Patent Description:
Such suspension lugs protrude from the store and contribute to the aerodynamic drag after the store has been released from the parent aircraft, when the store is in free flight, or in free fall on its way to the ground.

To minimise this drag the lug could fold back e.g. under spring action, leaving no or a reduced protrusion. However, then the un-folded lug must be retained in the erect condition against the spring action during loading onto the release unit hooks, which is problematic.

<CIT>, <CIT> and <CIT> disclose self-retracting bomb suspension lugs which are linearly withdrawable into a housing under spring bias, when the weight of the bomb is released from the lug. For loading the bomb onto a suspension hook, the lug may be held in an extended position by a cocking mechanism. Loading the bomb onto the suspension hook causes the suspension lug to be pulled further outward from the housing against the spring bias, thereby releasing the cocking mechanism. Then when the bomb is released from the suspension hook, the spring bias is able to retract the suspension lug fully into the housing. However, to achieve a streamlined configuration when retracted, such linearly retractable suspension lugs are relatively intrusive as far as the store internals are concerned. The housing must be at least as deep as the height of the extended suspension hook.

More compact foldable store suspension lug arrangements are known, as shown for example in <CIT>. However, because the foldable store suspension lug rotates about a fixed axis, it is held in its upright or unfolded position by a manually withdrawable safety pin. , e.g., <FIG>, and paragraphs [<NUM>] and [<NUM>]). Such an arrangement does not on loading the store automatically set the foldable suspension lug to fold down upon release of the store. Automatically released cocking mechanisms of the kind known in relation to linearly retractable lugs cannot be used in the case of a folding lug rotating on a fixed axis. Problems can therefore arise e.g. if the safety pin is inadvertently left in place after loading the store.

The present invention accordingly provides a store suspension lug assembly as defined in claim <NUM>. With the lug portion held in the extended position by the locking mechanism, the store may be easily loaded onto the suspension hook of the release unit. The suspension hook can then act on the lug portion to set the locking mechanism to the released state in which the lug portion is movable relative to the base. Then when the suspension hook is disengaged from the lug portion as the store is released from the release unit, the mechanical bias moves the lug portion to the retracted position, so as to reduce aerodynamic drag on the released store. Thus, no separate step is required by the ground crew to release the locking mechanism, reducing the possibility of incorrect suspension lug operation due to human error.

A part of the locking mechanism is arranged in or on the lug portion, so that the weight of the store acting on the suspension hook via the lug portion also acts to set the locking mechanism to the released state. Then when the suspension hook is disengaged from the lug portion as the store is released from the release unit, the lug portion will move automatically to the retracted position under the mechanical bias.

After the locking mechanism is set to the released state and until the suspension hook is disengaged from the lug portion, the lug portion may be maintained in the extended position against the mechanical bias in a simple manner by its engagement with the suspension hook.

The hinged coupling between the base and the lug portion provides for a compact overall structure and low aerodynamic profile when the lug portion is in the retracted position.

The locking member may be slidable transversely of a hinge axis of the hinged coupling. In this way the locking member may easily engage with and disengage from other parts of the locking mechanism to hold the lug portion in its extended position or release the lug portion for movement to its retracted position.

The locking member may be generally U-shaped, for example. The base of the U may extend across the portal of the lug portion bordering or close to a top edge thereof, and the legs of the U may extend along sides of the lug portion, e.g. bordering the portal. For example, the lug portion may also be generally U-shaped.

The locking mechanism may comprise a keeper coupled to the base and mechanically biased from an active position in which it is lockingly engageable by the locking member to set the locking mechanism into the locked state, to an inoperative position in which the keeper is not lockingly engageable by the locking member. Thus, when the locking member is disengaged from the keeper, the keeper moves to the inoperative position under its mechanical bias. The locking member is thereby prevented from re-engaging the keeper, so that the locking mechanism remains in the released state and the lug portion can move towards the retracted position under its mechanical bias.

The keeper may comprise a cam surface engageable by the locking member so as to move the keeper from the inoperative position to the active position. For example, the locking member may so engage the cam surface to cause such movement of the keeper as the lug portion is moved from the retracted position to the extended position. Thus the locking mechanism may be automatically set to the locked state as the lug portion is moved from the retracted position to the extended position. The keeper may for example be movable longitudinally with respect to a hinge axis of the lug portion.

The keeper may comprise a second active position in which it is lockingly engageable by the locking member to hold the lug portion in the retracted position. The second active position of the keeper may correspond to the inoperative position relative to the base, but with the locking member carried by the lug portion as it moves to the retracted position, so as to lockingly re-engage the keeper. The lug portion may thus be held securely in the retracted position until the store is ready to be loaded onto the suspension hook.

The locking member may be mechanically biased towards the keeper. Hence the locking member can lockingly engage the keeper in the second active position even if the locking member is generally horizontal so that it is not biased towards the keeper under its own weight. Mechanically biasing the locking member in this way can also assist its locking engagement with the keeper in the first active position.

The above and other optional features and advantages of the invention are further elucidated by the following description of an illustrative embodiment of the invention made with reference to the drawings, in which:.

Referring firstly to <FIG>, the illustrative store suspension lug assembly <NUM> comprises a base <NUM> and a looped lug portion <NUM> hingedly coupled to the base <NUM> by a hinge pin <NUM>. The base <NUM> is securable to a suitable strong point on the store (not shown), positioned so that the suspension lug assembly <NUM> will be appropriately aligned with the corresponding suspension hook of the parent aircraft release unit (not shown). The base <NUM> is provided with three countersunk bolt holes <NUM> for this purpose. The hinge pin <NUM> is a press fit in the lug portion <NUM> and a close rotating/sliding fit in the base <NUM>. Therefore the lug portion <NUM> and hinge pin <NUM> can be rotated as a unit relative to the base <NUM>, between a retracted position in which the lug portion <NUM> lies generally horizontally in a pocket <NUM> within the base <NUM>, and an extended position in which the lug portion <NUM> stands up generally vertically from the base <NUM>. In this extended position a portal <NUM> in the lug portion <NUM> is accessible for reception of the release unit hook (not shown), for suspending the store from the parent aircraft.

A torsion spring <NUM> is fitted about the hinge pin <NUM> and has a first end 24a braced against the store and/or received in a retaining slot <NUM> in the base <NUM>. A second end of the torsion spring <NUM> (not visible in <FIG>) is braced against the lug portion <NUM> in a slot <NUM>, so as to mechanically bias the lug portion towards and into the "down" or retracted position within the pocket <NUM>. The torsion spring <NUM> is omitted from <FIG> for simplicity.

Prior to fitment to the release unit of the parent aircraft, stores can be delivered and handled with the lug portion <NUM> locked in the "down" or retracted position. This helps to prevent damage to the lug portion <NUM> and its environment by any accidental knocks. To prepare the store for fitment to the release unit hook via the suspension lug assembly <NUM>, a flat bladed tool is inserted into an access notch <NUM> to disengage a locking mechanism as further explained later below. Another tool can then be inserted into a tool interface <NUM> formed in or on one end of the hinge pin <NUM> and used to rotate the lug portion <NUM> up into the extended position as shown in <FIG>, against the bias of the spring <NUM>. Although the drawings show a flat blade screwdriver slot, any suitable tool interface could be provided as desired (hex wrench, crosshead, etc). The locking mechanism also ensures that the lug portion <NUM> will remain "up" once fully extended, as further explained below.

Referring now to <FIG>, the locking mechanism comprises a locking member <NUM> in the form of a U shaped locking bar slidably received within the lug portion <NUM>. In <FIG>, the lug portion <NUM> and hinge pin <NUM> are omitted, so that the U-shaped locking bar <NUM> is more clearly visible (viewed from above, in a position in which the lug portion <NUM>, if it were present, would be in the "up" position). The locking member/locking bar <NUM> is slidable in the lug portion <NUM> in a direction radially towards or away from the hinge pin <NUM>. The locking mechanism further comprises a keeper <NUM> mechanically coupled to the base <NUM>. In the illustrative example, the keeper is provided in the form of a locking disc <NUM> which is mechanically coupled to the base by being axially slidably received on the hinge pin <NUM>. The keeper/locking disc <NUM> has an axially extending guide slot <NUM>. A guide pin <NUM> has a first end fixedly received in a drilling <NUM> in the base <NUM> and a second end freely projecting from the drilling <NUM>, into the guide slot <NUM>. The keeper/locking disc <NUM> is thereby guided for axial movement on the hinge pin <NUM>, without rotation relative to the base <NUM>. The keeper/locking disc <NUM> is mechanically biased outwards, towards the left hand end of the locking pin <NUM> as shown in <FIG>, by a wavy spring <NUM>. This spring is received in an annular recess formed in the body of the keeper/locking disc <NUM> and is braced between the bottom of the annular recess and the base <NUM>.

<FIG> show the locking mechanism in the locked state, in which the lug portion <NUM> is held in the extended or "up" position relative to the base <NUM>. This state arises because an end of the locking member/locking bar <NUM> enters into a first receiving hole <NUM> in the keeper/locking disc <NUM> (see <FIG>) in a manner further explained later below. The lug portion <NUM> and hinge pin <NUM> are thereby prevented from rotating relative to the keeper/locking disc <NUM> and base <NUM>. This keeps the lug portion <NUM> in the upright, extended position, against the mechanical bias of the torsion spring <NUM>, for loading of the store onto the release unit hook.

As best seen in <FIG>, a base part of the U-shaped locking bar <NUM> forming the locking member extends across the top edge region of the portal <NUM> in the lug portion <NUM>. A leaf spring (not visible in the drawings) is interposed between this base part and the bottom of a corresponding reception recess in the adjacent part of the lug portion <NUM>. The leaf spring biases the locking bar <NUM> towards the hinge pin <NUM> and therefore together with the weight of the locking bar <NUM>, pushes the end of the locking bar <NUM> into the first receiving hole <NUM> when the keeper/locking disc <NUM> is in its innermost, active position as shown in <FIG>. As the lug portion <NUM> is brought into engagement with the release unit suspension hook in the portal <NUM>, the weight of the store is reacted through the suspension hook and acts on the locking bar <NUM> to retract it into the reception recess in the lug portion <NUM>. The end of the locking bar <NUM> is thereby withdrawn from the first receiving hole <NUM>.

The keeper/locking disc <NUM> then moves outward under the force of the wavy spring <NUM>, obscuring the first receiving hole <NUM>, and hence preventing re-engagement of the locking bar <NUM> end. This configuration is shown in <FIG>. At this point, the lug portion <NUM> is prevented from rotating under the bias of the torsion spring <NUM> by presence of the release unit suspension hook.

The weight of the store acting on the lug portion <NUM> is removed at ejection. But the end of the locking bar cannot re-engage with the keeper/locking disc <NUM>, which has moved axially outward to obscure the first receiving hole <NUM>. The keeper/locking disc <NUM> is thus in the inoperative position, in which it is not lockingly engageable by the locking member/locking bar <NUM> when the lug portion <NUM> is in the "up" or extended position. At store ejection, the suspension hook is also withdrawn from the lug portal <NUM>. This leaves the torsion spring <NUM> free to rotate the lug portion <NUM> (and the stowed locking bar <NUM>) towards the down or retracted position. <FIG> shows such rotation in progress. Thus upon opening (release) of the release unit suspension hook, the lug portion <NUM> folds back without the locking member/locking bar <NUM> reengaging, resulting in a retracted folded lug portion <NUM> and a smooth aerodynamic profile to the store.

Returning to <FIG>, as the lug portion <NUM> (not shown in this Figure) comes down into the pocket <NUM>, the end of the locking bar aligns with a second receiving hole <NUM> in the keeper/locking disc <NUM>. The locking bar <NUM> is biased into engagement with this second receiving hole <NUM> by the unseen leaf spring in the reception recess of the lug portion <NUM>. The lug portion <NUM> is thereby locked in the fully retracted or "down" position. Hence the outward, inoperative position of the keeper/locking disc <NUM> relative to the base <NUM> when the lug portion <NUM> is in its extended position also corresponds to a second active position of the keeper/locking disc <NUM> when the lug portion <NUM> is in its retracted position.

Referring still mainly to <FIG>, a portion <NUM> of the outer circumferential surface of the keeper/locking disc <NUM> between the first <NUM> and second <NUM> receiving holes, is recessed to define an axially outwardly facing, helical cam surface <NUM>. When the end of the locking member/locking bar <NUM> is withdrawn from the second receiving hole <NUM> (e.g. by inserting a flat-bladed tool into the access notch <NUM> as described above, and displacing the locking bar <NUM> against the action of the unseen leaf spring - see <FIG>), this end still projects slightly from the lug portion <NUM>, so as to engage the cam surface <NUM>. As the lug portion <NUM> is raised towards the extended position, the projecting end of the locking member/locking bar <NUM> therefore moves along the cam surface <NUM> and pushes the keeper/locking disc <NUM> axially inwards along the hinge pin <NUM>, against the action of the wavy spring <NUM>. When the lug portion <NUM> reaches its fully extended position, the keeper/locking disc <NUM> is therefore set/reset to its active position and the end of the locking member/locking bar <NUM> is able to drop/snap into the first receiving hole <NUM> under its own weight and/or under the action of the unseen leaf spring (this condition of the locking mechanism being shown in <FIG>).

Claim 1:
A store suspension lug assembly (<NUM>) comprising a base (<NUM>) securable to or incorporated in a store, a lug portion (<NUM>), and a hinged coupling (<NUM>) by which the lug portion (<NUM>) is coupled to the base (<NUM>) so as to be movable between an extended position in which the lug portion (<NUM>) is engageable by a suspension hook of a release unit and a retracted position presenting a lower aerodynamic profile than in the extended position; the lug portion (<NUM>) being mechanically biased towards the retracted position; characterised in that the store suspension lug assembly (<NUM>) further comprises a locking mechanism (<NUM>, <NUM>) having a locked state in which the lug portion (<NUM>) is held in the extended position; wherein the locking mechanism (<NUM>, <NUM>) is moved from the locked state to a released state by the suspension hook when the suspension hook is engaged with the lug portion to support the weight of the store and a part (<NUM>) of the locking mechanism (<NUM>, <NUM>) is arranged in or on the lug portion (<NUM>), so that the weight of the store acting on the suspension hook via the lug portion (<NUM>) also acts to set the locking mechanism (<NUM>, <NUM>) to the released state; the part of the locking mechanism comprising a locking member (<NUM>) extending across a portal (<NUM>) in the lug portion (<NUM>) configured for reception of the suspension hook so that the locking member (<NUM>) can be acted on by the suspension hook, the locking member (<NUM>) being slidably received within the lug portion (<NUM>) to engage with and disengage from other parts (<NUM>) of the locking mechanism to hold the lug portion (<NUM>) in its extended position or release the lug portion (<NUM>) for movement to its retracted position.