*The Evolution of the Composite Fuselage: A Manufacturing Perspective DOI: http://dx.doi.org/10.5772/intechopen.82353*

*Aerospace Engineering*

**2.8 787 vs. A350**

*2.8.1 Boeing 787*

Airbus has an updated design, The Beluga XL, based on the larger Airbus A330-200. Five aircraft are planned to be built as replacements for the existing aircraft and used primarily for A350 work. The Beluga XL is designed with the

The Boeing 787 and the Airbus A350 aircraft share many similarities in size, configuration, manufacturing methods and mission (**Figure 26**). The primary difference between the composite fuselage structures of the two programs is the exclusive usage of IML controlled cure tooling and full barrel fabrication applied by Boeing and the sector panel approach selected by Airbus with a high percent incorporation of cobonded fuselage skin stiffeners. The true results of these decisions will not be known until more information can be collected about actual fabrication and

The ACT/ATCAS program had a tremendous influence on the direction Boeing

selected for the 787 program. Lessons learned from all aspect of the program influenced everything from the material systems that were selected to the tooling materials, structural arrangement, and the selection of IML tooled, full barrel fuselage structures. Major considerations that influenced that decision were the concerns about the cost of the assembly of very large stiffened structure and the

The program helped Boeing better understand the assembly loads related to composite panel warpage from cured part spring back and cocured and/or cobonded stiffener or frame mislocation. At minimum, these loads need to be understood and accounted for in the part design. Boeing saw an opportunity to minimize these assembly related penalties to the design by the tooling and struc-

Boeing's selection of the AFP process over a male mandrel that serves as both a layup and cure tool is forgiving enough to accommodate different caul plate approaches on different sections of the fuselage. All the fuselage sections use

capacity to ship two A350 wings simultaneously [9].

assembly costs being realized by Boeing and Airbus.

stresses induced on the structure due to assembly.

tural arrangement approach applied on the 787.

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**Figure 26.**

*787 and A350 fuselage sections.*

multiple caul plates that nest together to cover the entire outer mold line of the fuselage. The cauls are floating on the surface of the skin and move with the skin during cure to establish the cured part OML whenever and wherever it is at the time the resin gels and things stop moving. Shared characteristics of the cauls include the ability to be individually and positively located before cure and removed individually after cure. Also the ability to ensure the cauls do not interfere with each other during cure. However, differences do exist in the choice of material (either graphite reinforced composite cauls or aluminum cauls) and in the thickness of the caul. In some cases, the composite caul is very thick and stiff and will behave more rigidly during the cure cycle. In other barrel sections, a thin aluminum caul is employed, which will more closely conform to the surface of the as AFP laminated skin. Both extremes are successfully being used by different fabrication partners.

Invar was the material of choice for Sections 43, 44 and 46 and the tail. Invar tooling was not the right choice for Spirit as it designed the layup mandrel/cure tooling for Section 41. An invar tool of that size and weight would have imposed very expensive requirements on the foundation of the AFP machine that winds the skin. The size of the motors and energy required to turn and manipulate the mandrel during the fiber placement process was also determined to be prohibitive. Instead Spirit elected to fabricate graphite reinforced BMI mandrels fabricated on invar cure tools and then machined to final IML dimensions (**Figure 27**).

Composite tooling is also used for Sections 47 and 48. In addition to lower mandrel weight, faster heat up and cool down rates contributed to this decision.

All the partners on the 787 program follow similar manufacturing processes for fabricating cocured, hat stiffened, full fuselage barrel sections. All use AFP over IML controlled male layup mandrels that also serve as cure tools. Each section (except the tail) uses multi-piece breakdown mandrels which are disassembled and removed from inside the fuselage after cure (**Figures 28** and **29**).

Alenia manufactures Sections 44 and 46 of the 787. Section 44 is a composite half barrel section that covers the main wing box. The lower portion of this fuselage section is mostly metallic and the structure is designed to handle the primary loads from the wings and landing gear.

Fabrication of fuselage barrel Sections 47 and 48 were originally contracted to Vought as part of their statement of work (SOW) on the 787 program. Financial pressures driven by initial program delays led to Boeing acquiring the Vought SOW including partnership in subassembly work with Alenia (**Figures 30**–**32**).

**Figure 27.** *Spirit 787 Section 41. Photo: Bill Carey.*

**Figure 28.** *787 Section 43. Source: Boeing.*

The tail is the only barrel section that does not require a breakdown cure mandrel. The natural draft angles allow for cured part removal by simply sliding the cured part off the mandrel.

Boeing achieved stretch version of the 787 by extending the fuselage sections on either side of the wing center of gravity. The 20′ stretch for the −9 was achieved by adding 10′ to Sections 43 and 47. The additional 18′ added for the −10 configurations was achieved by adding 10′ to the forward fuselage and 8′ aft end. When new AFP mandrels were added to meet production ramp-up rate needs and to meet the −9 configurations, the tools were designed to support −10 also.
