*2.8.2 Airbus A350 XWB*

While the focus of this paper has concentrated on developments in the United States, the composites community in Europe was just as active. There were many

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**Figure 31.**

*787 Tail. Source: Boeing.*

*The Evolution of the Composite Fuselage: A Manufacturing Perspective*

R&D programs that were directed at high performance composites design and

The results of this work along with many lessons learned on historical programs fed into the approach taken on the A350XWB program (XWB stands for eXtra Wide Body). The A350 composite fuselage manufacturing approach is not as uniform as

The A350 incorporates one complete barrel section, the tail, produced in Spain that uses an approach similar to the one used by Boeing and its partners on the 787 (**Figure 33**). The rest of the A350 fuselage follows a more conventional panel assembly approach, but with some unique manufacturing process used along the way. The use of AFP, invar tooling and longitudinally incorporated omega (like the Greek letter Ω) stiffeners, more traditionally called hat stiffeners, are also common between the programs. The panel approach used on the A350 supports long part lengths and this is reflected in Section 15 which is approximately 65′ in length. How the omega stiffeners are incorporated on the fuselage panels is quite different

*DOI: http://dx.doi.org/10.5772/intechopen.82353*

manufacturing activities [10].

*787 Sections 47 and 48. Source: Boeing.*

**Figure 30.**

between sections and suppliers.

the method selected by Boeing on the 787.

**Figure 29.** *Sections 44 and 46. Source: Boeing.*

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

**Figure 30.** *787 Sections 47 and 48. Source: Boeing.*

*Aerospace Engineering*

cured part off the mandrel.

*787 Section 43. Source: Boeing.*

**Figure 28.**

*2.8.2 Airbus A350 XWB*

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

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

While the focus of this paper has concentrated on developments in the United States, the composites community in Europe was just as active. There were many

the −9 configurations, the tools were designed to support −10 also.

**116**

**Figure 29.**

*Sections 44 and 46. Source: Boeing.*

R&D programs that were directed at high performance composites design and manufacturing activities [10].

The results of this work along with many lessons learned on historical programs fed into the approach taken on the A350XWB program (XWB stands for eXtra Wide Body). The A350 composite fuselage manufacturing approach is not as uniform as the method selected by Boeing on the 787.

The A350 incorporates one complete barrel section, the tail, produced in Spain that uses an approach similar to the one used by Boeing and its partners on the 787 (**Figure 33**). The rest of the A350 fuselage follows a more conventional panel assembly approach, but with some unique manufacturing process used along the way. The use of AFP, invar tooling and longitudinally incorporated omega (like the Greek letter Ω) stiffeners, more traditionally called hat stiffeners, are also common between the programs. The panel approach used on the A350 supports long part lengths and this is reflected in Section 15 which is approximately 65′ in length. How the omega stiffeners are incorporated on the fuselage panels is quite different between sections and suppliers.

**Figure 31.** *787 Tail. Source: Boeing.*

#### **Figure 32.** *Airbus A350.*

Spirit is a common key supplier on both programs and the fabrication approaches share some key characteristics. Spirit produces Section 15 of the A350 and applies the sector panel approach that is common throughout the fuselage. Spirit cocures the omegas using an IML controlled layup/cure tool with a stiff composite caul plate to control the aerodynamic OML surface smoothness. Uncured omega stiffeners are laminated, formed and located into troughs machined into the invar tool. Inflatable rubber bladders are located on top of the omega laminates and fill the void between the omega and the AFP skin that is laminated on top of over the assembly. The part is autoclave cured and the rubber bladders removed after cure leaving the cocured, and now hollow, omega on the panel (**Figure 34**).

The rest of the A350 fuselage structure uses cobonding to incorporate the omega stiffeners with the fuselage skin (**Figure 35**). Precured omega stiffeners are located onto green AFP skins with a layer of film adhesive between the elements and then autoclave cured (**Figure 36**). During the cobonding cycle shaped tube bags are located inside the cured stiffener and are open to autoclave pressure during the cure/cobonding cycle to ensure the already cured stringer does not collapse or become damaged when subjected to autoclave pressure (**Figures 36** and **37**).

**119**

**Figure 35.**

*A350 fuselage panel. Source: CTC Stade.*

*The Evolution of the Composite Fuselage: A Manufacturing Perspective*

Like the 787 program, liquid molding processes are used to fabricate fuselage frames which are mechanically attached to the skins. The structural arrangements

One significant difference (if not THE most significant difference) is the frame integration to the fuselage. The 787 incorporates a "mouse hole" in the frame that nests around the hat stiffener and is attached directly to the IML of the fuselage skin. Boeing can do this because the IML surface of the 787 is a tooled surface with features that have controlled heights and locations. This includes hat stiffeners and skin joggles. Both programs use fuselage frames produced using a closed molding process that tools the surface that mates with the skin. On the 787, this creates a

and assembly methods used by both programs are remarkably similar.

*DOI: http://dx.doi.org/10.5772/intechopen.82353*

**Figure 34.**

*A350 fuselage side panel. Source: Spirit.*

**Figure 33.** *A350 fuselage panel and tail. Source: Airbus.*

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

**Figure 34.** *A350 fuselage side panel. Source: Spirit.*

*Aerospace Engineering*

**Figure 32.** *Airbus A350.*

Spirit is a common key supplier on both programs and the fabrication approaches share some key characteristics. Spirit produces Section 15 of the A350 and applies the sector panel approach that is common throughout the fuselage. Spirit cocures the omegas using an IML controlled layup/cure tool with a stiff composite caul plate to control the aerodynamic OML surface smoothness. Uncured omega stiffeners are laminated, formed and located into troughs machined into the invar tool. Inflatable rubber bladders are located on top of the omega laminates and fill the void between the omega and the AFP skin that is laminated on top of over the assembly. The part is autoclave cured and the rubber bladders removed after cure leaving the cocured, and now hollow, omega on the panel (**Figure 34**). The rest of the A350 fuselage structure uses cobonding to incorporate the omega stiffeners with the fuselage skin (**Figure 35**). Precured omega stiffeners are located onto green AFP skins with a layer of film adhesive between the elements and then autoclave cured (**Figure 36**). During the cobonding cycle shaped tube bags are located inside the cured stiffener and are open to autoclave pressure during the cure/cobonding cycle to ensure the already cured stringer does not collapse or become damaged when subjected to autoclave pressure (**Figures 36** and **37**).

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**Figure 33.**

*A350 fuselage panel and tail. Source: Airbus.*

Like the 787 program, liquid molding processes are used to fabricate fuselage frames which are mechanically attached to the skins. The structural arrangements and assembly methods used by both programs are remarkably similar.

One significant difference (if not THE most significant difference) is the frame integration to the fuselage. The 787 incorporates a "mouse hole" in the frame that nests around the hat stiffener and is attached directly to the IML of the fuselage skin. Boeing can do this because the IML surface of the 787 is a tooled surface with features that have controlled heights and locations. This includes hat stiffeners and skin joggles. Both programs use fuselage frames produced using a closed molding process that tools the surface that mates with the skin. On the 787, this creates a

**Figure 35.** *A350 fuselage panel. Source: CTC Stade.*

**Figure 36.** *A350 precured omega stringers. Source: Deseret News, Jeffrey D. Allred; CW/Photos: Jeff Sloan.*

tooled surface-to-tooled surface interface creating a very predictable assembly. Components fit together as well as it can be produced because early in the program, it paid the price of being designed for assembly (**Figure 38**).

The A350 fuselage frames are attached only at the crowns of the omega stiffeners using secondary clips. Airbus did not try to attach the frames directly to the skins because the IML of the fuselage skin is not a controlled surface. It is a bagged surface that might use caul plates to create uniform pressure and a smooth surface, but the IML surface "floats" depending on factors such as bagging, resin bleed and initial prepreg resin content. Just as the OML of each 787 fuselage "floats" and is different aircraft-to-aircraft depending on these same factors. Airbus uses a standard carbon fiber reinforced clip, molded from thermoplastic material, to absorb the skin fabrication tolerance in the assembly process (**Figure 39**).

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*The Evolution of the Composite Fuselage: A Manufacturing Perspective*

*DOI: http://dx.doi.org/10.5772/intechopen.82353*

**Figure 38.** *787 fuselage.*

**Figure 39.**

**3. Future developments/trends**

*A350 fuselage. Source: Borga Paquito.*

There are several recently developed commercial aircraft, such as the Bombardier C Series, Mitsubishi's MRJ, and Comac's C919, that all have similar overall airframe architecture as the 787 and the A350. However, none of these aircraft incorporate an all composite fuselage. The advantages for composites on large, wide body aircraft have been validated by the short service history of the 787 and even shorter history of the A350. The debate regarding smaller aircraft achiev-

Wide body aircraft spend much of their life cruising at 40,000 ft. and the structure is sized for pressure loads and structural needs—this provides adequate thickness for good damage tolerant designs. The fuselage designs for single aisle aircraft could be more efficient based on cabin pressure and structural loading alone. But, to provide for designs that will be tolerant of many more takeoff and landings and in service hazards such as luggage and catering carts, dropped tools and equipment, hail and bird strikes, the fuselage panels must be thicker and heavier, thus sacrificing weight.

ing the same gains continues for Next Generation Single Aisles.

**Figure 37.** *A350 omega stringer cobonding [11].*

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

**Figure 38.** *787 fuselage.*

*Aerospace Engineering*

**Figure 36.**

tooled surface-to-tooled surface interface creating a very predictable assembly. Components fit together as well as it can be produced because early in the program,

*A350 precured omega stringers. Source: Deseret News, Jeffrey D. Allred; CW/Photos: Jeff Sloan.*

The A350 fuselage frames are attached only at the crowns of the omega stiffeners using secondary clips. Airbus did not try to attach the frames directly to the skins because the IML of the fuselage skin is not a controlled surface. It is a bagged surface that might use caul plates to create uniform pressure and a smooth surface, but the IML surface "floats" depending on factors such as bagging, resin bleed and initial prepreg resin content. Just as the OML of each 787 fuselage "floats" and is different aircraft-to-aircraft depending on these same factors. Airbus uses a standard carbon fiber reinforced clip, molded from thermoplastic material, to absorb

it paid the price of being designed for assembly (**Figure 38**).

the skin fabrication tolerance in the assembly process (**Figure 39**).

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**Figure 37.**

*A350 omega stringer cobonding [11].*

**Figure 39.** *A350 fuselage. Source: Borga Paquito.*
