As per the Airbus document regarding the A380 Transport Project and Logistics, which I provided a link to above, the 11.3 tonnes centre wing box is, in fact, included in the weight for the A380's centre fuselage (44 metric tonnes).
I did read that document, however it does not do as you claim, all it is explaining is how they are getting various assembled sections to the FAL. The centre wing box as I posted previously is it’s own sub assembly, it is an essential part of the wing design. You can also add up the weights of the left and right wings and the centre wing box to calculate the total wing assembly weight.
If you are interested in the sort of process that is used to design a wing this paper is a good overview of the modern techniques used to arrive at an optimised design. https://doi.org/10.1016/j.ast.2010.08.005
In that paper they were able to calculate the primary and secondary wing components via an multidisciplinary process, this is what they came up with for an A340-200 style wing.https://i.ibb.co/dWTXfqR/87-AC2300-A472 ... -F45-C.jpg
The centre wing box is generally the first sub assembly completed on any Airbus aircraft. On the A350 it’s then moved and incorporated into section 15, then section 15 is moved to the FAL. Trying to suggest that the centre wing box is not part of the wing structure or design and its part of the fuselage just because of the way they choose to optimise their assembly process is disingenuous.
Come on, this is ridiculous. Of course, the centre wing box is part of the wing structure and I've never suggested otherwise. However, that's not the issue here.
The fact of the matter is that the weight of the centre wing box is counted as part of the centre fuselage if the centre fuselage arrives at the final assembly line with the centre wing box fully integrated into its structure. That's typically the case for low wing aircraft. On high wing aircraft, such as the A400M, the outer wing (left and right) is mated to the centre wing box before being joined to the centre fuselage. Hence, the weight breakdown of the A400M's centre fuselage at its arrival at the FAL does not include the weight of its centre wing box.
Furthermore, this is a standard method of component weight breakdown, at the point of entering the FAL, for all aerospace vehicles (i.e. airliners, fighter aircraft, space shuttles etc.)
With respect to the Space Shuttle Orbiter, for example, here are relevant excerpts from the Orbiter Weight Statement for OV-103*
Outer Panel Interim Section_________________2,291.4
Outer Panel Torque Box____________________6,236.4
Outer Panel Leading Edge___________________188.2
Outer Panel Trailing Edge__________________1,306.7
Operating Mechanisms and Controls___________549.4
Miscellaneous Provisions and Support__________112.8
Elevon Inboard Surface____________________1,291.0
Elevon Inboard Support Mechanism___________278.2
Elevon Outboard Surface____________________921.6
Elevon Outboard Support Mechanism__________339.6
Mid-Fuselage _ ________________________10,974.0 NB: Including the wing carry-through structure.
Aft-Fuselage (thrust structure)______________3,182.4
* Page 440
Dennis R. Jenkins: SPACE SHUTTLE, The History of the National Transportation System, The First 100 Missions
ISBN: 0-9633974-5-1, April 2001
The wing is an aerodynamic lifting surface that provides conventional lift and control for the orbiter. The left and right wings consist of the wing glove; the intermediate section, which includes the main landing gear well; the torque box; the forward spar for mounting the reusable reinforced carbon-carbon leading edge structure thermal protection system; the wing/elevon interface; the elevon seal panels; and the elevons.
The wing is constructed of conventional aluminum alloy with a multirib and spar arrangement with skin-stringer-stiffened covers or honeycomb skin covers. Each wing is approximately 60 feet long at the fuselage intersection and has a maximum thickness of 5 feet.
The forward wing box is an extension of the basic wing that aerodynamically blends the wing leading edge into the midfuselage wing glove. The forward wing box is a conventional design of aluminum ribs, aluminum tubes and tubular struts. The upper and lower wing skin panels are stiffened aluminum. The leading edge spar is constructed of corrugated aluminum.
The intermediate wing section consists of the conventional aluminum multiribs and aluminum tubes. The upper and lower skin covers are constructed of aluminum honeycomb. A portion of the lower wing surface skin panel includes the main landing gear door. The intermediate section houses the main landing gear compartment and reacts a portion of the main landing gear loads. A structural rib supports the outboard main landing gear door hinges and the main landing gear trunnion and drag link. The support for the inboard main landing gear trunnion and drag link attachment is provided by the midfuselage. The main landing gear door is conventional aluminum honeycomb.
The four major spars are constructed of corrugated aluminum to minimize thermal loads. The forward spar provides the attachment for the thermal protection system reusable reinforced carbon-carbon leading edge structure. The rear spar provides the attachment interfaces for the elevons, hinged upper seal panels, and associated hydraulic and electrical system components. The upper and lower wing skin panels are stiffened aluminum.
The elevons provide orbiter flight control during atmospheric flight. The two-piece elevons are conventional aluminum multirib and beam construction with aluminum honeycomb skins for compatibility with the acoustic environment and thermal interaction. The elevons are divided into two segments for each wing, and each segment is supported by three hinges. The elevons are attached to the flight control system hydraulic actuators at points along their forward extremities, and all hinge moments are reacted at these points. Each elevon travels 40 degrees up and 25 degrees down.
The transition area on the upper surface between the torque box and the movable elevon consists of a series of hinged panels that provide a closeout of the wing-to-elevon cavity. These panels are of Inconel honeycomb sandwich construction outboard of wing station Y w 312.5 and of titanium honeycomb sandwich construction inboard of wing station Y w 312.5. The upper leading edge of each elevon incorporates titanium rub strips. The rub strips are of titanium honeycomb construction and are not covered with the thermal protection system reusable surface insulation. They provide the sealing surface area for the elevon seal panels.
The exposed areas of the wings, main landing gear doors and elevons are covered with reusable surface insulation thermal protection system materials except for the elevon seal panels.
Thermal seals are provided on the elevon lower cove area along with thermal spring seals on the upper rub panels. Pressure seals and thermal barriers are provided on the main landing gear doors.
The wing is attached to the fuselage with a tension bolt splice along the upper surface. A shear splice along the lower surface in the area of the fuselage carry-through completes attachment interface.
Prior to the manufacturing of the wings for Discovery (OV-103) and Atlantis (OV-104), a weight reduction program resulted in a redesign of certain areas of the wing structure. An assessment of wing air loads was made from actual flight data that indicated greater loads on the wing structure. As a result, to maintain positive margins of safety during ascent, structural modifications were incorporated into certain areas of the wings. The modifications consisted of the addition of doublers and stiffeners.
The wing, elevon and main landing gear door contractor is Grumman Corp., Bethpage, N.Y.
The midfuselage structure interfaces with the forward fuselage, aft fuselage and wings. It supports the payload bay doors, hinges, tie-down fittings, forward wing glove, and various orbiter system components and forms the payload bay area.
The forward and aft ends of the midfuselage are open, with reinforced skin and longerons interfacing with the bulkheads of the forward and aft fuselages. The midfuselage is primarily an aluminum structure 60 feet long, 17 feet wide and 13 feet high. It weighs approximately 13,502 pounds.
The midfuselage skins are integrally machined by numerical control. The panels above the wing glove and the wings for the forward eight bays have longitudinal T-stringers. The five aft bays have aluminum honeycomb panels. The side skins in the shadow of the wing are also numerically control machined but have vertical stiffeners.
Twelve main-frame assemblies stabilize the midfuselage structure. The assemblies consist of vertical side elements and horizontal elements. The side elements are machined; whereas the horizontal elements are boron/aluminum tubes with bonded titanium end fittings, which reduced the weight by 49 percent (approximately 305 pounds).
In the upper portion of the midfuselage are the sill and door longerons. The machined sill longerons not only make up the primary body-bending elements, but also take the longitudinal loads from payloads in the payload bay. The payload bay door longerons and associated structure are attached to the 13 payload bay door hinges. These hinges provide the vertical reaction from the payload bay doors. Five of the hinges react the payload bay door shears. The sill longeron also provides the base support for the payload bay manipulator arm (if installed) and its stowage provisions, the Ku-band rendezvous antenna, the antenna base support and its stowage provisions, and the payload bay door actuation system.
The side wall forward of the wing carry-through structure provides the inboard support for the main landing gear. The total lateral landing gear loads are reacted by the midfuselage structure.
The midfuselage also supports the two electrical wire trays that contain the wiring between the crew compartment and aft fuselage.
Plumbing and wiring in the lower portion of the midfuselage are supported by fiberglass milk stools.
The remainder of the exposed areas of the midfuselage is covered with the reusable surface insulation thermal protection system.
Because of additional detailed analysis of actual flight data concerning descent stress thermal gradient loads, torsional straps were added to the lower midfuselage stringers in bays 1 through 11. The torsional straps tie all stringers together similarly to a box section, which eliminates rotational (torsional) capabilities to provide positive margins of safety.
Also, because of additional detailed analysis of actual flight data during descent, room-temperature vulcanizing silicone rubber material was bonded to the lower midfuselage from bay 4 through 12 to act as a heat sink and distribute temperatures evenly across the bottom of the midfuselage, which will reduce thermal gradients and ensure positive margins of safety.
The contractor for the midfuselage is General Dynamics Corp., Convair Aerospace Division, San Diego, Calif.