Patent Description:
Two types of standard attachment methods for air-carried weapons include rails and suspension lugs. Weapons carried by suspension lugs are increasingly common, as aircraft move toward internal carriage of weapons where rail launching is not applicable. While suspension lugs are standard items and are compatible with a large number of military standard bomb racks, these lugs protrude from the outer mold line of the weapon and impose a significant aerodynamic penalty. The aerodynamic issues become more pronounced as weapon speed increases and/or weapon size decreases, which are current trends. To address aerodynamic issues, several weapon systems have adopted variants of the standard suspension lugs that rotate into the airframe after weapon release, via spring loaded mechanisms. While reducing the aerodynamic penalty of the protruding lug, it does not create a smooth, uninterrupted surface on the weapon's outer mold line and the mechanism(s) consume critical packaging volume.

New attachment means are desirable for creating an aerodynamic surface without significantly impacting packaging volume.

<CIT> discloses a self-retracting bomb suspension lug assembly for being releasably supported by a hook or the like of an airplane bomb rack. The lug is mounted within a housing for axial movement and has an outer surface conforming to the shape of the bomb so as to eliminate aerodynamic drag when the bomb is released. Springs, such as a stack of Belleville springs, are disposed for biasing the lug inward when the bomb is released and the weight of the bomb no longer bears on the lug. Finger springs and pawls engagable with a groove in the bottom surface of the lug are provided to maintain the lug in partially extended loading position wherein the top of the lug is accessible for being grasped. To cock the lug, it is moved slightly inward against the force of the lug biasing spring, and the finger springs are forced radially inward to engage the groove. Upon grasping of the top of the lug, the weight of the bomb forces it to become fully extended, releasing the pawls from the grooves and clearing a downward path for full retraction of the lug when the weight of the bomb is released.

<CIT> discloses the invention relating to a suspension lug (suspension eye) for a missile, which suspension lug is guided by a groove and behind which said groove engages, and which can automatically be ejected from the missile after it has been launched from the aircraft.

<CIT> relates to a aircraft bomb, fitted with a suspension eye or suspension rod, by which the bomb is attached an aircraft can be hung, for example, on the hook of one. bomb-dropping device.

<CIT> discloses a device for ejecting a store from an aircraft stores rack. The device comprises a tubular member having an internal bore along its longitudinal axis. A plurality of resilient lug retainer fingers are attached at one end of the tubular member and extend about and parallel to the longitudinal axis of the tubular member, movable from a first position, in engagement with a lug mounted on the store, to a second position, disengaged from the lug. A collar is mounted about the tubular member movable from a first position, wherein the collar holds the retaining fingers in engagement with the lug, to a second position, wherein the collar is disengaged from the retaining fingers. An ejector ram is mounted within the bore of the tubular member. An actuation system is provided which is adapted to first move the collar from the first to the second position and, afterwards, drive the ram into the lug causing the retaining fingers to move from the first to the second position, thus disengaging the retainer fingers from the lug, and forcibly ejecting the store from the aircraft.

<CIT> discloses a system for releasably supporting a store on a rack comprising a conical lug mounted on the store and a hollow locking ring which extends between minor and major rims defining circular openings, respectively. A plurality of ribs extends between the minor and major rims at equally spaced circumferential locations. The ribs are aligned with the longitudinal axis of the locking ring and define windows between them. A collet includes a mounting head for attachment to the rack and a plurality of integral, circumferentially spaced, resilient, locking fingers, equal in number to the ribs and windows in the locking ring, which extend divergingly, away from the mounting head and have terminal projections which extend radially inwardly. Each locking finger is smaller than its associated window in the locking ring means. The collet nests with the locking ring such that the mounting head extends through its minor opening for attachment to the rack means and with the locking fingers projecting toward its major opening. Upon insertion of the lug into a reception region defined by the mounting head and the locking fingers and with each of the locking fingers aligned with an associated one of the windows, the locking fingers are engaged by the lug and urged radially outwardly into their associated windows until the terminal projections on the locking fingers firmly engage the annular groove on the lug, thereby securing the store to the rack. An actuating mechanism rotates the locking ring between a release position whereat each locking finger is radially aligned with an associated window and a locking position whereat each locking finger is aligned with an associated rib. An ejection mechanism may be provided on the rack for selectively ejecting the store from the rack means when the locking ring is in the release position.

According to a first aspect, the present disclosure provides a suspension lug arrangement according to claim <NUM>.

According to a second aspect, the present disclosure provides a system for releasably mounting a store suitable for aerial deployment, according to claim <NUM>.

This disclosure presents a suspension lug arrangement for an airborne store that includes a recessed lug and a spring-loaded plug for providing a smooth and aerodynamic outer store surface when disengaged from a mounting rack. The mounting rack includes a collet assembly corresponding to each suspension lug region on the store. Each collet assembly includes a collar, a shaft, and a plurality of hooked fingers for releasably engaging the recessed lug on the store.

<FIG> is a perspective schematic view of store <NUM> mounted to rack <NUM> which can itself be mounted to aircraft <NUM>. Aircraft <NUM> is shown as a jet aircraft but can generally be a manned or unmanned, fixed-wing or rotor craft having one or more locations (e.g., an underside of a wing or fuselage, internal bay, etc.) for mounting store <NUM> via rack <NUM>. In an exemplary embodiment, store <NUM> carries munitions (i.e., is a bomb, missile, rocket, etc.) with a mass ranging from <NUM> to <NUM> ( <NUM> pounds up to <NUM>,<NUM> pounds).

In an alternative embodiment, store <NUM> can be any object suitable for aerial deployment, such as a chaff, a fuel pod, a micro-drone, or a surveillance package, to name a few non-limiting examples. As shown in <FIG>, store <NUM> has a main body <NUM> that can include additional features (e.g., radome, fins, sway braces, etc.) not shown for simplicity.

<FIG> is a schematic perspective view of body <NUM> of store <NUM> showing suspension lug regions <NUM>. <FIG> is a cross-sectional view of a suspension lug region <NUM> taken along line <NUM>- <NUM> of <FIG> and <FIG> will be discussed together. Each region <NUM> includes lug <NUM>, well <NUM>, compressible member <NUM>, and plug <NUM>. Lug <NUM> includes base <NUM> in communication with body <NUM>, and an oppositely disposed head <NUM>. Base <NUM> has a first width W1 in the direction of longitudinal body axis B and head <NUM> has a second width W2. In the embodiment shown, lug <NUM> is a circular structure such that the first and second widths W1, W2 can alternatively be referred to as first and second diameters D1 and D2, respectively. Second width W2 is greater than first width W1 giving lug <NUM> a generally T-shaped cross-sectional geometry. In an alternative embodiment, lug <NUM> can have other geometries such as polygonal or elliptical, with generally equal dimensions (e.g., squared, hexagonal, etc.) or elongate in one direction, for example, with a greater length (not shown) perpendicular to the width. Lug can be formed from a metallic material such as steel. Although a variety of lug geometries are conceivable, all would maintain a head wider, at least in one dimension, than the base.

Base <NUM> can be attached to body <NUM> of store <NUM> using a metallurgical joining technique (e.g., welding, brazing, etc.), or base <NUM> can be fastened to body <NUM> via threaded engagement or some other fastening means. Head <NUM> has an outer surface <NUM> (surface furthest from base <NUM>) aligned with the outer surface of body <NUM>, and an inner surface <NUM> which can be an overhang surface created by the greater width W2 of head <NUM>. Inner surface <NUM> can be slightly angled with respect to body axis B.

Well <NUM> is shown as a void surrounding lug <NUM> and is defined by an axially disposed floor <NUM> and radially disposed wall <NUM>, relative to body axis B. Compressible member <NUM> is shown as a spring (hereinafter referred to as spring <NUM>) and can be compressed in the radial direction toward floor <NUM> under an applied force. As the force is reduced/removed, spring <NUM> expands upward toward head <NUM> of lug <NUM>. Plug <NUM> is disposed within well <NUM> and includes outer surface <NUM> and peripheral surface <NUM> in contact with and slidable along wall <NUM> of well <NUM>. Plug also includes seat <NUM> engageable with inner surface <NUM> of head <NUM> in its radially outermost position. Such position occurs when no (or insignificant) force acts to compress spring <NUM>. In such a state, as is shown in <FIG>, the outer surface of body <NUM> is aligned with outer surface <NUM> of head <NUM> and outer surface <NUM> of plug <NUM> to create a generally smooth and uninterrupted surface along body <NUM>. Plug <NUM> is prevented from extending beyond the extent of outer surface <NUM> of head <NUM> because of the engagement of seat <NUM> and inner surface <NUM>. Plug <NUM> further includes recess <NUM> for engaging spring <NUM> such that plug <NUM> is movable within well <NUM> with spring <NUM>. Spring <NUM> and plug <NUM> can be made from metallic materials.

In the embodiment shown, lug <NUM> is concentric with well <NUM>, spring <NUM>, and plug <NUM>, each of which fully surrounds lug <NUM>. In an alternative embodiment, any of well <NUM>, spring <NUM>, and plug <NUM> may be multiple pieces and/or may not completely surround lug <NUM>. For example, well <NUM> could be configured as two arcuate recesses, each housing a spring <NUM> and plug <NUM>. Other geometries and/or multi-piece configurations are contemplated herein. The operation of lug <NUM> and well <NUM> are described in greater detail below with regard to <FIG>.

<FIG> is a cross-sectional view of store <NUM> and rack <NUM> in a first state in which store <NUM> is releasably mounted to rack <NUM>. <FIG> is an enlarged cross-sectional view of detail A5 of <FIG>. <FIG> is an exploded view of a collet assembly shown in <FIG> and <FIG>. <FIG> will be discussed together.

As shown in <FIG>, store <NUM> includes two suspension lug regions <NUM>, spaced apart a distance S, which can be, for example, <NUM> (<NUM> in) to <NUM> (<NUM> in), based on common military specifications for airborne stores. Other distances are contemplated herein based on the type, size, and weight of store, to name a few non-limiting examples. Rack <NUM> includes two collet assemblies <NUM> corresponding to lug regions <NUM> of store <NUM>. Each collet assembly <NUM> includes cylindrical collar <NUM> having a collar axis C, shaft <NUM> movable in the axial direction relative to collar axis C, hooked fingers <NUM> (only two are visible) attached to shaft <NUM>, and a spring <NUM> for each hooked finger <NUM>. Each of collar <NUM>, shaft <NUM>, hooked fingers <NUM>, and springs <NUM> can be formed from various metallic materials or other materials suitable for store-mounting applications.

Collar <NUM> includes inner surface <NUM> (labeled in <FIG>) against which a portion of each hooked finger <NUM> can come into contact, as is shown in <FIG>. Collar <NUM> further extends beyond rack <NUM> for engagement with well <NUM> of the corresponding suspension lug region <NUM>. Shaft <NUM> is coaxial with and slidable within collar <NUM>. In the first state shown in <FIG> and <FIG>, shaft is partially disposed within bore <NUM> (labeled in <FIG>) of rack <NUM> and collar <NUM>. Thus, the first state of rack <NUM> and store <NUM> corresponds to a retracted state of shaft <NUM>. An exemplary embodiment includes six hooked fingers <NUM>. As such, shaft <NUM> is shown in <FIG> as a hexagonal structure with six sides, each side configured to accommodate a hooked finger <NUM>, although only one is shown in <FIG> for simplicity. However, an alternative embodiment can include anywhere from two to six hooked fingers evenly circumferentially spaced about shaft <NUM>. In an embodiment in which lug <NUM> is non-circular, collar <NUM> and shaft <NUM> can be correspondingly shaped to engage with lug <NUM>. In such an embodiment, hooked fingers <NUM> can be disposed about shaft <NUM> in any manner necessary to be evenly distributed about lug <NUM> when engaged. For even load distribution, hooked fingers <NUM> can be distributed evenly about the circumference of shaft <NUM>.

Each spring <NUM> can be at least partially disposed in spring bore <NUM> (visible and labeled in <FIG>) of collar <NUM>. Each hooked finger <NUM> can be attached to collar <NUM> by pin <NUM> about which each hooked finger <NUM> is rotatable to allow each hooked finger <NUM> to move radially, with respect to collar axis C, as is discussed in greater detail below. Each hooked finger <NUM> has a hooked end <NUM> engageable with head <NUM> of lug <NUM> in the first state, as is shown in <FIG> and <FIG>. In the first state, collar <NUM> and hooked fingers <NUM> force plug <NUM> and spring <NUM> downward (toward floor <NUM> of well <NUM>) permitting hooked end <NUM> of each hooked finger <NUM> to engage with head <NUM> of lug <NUM>, including head inner surface <NUM>. Inner surface <NUM> of collar <NUM> prevents radial outward movement of hooked fingers <NUM> such that store <NUM> is secured, via suspension lug region <NUM>, to rack <NUM>.

<FIG> is a cross-sectional view of store <NUM> and rack <NUM> in a second, intermediate state in which store <NUM> is being released from rack <NUM>. <FIG> is an enlarged cross-sectional view of detail A8 of <FIG>. <FIG> and <FIG> will be discussed together.

In the second state, piston plunger <NUM>, represented schematically by a downward-facing arrow, pushes store <NUM> downward/away from rack <NUM>. Piston plunger <NUM> can be a pneumatic or hydraulic piston, or other type of actuator known in the art. As piston plunger <NUM> acts to push store <NUM> downward (away from rack <NUM>), each shaft <NUM> correspondingly moves downward from bore <NUM> and collar <NUM> such that a portion of shaft <NUM> extends beyond collar <NUM>. Hooked fingers <NUM> are similarly moved downward and beyond collar <NUM>, as they are attached to shaft <NUM>. Because hooked fingers <NUM> are no longer radially constrained by inner surface <NUM> of collar <NUM>, each spring <NUM> acts to force a hooked finger <NUM> radially outward, relative to collar axis C. The angle of inner surface <NUM> of head <NUM> also facilitates this outward movement. This causes hooked ends <NUM> to disengage from head <NUM> of lug <NUM>, and spring <NUM> releases from its contracted position and forces plug <NUM> in the direction of head <NUM>.

<FIG> is a cross-sectional view of store <NUM> and rack <NUM> in a third state in which store <NUM> is disengaged from rack <NUM>. <FIG> is an enlarged cross-sectional view of detail A10 of <FIG> and <FIG> will be discussed together.

In the third state, store <NUM> is disengaged (i.e., fully released) from rack <NUM>. As hooked ends <NUM> disengage from head <NUM> in the second state, spring <NUM> releases from a compressed state and it travels away from floor <NUM> of well <NUM> pushing plug <NUM> upward until seat <NUM> of plug <NUM> engages inner surface <NUM> of head <NUM>. The engagement of seat <NUM> and inner surface <NUM> (both labeled in <FIG>) halts upward travel of spring <NUM> and plug <NUM>, and outer surface <NUM> of plug <NUM> is aligned with outer surface <NUM> of head <NUM> and the outer surface of body <NUM> as is shown and described with respect to <FIG>. This provides a smooth, aerodynamic outer contour along body <NUM> of store <NUM>.

The third state corresponds to an extended state of shaft <NUM>, in which it does not occupy bore <NUM> and extends beyond collar <NUM>. Also in the third state, each hooked finger <NUM> (four are visible in <FIG> with two being out of plane) is no longer constrained by engagement with head <NUM> of lug <NUM> or being fully retracted within collar <NUM>. Thus, the force exerted by spring <NUM> moves the corresponding hooked finger <NUM> radially away from shaft <NUM>, relative to collar axis C. As is shown in <FIG>, radial movement is, however, limited, by abutting of the portion of hooked finger <NUM> nearest pin <NUM> with inner surface <NUM> of collar <NUM>.

Store <NUM> and/or rack <NUM> described above can alternatively have a variety of configurations not discussed above, such as more than two lugs <NUM> disposed about body <NUM> with corresponding collet assemblies <NUM> on rack <NUM>. Collet assembly <NUM> can include more than six hooked fingers <NUM> based on the size of lugs <NUM> and store <NUM>. Springs <NUM> can also be replaced with linkage assemblies for facilitating radial movement of hooked fingers <NUM>. Other configurations are contemplated herein.

Claim 1:
A suspension lug arrangement for a store suitable for aerial deployment, the store having an outer surface, the suspension lug (<NUM>) arrangement comprising:
at least one lug region (<NUM>) comprising a lug configured to be disposed in a body of the store,
the lug comprising:
a base portion (<NUM>) configured to be embedded within and configured to be joined to the body (<NUM>) of the store; and
a head portion (<NUM>) configured to extend outward from the base portion to the outer surface of the store, the head portion comprising an outer surface (<NUM>) configured to be aligned with an adjacent portion of the outer surface of the body;
the suspension lug (<NUM>) arrangement further comprising:
a well (<NUM>) at least partially surrounding the lug;
a compressible member (<NUM>) disposed within the well; and a plug (<NUM>) retained within the well and engaging the compressible member disposed therein, wherein the plug comprises:
a seat (<NUM>) for engaging an inner surface (<NUM>) of the head of the lug;
a recess (<NUM>) for engaging the compressible member; and
a peripheral surface (<NUM>) slidable along a wall (<NUM>) of the well.