Abstract: A mooring device for use, particularly in the mooring of an aircraft such as a helicopter on the deck of a ship includes a grid having an upper surface adapted for engagement by a harpoon carried by the aircraft. The grid comprises a plurality of substantially identical elements and retaining means secured to the deck and adapted to retain the elements in juxtaposed relationship. In one embodiment the elements are generally rectangular in plan and have an upper surface provided with both full and half apertures arranged so that when in said juxtaposed relationship, the elements combine to provide a generally continuous apertured upper surface.

Abstract: The apparatus comprises a trolley movable along a trackway on the deck. A vertically extendable and retractable probe is carried by a laterally movable mounting structure adjacent one end of the trolley and has an upper end arranged for location in an engagement provided beneath the helicopter fuselage. The probe is power operated and is arranged to be capable of selectively applying a downward force on the helicopter when the probe is located in the engagement, and a locking device is provided to selectively lock the probe mounting structure in a centralized position on the trolley. In one described embodiment, the apparatus is particularly adapted for use with a harpoon type deck-lock system.

Abstract: A method for marking an identification at pre-selected intervals along a length of cable by laser marking device comprises the steps of sequentially moving longitudinally spaced-apart portions of the cable along a marking platen and positioning and operating the laser to mark the stationary cable portion while the other cable portion is being moved. In a preferred embodiment of the cable marking apparatus, each of a plurality of cables is routed across a marking platen, down through a downstream aperture, up through an upstream aperture to form a slack loop beneath the platen and back across the platen so that the longitudinally spaced-apart portions are located in parallel juxtaposed relationship across the platen.

Abstract: A helicopter including a power absorber arranged to selectively absorb power from a sustaining rotor system during deceleration. In an illustrated embodiment for a helicopter having a single sustaining rotor, the power absorber comprises a tail rotor assembly having two tail rotors located one on each side of a tail cone, and a control operative to adjust the pitch setting of the tail rotors to provide lateral thrust forces in opposed directions with a net lateral thrust force in one direction in order to maintain a desired heading during deceleration.

Abstract: A freewheel coupling for drivingly connecting co-axial driving and driven shafts includes preventer means adapted to automatically prevent engagement except when the speed of rotation of the driving and driven shafts is substantially synchronized. The preventer means comprises a ball bearing having a ball race located in circumferential trackways in inner and outer races attached respectively to first and second coupling parts, and having a plurality of slots extending laterally from one of the trackways so as to permit relative axial movement of the coupling parts by movement of the balls of the ball race in the slots.

Abstract: A helicopter rotor has at least one pair of diametrically opposed rotor blades interconnected by a strap member flexible in torsion and in a plane perpendicular to a plane of rotation and stiff in a plane coincident with the plane of rotation. A torsionally flexible tie-bar having a tensile elastic modulus greater than that of the strap member is extended between pivotal attachments adjacent opposed ends of the interconnecting strap member.In operation, a major portion of centrifugal loads caused by the rotating blades is carried by the tie-bar.

Abstract: This invention provides a helicopter airspeed indicating system for providing an indication of a theoretical airspeed of a helicopter in which it is fitted. The airspeed is calculated using measured weight and power values and a known relationship between power, weight and airspeed characteristics of the helicopter, and is particularly useful for providing an indication of helicopter airspeed at the low end of an overall speed range.

Abstract: A helicopter rotor includes a rotor head arranged to support a plurality of rotor blades for rotation about an axis. The rotor head comprises a generally hollow structure, and each rotor blade is supported by an elastomeric bearing arranged to permit blade flap, lead/lag and feathering movements. A resilient support means is housed within the structure and is operatively associated with each rotor blade so as to provide controlled restraint of rotor blade movements in the blade flap plane. In the illustrated embodiment, the support means comprises interconnected inner and outer elastomeric assemblies, the outer assembly being connected to each rotor blade through a common elastomeric lead/lag damper unit which provides inter-blade damping of blade lead/lag movements. The outer elastomeric assembly also provides an automatic blade droop stop.

Abstract: A helicopter rotor includes a rotor head having, for each of a plurality of rotor blades, an elastomeric bearing and a damper that is arranged to provide controlled restraint of rotor blade movement in both the flap and lead/lag planes. The damper can be arranged to exhibit either substantially equal stiffness in both operational planes or any desired stiffness ratio. In a preferred embodiment of the latter arrangement, the desired stiffness in the respective planes are provided by separate components incorporated in the single damper. The damper may be situated either inboard or outboard of the elastomeric bearing.

Abstract: This invention is concerned with helicopter rotor control systems which hitherto have tended to comprise complex assemblies which are costly to manufacture and maintain and which are vulnerable to external damage.A helicopter rotor is disclosed in which each of a plurality of radially extending rotor blades is attached to the outer end of an individual spindle 19 having its inner end protruding into the interior of a hollow rotor hub structure 12 and supported by bearing means 21 arranged to permit rotational movement of the spindle 19 about its axis. A pitch control lever 22 is attached to the inner end of each spindle 19 and is articulated, through a universal joint, to the upper end of an individual connecting rod 38, 39, 40 and 41, the lower ends of the connecting rods being attached to a common housing 42 having independently rotatable means for connection to helicopter flying controls.

Abstract: A vibration absorber for a helicopter rotor includes a hub portion, a mass portion encircling the hub portion and a plurality of resilient arms extending in a spaced-apart spiral pattern between the hub and the mass. In operation, the hub portion of the vibration absorber is mounted on a helicopter rotor so as to be rotated with the rotor about an axis of rotation of the rotor, the resilient arms ensuring that the mass is capable of equal resilient deflection in any direction within its plane of rotation whereby the vibration absorber simultaneously reduces in-plane vibration forces of different frequencies.

Abstract: This invention relates to helicopter rotors in which the rotor blades are supported by flexure members and resilient means to permit flap and lead/lag movements.Hitherto such support means have been subjected to centrifugal forces thus complicating their design and requiring compromises such that optimum properties in flap and lead/lag planes have been unattainable.In this invention, each blade is attached by an individual spindle 19 supported in an elastomeric bearing 21 secured in a hollow rotor hub 12. Arms 26, flexible in a flapping plane, extend from the rotor hub 12 and a bearing 46 at the outer end of each spindle is attached to its associated arms through resilient means 30 to permit lead/lag movement of the spindle 19 relative the arms 26.In operation, centrifugal loads are transmitted to the hub 12 so that the arms 26 and resilient means 30 can be designed to provide optimum properties in the flap and lead/lag planes.

Abstract: A load-supporting structure comprises a plurality of similar longitudinally extending truss members each having upper and lower spaced-apart chords and intermediate joining members. The chords and joining members are constructed of rectangular tubular members, the joining members being arranged to overlap adjacent side surfaces of the respective chords which, in a preferred embodiment in which the tubular members are constructed of fibre-reinforced plastics material, provides large bond areas resulting in a strong lightweight structure.The load-supporting structures of the invention find particular application in forming the individual trackways of a temporary bridge structure, means being provided for attaching structures end-to-end and to suitable ramp portions.

Abstract: An unmanned helicopter capable of controlled free flight comprises a plurality of separable modules arranged in a substantially vertically stacked assembly symmetrical about a vertical axis. The modules include an uppermost propulsion module, a central fuel tank module and a lowermost control and payload module.

Abstract: The invention discloses an ejector release unit having a bell crank lever to positively lock the store retaining hooks in their retracted positions following release of a store. One arm of the lever is operatively associated with a surface on an adjustment hook when the hook is in its retracted position and the other arm of the lever is contacted by one end of a plunger. The other end of the plunger contacts a surface of the store so that, as the store is lifted into position, the lever is automatically moved out of engagement with the hook to permit the hook to be moved to its engaged position.

Abstract: A vibration absorber includes a hub arranged for rotation during operation about an aixs, a mass encircling the hub and a plurality of resilient arms extending in a spaced-apart spiral pattern between the hub and the mass so that the mass rotates with the hub in a plane of rotation perpendicular to the axis and is capable of equal resilient deflection in any direction within its plane of rotation. In operation the absorber operates as a spring mass device and finds particular application in damping vibrations in a helicopter rotor due to the facility to simultaneously cancel vibration forces of different frequencies.

Abstract: An ejector release unit for carrying aircraft stores is provided having single-pronged or double-pronged hooks adapted to be pivotably mounted on the unit. The hooks are utilized with wedges, spigots, and crutch arm adaptors in arrangements that enable interchangeable selective fitment to the unit. This arrangement provides for sway bracing of a store to be carried by the unit by a crutched or crutchless system as is required. Two alternative crutched arrangements are disclosed.

Abstract: A helicopter rotor includes, for each of a plurality of rotor blades, a generally radially extending flexure member to accommodate blade flap movements, a feathering hinge for pitch change movements and an elastic shear mounting located within the feathering hinge to accommodate rotor blade lead and lag movements. Spaced-apart elastomeric bearings are utilized in the feathering hinge, and the elastic shear mounting is associated with the outer elastomeric bearing and is arranged to be substantially equally resilient in both the lead/lag and flap planes. The arrangement facilitates the incorporation of automatic damping in the lead/lag plane by selection of suitable material for the elastic shear mounting.

Abstract: This invention concerns fibre reinforced plastics structures, and is particularly concerned with the attachment of such structures, for example, a helicopter rotor blade, to a supporting metal member by bolting through holes provided in the structure. Accordingly the invention teaches an arrangement in which the or each attachment hole is defined by at least two metal bushes secured in the structure with the outer ends of the outermost bushes flush with the surfaces of the structure and so that the bushes are spaced-apart axially within the structure.In a preferred embodiment, a resilient washer is located in the spacing between ends of adjacent bushes and in contact therewith.

Abstract: An inflatable skirting assembly acting as a barrier to the supporting cushion of a gaseous cushion supported vehicle, the skirting assembly being constructed from a single sheet of flexible material suspended from the vehicle to form an unrestrained loop in a vertical cross-section.