Aerodynamics Assignment A350 vs B787 A.S

‘Reduction’ is a term heavily used by

the two world’s leading manufacturers

in the production of both the B787 and

A350 XWB. Followed by ‘economic

saving costs’ due to the innovative

technology that enabled automated

manufacturing, high performance

engines, aircraft aerodynamics

improvement and other robust

developments that the airliners will

take full advantage of.

Airbus 350 XWB and Boeing 787

Analising the design approach, materials,

structure and systems used in the two new

generation aircrafts

Submited to: Pat Murray

Alexandra Slabutu

C13758205

B.Eng.Tech. in Aviation Technology

DT 011/2

AIRBUS 350 XWB AND BOEING 787 MAY 9, 2015 ALEXANDRA SLABUTU C13758205

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Declaration

This is an original work. All references and assistance are acknowledged.

Signed:

Date: 12th May 2015

Candidate Name: Alexandra Slabutu

If an assignment or project or part of an assignment or project has been plagiarized

from any source, this will result in a fail for that assignment or project. (DIT, 2011)


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Abstract

‘Reduction’ is a term heavily used by the two world’s leading manufacturers in the

production of both B787 and A350 XWB. Followed by economic savings costs due to the

innovative technology that enabled automated manufacturing, high performance engines,

aircraft aerodynamics improvement and other robust developments that the airliners will take

full advantage of. Carbon Fiber Reinforced Pastic (CFRP) materials have revolutionised the

way aircrafts are built, however these pose uncertanties as well in terms to the fuselage

straingth and major repairs.

The advantages that the Dreamliner and the A350 provide to their owner, may be seen as

concerns to the Maintenance Repair and Overaul (MRO) organisations due to the fact that

automation will take over, thus workforce will decrease and also due to the lesser

maintenance checks that these aircrafts will require.

Key words: innovation, technology, aircraft, reliability, savings, cost efficiency, robustness,

advancement, development, next generation, jetliner, fuel efficiency, dreamliner, reduction,

efficiency, composite materials, airlines, emission.


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Abbreviations:

CFRP – Carbon Fiber Reinforced Plastic

EBA – Electric Brake Actuator

EH – Electrohydraulic

EHA- Electrohydrostatic

EIS – Entry In Service

EM – Electromechanical

HID – High Intensity Discharge

IATA – International Air Transport Association

LED – Light Emitting Diode

MEA – More Electric Architecture

MRO – Maintenance Repair Overhaul

XWB – Xtra Wide Body


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Contents

1. Introduction ............................................................................................................................... 5

2. Boeing 787 Dreamliner vs Airbus 350 XWB .......................................................................... 5

2.1 Design Approach ..................................................................................................................... 5

2.2 Materials and Structure ......................................................................................................... 6

2.3 Systems Arhitecture ................................................................................................................ 9

3. Conclusion ............................................................................................................................... 11

4. References .................................................................................................................................... 13


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1. Introduction

ast paced technology development together with the demand of air travel have imposed a

challege to the world’s largest aircraft manufacturers, Airbus and Boeing. These had to

respond promptly with innovative ideas that would satisfly the industry, in the current and

future economic climate, by projecting new aircraft type designs that would have multiple

capabilities such as: to be fuel efficient, improve performance, environmental friendly, reduce

maintenance costs, reduce weight, incorporate state of art technology, optimising passenger

comfort and most importantly be an overall cost effective aircrafts.

Both the Airbus A350 XWB and the Boeing B787 represent a new approach by the two

companies to commercial air transport. While both share common features of new

technologies, there are distinct differences between them in terms of design, materials,

structures and systems.

The two pioneering aircraft types have been designed and built in close collaboration with the

airliners considerations, in order to respond to their needs and maximise the aircrafts value on

the market. The B787 Dreamliner has however implemented a totally new approach in its

design, being a More Electric Architecture, MEA, wheather the A350 XWB although still

very much technologically improved, it focused more on reliability by adopting many

designes from the A380 and A330 aircraft family types. This gives an advantage to the A350

as all the borrowed systems/designs from the A380 and A330 have proved to be a success

already and moreover communality is highly emphasised in Airbus thus improving airliners

operational costs, meaning that crew training and maintenance costs are utterly reduced.

Throughout this assignment, a thorough analysis will be developed on both the A350 and

B787 focusing on their design philosophy, materials, structure and systems.

Boeing’s B787 aircraft design philosophy is based on life-cycle cost design, ensuring that its

operartors will benefit high reduction in maintenance costs. Boeing’s approach looked at the

costs produced by various factors such as: drag, weight, noise, schedule reliability,

2. Boeing 787 Dreamliner vs Airbus 350 XWB

2.1 Design Approach


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develoment and build cost, that affect the aircraft throughout its life time. By doing this they

have introduced two distinct performance measures: maintenance cost and airplane

availability. (Hale, n.d.) Like the B787, the A350 jetliner is designed having the customer’s

needs in mind, providing reliability and reduced maintenance costs. Its smart design

implements a series of the most efficient materials possible for each and every aircraft

component. Apart from the composite and metalic materiales being used, the A350 adapts

other advanced ulta-light alloys such as aluminium-lithium and titanium. These materials

have prolonged the A350 maintenance service checks from six to twelve years, thus saving

revenue for the airliners.

2.2 Materials and Structure

Both aircrafts airframe and structure contain high percentage of composite and titanium

materials (A350: 53% CFRP, 14% Titanium – Fig.1; B787: 50% CFRP, 14% Titanium-

Fig.2) more than their previous aircraft types. These innovative materials have helped reduce

the overall weight of the two aircrafts subsequently reducing their fuel consumption, thus

bringing more profitability to the owner. That being said, the greatest advantage of these

materials is their corrosion and fatigue resistance and strength durability, contrary to the

aluminium materials.

Fig 1. Airbus A350 Materials (Airbus, n/a)

Although composites are not great in dealing with compression loads, it excels in tension.

Compared to aluminium, titanium proved to be prefered to use in areas such as galleys, seat

rails, metallic frames in the lower part of the fuselage and the nose section of the A350 XWB,


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due to its advantages which are mentioned above. Carbon Fiber Reinforced Plastic (CFRP) is

found in the following structures of the A350: window frames, fuselage panels, keel beam

frames, clips, wing box single piece top and bottom covers that are 32m long. The

empennage uses CFRP too. The fuselage innovation used by Airbus is the first time being put

in practice, moving forward from its tradinionl concepts. The aircraft pressurised cabin is

divided into three main distinctive sections which are made of four CFRP panels and one

barrel fuselage design for the non-pressurised aft part of the aircraft, adding improved aircraft

performance. The circumferential joints are assembled in such a way that are not exposed to

the heavy loadead areas like the wing to fuselage section. The thickness of the carbon fiber

composite varies throughout the fusselage structure, requiring higher level of CFRP in areas

that are more prompt to impact like the door surroundings, compared to lower risk areas. This

is a damage tolerance design which is a vital part of the airworthiness regulation that the

aircraft has been subjected to. (F Gaible, 2013)

The 787 and 350 structure include various composite materials such as: glass/carbon hybrid,

fiberglass, carbon laminate which is made of layers of carbon fiber impregnated with a

polymer and carbon sandwich which is similar to a honeycomb shape.


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Fig.2 B787 Material distribution (Hale, n.d.)

In contrast B787 fuselage is purely made of one-piece barrel shape sections, with no

longitudinal splices, improving the aircraft’s weight and maintenance costs. Its assembly was

fully automated, having saved labour and equipment costs. The repair technics are the same

as the ones used on the metallic aircrafts which is using bolted repairs but also offering the

option of bonded composite repairs which allows better aesthetic and aerodynamic finish.

However the bonded repaires are only allowed for temporary fixture, as its not accepted by

the airworthiness authorities. (Mash, 2012) The A350 on the other hand utilises standard

bolted repair concept for structural damages and bonded repairs for minor cosmetic damage.

The skin panels of the A350 and the barrel sections of the B787 use same method of

connection, the conventional fasteners technique and lap joints between them. (Marsh, 2007)

New technologic software has allowed Airbus to inspect all the drilled holes in the A350, in a

more efficiently and faster method. ‘Percephone’ is an ultrasonic inspection tool that detects

possible delamination. A kit made of a mini-tablet, a water spray container and various daisy

probes, enables the operator to check the drilled holes within minutes and connects him/her

automatically to the software. Basically water is sprayed into the hole till is fully filled,

facilitating the coupling between the module and the hole which needs inspection, then the

probe is aimed at the hole. Coloured imaginary is displayed representing different codes such

as red for delaminated hole, orange for contentious cases and green if the hole is correct. This

ultrasonic development not only saves rime, training and maintenance costs it improves

traceability for the inspection of the 36,000 existing holes located on the forward and centre

parts of the aircraft. (F Gaible, 2013, p. 31)


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The two manufacturers rely very much on automated production for building the A350 and

B787 due to the available innovative technologies. 3D printing is one of the techologies that

helped producing around 1000 parts for the A350, giving advantage to “Airbus which has

managed to save money and reduce manufacturing time to meet their required deadlines”.

(KRASSENSTEIN, 2015)

The A350 carbon wing has a span of 64 meters and includes winglets and high-lift devices.

An approximate speed of Mach 0.85, similar to the speed of the B787, is achieved due to the

aerodynamically efficient 33 degree swept wing.

2.3 Systems Arhitecture

Boeing’s ambitious system design on the Dreamliner, has a new approach that no other large

comercial aircraft has conceived before, a more electric system arhitecture that essentialy

doesn’s require bleed air from its two engine type variations: the Rolls-Royce Trent 1000/

GNnx. The electric operating systems in the 787 are: hydraulic pumps, cabin pressurisation,

engine start, APU start and wing ice protection. Only one system still uses bleed air, the anti-

ice system for the engine inlets. Unlike the conventional APU which drives pneumatic load

compressor the new APU uses a starter generator that promises to be four times more

reliable. The engines also benefit of electrical power generation, a fundament change that

eliminates the pneumatic starter from the engine. Ducts, valves, heat shields, overheat

monitoring systems and duct burst protection systems are the functions that have been

removed from the 787 airframe due to the bleedless engine system.

Airbus A380 system designs have contributed to the newer jetliner build concepts which

together with other advanced technologies have made the A350 the most sofisticated aircraft

in the Airbus family fleet. Its hydraulic systems is an example of how A380 influenced the

manufacturer to implement it again, as it proved to be a robust design that the airliners were

satisfied with its performance. The system comprises of two hydraulic circuits contrary to the

three circuits that the rest of the Airbus aircrafts have. Flight controls, nose wheel steering

and landing gear actuation are some of the systems that are powered by these hydraulic

circuits. Moreover the A350 XWB has a simplified fuel system with fewer pumps and valves.

These reductions like the B787 add advantageous benefits for the air carriers when operates

them commercially, saving capital due to weight saving and lesser maintenance visits. The


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manufacturers also benefit from having fewer systems for the aircrafts as it improves their

production to in service operation. (Airbus, n/a) The 787 and 350 have incorporated a 5000

psi system operating pressure, similar to the A380.

Fly-by-wire is used in both B787 and A350, replacing the mechanical system of cables and

pulleys with electrical signals that actuate the control surfaces. The Dreamliner incorporates

triple redundant systems to move its control surfaces, the third being an hydraulic system

compartmentalised with valves, and pressure is maintained using electrical compressors. The

fly-by-wire in the A350 uses a fully electrical three axis flight controls, providing extra flight

safety, reduction of mechanical parts and reduced pilot workload. From the commercial

operational point of view the A350 has a huge advantige over the Dreamliner in terms of the

fly-by-wire system, by providing the communality experience to the flight deck crew which

Airbus has incorporated throughout its entire aircraft family for many years.

The primary flight control system in the A350 includes a mix of electrohydraulic (EH) and

advanced electrohydrostatic (EHA) actuators to control the rudder, aileron, elevator and

spoiler flight surfaces. The Dreamliner adapts a very similar system with the exception that it

has an electromechanical (EM) servoactuators instead of the EHA actuator, which helps

control the flight surfaces. (Moog, 2013)

Electric brakes is an application of the MEA on the Dreamliner, a technological advancement

from the hydraulically actuated brakes (Hale, n.d.). Four independent electric brake actuators

(EBA) are available per wheel, allowing one of them to act as inoperative in the likely event

of a failure. By having this type of electrical system Boeing finds it easier monitoring the

status and health of the aircraft in general compared to the pneumatic or hydraulic systems.

The advantages that the airlines can benefit from monitoring the brakes are: electrical

monitoring of brake wear, fault detection and isolation, the ability to eliminate scheduled

visual brake wear inspections and extended parking times.

In regard to the 787’s cabin design, it can be noticed that the mechanical window shades have

been replaced with electro-cromatic dimmable windows which have a projected life of more

than 20 years. In addition high-intensity discharge (HID) and light emitting diode (LED)

lighting have been implemented in all cabins, flight deck and on aircraft exterior, having a

life longevity more that its counterparts due to no filament presence.


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3. Conclusion

The main scope of having developing these technologically advanced aircrafts is to respond

to today’s rapid growth in terms of transport by air demand and adapt to the technology

evolution. Close collaboration have been maintened between the airliners and the

manufacturers in order to tailor their needs in the production of the B787 and A350 XWB.

This assignement has been looked at the various materials used for the aircraft’s structure, the

systems and the design philosophy approch used on both the 787 and 350. The changes

implemented are very bold and promising, especially with the 787 MEA, wheather the 350

has adopted some of the elements from its precessors, the A380 and A330, keeping it more

conventionally focused. However the biggest change is the use of composite materials, no

other commercial aircrafts have used these high amounts of CFRP before. Its advantages are

tremendeous and airliners find it very attractive. Reliability and having economic costs

reduced are buzz words constantly used by the two world leading manufacturers. Composite

materials have never been

used on this scale before,

therefore it comes with

many uncertanties that the

aviation industry take the

responsability for and yet

have no answer.

Fig.3 MRO Costs (IATA,

2014)

The obvious concerns

relate to the durability of

the material under

conditions that cannot be

tested by the

manufacturers, such as how

many repairs of different

types can the structure

sustain until it breaks down


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(Marsh, 2012). After an impact the composite materials unlike metals, don’t show sign at the

surface, that the laminate has suffered damage, “...composites can spring back from low-

energy impact such that damage several plies down within the laminate can be hidden behind

an apparently unharmed surface.” (Marsh, 2012) Despite this Boeing and Airbus research

have found a solution based on a ultrasonic hand held enquipment which enaibles the

technician to detect if the laminate is damaged or not.

Reduced aircraft parts due to the innovative materials and advanced systems, lesser

workforce due to automation and prolonged maintenace check intervals due to the

technologies involved in building these two aircrafts, are some of the great achievements

established by Boeing and Airbus and that the airliners avail from. Despite these great

attributes, the Maintenance Repair and Overhaul Market may see them as challenges.

However according to the (IATA, 2014) report “Global MRO spend in 2013 was estimated at

$ 131 Bill., including overhead. Civil air transport (commercial) was valued at 46% ($60.7

Bill.). Market size is estimated to reach $89 Bill. in 2023.” (Fig 3.)

The good news for the MRO market is that the aircraft retirement will nearly double in a

decade time, due to the more efficient and young aircraft’s EIS. This means that the

aftermarket will benefit high pool of spare parts which will increase availability and spend on

surplus parts, composed at 65% of engine parts.

Regardless the relentless efforts made by Airbus and Boeing to help the MRO and other

material/parts suppliers to train on the technologies that are being used in the two new

aircrafts, it will be a challenge that will take some time until every destination that the two

will touch down, will have the adequent training and equipment required for maintening the

350 and 787. Also the new regulatory rules focusing on both aircrafts it will probably face

problems as differences may arise between the various authorities and its implementation and

adaptation may take time and capital to develop.

Nonetheless, Boeing and Airbus have developed three variants, the 787-8/9/10 and 350-

800/900/1000, that will provide their customers with ultra long ranges and extra passenger

capacity. The two manufacturers promise a 20% savings in the operation costs, and 20%

fewer emissions that will add value to the airline business.


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4. References

Airbus, n/a. Innovation. [Online]

Available at: www.a350xwb.com/innovation/ [Accessed 08 May 2015].

F Gaible, P. G., 2013. Intelligent airframe design. FAST, June, pp. 28-31.

Hale, J., n.d. Boeing. [Online]

Available at:

http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/AERO_Q406_article4.pdf

[Accessed 05 05 2015].

IATA, 2014. Airline Maintenance Cost Executive Commentary, Montreal: IATA.

KRASSENSTEIN, B., 2015. 3dprinting. [Online]

Available at: http://3dprint.com/63169/airbus-a350-xwb-3d-print/

[Accessed 8 May 2015].

Marsh, G., 2007. Airbus takes on Boeing with reinforced plastic A350 XWB. Reinforced Plastics, n/a

December, p. 27.

Marsh, G., 2012. The challenge of composite fuselage repair. Reinforced plastics, May, pp. 30-35.

Mash, G., 2012. The challenge of composite fuselage repair. Reinforced Plastics, p. 31.

Moog, 2013. Moog. [Online]

Available at: http://www.moog.com/markets/aircraft/civil-aircraft/commercial-transport/system-

provider-for-the-boeing-787-dreamliner/ [Accessed 10 May 2015].

Documents

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