Folding fin to be deployed upon acceleration

Abstract: A device, particularly a missile (4), includes a body having an appendage, e.g., a wing (6), normally folded in an inoperative position and to be unfolded to an operative position when the body is accelerated in the direction of the longitudinal axis of the body. The appendage is pivotally mounted about a first pivot axis (PP₁) extending perpendicularly to the longitudinal axis of the body, and also about a second pivot axis (PP₂) extending parallel to the longitudinal axis of the body. The center of gravity (CG) of the appendage is outwardly of the first pivot axis in the folded condition of the appendage such that the acceleration of the body produces a moment pivotting the appendage about the first pivot axis.

Description: The present invention relates to a device including a body having a folded appendage which is to be deployed upon acceleration of the body. The invention is particularly useful with respect to missiles or other forms of aircraft or seacraft having one or more wings, fins, vanes or the like, which are normally folded on the body but which are to be unfolded to a deployed condition upon acceleration of the body. The invention is therefore described below with respect to such an application, but it will be appreciated that the invention could also advantageously be used in other applications as well, e.g., for deploying antenna systems, solar collector panels, etc., in spacecraft. Missiles are conventionally housed in canisters and frequently include foldable wings which are folded in order to accommodate the missile within the canister. In the conventional foldable wing construction, the wing is pivotally mounted from a folded, non-operative, position while the missile is in the canister, to an extended or operative position after the missile leaves the canister. Such a construction permits the use of wings having relatively large wing spans to be accommodated in relatively small canisters. A device as defined in the precharacterizing portion of independent claim 1 is disclosed in US-A-4,588,146 which concerns a biaxial folding wing having a torsion spring for pivoting the wing about an axis parallel to the wing span and to the longitudinal axis of a missile body in the folded condition of the wing, and two extension springs for pivoting the wing about an axis right-angularly crossing the longitudinal axis of the missile body. Other folding fin or wing devices are disclosed in GB-A-1,187,035 and US-A-4,667,899 according to which the fin or wing is mounted on a mounting member pivotable on a radial axis of the missile body and the wing is pivotable on the mounting movable about an axis extending in the chordal direction of the wing. The object of the present invention is to provide a device including a body with a novel mounting for a foldable appendage to be unfolded or deployed upon the acceleration of the body in the direction of its longitudinal axis. According to the present invention, to achieve this, there is provided a device including a body having an appendage normally folded in an inoperative position on the body and to be unfolded from a folded condition to an operative position when the body is accelerated in the direction of the longitudinal axis of the body; wherein said appendage is mounted on the body by a hinge member pivotally mounted on the body about a first pivot axis which right angularly crosses the longitudinal axis of said body, and the appendage is pivotably mounted on the hinge member about a second pivot axis extending in the folded condition of the appendage parallel to the longitudinal axis of said body; characterized in that the center of gravity of the appendage is outwardly of the first pivot axis in the folded condition of the appendage, such that the acceleration of the body produces a moment pivoting the appendage about the first pivot axis. According to preferred embodiment of the invention described below, the second pivot axis is outwardly of the first pivot axis and of the appendage center of gravity in the folded condition of the appendage, the acceleration of the body being effective to pivot the appendage about the first pivot axis to move the appendage center of gravity outwardly of the second pivot axis, and then being effective to pivot the appendage about the second pivot axis. In such a construction, the acceleration (or inertial) forces alone may be sufficient to fully open the appendage. However, according to another feature in the described preferred embodiment, it may desirable to include a spring which is prestressed in the fully folded condition of the appendage to produce an initial moment tending to pivot the appendage about the second pivot axis. In the described embodiment, the spring is a torsion bar. According to further features in the preferred embodiment of the invention described below, the body is a missile, and the appendage is a wing. In its fully folded condition, the wing occupies a plane which is generally tangential to the outer surface of the missile. The wing is pivotally mounted about the first and second pivot axes to occupy a plane which is substantially radial to the missile. A missile including foldable wings constructed in accordance with the above features may have a relatively large wing span in the operative condition of the wings, and may still be accommodated in a relatively small canister in the non-operative condition of the wings. Further features and advantages of the invention will be apparent from the description below. The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: Fig. 1 is a front elevational view illustrating a missile constructed in accordance with the invention and housed within a canister; Fig. 2 is a perspective view illustrating one wing of the missile of Fig. 1 in the fully-folded condition of the wing when the missile is in the canister; Fig. 3 is a front elevational view illustrating the movement of the wing about one of its pivot axes; Fig. 4 is a perspective view illustrating the missile wing in its position (theoretical) after having moved about the pivot axis of Fig. 3); Fig. 5 is a side elevational view illustrating the movement of the wing about the other of its pivot axes; and Fig. 6 is a sectional view illustrating an example of the locking mechanism for locking the wing in its fully-open, operative condition. With reference first to Fig. 1, there is illustrated a canister, generally designated 2, housing a missile 4 having four foldable wings 6. Each of the four foldable wings is mounted to the missile 4 by a pivotal assembly, generally designated 8. In the fully-folded condition of the wings 6, the wings are folded so as to be very close to or in contact with the outer surface of the missile 4, and thereby to minimize the size of the canister 2 necessary to accommodate the missile with its foldable wings. The fully-folded condition of each wing 6 in Fig. 1 is more particularly illustrated in Figs. 2 and 3. It will be seen from Fig. 3 that the wing, when in its fully-folded condition (shown in full lines), occupies a plane which is generally tangential to the outer surface of the missile, and with one longitudinal edge 6a of the wing substantially parallel to the missile longitudinal axis 4a. In the fully-open condition of the wing (shown in full lines in Fig. 5), the wing assumes a position which is substantially radial to the missile. The mounting assembly 8 for each of the four foldable wings 6 is located at the rear corner of the respective wing overlying the longitudinal axis 4a of the missile. Each assembly 8 includes a socket member 10 fixed to the missile parallel to its longitudinal axis, a stem 12 fixed to one end of the wing 6, and a hinge member 14. A pivot pin PP 1 , defining a first pivot axis, right angularly crosses the missile longitudinal axis 4a in spaced relationship and passes through the inner end of hinge member 14 and socket member 10. A second pivot pin PP 2 , defining a second pivot axis, extends parallel to the missile longitudinal axis 4a and passes through the outer end of hinge member 14 and the stem 12. Socket member 10 includes a forward section formed with a socket 10a configured to receive the stem 12 in the fully extended, or operative, position of the wing 6 as shown in full lines in Fig. 5. Socket member 10 is further formed with a rear section 10b which is aerodynamically shaped, decreasing in width towards it rear tip, and conforms to the dynamically-shaped rear section 6b of the wing 6. The socket member 10 may be fixed to the missile in any suitable member, as by fasteners 10c (Fig. 4) passing through the rear section of the socket member. Socket member 10 further includes a locking device which locks the wing 6 when in its fully-open, operative condition, as illustrated in full lines in Fig. 5 and particularly in Fig. 6. Thus, as shown in the latter figure, the locking device includes a plunger 20 received within a cavity 22 formed in socket member 10 and normally urged, by spring 24, to project the head 26 of the plunger 20 through a bore 28 formed in the socket member. Stem 12 is formed with a recess 30 extending to the bottom edge 32 of the stem when the stem is received within the socket 10a of socket member 10. The edge 34 of stem 12, between its recess 30 and its lower edge 32, is tapered, as shown at 34; and the outer face of plunger 26 projecting in recess 30 is correspondingly tapered, as shown at 36. The two tapered surfaces 34 and 36 define camming surfaces which automatically, upon the stem 12 entering socket 10a, cam the plunger 20 in one direction (rightwardly, Fig. 6) against spring 24, to permit the full entry of the stem into the socket. As soon as the stem has completely entered the socket, spring 24 snaps plunger 20 in the opposite direction (leftwardly, Fig. 6) to move the outer portion of its head 26 into recess 30 of the stem, thereby firmly locking the stem in the socket 10a. As will be described more particularly below, the wing 6 may be pivoted from its fully-folded position to its fully-open position only by inertial, i.e., acceleration, forces. However, a spring may be included to initiate and/or to enhance this movement of the wing. In this case, such a spring is provided in the form of a torsion bar 40 extending along the lower thickened edge 6a of the wing. Torsion bar 40 is prestressed in torsion in the fully-folded condition of the wing as shown in Figs. 1 and 2, so that as soon as the missile leaves the canister 2, the prestressed torsion bar 40 initiates or augments the pivoting of the wing 6 about pivot axis PP 2 towards the partially-open (theoretical) condition illustrated in Figs. 3 and 4. The illustrated arrangement operates in the following manner: When the missile 4 is in the canister 2, its four wings 6 are in their fully-folded condition as illustrated in Figs. 1 and 2. In this fully-folded condition, each wing occupies a plane which is generally tangential to the outer surface of the missile 4; also the wing longitudinal edge 6a, coupled to the missile by means of the pivotal assembly 8, is substantially parallel to the missile longitudinal axis 4a, as best seen in Fig. 3. As also seen in Fig. 3, in this fully-folded condition of the wings, the inner surface of each wing contacts the outer corner of the socket member 10 at a contact point CP which is located laterally of the pivot axis PP 2 by the distance "k". The location of the center of gravity CG of the wing outwardly of the pivot axis PP 1 is at a distance "b". Accordingly, as soon as the missile 4 leaves the canister and accelerates in the direction of its longitudinal axis 4a, the acceleration of the missile produces an inertial force through the center of gravity CG opposite to the direction of acceleration of the missile. The reaction force produced at the center of gravity CG of the wing, multiplied by the distance "b", produces a moment pivoting the wing 6 about pivot axis PP 1 . This pivoting of the wing about pivot axis PP 1 moves the wing center of gravity CG outwardly of the pivot axis PP 2 , so that the inertial force at the center of gravity CG of the wing now produces a moment tending to pivot the wing about pivot axis PP 2 . Thus, as soon as the missile leaves the canister, the wing 6 tends to pivot about both pivot axes PP 1 and PP 2 . The described embodiment includes the prestressed torsion bar 40. This torsion bar also applies a force producing a moment tending to pivot the wing about pivot axis PP 2 . It will thus be seen that the wing 6 is pivoted about both the pivot axis PP 1 and PP 2 as soon as the missile leaves the canister. As the wing moves about pivot axis PP 1 , its stem 12 (Fig. 4) approaches the socket member 10a fixed to the missile. As soon as the stem 12 begins to enter the socket member 10a, its cam surface 34 (Fig. 6) engages cam surface 36 of the locking plunger 20, to first retract the plunger within its cavity 22, and then to permit the spring 24 to snap the plunger head 26 into recess 30 of the stem, and thereby to firmly lock the wing 6 in its fully-extended position. It will be appreciated that the movement of wing 6 about both pivot axes increases the moment applied to the wing and thereby accelerates its pivotal movements. While the invention has been described with respect to one preferred embodiment, it will be appreciated that this is set forth merely for purposes of example, and that many variations may be made. For example, the torsion spring 40 could be omitted so long as the center of gravity CG of the wing 6 is outwardly of the first pivot axis PP 1 . In addition, the invention may be used in other applications, for example in deploying antenna assembles, solar panels, or the like in spacecraft, or deploying fins in torpedoes. Many other variations, modifications and applications of the invention will be apparent.

Claims: A device including a body (4) having an appendage (6) normally folded in an inoperative position on the body (4) and to be unfolded from a folded condition to an operative position when the body (4) is accelerated in the direction of the longitudinal axis (4a) of the body (4), wherein said appendage (6) is mounted on the body (4) by a hinge member (14) pivotally mounted on the body (4) about a first pivot axis (PP1) which right angularly crosses the longitudinal axis (4a) of said body (4), and the appendage (6) is pivotably mounted on the hinge member (14) about a second pivot axis (PP2) extending in the folded condition of the appendage (6) parallel to the longitudinal axis (4a) of said body (4); characterized in that the center of gravity (CG) of the appendage (6) is outwardly of the first pivot axis (PP1) in the folded condition of the appendage (6), such that the acceleration of the body (4) produces a moment pivoting the appendage (6) about the first pivot axis (PP1). The device according to claim 1, wherein said second pivot axis (PP2) is outwardly of the first pivot axis (PP1) and of the appendage center of gravity (CG) in the folded condition of the appendage (6), the acceleration of the body (4) being effective to pivot the appendage (6) about said first pivot axis (PP1) to move the appendage center of gravity (CG) outwardly of the second pivot axis (PP2), and then being effective to pivot the appendage (6) about said second pivot axis (PP2). The device according to either of claims 1 or 2, wherein said appendage (6) includes a spring which is prestressed in the fully folded condition of the appendage (6) to produce an initial moment tending to pivot the appendage (6) about said second pivot axis (PP2). The device according to claim 3, wherein said spring is a torsion bar (40). The device according to any one of claims 1 to 4, wherein said body is a missile body (4), and said appendage is a wing (6) which, in its folded condition, occupies a plane which is generally tangential to the outer surface of the missile body (4); and wing (6) being pivotally mounted about said first and second pivot axis (PP1, PP2) to occupy a plane which is substantially radial to the missile body (4). The device according to claim 5, wherein said wing (6) is pivotally mounted by a mounting assembly (8) comprising: a socket member (10) fixed to the missile body (4); a stem (12) fixed to the pivotally mounted end of the wing (6); the hinge member (14) pivotally mounted at one end to the socket member (10) about said first pivot axis (PP1) and pivotally mounted at its opposite end to said stem (12) about said second pivot axis (PP2); and a locking device located within said socket member (10) for engaging and locking said stem (12) when received in the socket member (10) after the wing (6) has pivoted about said first and second pivotal axes (PP1, PP2). The device according to claim 6, wherein said first pivot axis (PP1) is constituted of a first pivot pin between said socket member (10) fixed to the missile body (4) and one end of the hinge member (14), and said second pivot axis (PP2) is constituted of a second pivot pin between the opposite end of the hinge member (14) and said stem (12). The device according to claim 6, wherein said locking device includes a plunger (20) and a spring (24) urging said plunger (20) to a locking position with respect to said stem (12); said plunger (20) and stem (12) being formed with cooperable camming surfaces (34, 36) which automatically, upon the stem (12) being moved initially into said socket member (10), cam the plunger (20) in one direction against said spring (24) to thereby permit full entry of the stem (12) into the socket member (10), and then to permit the spring (24) to move the plunger (20) in the opposite direction to lock the stem (12) in said socket member (10). The device according to claim 8, wherein said stem (12) is formed with a recess (30) for receiving said plunger (20); said recess (30) extending to the lower edge (32) of the stem (12); the edge of the stem (12) between said recess (30) and the lower edge (32) being tapered to form one (34) of said camming surfaces (34, 36). The combination of a missile and a canister (2) therefor, said missile (4) including at least one foldable wing (6) according to any one of claims 5-9.

Inventors: ROM HANAN, YEHEZKELI ODED, ROM, HANAN, YEHEZKELI, ODED
Applicants: ISRAEL STATE, STATE OF ISRAEL-MINISTRY OF DEFENCE RAFAEL ARMAMENT DEVELOPMENT AUTHORITY
Application year: 1993
Main classification: F42B10
IPC codes: F42B10