load is present, a force shown by the arrowed line142acting on the control surface14, for example, is reacted by an equal force shown by the arrowed line144acting on the diametrically opposed control surface18resulting in a zero rotational force. The same action occurs for control surfaces12and16as shown by force arrowed lines146and148, respectively. Under such conditions in the present embodiment, the control surfaces12,14,16and18will not backdrive and will not cause premature deployment.

Also, during set-back force conditions, the control surfaces (which are canted over to the control surface side-wall support) are forced onto their respective side-wall supports. Thus, the side-wall supports absorb some of the set-back load into the housing structure20. In addition, the control surface retainer disk50is forced downwards onto the control surfaces which aids to prevent control surface rotation toward the slot. During set-forward or muzzle exit conditions, a force is exerted on the control surfaces which tries to move the control surfaces off the side-wall support toward the zero degrees or deployment position. In the present embodiment, control surface rotation is limited by a balanced actuation output, inefficiency in the drive mechanism, gear ratio (higher is better), anti-backdrive features of the cavity and slot wall, some resolved force into the control surface retainer disk and short set-forward time duration in which the control surface has too much inertia to move significantly.

Once the GAV is launched and in flight, the motor controller of the unit10is operative to receive a deployment command via connector44. Upon receipt of the control surface deployment command, the control surface motor actuators are controlled by the motor controller80to move their respective control surfaces from their stowed positions (seeFIGS. 4A and 4B) to the zero degrees or ready for deployment positions (seeFIGS. 3A and 3B). During the movement from the stowed to zero degree positions, the control surfaces are forced against their respective angled ledges due to the radial centripetal forces exerted thereon. Thus, the control surfaces tend to resist movement while in their stowed positions due to friction imposed by their respective ledges. In the present embodiment, the respective motor actuators are designed to be capable of overcoming control surface frictional forces caused by the control surface rubbing against its respective angled ledge. The actuator motors are also designed to be capable of overcoming the force exerted by the sloping feature of the angled ledge.

As each control surface moves towards its zero degree position in the same rotational sense as described herein above, the control surface retainer disk50rotates about its pivot point60in the direction of the control surface movement. Accordingly, once the control surfaces are at their respective zero degree positions, they are aligned in their respective slotted openings and are free to be deployed. When the control surfaces are in the ready to be deployed position (seeFIGS. 3A and 3B), the motor controller80is operational to control the actuator motors to cause a simultaneous rotation of the control surfaces12,14,16and18about their respective axis70until the control surfaces are in their deployed positions (seeFIGS. 1A and 1B). As noted above, during deployment, the control surfaces12,14,16and18are aligned with and pass through openings in the outer shell of the GAV so that when deployed, the control surfaces protrude out from the shell in the air stream of the GAV to guide the flight thereof.

It is understood that for standard ground, ship, underwater or air launched applications of a GAV, the slotted control surface retainer disk50may not be needed. However, for certain environment conditions, such as extreme vibration, high shock or very high acceleration such as in a gun launch application of a GAV, the slotted control surface retainer disk50is desirable to prevent the control surface backdriving of the actuator motor during set-back and balloting conditions.

In spin applications of the GAV, the centrifugal force exerted radially on the control surfaces by the spin of the GAV will cause the control surfaces to be forced away from the housing20as they become aligned with their respective slotted openings. Thus, the deployment movement may be initiated by these radial centrifugal forces. However, in those GAV applications in which no spin of the GAV is anticipated, some additional apparatus may be desirable to momentarily force the control surfaces away from their static ready for deployment positions (seeFIGS. 3A and 3B) to start the deployment movement thereof. In these instances, a spring like member, like a torsional spring, for example, may be disposed at the pivot pin of each control surface or in each control surface cavity to momentarily apply a force radially outward on the corresponding control surface as it is aligned with its slotted opening of the housing20. It is understood that in this embodiment, each actuator motor and associated gear train will have to be designed to be capable of compressing the corresponding spring like member when folding the corresponding control surface into its cavity.

While the present invention has been described herein above in connection with one or more embodiments, it is understood that this was done by way of example with no intention of limiting the present invention in any way. Accordingly, the present invention should not be limited by the foregoing described embodiments, but rather, construed in breadth and broad scope in accordance with the recitation of the claims appended hereto.