Wing-box structure
A wing-box structure for an aircraft is disclosed having an upper cover, a lower cover, longitudinal forward and rearward spars, and a plurality of transverse ribs. One of the transverse ribs is retained by a pair of opposed captive features disposed on an interior side of either the forward and rearward spars or the upper and lower covers. The rib is bonded rib to the forward and rearward spars and/or the upper and lower covers at a location where the rib is retained.
1. A wing-box structure for an aircraft, comprising:
an upper cover,
a lower cover,
longitudinal forward and rearward spars, and
a plurality of transverse ribs, wherein one of the transverse ribs is retained by a pair of opposed captive features disposed on an interior side of either the forward and rearward spars or the upper and lower covers, and adhesive or weldable material for bonding the rib to the forward and rearward spars and/or the upper and lower covers at a location where the rib is retained,
wherein the captive features each comprise a projection or a recess on or into the interior surface of the forward and rearward spars or the upper and lower covers with which the rib is engaged to constrain the rib from translation over the interior surface, and
wherein, during assembly of the wing-box structure, the rib is configured to be translated in the longitudinal direction of the wing-box structure to become captive against or in the projection or recess to form a snap-fit connection.
2. A wing-box structure according to claim 1 , wherein the captive features are attached to or integrated with the forward and rearward spars or the upper and lower covers.
3. A wing-box structure according to claim 1 , wherein each projection is a ramp having a sloping face and a bluff face.
4. A wing-box structure according to claim 1 , wherein each recess cooperates with a respective projection formed on the rib, or wherein each projection cooperates with a respective projection formed on the rib.
5. A wing-box structure according to claim 1 , further comprising one or more fasteners for fastening the rib to the forward and rearward spars and/or the upper and lower covers at a location where the rib is retained.
6. A wing-box structure according to claim 1 , wherein at least one of the forward and rearward spars is integrally formed with at least one of the upper and lower covers.
7. A wing-box structure according to claim 1 , wherein the forward and rearward spars and/or the upper and lower covers converge in the longitudinal direction of the wing-box structure.
8. A wing-box structure according to claim 7 , wherein the convergence of the forward and rearward spars and/or the upper and lower covers constrains movement of the rib away from the captive features, so that the rib is retained between the captive features and the convergent geometry.
9. A wing-box structure according to claim 1 , wherein the captive features are configured to allow one-way installation of the rib.
10. A wing-box structure according to claim 1 , further comprising a respective pair of opposed captive features on either the forward and rearward spars or the upper and lower covers for each respective transverse rib, wherein each of the respective transverse ribs is retained by the respective pair of opposed captive features.
11. An aircraft wing, vertical tailplane, horizontal tailplane, wing-tip device, or any aerofoil structure comprising a wing-box structure according to claim 1 .
12. A wing-box structure according to claim 1 , wherein the captive features provide a mechanical engagement between an interior surface of the forward and rearward spars or the upper and lower covers and the rib to constrain the rib from longitudinal translation over the interior surface.
13. A method of assembling a wing-box structure, comprising:
at least partially assembling an upper cover, a lower cover, and longitudinal forward and rearward spars;
providing a pair of opposed captive features on an interior side of either the forward and rearward spars or the upper and lower covers;
passing at least one transverse rib along the at least partially assembled upper and lower covers and longitudinal forward and rearward spars until the rib engages with the pair of opposed captive features so that the rib is retained by the pair of opposed captive features in a snap-fit connection; and
bonding the rib to the forward and rearward spars and/or the upper and lower covers at a location where the rib is retained.
14. A method according to claim 13 , further comprising providing a respective pair of opposed captive features on either the forward and rearward spars or the upper and lower covers for each respective transverse rib, and passing each of a plurality of transverse ribs along the at least partially assembled upper and lower covers and longitudinal forward and rearward spars until the respective rib engages with the pair of opposed captive features so that the respective rib is retained by the respective pair of opposed captive features.
15. A method according to claim 14 , wherein the forward and rearward spars and/or the upper and lower covers converge in the longitudinal direction of the wing-box structure, and wherein the plurality of transverse ribs have different sizes, the method further comprising passing the plurality of transverse ribs along the assembly in the direction of the convergence in order of increasing rib size.
16. A method according to claim 14 , wherein the at least one transverse rib is passed along the assembly in a first orientation in which the rib is tilted towards a plane of the upper or lower covers, and then rotated to a second orientation in the vicinity of the pair of opposed captive features.
17. A method according to claim 13 , wherein the at least one transverse rib is moved in the longitudinal direction of the wing-box structure over an interior surface of the at least partially assembled upper and lower covers and longitudinal forward and rearward spars until the rib mechanically engages with the pair of opposed captive features so that the rib is retained by the pair of opposed captive features to constrain the rib from longitudinal translation over the interior surface.
18. A wing-box structure for an aircraft, comprising:
an upper cover,
a lower cover,
longitudinal forward and rearward spars, and
a plurality of transverse ribs, wherein one of the transverse ribs is retained by a pair of opposed captive features disposed on an interior side of either the forward and rearward spars or the upper and lower covers, and adhesive or weldable material for bonding the rib to the forward and rearward spars and/or the upper and lower covers at a location where the rib is retained,
wherein the captive features each comprises a projection or a recess disposed on the interior surface of the forward and rearward spars or the upper and lower covers, and
wherein each projection includes a ramped surface oriented in the longitudinal direction of the wing-box structure to guide the rib during insertion, and a bluff face oriented to retain the rib after insertion after insertion;
wherein, during assembly of the wing-box structure, the rib is configured to be translated in the longitudinal direction of the wing-box structure to become captive against or in the projection or recess.