jonathon rowan-undergraduate project

The design and analysis of a supercritical aerofoil

for a concept commercial aircraft using CFD

package’s, incorporating materials research

Jonathon Michael Rowan

Supervised by Martin Fiddler

A Final Year Project Report

submitted to the

Faculty of Computing, Engineering and Technology

In partial fulfilment of the requirements for the degree:

Aeronautical Technology BSc.

Staffordshire University

Stoke-On-Trent

April 2014

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Jonathon M Rowan – Final Year Project


“Scientists investigate that which already is; engineers

create that which has never been.”

Albert Einstein

“Strive for perfection in everything you do. Take the best that exists

and make it better. When it does not exist, design it."

Sir Henry Royce

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Abstract

The modern aviation industry is focussed on efficiency and design sustainability. This document

reviews the design and analysis of a supercritical aerofoil section for use in the design of a

conceptual wing arrangement, specifically designed for the new Boeing 777x aircraft. This document

will examine three areas of wing design:

1. Aerofoil cross section.

2. Advanced aircraft wing design.

3. Advanced material application.

The principle focus of this investigation is to improve the lift- to-drag performance and thus

economic efficiency of aircraft though the examination of the three areas of wing design listed

above.

A supercritical aerofoil investigation was completed. The main objective was to design a more

efficient aerofoil section that allows high speed transonic flight, whilst retaining impressive lift-to-

drag ratio.

A concept aircraft investigation was completed. The main objective was to design a conceptual wing

arrangement for the new Boeing 777x aircraft that provides increased efficiency whilst flying in

cruise configuration.

An advanced material selection review was completed. The main objective was to select the

optimum material available to the aviation industry for use in the construction of the aerofoil.

Advanced materials offer significant benefits in efficiency due to reduced weight.

Advanced computational fluid dynamics software ANSYS Fluent was used during the course of this

final year project. This software was used as less sophisticated fluid dynamics software e.g. Cham

Pheonics, cannot run simulations accurately in the transonic speed envelope.

The use of ANSYS Fluent enabled trustworthy testing to show the design of aerofoils that provide

higher lift to drag those current aerofoils. It was also proven that advanced non-planar wing designs

show improved lift to drag to current conventional wing arrangements.

The results presented in this Final Year Project confirm that advanced box wing designs (such as the

Lockheed Martin Box Plane) can offer significant aerodynamic improvements whilst retaining many

conventional parameters of aircraft design. The results show that advanced box wing aircraft offer a

second option in conceptual aircraft design as an alternative to blended wing designs.

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Contents

Abstract ................................................................................................................................................... 2

Schedule of figures .................................................................................................................................. 5

Acknowledgements ................................................................................................................................. 8

Chapter 1 - Introduction ......................................................................................................................... 9

1.1 - Aims and objectives ........................................................................................................ 11

Chapter 2 - Aerofoil Design – shape & cross-section ............................................................................ 13

2.1 - Aerofoil Design Parameters .................................................................................................. 14

2.2 Supercritical aerofoil design .................................................................................................... 15

2.3 - Supercritical aerofoil benefits ............................................................................................... 18

2.4 - Examples of current transonic aerofoils ............................................................................... 19

2.5 – Supercritical aerofoil modelling ........................................................................................... 21

2.6 - Aerofoil families .................................................................................................................... 22

2.7.1 Initial aerofoil performance testing ............................................................................................. 23

2.7.2 - Experiment verification ...................................................................................................... 24

2.7.3 - Primary aerofoil testing results .......................................................................................... 25

2.7.4 - Initial test results ............................................................................................................... 31

2.7.5 – Supercritical design phase 2 - aerofoil research ............................................................... 32

2.7.6 - Supercritical design phase 2- simulation results ............................................................... 33

2.8 Supercritical design phase 2 - Redesign approach .................................................................. 35

2.8.1 - Supercritical aerofoil testing analysis ................................................................................ 40

2.8.3 Decision and aerofoil design evaluation .............................................................................. 42

Chapter 3 - Advanced aircraft wing design ........................................................................................... 43

3.1 - Concept commercial aircraft research .................................................................................. 44

3.2 - Initial design concept ...................................................................................................... 48

3.3 - Similar projects/inspiration .................................................................................................. 49

3.4 - Current aircraft lift to drag performance .............................................................................. 52

3.5.1 – Concept design plan and objectives .................................................................................. 53

3.5.2 - Angle of incidence .............................................................................................................. 54

Experiment analysis ...................................................................................................................... 68

Conclusion on advanced box wing designs for commercial use ................................................... 70

Chapter 4 – Materials selection for advanced box wing design. .......................................................... 71

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4.1 Materials research .................................................................................................................. 72

4.2 - Advantages of advancements in material technology.......................................................... 74

4.3 - Material selection using CES-Edupack .................................................................................. 75

4.4 Material selection conclusion ................................................................................................. 81

5.0 - Rendered Images of final design ................................................................................................... 84

Discussion.............................................................................................................................................. 86

Conclusion ............................................................................................................................................. 89

Recommendations ................................................................................................................................ 91

Bibliography .......................................................................................................................................... 92

APPENDIX A – Drag terms .................................................................................................................... 95

APPENDIX B - ‘Technical literature review’ .......................................................................................... 97

APPENDIX C – Aerofoil database links ............................................................................................... 101

Appendix D – ‘Boeing 777 Design parameters’ .................................................................................. 103

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Schedule of figures

Figure 1 - Shows the typical parameters that are used define the design of an aerofoil. The

terminology used is explained below. (Cantrell, 2012) ........................................................................ 14

Figure 2 - An example of a supercritical aerofoil and where the shockwave is produced (Aircraft

Recongnition, 2014) .............................................................................................................................. 15

Figure 3 - Co-ordinate sketch of National Propulsion Laboratory (NPL) 9510 Transonic Aerofoil

(University, Illinois, 2013) ..................................................................................................................... 19

Figure 4 - Co-ordinate sketch of the McDonnell/Douglas DSMA-523 Transonic Aerofoil with sharp

trailing edge (University, Illinois, 2013) ................................................................................................ 20

Figure 5 - Co-ordinate sketch of the NASA SC(2)-0610 supercritical aerofoil ...................................... 20

Figure 6 - NPL 9510 AEROFOIL - NPL 9510 transonic aerofoil modelled using Creo Parametric design

modeller. ............................................................................................................................................... 21

Figure 7 - McDonnell/Douglas DSMA-523 transonic aerofoil with sharp trailing edge modelled to

exact coordinates using Creo Parametric ............................................................................................. 21

Figure 8 - NASA SC(2)-0610 supercritical aerofoil modelled to exact coordinates using Creo

Parametric ............................................................................................................................................. 21

Figure 9 - Shows a pressure contour colour map for the NPL 9510 supercritical aerofoil. .................. 25

Figure 10 - The pressure contour map for the Dsma-523A Aerofoil produced by ANSYS fluent post

CFD processor. ...................................................................................................................................... 26

Figure 11 - The relative pressure contour map for aerofoil SC(2)-0610 ............................................... 27

Figure 12 - Shows the relative contour map for S.U.A.D.1 which shows poorer performance in

comparison to the researched aerofoils. .............................................................................................. 28

Figure 13 - Pressure contour around S.U.A.D.2 which offers the lowest lift to drag of all tested

aerofoils. This is caused by a lack of pressure under the lower surface ............................................... 29

Figure 14 - Pressure contour map around the best performing S.U.A.D. family aerofoil to this point.

The substantial increase in lift was produced by a much more concave aft section. .......................... 30

Figure 15 - Primary aerofoil testing bar chart showing the DSMA-523A aerofoil to have performed

best in terms of lift to drag. .................................................................................................................. 31

Figure 16 - NYU/Grumman K-1 transonic aerofoil ................................................................................ 32

Figure 17 - RAE 2822 transonic Aerofoil ............................................................................................... 32

Figure 18 - Pressure contour map from the simulation using the NYU-Grumman K-1 aerofoil. This

aerofoil shows significant performance improvements. ...................................................................... 33

Figure 19 - Pressure contour map showing the relative pressures around the RAE 2822 transonic

aerofoil. This shows the highest lift to drag result of any researched aerofoil. ................................... 34

Figure 20 - The first redesigned aerofoil using parameters from other aerofoils. This image shows the

pressures around the S.U.A.D.4 project designed aerofoil. ................................................................. 36

Figure 21 - S.U.A.D.5 pressure contours showing high pressure build up underneath especially in aft

section of the aerofoil. .......................................................................................................................... 37

Figure 22 - Shows the pressure contour map from the highest lift to drag ratio aerofoil tested in the

simulation S.U.A.D.6. ............................................................................................................................ 38

Figure 23 - The table below shows the results generated from the aerofoil testing completed in

ANSYS Fluent. ........................................................................................................................................ 40

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Figure 24 - Graph – showing the complete results from the aerofoil simulations shown on a bar

chart. ..................................................................................................................................................... 40

Figure 25 - One example of a blended wing concept currently being analysed is the Boeing x-48 ..... 45

Figure 26 - Shows potential design ideas for a morphing wing and the structural aerodynamic

changes it would make in flight. (Centre for Mechanics and Control, 2004) ....................................... 46

Figure 27 - This image shows the performance of vortex drag production for a number a of different

aircraft wings. The picture shows that a box plane produces the least relative vortex drag when

compared to a number of different designs. ........................................................................................ 47

Figure 28 - Potential design ideas include the typical box wing configuration and Boeings fluid wing

configuration. ........................................................................................................................................ 48

Figure 29 - The Lockheed Martin Advanced Box Plane was the main inspiration for this project – it is

often presented as a future aircraft variant. The design is a typical advance box wing. ..................... 49

Figure 30 - The final design of the Prandtl concept Aircraft. This design was the produced at Pisa

University. The project had the aim of designing an aircraft that would carry over 800 passengers. . 50

Figure 31 - Shows the comparison in optimum induced drag of a biplane and optimum induced drag

of ‘best wing systems’. .......................................................................................................................... 50

Figure 32 - Shows the A9 Dragonfly - a medium size long haul aircraft design using the advanced box

wing design. .......................................................................................................................................... 51

Figure 33 - provides the Lift to drag performance for the commercial aircraft shown: ...................... 52

Figure 34 - research results - incidence of incidence. .......................................................................... 54

Figure 35 - Show the pressure contours around aerofoil S.U.A.D.6 at its optimum angle of attack

which was 2 degrees where its lift-to-drag performance is over 60. ................................................... 55

Figure 36 - Show the velocity contours around aerofoil S.U.A.D.6 at its optimum angle of attack

which was 2 degrees where its lift-to-drag performance is over 60. ................................................... 55

Figure 37 - A 777 replica designed to the same design parameters found on the Boeing technical

information website. ............................................................................................................................. 56

Figure 38 - Pressure 1 contours around the surface of a 777 .............................................................. 56

Figure 39 - Pressure 2 contours around surface of a Boeing 777 ......................................................... 57

Figure 40 - Velocity 1 around a Boeing 777 .......................................................................................... 57

Figure 41 - Velocity 2, velocity contours around surface of a Boeing 777 ........................................... 57

Figure 42 - 777-300 scale model with engines attached. ..................................................................... 58

Figure 43 - Pressure contours around a Boeing 777 with engines ....................................................... 58

Figure 44 - Pressure contours image 2 ................................................................................................. 59

Figure 45 - Velocity contours around the surface of a Boeing 777 with engines ................................. 59

Figure 46 - Velocity contours image 2 .................................................................................................. 59

Figure 47 - The first concept wing design for commercial aircraft is a typical box wing design this

design is titles the 777x concept 1. ....................................................................................................... 60

Figure 48 - Pressure contours around the surface of 777x concept 1 .................................................. 60

Figure 49 - Pressure contours image 2 ................................................................................................. 61

Figure 50 - Velocity contours around the surface of 777x1 ................................................................. 61

Figure 51 - Velocity contours image 2 .................................................................................................. 61

Figure 52 - 777x concept 2 is an advanced box design original to the project..................................... 62

Figure 53 - Pressure Contours around 777 x concepts 2 ...................................................................... 62

Figure 54 - Pressure contours image showing an underside view of the 777x concept2 .................... 63

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Figure 55 - Velocity contours around the 777 x concept 2 ................................................................... 63

Figure 56 - Velocity contours showing the under view of the 777x concept 2 .................................... 63

Figure 57 - The second designed advanced box wing original to this project titles 777x concept 3 ... 64

Figure 58 - Pressure contours around 777 x concepts 3 ...................................................................... 64

Figure 59 - Pressure contours showing different view of 777x concept 3 ........................................... 65

Figure 60 - Velocity contours of 777x concept 3 .................................................................................. 65

Figure 61 - Velocity contours image 2 of the 777x concept 3 .............................................................. 65

Figure 62 - The Final design is more of a biplane than a box plane this aircraft design is titles 777x

concept 4............................................................................................................................................... 66

Figure 63 - Pressure contours around 777 x concepts 4 ...................................................................... 66

Figure 64 - Second image of pressure contours around 777 x concepts 4 ........................................... 67

Figure 65 - Velocity contours around 777 x concepts 4 ....................................................................... 67

Figure 66 - velocity contours around 777 x concepts 4 ........................................................................ 67

Figure 67 - This table of figures shows the performance of lift to drag ratio of each aircraft design

tested. It is demonstrated that each of the non-planar advanced box style wings offers significant

advantages in lift to drag performance. ............................................................................................... 68

Figure 68 - Lift to drag results of each aircraft shown on a line graph ................................................. 68

Figure 69 - Similar graph to figure 68 however this time the information is represented on a bar

chart. ..................................................................................................................................................... 69

Figure 70 - A bar chart comparing a current Boeing 777 against the best performing box wing the

777x concept 3 ...................................................................................................................................... 69

Figure 71 - shows the percentage of composite materials in the Boeing fleet as they have evolved

the 787 is now made up of 50% composite with the entire wing structure made using ..................... 73

Figure 72 - Shows the advancement in material technology and predicts future technology levels the

current technologies being used in the 777 are pre 2000 need a drastic overall. ............................... 74

Figure 73 - An image demonstrating the 4 main design needs of aircraft wings. ................................ 75

Figure 74 - Graph showing young’s modulus against density, only the colour circles are materials that

have passed the limit stage................................................................................................................... 78

Figure 75 - When the selection line is used the following materials are the best 5 shown in this figure

.............................................................................................................................................................. 78

Figure 76 - Elastic limit vs density graph only the coloured circles have passed the limit stage ......... 79

Figure 77 - Yield strength vs density, using a selection line to find the top 5 performing materials. .. 79

Figure 78 - Fracture toughness vs density ............................................................................................ 80

Figure 79 - Fracture toughness vs density using a selection line to select the top 5 materials. .......... 80

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Acknowledgements

I would like to take this opportunity to thank to a number of people that helped and encouraged me

in the completion of this Final year Project.

Firstly I would like to thank Staffordshire University for providing excellent facilities throughout my

three years studying at the University. These facilities have helped me achieve the objectives of my

Final Year Project.

I would also like to thank Mr Martin Fiddler who has provided an excellent learning culture

throughout the course and provided sound and reliable support throughout the duration of this Final

Year Project. Mr Fiddler’s guidance has been invaluable and he has helped me to strive to achieve

the projects objectives and to stay focussed.

I would like to express my gratitude to Mrs Debi-Marie Roberts whom I relied upon for a second

opinion and who has given me the knowledge of aerodynamics has allowed me to generate high

quality data for this project. Debi was always there in times when I was struggling with my data

collection.

I would also like to thank my Mother and Father who have provided me with constant support and

who are always a reliable source of help and advice. Their support has allowed me to work to

achieve the best possible outcome from my studies at Staffordshire University. I hope to make them

proud with the result I obtain for this project.

Jonathon Michael Rowan.

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Chapter 1 - Introduction

Overview

The aviation industry is growing at a remarkable rate. This is driven by a Global population increase

and the increase in demand for air travel and transport from emerging and powerful economies in

Countries such as India, China and Brazil. Air travel is becoming increasingly accessible to more and

more people - this means more aircraft, more emissions and more pollution.

It is estimated that passenger and cargo air-traffic will grow by between two and three hundred per

cent in the next two decades. It is expected that medium and long range routes Worldwide will see a

particularly significant increase in air-traffic. (Frediani, 2005)

Given this increasing demand, the aviation industry is striving for efficiencies and giving close

attention to finding ways to make the industry more environmentally friendly and sustainable.

Making progress on these very significant challenges is the task facing all aeronautical design teams

around the World today.

This document details the work undertaken to design and analyse a supercritical aerofoil and wing

arrangement for a concept superjumbo variant aircraft. This concept aircraft would compete in the

aviation marketplace with aircraft such as the Airbus A380, the Boeing 747-700 and the Boeing 777x.

The project centres around 3 mains areas of aircraft wing design with added innovative aerodynamic

features. The chapter headings in the main body of this Final Year Project document will be:

- Aerofoil design - shape / Cross-section for supercritical aerofoils.

- Advanced aircraft wing design (including ‘Aerodynamic improving features’).

- Materials research and Optimum material selection

The project focuses upon innovation in efficiency and sustainable design. Inspiration for the project

came from a number of sources in particular research undertaken on supercritical aerofoils, and the

work completed by Charles Harris (Southampton University 1990) formed the basis of the

investigation into supercritical aerofoil design.

The design of a conceptual large commercial aircraft was inspired by the Lockheed Martin

‘advanced box wing project’ and the Prandtl Plane investigation and design completed at Pisa

University.

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Within each of the three main chapters there will be a detailed explanation of the research

undertaken as the project developed in addition to a clear demonstration of the results achieved

and analysis undertaken.

Project motivation

Justification for the project lies within the evident desire of the aviation industry for fuel efficiency

and the consequent reduction on the cost of air travel. A key aim of this design project was to

greatly improve the aerodynamic performance of commercial aircraft. This is coupled with the aim

of producing this improvement to achieve a key output – the capability to carry more people at the

lowest possible cost. Mass air travel will become increasingly popular with the travelling public and

airline operators will wish to operate the most cost effective service in the delivery of service to their

customers.

The project provides analysis on the complex transitional flows between subsonic and supersonic

speeds and aims to show innovative design in aerofoil shape and wing structure - with an emphasis

placed upon innovation in efficiency.

In aviation there are two main types of drag that can affect the performance of the aircraft thus

increasing fuel costs. These are 1Induced Drag and 2Parasitic Drag. A significant objective in the

creation of the concept aircraft design developed during the course of this project was to make the

concept aircraft meet the challenge of a ‘cross-over’ design that delivers improved performance at

low speeds where induced drag is the dominant drag force present and in cruise configuration

where parasitic drag is predominant.

Meeting the challenge of innovation is extremely important in the aviation industry and innovation

provides a strong focus for this project. The commercial success of the innovative Boeing 787

Dreamliner demonstrates the importance of innovations that deliver cost and other benefits to

airline operators and passengers. Boeing has a significant order back-log due to the appreciation of

the benefits the Boeing 787 Dreamliner delivers when compared to other aircraft.

There is no doubt that the Boeing 787 Dreamliner’s design includes a number of innovations that

deliver significant reductions in fuel consumption and total emissions in addition to other benefits.

Whilst recognising the achievements of the Boeing design team, this project has been completed

1 Defined in appendices

2 Defined in appendices

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with firm belief that more radical designs have the potential to deliver more efficient and

economical flight.

1.1 - Aims and objectives

The overall aims of the project were to; analyse a supercritical aerofoil and wing arrangement for a

concept superjumbo variant aircraft; provide valuable research in the design of a suitable

supercritical ‘high speed’ transonic aerofoil design and to demonstrate this design could be

introduced in aircraft manufacture using the most appropriate high performing, low weight

advanced materials.

From the outset, the objectives of the project were to deliver:

An aerofoil design that offers high cruise speed and that provides improved aerodynamic

performance for improved efficiency in transonic transport.

A project that has commercial value with emphasis placed on innovation in the three areas

of aircraft wing design noted above.

A concept wing design for a commercial aircraft that demonstrates innovation that delivers

improved aerodynamic performance offering new levels of efficiency.

The selection of the optimum performing material for use in the construction of a modern

aircraft.

Time constraints, data collection difficulties and data accuracy were challenges faced in the

completion of this project. Two solutions dealt with these issues:

Careful time planning and strict adherence to deadlines in the completion of the various

work stages.

The projects use of advanced computational fluid dynamics ANSYS Fluent software to

produce results that are reliable and can be used to draw significant and meaningful

conclusions.

The projects main conclusions demonstrate that increased aircraft efficiency is possible through

improvements in the three areas of design researched. Improved lift-to-drag results can be achieved

by improvements in aerofoil sections and by advanced non-planar wing design. In addition,

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improvements in aircraft performance can be achieved through the use of advanced materials in

there construction.

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Chapter 2 - Aerofoil Design – shape & cross-section

This chapter of focusses on the design analysis and review of supercritical aerofoils. This research

will be applied later in the project in the design of a conceptual wing. Research will focus on the

design parameters of supercritical aerofoils designed for transonic. This research is important as it

will reveal why the performance of such supercritical aerofoils makes them suitable for commercial

use.

Analysis of the design parameters and the aerodynamic performance of three transonic aerofoils will

be considered and reviewed. These transonic aerofoils have been designed by the some of the most

experienced aviation businesses in the world – it is therefore important to understand them fully

before contemplating design improvements.

New designs will be then be created and undergo the same testing as the commercially designed

aerofoil. This will be followed by performance evaluation analysis of the new aerofoil designs in

different configurations and scenarios.

Following this analysis, the research will lead to a recommendation with justification as to the

aerofoil design that is to be used for the conceptual aircraft.

Chapter 2 objectives

The objectives set for this chapter are to:

Describe and discuss the parameters used when designing aerofoils.

Understand the application of parameters in design of transonic supercritical aerofoil

sections and explain the benefits achieved for commercial use.

Research and understand the design and performance of current aerofoils designed by

important aviation companies.

Design a selection of transonic aerofoils following examination of other transonic aerofoils.

Conduct accurate and testing on a selection of the newly designed aerofoils.

Complete analysis on the best performing newly designed aerofoils.

Select the best performing aerofoil from those tested and make clear the reasons it will be

used in the design of the advanced box-wing reconfiguration of a Boeing 777x.

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2.1 - Aerofoil Design Parameters

Figure 1 -shows the typical parameters that are used define the design of an aerofoil. The terminology used is explained below. (Cantrell, 2012)

Leading edge – The frontal point of the aerofoil where first contact with the air occurs.

Trailing edge - Where the upper surface and lower surface meet at the rear of the aerofoil – the final

point of the aerofoils body.

Chord line - The straight line that connects the leading and trailing edges of the aerofoil.

Angle of attack – The angle at which the chord line faces the oncoming air.

Chord - The length of the chord line from leading edge to trailing edge. This is the characteristic

longitudinal dimension of the aerofoil.

Camber – The difference in curvature between the top surface and the bottom surface. This is

known as the asymmetrical difference.

Maximum camber – The point at which the distance between the upper and lower surfaces is at its

maximum.

(Cantrell, 2012)

The remaining design parameters are not shown in Figure 1:

Mean camber line – The mean camber line is a line drawn halfway between the upper and lower

surfaces. The chord line connects the ends of the mean camber line.

Upper camber - The curvature and shape that is between the upper surface and the chord line.

Lower camber – The curvature shape that defines the chord line and the lower surface.

(Cantrell, 2012)

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2.2 Supercritical aerofoil design

A supercritical aerofoil is an aerofoil specifically designed for higher efficiency performance in the

transonic speed range (Skybrary, 2012). When an aircraft with a conventional wing nears the speed

of sound (Mach 1), air flowing across the top of the wing moves faster than Mach 1 and becomes

supersonic. This creates a shock wave on the wing's upper surface despite the fact that the aircraft,

as a whole, has not exceeded Mach 1 (NASA, 2004). The aircraft at this point is flying at what is

called its ‘critical speed’. The shockwave causes the smooth flow of air hugging the wing's upper

surface (the boundary layer) to separate from the wing and create turbulence. Separated boundary

layers are like the wakes left in water behind a speed boat - the air is unsteady and churning and

drag increases. This increases fuel consumption, can lead to a decrease in speed and cause excessive

component vibrations.

A major aim in design of a supercritical aerofoil is to delay the onset of wave drag that becomes

apparent through shockwave formation upon the upper surface as the air breaks the speed of

sound. (NASA, 2004)

Figure 2- An example of a supercritical aerofoil and where the shockwave is produced (Aircraft Recognition, 2014)

There are typical designs features associated with supercritical aerofoils that differ from traditional

aerofoil design parameters. These features are:

A flattened upper surface which stops the air speeding up as much as it does on a curved

upper surface.

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A highly curved lift producing rear/aft section. This is to compensate for the lack of lift the

front end of the aerofoil produces.

A large leading edge radius which slightly slows the air so that it does not reach the critical

speed where the boundary layer separates creating unwanted drag.

These features allow for greater performance in drag reduction and make the aerofoils invaluable to

high performance transonic flight.

Modern aircraft can cruise at a higher subsonic speed well into supercritical range. Less drag at

these speeds is mainly to these supercritical aerofoils. An aircraft designed with supercritical wing

sections will use less fuel than it would otherwise consume. Higher subsonic cruise speeds and less

drag means that aircraft can travel faster using less fuel thus providing increased range and payload.

These factors help reduce the cost of passenger tickets and cargo transport.

Design objectives and challenges

Supercritical sections refer to a special type of aerofoil that is designed to operate efficiently within

the transonic speed range. The design objectives of a supercritical aerofoil are:

To carry as much lift as is practical on the aft potion of the section where the flow is

subsonic. (Tamkang University , 2012)

To ensure the aerofoils upper surface are as Flat and smooth as possible - this prevents the

air reaching critical Mach speeds to early over the upper surface of the aerofoil body.

To ensure the rear/aft section of the aerofoil is suitably cambered to produce high lift - this

is to compensate for the lack of lift that the smooth upper surface creates. (Tamkang

University , 2012)

To ensure and efficient level of lift is produced on the forward portion of the upper surface.

As the Local airspeed over the top surface increase the pressure near the nose is diminished.

Without additional blunting of the nose extra lift that could be generated here will be lost.

The design challenges associated with supercritical aerofoils are:

Reduction of shockwave formation. This generally means limiting the minimum pressure

coefficient occurring between the upper and lower surface.

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Excessive rear production of lift. This can lead to negative pitching moments with trim drag

and structural weight constraints. (Harris, 1990)

In extreme situations the adverse pressure gradient caused on the rear lower surface can

produce boundary layer separation. (Harris, 1990)

Extremely thin trailing edges to the aerofoils/ wing section have proved beyond

manufacturing capabilities. This means that certain theoretical aerofoils are impossible to

use into aircraft design. (Harris, 1990)

Supercritical sections and similar shock-free designs often are very sensitive to Mach and lift

coefficient and can perform poorly in operating conditions for which they were not

designed. (Harris, 1990)

"Drag creep" can often be a common occurrence. This happens when substantial section

drag increases with Mach number. This can occur even at speeds below the design value.

(Harris, 1990)

It is extremely important to be cautious in the design of supercritical aerofoils. Several major designs

of supercritical wing sections have looked promising initially but have created serious problems

when incorporated into an aircraft design. (Harris, 1990)

The Supercritical design challenge is to create an aerofoil section with high lift without causing

strong shock waves thus reducing drag caused by boundary layer separation. A supercritical aerofoil

can generally tolerate some supersonic flow without drastic increases in the drag. A generalised rule

for supercritical wing sections is that the maximum Mach numbers should not exceed Mach 1.2 to

1.3 to successfully minimise the effect of drag caused by shockwaves. (Tamkang University , 2012)

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2.3 - Supercritical aerofoil benefits

The use of supercritical aerofoils is vital in modern day aviation. There use delivers the following

benefits:

1. Significantly reduced shockwave induced boundary layer separation. This is achieved bcy

keeping flow over the aerofoil smooth and at regulated speeds.

2. The production of a smaller, weaker shock wave at a position further aft on the wing

than tradition aerofoils.

3. The potential for more efficient wing design. The supercritical aerofoil allows for a

reduction in wing sweep or an increase in wing thickness without the corresponding

increase in wave drag that would be associated with a typical aerofoil.

4. Higher lift to drag ratio associated with supercritical aerofoils allows for reduction in fuel

consumption.

(Harris, 1990)

Lift to drag

The main performance parameter used to compare the test supercritical aerofoils will be the results

for lift-to-drag. Lift to drag is a measure of the lift produced divided by the resultant drag forces

acting upon the aerofoil. There are many advantages in maximising the lift to drag of supercritical

aerofoil sections and aircraft wings in general.

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2.4 - Examples of current transonic aerofoils

The first stage in the design of a supercritical aerofoil to be used in combination with the concept

wing for a commercial aircraft is to review the performance of a selection of supercritical and

transonic aerofoils. Following research of a number of supercritical aerofoils I have chosen three

‘candidate’ supercritical aerofoils on which to conduct further research. The aerofoils I have chosen

to review are:

1. National Propulsion Laboratory (NPL) 9510 Transonic Aerofoil

2. McDonnell/Douglas DSMA-523 Transonic Aerofoil with sharp trailing edge

3. NASA SC(2)-0610 Aerofoil

These supercritical aerofoils where remodelled using Creo Parametric 2.0 and then tested, analysed

and compared in an aerodynamic test. This remodelling is undertaken to ensure that precisely the

same test parameters are applied to each aerofoil. This will mean that comparative analysis between

the performance of these supercritical aerofoils and the performance of the project designed

supercritical aerofoil will produce a meaningful comparison and analysis.

1. National Propulsion Laboratory (NPL) 9510 Transonic Aerofoil

This aerofoil was designed by a NASA project for use by aircraft in transonic flight. It is purely

experimental and has not been used in any commercial or military aircraft. However, the design is

interesting including design features that may assist the aims of this project. (Jenkins, 1983)

Figure 3 - Co-ordinate sketch of National Propulsion Laboratory (NPL) 9510 Transonic Aerofoil (University, Illinois, 2013)

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2. McDonnell/Douglas DSMA-523 Transonic Aerofoil with sharp trailing edge

McDonnell/Douglas is a large and successful aviation business that has been responsible for a

number of successful commercial jet aircraft. A supercritical aerofoil designed by such a prestigious

company warrants close examination and investigation.

Figure 4 - Co-ordinate sketch of the McDonnell/Douglas DSMA-523 Transonic Aerofoil with sharp trailing edge (University, Illinois, 2013)

3. NASA SC (2)-0610 Aerofoil

This supercritical aerofoil is of particular interest as it has been identified as the possible ‘root

supercritical aerofoil’ profile of the supercritical aerofoil used on the Airbus A380 aircraft (University,

Illionois, 2013)

Figure 5 - – Co-ordinate sketch of the NASA SC (2)-0610 supercritical aerofoil (University, Illinois, 2013)

Prior to aerodynamic testing and comparison with the concept aerofoil designs created as part of

this project, these aerofoils were remodelled using Creo Parametric 2.

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2.5 – Supercritical aerofoil modelling

Figure 6 - NPL 9510 AEROFOIL - NPL 9510 transonic aerofoil modelled using Creo Parametric design modeller.

Figure 7 - McDonnell/Douglas DSMA-523 transonic aerofoil with sharp trailing edge modelled to exact coordinates using Creo Parametric

Figure 8 - NASA SC (2)-0610 supercritical aerofoil modelled to exact coordinates using Creo Parametric

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2.6 - Aerofoil families

When aerofoils are designed they are designated into ‘aerofoil families’. These ‘families’ use the

same initial name (usually an acronym) followed by the allocation of a number to identify the

development stage the aerofoil has reached. There are many famous aerofoil families most notably

the NACA aerofoil series.

The aerofoil family created during this project will use the acronym S.U.A.D.

S.U.A.D. - STAFFORDSHIRE UNIVERSITY AERODYNAMIC DESIGN

S.U.A.D. Aerofoils follow a logical numbering system with the first design known as S.U.A.D.1

followed logically by S.U.A.D.2. The approach provides a simple method of identifying the

development stage of the supercritical aerofoils.

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2.7.1 Initial aerofoil performance testing

Each aerofoil was tested using precisely the same simulation parameters with the aerofoils in cruise

configuration. The test was performed using ANSYS Fluent – this software can perform highly

detailed analysis at transonic speeds. Initially, the tests were completed using the Cham Phoenics

software package. However this software package did not provide accurate information and the

results obtained proved unusable.

The primary objectives of the test were to establish which supercritical aerofoil was best performing

in terms of lift to drag ratio and to study the performance of each supercritical aerofoil in close

detail.

The simulation parameters were:

Air density = 0.1842 – Representing FL 300

Alpha (Aerofoil angle of attack) = 4.0

Airspeed = 0.8 Mach

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2.7.2 - Experiment verification

Prior to testing, the test parameters had to be determined and it was important to verify that the

results that would be obtained from the software package. Verification of the results is vital to

ensure there would be a correct understanding of the simulations results and to ensure correct

conclusions were reached.

Verification was achieved by reference to NASA Contractor Report 166005. This presents the results

of an experiment carried out on the NPL 9510 aerofoil at The University of Southampton by S. W. D.

Wolf. The report logs results for both the coefficient of drag and coefficient of lift and this can be

used to deduce the lift to drag ratio of the supercritical aerofoil tested. The simulation parameters

that were used by S.W.D. Wolf were applied in a simulation using ANSYS Fluent.

Comparative test results:

NPL SECTION ANALYSIS 9510 PROJECT Simulations NPL 9510

ALPHA = 4.0 Alpha = 4.0

MACH NO. =0.8002 Mach number 0.8

LIFT TO DRAG RESULT 32.58 LIFT TO DRAG RESULT 34.3

the results obtained from the simulation completed during the course of this project are extremely

close to the results detailed in NASA Contractor Report 166005. Therefore it is reasonable to

conclude:

The test parameters of the simulations conducted during the course of this project are

correct.

The results obtained are verified sufficiently and that accurate conclusions can be reached in

future tests.

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2.7.3 - Primary aerofoil testing results

NPL9510 – LIFT TO DRAG RESULT OF 34.3

PRESSURE

Figure 9 - Shows a pressure contour colour map for the NPL 9510 supercritical aerofoil.

VELOCITY

Figure 9a - Shows the velocity contour colour map around the NPL 9510 aerofoil.

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DSMA-523a - LIFT TO DRAG RESULT OF 35.9

PRESSURE

Figure 10 - The pressure contour map for the Dsma-523A Aerofoil produced by ANSYS fluent post CFD processor.

VELOCITY

Figure 10a – The velocity contour map for the Dsma-523A Aerofoil.

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SC (2)-0610 - LIFT TO DRAG RESULT 28.5

PRESSURE

Figure 11 - The relative pressure contour map for aerofoil SC (2)-0610

VELOCITY

Figure 11a - The relative velocity contour map for the aerofoil SC (2)-0610

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S.U.A.D.1 – LIFT TO DRAG 28.7

PRESSURE

Figure 12 – Shows the relative contour map for S.U.A.D.1 which shows poorer performance in comparison to the researched aerofoils.

VELOCITY

Figure 12a - Shows velocity contours around the S.U.A.D.1 aerofoil. This image shows significant velocity increase over the leading edge on the top surface - this is a negative feature for a supercritical section as a desired design features seeks to limit this.

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S.U.A.D.2 LIFT TO DRAG – 26

PRESSURE

Figure 13 - Pressure contour around S.U.A.D.2 which offers the lowest lift to drag of all tested aerofoils. This is caused by a lack of pressure under the lower surface

VELOCITY

Figure 13a - A velocity contour map around the S.U.A.D.2 aerofoil. It would appear there has been boundary layer separation quite early along the top section because the air flow is disturbed and slower.

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S.U.A.D.3 – LIFT TO DRAG RATIO 31

PRESSURE

Figure 14 - Pressure contour map around the best performing S.U.A.D. family aerofoil to this point. The substantial increase in lift was produced by a much more concave aft section.

VELOCITY

Figure 14a - Velocity contour map for the S.U.A.D.3 There is early boundary layer separation shown on the upper surface.

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2.7.4 - Initial test results

Figure 15 - Primary aerofoil testing bar chart showing the DSMA-523A aerofoil to have performed best in terms of lift to drag.

The results from the Initial testing show that the concept supercritical aerofoils created for the

project have failed to generate higher lift-to-drag results than the researched aerofoils. The highest

lift to drag generated was 35.9 by the DSMA-523a aerofoil - this is an impressive result.

The objective at this stage of the project was to design a supercritical aerofoil that performs better

than current aerofoils and this was proving to be a significant challenge.

The main issue in the design of the concept aerofoils was unsmooth sections. This created an early

boundary layer separation which caused a significant increase in drag produced by the aerofoils.

The concept aerofoil did generate reasonable and improved levels of lift however it was the drag

issue that contributed to the reduction in the lift-to-drag results.

0 5 10 15 20 25 30 35 40

SC_6010

NPL

Dsma

SUAD

SUAD2

SUAD3

Primary Aerofoil Testing

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2.7.5 – Supercritical design phase 2 - aerofoil research

Following the unsuccessful initial design stage, further focus was placed on the design effort and

further research was undertaken. Two further supercritical aerofoil designs where selected and

tested using the same test parameter as with the previous experiment.

The secondary aerofoil research focused on conceptual supercritical aerofoil sections that appeared

to offer an opportunity for improved lift to drag ratio results. (University, Illionois, 2013)

The two supercritical aerofoils selected for further analysis where:

Figure 16 - NYU/Grumman K-1 transonic aerofoil

Figure 17 - RAE 2822 transonic Aerofoil

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2.7.6 - Supercritical design phase 2- simulation results

NYU/Grumman K-1 transonic aerofoil – LIFT TO DRAG 46.6

PRESSURE

Figure 18 – Pressure contour map from the simulation using the NYU-Grumman K-1 aerofoil. This aerofoil shows significant performance improvements.

VELOCITY

Figure 18a - Velocity contour map around the experimental aerofoil section NYU-Grumman K1.

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RAE 2822 transonic Aerofoil- LIFT T0 DRAG 48.5

PRESSURE

Figure 19- Pressure contour map showing the relative pressures around the RAE 2822 transonic aerofoil. This shows the highest lift to drag result of any researched aerofoil.

VELOCITY

Figure 19a - Shows the velocity contours from the simulation using the RAE 2822.

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2.8 Supercritical design phase 2 - Redesign approach

Instead of further remodelling, it was considered the most appropriate approach to creating an

improved aerofoil section would be to:

Identify the best performing features of the researched aerofoils

And

combine these features as far as is practically possible with the features of other aerofoils

that demonstrate excellent performance

The hypothesis was that this combination should produce an aerofoil that has the performance

advantages of both. The target was to improve on the already impressive result from the RAE 2822

aerofoil of a 48.5 lift to drag ratio.

This redesign approach was needed as it was clear that all of the researched aerofoils were designed

with extremely smooth curvature. The Creo Parametric 2.0 design software was unable to replicate

this feature. The lack of extremely smooth curvatures resulted in boundary layer separation over the

upper surface of the test aerofoils. As a result of the turbulent air increased drag figures where

shown in the simulation. These drag figures effected the overall efficiency and performance of the

test supercritical aerofoils sections.

There is specific design parameters needed for a supercritical aerofoil, operating within the

transonic speed range, to perform highly. The optimum parameters are:

1. Flattened smooth upper aerofoil surface which stops the air reaching critical Mach speeds to

early over the upper surface.

2. A highly curved lift producing rear/aft section. This is to compensate for the lack of lift that

the smooth upper surface creates.

3. A large leading edge radius to keep the pressure gradient positive at the front end aiding the

production of lift.

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S.U.A.D.4 – LIFT TO DRAG 41

The first redesign concept was to use the top surface of the NYU-GRUNMAN K1 aerofoil and use a

high lift producing - rear/aft section surface of the McDonnell/Douglas DSMA-523 aerofoil. In the

primary design phase, the DSMA-523 aerofoil was the best performing. The aim was that, through

the use of a smoother flatter upper surface, the S.U.A.D.4 would perform better and show

significantly improved results.

PRESSURE

Figure 20 - The first redesigned aerofoil using parameters from other aerofoils. This image shows the pressures around the S.U.A.D.4 project designed aerofoil.

VELOCITY

Figure 20a – The velocity contour map showing impressive flow over the top surface of the aerofoil of S.U.A.D.4

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S.U.A.D.5 – LIFT TO DRAG RATIO 45

The same re-design approach was used in the design on S.U.A.D.5. This aerofoil utilises the RAE

2822’s upper surface that is smooth and particularly flat. Once again the rear aft section was

changed in an attempt to generate more lift. The rear section used is from the NPL-9510 aerofoil

from primary testing.

PRESSURE

Figure 21 - S.U.A.D.5 pressure contours showing high pressure build up underneath especially in aft section of the aerofoil.

VELOCITY

Figure 21a - The velocity contours around S.U.A.D.5

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S.U.A.D.6 - lift to drag 49.5

S.U.A.D.6 is a combination of the NYU-Grunman k1 aerofoil and the RAE 2822 aerofoil - the two

most successful aerofoils that had been tested at this stage.

S.U.A.D.6 generated a lift to drag ratio that exceeded all others. This was achieved through a design

combination of the best design features from the best two aerofoils tested. The NYU-Grunman k1

aerofoil has a larger leading edge frontal radius which is a desired design feature. The NYU-Grunman

k1 aerofoil has the flattest, smoothest and longest upper surface - this allows the air to flow on the

upper surface without boundary layer separation - this is a desired design feature.

The RAE 2822 has a harsher curvature around the aft section - this generates substantial lift. The

aerofoil does however have a very smooth surface that does not produce excessive levels of drag.

PRESSURE

Figure 22 - Shows the pressure contour map from the highest lift to drag ratio aerofoil tested in the simulation S.U.A.D.6.

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VELOCITY

Figure 22a - The velocity contour map for the S.U.A.D.6 aerofoil shows good flow over the top surface flow that only separates around the aft section.

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2.8.1 - Supercritical aerofoil testing analysis

Test results:

Aerofoil Lift Drag lift to drag ratio

SC-6010 0.004265900 0.000149790 28.47920422

NPL- 5910 0.00635580 0.00018516 34.32598833

DSMA-523 0.007374800 0.000205420 35.90108071

S.U.A.D. 0.0012187000000 0.0000420460000 28.98492128

S.U.A.D.2 0.006162800 0.000235330 26.18790634

S.U.A.D.3 0.00653310 0.00020891 31.27231822

NYU - Grunman K1 0.028218 0.000605 46.61974623

RAE 2822 0.024993 0.000511 48.10041088

S.U.A.D.4 0.02690400 0.00067028 40.1384496

S.U.A.D.5 0.02628900 0.00058937 44.60525646

S.U.A.D.6 0.02536300 0.00051284 49.55597067 Figure 23 - The table below shows the results generated from the aerofoil testing completed in ANSYS Fluent.

Figure 24 – Graph – showing the complete results from the aerofoil simulations shown on a bar chart.

0 10 20 30 40 50 60

SC_6010

NPL 9510

Dsma 523a

SUAD

SUAD2

SUAD3

NYU k1 grunmen

RAE 2822

SUAD4

SUAD5

SUAD 6

Complete Aerofoil Testing

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Following the testing of three aerofoils from the S.U.A.D. family, no considerable improvement in lift

to drag ratio had been achieved when compared to the commercially researched and tested

aerofoils. This led to further research of different experimental transonic aerofoil. Two aerofoils

(RAE 2822 and NYU K1 grunman) became the basis for the design of S.U.A.D.4 and S.U.A.D.5.

The S.U.A.D.4 and S.U.A.D.5 aerofoils where studied and modified with the aims of drag reduction

and stopping early shockwave formation thus improving performance. This was achieved by

including a sharper trailing edge and a smoother longer top section - this allowed for greater laminar

flow above the top edge these aerofoils where then tested. The outcome was a success and

significantly higher lift to drag results was achieved. S.U.A.D.6 provides a lift to drag of 49.5 - this is

extremely efficient and exceeds the performance of the commercial aerofoils selected for the

simulation.

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2.8.3 Decision and aerofoil design evaluation

The supercritical aerofoil design stage of this project has been a relative success. The result shown

above shows a definite improvement in lift to drag efficiency has been achieved.

From this point, aerofoil S.U.A.D.6 will be the only aerofoil section used in the design of a conceptual

aircraft. The aerofoil makes use of desired design features from other aerofoils and is the most

efficient aerofoil tested. Although this aerofoil is not unique as it uses different sections from other

designs, it does present an improvement.

A comparison of S.U.A.D.6 with the SC (2)-0610 aerofoil (the root aerofoil for the Airbus A380) shows

that the S.U.A.D. 6 provides significant increases in lift to drag. The improvement is a 75% increase in

lift to drag performance. This would deliver the benefits of reduced fuel consumption and overall

efficiency improvement.

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Chapter 3 - Advanced aircraft wing design

This chapter will detail the creation of a concept wing design for commercial aircraft using the

S.U.A.D.6 aerofoil. The aim is to improve the aerodynamic performance of commercial aircraft.

The focus of the aerodynamic improvements will be to improve operational efficiency. Gaining

efficiency improvements is a very important consideration for the aviation industry for the

protection of the environment and other reasons. Achieving improved fuel efficiency is a particular

consideration with fuel costs accounting for approximately 25% of airline operator’s costs. (Lee,

1998)

Improving efficiency is also important for the customers of airline operators – a reduction in running

should result in a reduction in the cost of tickets for passengers and costs charged by the airline

operators for cargo transport.

The lift to drag ratio of an aircraft is a measure of its aerodynamic performance and it is the

improvement in lift-to-drag that is the desired feature. A higher lift to drag ratio delivers the benefits

of improved cost and other efficiencies and improved climb rate.

The area of particular focus for this project is in improving efficiency is cruise flight. Aircraft spend

95% (Lee, 1998) of their flying time in cruise flight - this therefore provides an opportunity for the

introduction of improvement that will deliver significant benefits.

Chapter 2 - Aims and Objectives

These are to:

Present a unique design of a wing arrangement.

Incorporate aerodynamic improving design features based on the work completed during

this projects research

Improve on the lift to drag ratio performance of a current commercial aircraft

Present the analysis of aerodynamic performance of the wing arrangement using ANSYS

Fluent computation fluid dynamics software.

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3.1 - Concept commercial aircraft research

There is a great deal of research available in the area of conceptual commercial aircraft design that

focuses on aerodynamic improvement. The research undertaken for this project focused on three

aircraft designs:

1. Blended wings.

2. Morphing wing technology.

3. Non planar - Advanced closed/box wing.

Blended wings

This design blends wings into a smooth, wide, flat, tailless fuselage. This wide fuselage is often

shaped like an aerofoil and therefore produces most of the aircraft lift with the wings contributing

lift and overall balance. This configuration enables the entire aircraft to contribute to the lift with

less drag compared to the conventional cylindrical fuselage. The result of this is improved fuel

economy and aircraft range. Blended wings are often referred to as ‘flying wings’ as they are

typically designed using an aerofoil shaped body. (HUANG, 2012)

A great deal of research and development has been undertaken in the area of blended wing design

and to some they represent the future of air travel (Armstrong flight research centre (NASA), 2010).

The aircraft manufacturer Boeing has designed a test aircraft incorporating a blended wing – the X-

48. This aircraft was constructed at the Cranfield Aerospace Centre in the United Kingdom but the

design remains as an unmanned aircraft at present.

The blended wing body aircraft has a smaller frontal area than conventional aircraft design. As a

result of this there is less drag caused by the body. In addition to this there is the added benefit of

increased lift due to the design being based on an aerofoil.

The most significant benefits delivered by the blended wing design are aerodynamic improvements

and improved fuel efficiency. The design also has the advantage of improving the structural integrity

of the aircraft - this due to the integration of the wing structure with fuselage. This integration

means that the maximum wing bending moment and shear are approximately half of that for a

conventional configuration this means that structural weight saving can be achieved. (HUANG, 2012)

The blended wing body design under review features three jet engines mounted on the aircraft and

positioned, so that engine noise is shielded by the aircraft. This can significantly reduce the noise

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level experienced. However mounting engines at the rear can be dangerous as high angles of attack

can limit airflow reaching the engines and result in engine stall. Airports during take-off and

landing

Further challenges arise as the pilot, engines, flight equipment and payload must all fit all within the

depth of the wing section. A wing that is deep enough to accommodate all of these elements will

have an increased frontal area when compared to a conventional wing and fuselage - this results in

higher drag and reduces the drag advantages of the design.

Figure 25 - One example of a blended wing concept currently being analysed is the Boeing x-48

Morphing wings

Aircraft morphing wings affect the aerodynamic characteristics and abilities of aircraft through a

dramatic change in the shape of the aircraft. Several complex aircraft morphing system designs have

exist including rotating, sliding and inflating mechanisms. There are many research projects

underway as researchers have identified the design has the capability to increase versatility and

maximise aircraft efficiency for the duration of the flight. (Min, 2008)

The ‘Defence Advanced Research Projects Agency’ (DARPA)’, considers a morphing aircraft to be an

‘adaptable, time variant airframe, whose changes in geometry influence aerodynamic performance’.

Many conventional aircraft already incorporate features which significantly change the geometry of

the wings to influence there aerodynamic properties e.g. flaps and slats. However these features

cannot create a seamless aerofoil shape when extended as they operate using sliding rails and

hinges. (Center for Mechanics and Control, 2004)

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DARPA's concept of a Morphing aircraft is a multirole aircraft that:

Changes its state/shape substantially to adapt to the mission environment;

Provides superior system capability not possible without reconfiguration;

Uses integrated design of materials, distributed actuators, effectors and mechanisms to

reconfigure in flight. (Center for Mechanics and Control, 2004)

Figure 26 - Shows potential design ideas for a morphing wing and the structural aerodynamic changes it would make in flight. (Centre for Mechanics and Control, 2004)

The benefits of a morphing aircraft include the ability to change aerodynamic configuration to suit

different conditions – this would enable the aircraft to achieve high levels of efficiency in variable

conditions. The significant challenge of the design is that current material technology used in the

construction of the aircraft would mean a significant weight increases would be necessary to

produce the design. In addition, the design seems to be focused on military applications.

Commercial aircraft fly above the weather in stable conditions and changing the wing configuration

to suit conditions is much less important. In conclusion, this design does not need to be considered

in relation to meeting the aims of this project.

Advanced closed/box wing

Advanced closed/box wings are a type of non-planar wing that provide the deliver reduced induced

drag compared with traditional wings. The design also provides an increase in total lift. However, the

integration and assessment of non-planar wing concepts is complex. (I Kroo, 2005)

The term ‘closed wing’ is used to describe a number of wing designs including annular, joined and

box wings. Whilst there are no aircraft with these wing designs in commercial use, many significant

research projects have taken place, most notably the Lockheed Martin Advanced Box Wing and the

IDINTOS Project. The IDINTOS Project which a research project co-funded by the Regional

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Government of Tuscany (Italy) in 2011 as part of a project to design and manufacture an amphibious

ultra-light Prandtl Plane.

Closed wing surfaces exhibit a number of interesting structural and aerodynamic properties. A box

plane achieves the minimum possible induced drag for a given lift wingspan. A closed wing surface

has no wingtips whatsoever - this greatly reduces or eliminates wingtip drag. Such a design presents

very significant opportunity for the improvement of fuel efficiency in the airline industry.

Figure 27 - This image shows the performance of vortex drag production for a number a of different aircraft wings. The picture shows that a box plane produces the least relative vortex drag when compared to a number of different designs. (Frediani, 2005)

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3.2 - Initial design concept

Induced drag accounts for 40% of cruise drag and up to 80% of total drag at take-off. If a wing can be

designed and manufactured that reduces these values then it will have an obvious commercial value

(Frediani, 2005). Increasing wing span achieves reduction in induced drag. There is a great deal

research being undertaken in this area, particularly in relation to the performance capabilities of

blended wing design concepts (I Kroo, 2005).

“Induced drag may be easily reduced by increasing the span of a planar wing. A 10% increase in

wing span leads to a 17% reduction in induced drag” (Frediani, 2005)

However, these blended wing concepts represent a significant change in aircraft design. Blended

wing aircraft will cost significantly more in construction and maintenance. In addition the increased

weight of the blended wing aircraft will mean needed longer runways for safe take-off and landing.

Following evaluation of the three wing designs reviewed, the design of the concept aircraft will

include an advanced box non planar wing. As discussed above, this wing design provides for

significantly reduced induced drag. In addition, including this wing into the design of the concept

aircraft does not present significant design changes or challenges – the fuselage will remain

unaltered as will the engines. Indeed there may even be the possibility of considering the inclusion

of this wing design as a ‘retrofit option’ for existing aircraft. Such an option would only be

economically viable should the aerodynamic improvements obtained deliver significant

improvement in fuel economy and reduced emissions.

Potential Design ideas

Figure 28 - Potential design ideas include the typical box wing configuration and Boeings fluid wing configuration.

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3.3 - Similar projects/inspiration

Three aircraft that use an advance box wing design have been researched to help achieve the aims

of this project. These are:

The Lockheed Martin Advanced Box Plane

The Prandtl Plane

The Cranfield A9 Dragonfly

It has not been possible to obtain aerodynamic performance related results for these aircraft.

Therefore their role in the completion of this project is inspirational rather than providing an

opportunity for performance related comparative analysis with aerodynamic performance research.

Lockheed Martin advanced box wing concept aircraft

Figure 29 - The Lockheed Martin Advanced Box Plane was the main inspiration for this project – it is often presented as a future aircraft variant. The design is a typical advance box wing.

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Prandtl Concept Aircraft – Pisa University

The Prandtl Concept Aircraft is a superjumbo aircraft design proposed by Aldo Frediani, Matteo

Gasperini, Guido Saporito and Andrea Rimondi from the Department of Aerospace Engineering

“Lucio Lazzarino”, Pisa University, Italy. (Frediani, 2005)

The design of the Prandtl Concept Aircraft has been very influential in the project decision to

attempt to reduce lift to drag via the use of an advanced box wing.

A Prandtl Plane aircraft configuration is based on the concept of ‘Best Wing Systems’. Reference is

made to a theoretical result published by Prandtl in 1924, showing that the lifting system with the

minimum induced drag, under certain conditions, is a wing box in the front view.

“In a large transport aircraft during cruise flight, drag is mainly due to friction drag (45-50%) and

induced drag (40-45%) “ (Frediani, 2005)

Figure 31 - Shows the comparison in optimum induced drag of a biplane and optimum induced drag of ‘best wing systems’.

Figure 30 - The final design of the Prandtl concept Aircraft. This design was the produced at Pisa University. The project had the aim of designing an aircraft that would carry over 800 passengers.

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A9 Dragonfly – Cranfield University

The A9 Dragonfly is a research project carried out at Cranfield University. The design is a typical box

wing arrangement; the projects objective was to design a medium sized long haul aircraft.

Information regarding the aerodynamic performance of this aircraft is not freely available.

Figure 32 - Shows the A9 Dragonfly - a medium size long haul aircraft design using the advanced box wing design.

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3.4 - Current aircraft lift to drag performance

As this project aims to improve the lift to drag performance of a superjumbo or wide bodied concept

aircraft, it is vital to have the lift to drag performance figures for current wide-bodied commercial

aircraft - in particular the current lift to drag performance data for a Boeing 777.

The Boeing 777 is significant to this project as the concept wing design for commercial aircraft is

being designed around the current design parameters of a Boeing 777x aircraft.

Figure 33 - provides the Lift to drag performance for the commercial aircraft shown:

Aircraft Lift to drag performance

Airbus A330 19

Airbus A340 19

Airbus A380 19

Boeing 747 17

Boeing767 18

Boeing 777 19

Boeing 787 21

(Smith, 2009)

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3.5.1 – Concept design plan and objectives

The Boeing 777x

The design concept this project is following focusses attention on the Boeing 777 aircraft and in

particular the new Boeing 777x which is still at the design stage.

The aim is to build an advanced closed wing design that offers significant increase in lift to drag in

comparison to the old Boeing 777 design.

An advanced box style wing arrangement will be designed for inclusion in the new 777-9x aircraft.

This aircraft will be the largest single floored wide bodied aircraft available. Major airline operators

including Lufthansa and Emirates have already shown a great deal of interest in operating the

aircraft. (Boeing New airplane 777x, 2014)

A 1% reduction of drag for a large transport aircraft saves 400.000 litres of fuel and, 5000 Kg of

emissions per year. In a large transport aircraft during cruise flight 90% of total drag is mainly due to

friction drag and induced drag. (Frediani, 2005)

The advanced box wing aircraft being designed will use the aircraft specifications of the Boeing 777-

300 series aircraft. The new design will share:

1. Fuselage width.

2. Fuselage length.

3. Wing sweep angle.

4. Engine placement and size.

Keeping these test parameters the same allows for an accurate comparison of test results and for

well-informed conclusions to be reached.

A selection of box wing designs will be produced and a conclusion as to the most efficient design for

the 777x can be suggested.

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3.5.2 - Angle of incidence

Chapter 1 describes how an aerofoil was optimised through a combination of features of two

experimental aerofoils. A secondary research exercise will now be completed to establish at which

angle the aerofoil performs to the highest lift-to-drag ratio. This angle is important as it will be used

in the wing design for the ‘angle of incidence’ of the wing.

The angle of incidence is the angle the aerofoil sits at whilst the aircraft is at angle of attack 0. This

means the aircraft fuselage is producing the minimum amount of drag and the wings will be

producing the maximum lift to drag that they can achieve. Determining the most appropriate angle

of incidence will deliver the maximum lift to drag for each design.

Test parameters

S.U.A.D.6 will be tested at angles between 1 and 8 degrees. This range is used as no supercritical

aerofoils maximum lift to drag angle has fallen outside this range (Airfoil investigation database,

2013). The lift to drag ratios of each angle will be logged and the most appropriate angle will be

determined relative to the aims of the project.

Test results:

S.U.A.D. 6 AOA LIFT DRAG LIFT/DRAG

1 0.00322570 0.00005638 57.21659542

1.5 0.00383260 0.00006485 59.09854898

2 0.00440100 0.00007277 60.48154358

2.5 0.00480480 0.00009554 50.29150399

3 0.0052868 0.00011114 47.5688321

4 0.0064413 0.00012963 49.6898866

5 0.0073785 0.00020101 36.707129

6 0.0082537 0.00026035 31.7023238

7 0.0093413 0.00033611 27.7923894

8 0.0099492 0.00043162 23.05083175

Figure 34 - research results - incidence of incidence.

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Angle of attack 2 proved to be the highest lift to drag

Pressure

Figure 35 - Show the pressure contours around aerofoil S.U.A.D.6 at its optimum angle of attack which was 2 degrees where its lift-to-drag performance is over 60.

Velocity

Figure 36 - Show the velocity contours around aerofoil S.U.A.D.6 at its optimum angle of attack which was 2 degrees where its lift-to-drag performance is over 60.

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The current Boeing 777-300 aircraft

The current Boeing 777-300 aircraft is a very successful commercial aircraft that is economical to

operate and which has an excellent safety record. Prior to testing the concept wing design for a

commercial aircraft, a scale model of the original Boeing 777-300 created using Creo parametric.

The model was tested to verify the simulations figures 38-46 are accurate. The Target lift to drag was

19, the Project Simulation results for lift to drag were 17.2. These results verify the simulation.

Figure 37 - A 777 replica designed to the same design parameters found on the Boeing technical information website.

Pressure

Figure 38 - Pressure 1 contours around the surface of a 777

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Figure 39 - Pressure 2 contours around surface of a Boeing 777

Velocity

Figure 40 - Velocity 1 around a Boeing 777

Figure 41 - Velocity 2, velocity contours around surface of a Boeing 777

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Boeing 777-300 with engines

Lift-to-drag 12.5

Figure 42 - 777-300 scale model with engines attached.

Pressure

Figure 43 - Pressure contours around a Boeing 777 with engines

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Figure 44 - Pressure contours image 2

Velocity

Figure 45 - Velocity contours around the surface of a Boeing 777 with engines

Figure 46 - Velocity contours image 2

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Boeing 777x concept 1 – typical advanced box wing design

Figure 47 - The first concept wing design for commercial aircraft is a typical box wing design this design is titles the 777x concept 1.

Pressure

Figure 48 - Pressure contours around the surface of 777x concept 1

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Figure 49 - Pressure contours image 2

Velocity

Figure 50 - Velocity contours around the surface of 777x1

Figure 51 - Velocity contours image 2

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Boeing 777x concept 2 – project designed advanced box wing

Design 2 – lift to drag -14

Figure 52 - 777x concept 2 is an advanced box design original to the project.

Pressure

Figure 53 - Pressure Contours around 777 x concepts 2

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Figure 54 - Pressure contours image showing an underside view of the 777x concept2

Velocity

Figure 55 - Velocity contours around the 777 x concept 2

Figure 56 - Velocity contours showing the under view of the 777x concept 2

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Boeing 777x concept 3 – Project designed advanced box wing 2

Lift to drag result - 15

Figure 57 - The second designed advanced box wing original to this project titles 777x concept 3

Pressure

Figure 58 - Pressure contours around 777 x concepts 3

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Figure 59 - Pressure contours showing different view of 777x concept 3

Velocity

Figure 60 - Velocity contours of 777x concept 3

Figure 61 - Velocity contours image 2 of the 777x concept 3

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Boeing 777x concept 4 –project design advanced box wing 4

Lift to drag result -14

Figure 62 - The Final design is more of a biplane than a box plane this aircraft design is titles 777x concept 4

Pressure

Figure 63 - Pressure contours around 777 x concepts 4

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Figure 64 - Second image of pressure contours around 777 x concepts 4

Velocity

Figure 65 - Velocity contours around 777 x concepts 4

Figure 66 - velocity contours around 777 x concepts 4

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Experiment analysis

Aircraft Lift Drag Lift/Drag rounded

777-300-no engines 0.188590 0.010971 17.189864 17

777-300-with engines 0.173000 0.013932 12.417456 12

777-x1-with engines 0.771970 0.060745 12.708371 13

777-x2-with engines 1.013800 0.074001 13.699815 14

777-x3-with engines 1.140100 0.077171 14.773684 15

777-x4-Boxwing 1.270800 0.090662 14.016898 14

Figure 67 - This table of figures shows the performance of lift to drag ratio of each aircraft design tested. It is demonstrated that each of the non-planar advanced box style wings offers significant advantages in lift to drag performance.

Figure 68 - Lift to drag results of each aircraft shown on a line graph

0.0000002.0000004.0000006.0000008.000000

10.00000012.00000014.00000016.00000018.00000020.000000

Lift/Drag

Lift/Drag

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Figure 69 - Similar graph to figure 68 however this time the information is represented on a bar chart.

Figure 70 - A bar chart comparing a current Boeing 777 against the best performing box wing the 777x concept 3

0.000000

2.000000

4.000000

6.000000

8.000000

10.000000

12.000000

14.000000

16.000000

18.000000

Lift/Drag

777-300-noengines

777-300-withengines

777-9x1-withengines

777-9x2-withengines

777-9x3-withengines

777-9x4-Boxwing

0.000000

2.000000

4.000000

6.000000

8.000000

10.000000

12.000000

14.000000

16.000000

777-300-withengines 777-9x3-withengines

Lift/Drag

777-300-withengines

777-9x3-withengines

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Conclusion on advanced box wing designs for commercial use

The results above show that the advanced box wings yield a 30% increase in lift to drag when

compared to a Boeing 777 replica that was subjected to the same test.

The most successful design Boeing 777-x3 delivered a lift to drag ratio of almost 15 - this significantly

higher than the Boeing 777 replica model that delivered a lift to drag ratio of 12.7.

The advanced box wing design successfully improves lift to drag ratio for a commercial aircraft. This

conclusion can be reached as the performance all four concept wing designs for commercial aircraft

was better than the performance of the Boeing 777-300 series replica model in lift to drag ratio.

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Chapter 4 – Materials selection for advanced box wing design.

This is the third and final area of wing design that will be researched. The aim is to determine the

best possible material for the construction of the concept wings having regard to a number of

considerations including performance.

The research will concentrate on current aviation materials. In addition CES Edu-pack resource

software will be used to perform a thorough material selection. The output of the chapter will be a

suggestion as to the top five materials that could be used to deliver optimum performance in the

construction of a concept wing for commercial aircraft. Reference will be made to the cost of the

recommended materials and detailed technical information will be provided.

Attention will be paid to current research into the next generation materials of materials that may

be used the aviation industry.

Given recent developments in the aviation industry, the expected conclusion of this chapter is that

composite carbon fibre materials will prove to be the most appropriate material for the construction

of a concept wing for commercial aircraft.

Chapter 3 – Aims and objectives

Materials research focusing on current materials in use in the aviation industry.

Materials selection using CES-Edupack to identify the optimum material for a concept wing

for commercial aircraft.

Research into the next generation materials of materials that may be used the aviation

industry.

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4.1 Materials research

From the early days of powered flight, the materials used in the aviation industry have been in

constant development. Innovation of materials is vitally important for the aviation industry - the

material used in aircraft construction has significant effect on the performance and cost of operation

of aircraft.

In designing an aircraft wing, a very important consideration is to establish the optimal proportion of

the weight to strength/stiffness. The wing needs to be sufficiently strong and stiff to withstand the

variable operating conditions in which the aircraft will be used. Durability is an important factor.

Also, should a particular part of the wing fail it must not result in the destructive failure of the whole

aircraft.

The design process starts with a specification of the requirements and the specification of the

properties the wing will need to meet.

The design output will often be a compromise between material properties and weight. A most

important requirement of the aircraft wing is that it will perform its design function particularly in

critical situations when safety is paramount. (Aerostudents.com, 2013)

The deformation of a material at limit loads must not interfere with the safe operation of the

aircraft. Should the static strength requirement result in a component showing unacceptably high

deflections then the component is said to be ‘stiffness limited design’. (Aerostudents.com, 2013)

The material selected as a result of this investigation has to be able to support ultimate loads

without destructive failure. Further, the material must support limit loads without permanent

deformation of the structure. (Aerostudents.com, 2013)

Aluminum is the most widely used material in the aviation industry, however, should the properties

if aluminum not meets the necessary loads requirements within the size limitations of the wing

design, higher strength materials would be considered (Titanium or Steel). For the purposes of this

investigation Aluminum is too heavy to meet the performance requirements relating to increased

efficiency. Graphite/Epoxy resin based materials or Next Generation Materials will be considered.

An aircraft wing will produce lift because of the unequal pressure between its bottom and top

surfaces. This results in a shear force as well as bending moment, which are at their highest values at

the point where the wing meets the fuselage. The structure at this point needs to be very strong to

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resist the loads and moments but also quite stiff to stop wing bending. The wing will need to be thick

and strong at the point where it meets the fuselage. (Aerostudents.com, 2013)

Other matters for consideration

The advantage of engines mounted under the wing is that their weight is around the area in the lift is

being produced. This reduces the total fuselage weight reducing the shear force and bending

moment that occurs between wing root and fuselage. The rudder and ailerons will also create lift

causing torsion around the fuselage. Since the fuselage is a cylindrical shape it will be able to

withstand torsion very effectively. The landing gear can also generate loads causing torsion on the

fuselage. But the ultimate force caused by the landing gear is the shock produced during landing;

because of this shock absorbers are fitted that absorb the landing energy and thus reducing the

force applied to the structure. (Aerostudents.com, 2013)

(Boeing , 2012)

Figure 71 - shows the percentage of composite materials in the Boeing fleet as they have evolved the 787 is now made up of 50% composite with the entire wing structure made using

.

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4.2 - Advantages of advancements in material technology

This table shows the advantages of advancements in material technology to 3 different stakeholders.

To the designer To the factory To the airline

Reduce weight Advanced production techniques

Reduced fuel consumption

Fatigue and corrosion resistance

Fewer parts Fewer and easier inspections

New design possibilities Reduced production cost Reduce maintenance cost

Increased aerodynamic ability

Longer flight life

(Boeing , 2012)

Figure 72 - Shows the advancement in material technology and predicts future technology levels the current technologies being used in the 777 are pre 2000 and need an urgent review

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4.3 - Material selection using CES-Edupack

Material selection will now be undertaken to identify the optimum material for the concept wings

designed in chapter 2. The material selection process is undertaken following a review of the current

materials in use in the aviation industry.

The material selection process will consider:

1. Mechanical properties

2. Thermal properties

3. Electrical magnetic and optical properties

4. Chemical properties.

The aim of this project is to improve the current performance of the Boeing 777 wing so that

recommendations can be made regarding to make recommendations for the design of a concept

wing for a commercial aircraft.

The essential requirements of an aircraft wing are:

A. High stiffness B. High strength C. High toughness D. Low weight

Figure 73 - An image demonstrating the 4 main design parameters of aircraft wings.

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An aircraft wing is a stiffness-limited design at minimum mass (cost, energy, environmental impact)

and strength-limited design at minimum mass (cost, energy, environmental impact).

An aircraft wing is a BEAM (loaded in bending)

- Stiffness, length, shape specified; section area free

- Strength, length, shape specified; section area free

In the completion of the investigation the database used was level 3 aerospace from the academic

version of CES-Edu pack. This software package included details almost 4000 materials which have

applications in aviation industry - This is the most in-depth material investigation that can be

completed as part of this project given the available facilities.

The first stage of a material selection process is to perform a translation. A translation states

function, constraints, objectives and free variables of the design. Translations are always shown

before the main material selection process begins - it allows for clarity of thought regarding the

objectives and constraints.

A Translation performed for optimum material for use in an advanced box wing design for

concept wing design for commercial aircraft.

Function Optimum material for aircraft wing.

Constraints High stiffness High toughness High strength Resistance to corrosion Ease of maintenance

Objectives Minimum mass

Free variables Choice of material, choice of manufacturing technique

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Stage two - of the material selection process is to set up the database. Selection of material

classifications to involve in the selection, the material groups that where selected for this selection

where

Ceramics and glasses

Fibres and particulates

Hybrids, composites, foams, honeycombs

Metals and alloys

Polymers, plastics, elastomers

This totals around 4000 materials.

Stage three - of the selection process is to limit certain properties – This procedure excludes

materials from the selection process the materials that do not perform the function required.

The limited factors in this selection are as follows.

Density – Limited to a maximum of 3000

Young’s modulus (stiffness) – Minimum requirement of 10 GPA

Yield strength – Minimum requirement of 10 MPA

Tensile strength – Minimum requirement of 15 MPA

Fatigue strength at cycles – Minimum requirement of MPA

Fracture toughness – Minimum requirement of 15 MPA

Stage four in the material selection process is the screening and ranking for the correct material

using a graphs and the suitable selection line. The selection line gradient is controlled by the merit

index. (Ashby, 2009)

A beam in bending – stiffness limited design – Merit index = ρ / E1/2

A beam in bending – strength limited design – Merit index = ρ / σy2/3

(Ashby, 2009)

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High stiffness – low density

Figure 74 - Graph showing young’s modulus against density, only the colour circles are materials that have passed the limit stage

Figure 75 - When the selection line is used the following materials are the best 5 shown in this figure

Top 5 materials in rank order are:

1. Cyanate ester/HM carbon fiber, UD composite, 0° lamina 2. Beryllium, grade 0-50, hot isostatically pressed 3. Beryllium, grade I-220B, vacuum hot-pressed 4. Beryllium, grade I-250, hot isostatically pressed 5. Beryllium, grade I-70A, vacuum hot-pressed

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High strength – low density

Figure 76 - Elastic limit vs. density graph only the coloured circles have passed the limit stage

Figure 77- Yield strength vs. density, using a selection line to find the top 5 performing materials.


1. Cyanate ester/HM carbon fiber, UD composite, 0° lamina 2. BMI/HS carbon fiber, UD composite, 0° lamina 3. Polyimide/HS carbon fiber, woven fabric composite, biaxial laminate 4. Beryllium (50-127 micron, f) 5. Al-48%B(f), longitudinal

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High fracture toughness – low density

Figure 78 - Fracture toughness vs. density

Figure 79 - Fracture toughness vs. density using a selection line to select the top 5 materials.


1. BMI/HS carbon fiber, UD composite, 0° lamina 2. Magnesium, commercial purity 3. Cyanate ester/HM carbon fiber, UD composite, 0° lamina 4. Alumina silicate/Nextel 720, 45Vf - woven fabric 5. Polyimide/HS carbon fiber, woven fabric composite, biaxial laminate

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4.4 Material selection conclusion

Cyanate ester and high modulus carbon fibre composite 0° uni-directional lamina has been selected

as the material that is most suitable for use in a high performance wing arrangement for the new

777x aircraft. Cyanate ester and high modulus carbon fibre composite 0° uni-directional lamina is in

the top five materials in each of the following comparisons:

High stiffness – low density

High strength – low density

High fracture toughness – low density

Cyanate ester and high modulus carbon fibre composite 0° uni-directional lamina is already

commonly used in the aviation industry. Typical uses include high performance spacecraft/aircraft,

missiles, antenna & Randomes.

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4.5 Raw material cost comparisons

The average costs for materials that are commonly used in the aviation industry are shown below:

Aluminum Plate = $2 - $3 / lb.

Steel Plate = $5 - $10 / lb.

Titanium Plate = $15 - $25 / lb.

Fiberglass/Epoxy Prepare = $15 - $25 / lb.

Graphite/Epoxy Prepare = $50 - $100 / lb.

(Boeing , 2012)

Aluminium is significantly cheaper than the composite materials; however this investigation focuses

on performance. The highest performing material a Cyanate ester and high modulus carbon fibre

composite 0° uni-directional lamina, will cost around $25/ lb. (Boeing , 2012)

In addition to the raw material costs, there are further costs that need to be considered these are:

1. Detail Fabrication Costs

2. Assembly Costs

3. Life Cycle Costs

4. Cost of Weight (Loss of Payload, Increased Fuel Consumption)

5. Cost of Maintenance

(Boeing , 2012)

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4.6 Next generation materials

The material selection process was undertaken using CES –Edupack - a database produced at Oxford

University. The database has a large number of materials currently in use; however it does not

contain a record of next generation or innovative materials.

Examples of new generation materials include:

1. Aluminum Lithium

2. GLARE - Fiberglass Reinforced Aluminum

3. TiGr - Graphite Reinforced Titanium

4. Thermoplastics

5. Resin Transfer Molding (

6. Stitched Resin Fusion Injected

For a more in-depth materials selection for the concept wing design for commercial aircraft it is

suggested that further research is conducted on these materials to better understand the potential

they have to improve performance or reduce costs.

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5.0 - Rendered Images of final design

A collection of 4 high qualities renders where produced. Images of the final design are shown

rendered using Alias Showcase software.

Rendered image 1

Rendered image 2

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Rendered image 3

Rendered image 4

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Discussion

The original hypothesis of this final year project was to design and analyse a supercritical aerofoil for

a concept wing design for commercial aircraft with materials research to highlight and obtain the

optimum material for the design.

This meant that the project was divided into three main chapters the chapters:

- Aerofoil design - shape / Cross-section for supercritical aerofoils.

- Advanced aircraft wing design

- Materials research and Optimum material selection

The primary objective of the final year project was to design a supercritical aerofoil that had

improved lift to drag performance when compared with existing supercritical aerofoils. The design

objective was achieved with the design of a supercritical wing section that provides an improved Lift

to drag ratio when compared with researched supercritical aerofoils. The lift to drag of the designed

supercritical aerofoil was 49.5 – an increase on the highest researched supercritical aerofoil which

was 48. The design of the aerofoil section proved to be a difficult and detailed task and a great deal

of research based learning was necessary to ensure the work was completed to a standard that

delivered high quality results.

The difficulty of sketching extremely smooth surfaces in Creo Parametric proved to be a challenge

that limited the design of a unique supercritical aerofoil. To overcome this difficulty attention was

switched to the redesign of existing supercritical aerofoils to improve the performance of lift to drag

ratios.

The best development and results were achieved in the area of concept wing design for commercial

aircraft dealt with in chapter two. The objective was to design a conceptual aircraft that would

deliver improved aerodynamic efficiency for a large commercial aircraft. This has been achieved.

Three main alternative designs of concept commercial aircraft where researched and the decision

was taken to choose the advanced box wing design for use in a concept wing for commercial aircraft.

The advanced box wing is suggested in many sources as a possible concept design. However, it

proved impossible to find results of the aerodynamic performance. Given this lack of important

information it was necessary to conduct simulation work to prove the viability of the concept and

this work was completed.

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The design output of the project demonstrates a 30% increase in aerodynamic efficiency for an

advanced box wing aircraft. These results have implications for aircraft wing design. The project has

shown that the design is one that offers significant aerodynamic improvement and clearly there is a

need for further research and analysis.

The third task that was necessary to complete the design of a conceptual wing for commercial use

was optimum material selection. The material selection process was completed using CES-Edupack.

The CES – Edupack software includes a materials database with applications for aeronautical and

aviation industries.

The material selected for use was Cyanate ester and high modulus carbon fibre composite 0° uni-

directional lamina. This material is in current use in high performance applications in the aeronautic

aviation and motorsport industries.

Limitations in data collection

The computational fluid dynamic software ANSYS fluent was used during the project as it has major

advantages over other software packages e.g. Cham Phoenics. Whilst Cham Phoenics is a less

complex software package that is easier to use than ANSYS Fluent, it is unable to deal with the

complexities of the transonic speed range that the simulations where tested within.

The 2D simulations from the aerofoil tests in chapter 1 have been verified using previous tests of the

aerofoils from NASA and other sources - the results are extremely similar. This is because an aerofoil

is small and the geometry of an aerofoil is reasonably simple with no intersecting areas or changes in

topology. This means the grid around it can form in good detail and the solution can converge

quickly and accurately.

The verification of the aerofoil testing phase, comparing the projects results against results obtained

in a NASA certified experiment run at Southampton University, are shown below:

NPL SECTION ANALYSIS 9510 PROJECT Simulations NPL 9510

ALPHA = 4.0 Alpha = 4.0

MACH NO. =0.8002 Mach number 0.8

LIFT TO DRAG RESULT 32.58 LIFT TO DRAG RESULT 34.3

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The 3D simulations conducted on the 777x concept wing design were feasible. However there were

limitations. The first limitation was the level of detail the grid produces – the academic version of

ANSYS fluent limits the number of nodes and cells. The number of cells is limited to a figure below

510,000 – although this may sound like a large number, it does in fact remove the opportunity for

complex geometry as the grid will automatically over mesh the cells.

Secondly, the accepted topology of the model is limited in the academic version of ANSYS Fluent.

Failures linked to geometry and topologies are common. Finally the software packages results for

aircraft with engines attached are not reliable- the engine is not recognised as such and therefore

only drag is produced.

Verification of the aircraft testing phase is shown below. This is a comparison of actual lift to drag

results against the results obtained during the project. It shows that, although the project results fall

short, they are sufficiently close and the project conclusions can be accepted.

Actual 777 lift to drag results – 19.36

project tested 777 lift to drag results – 17.2

Limitations of the Material selection

The material selection was carried out using CES-Edupack academic version. The database used was

‘level 3 aerospace’ which contains 4800 different materials that all have current applications in the

aerospace/aeronautical industry. The material selection could have been improved by using a much

larger database that included innovative materials in addition to currently used materials. However,

this was not possible given the available facilities.

Implications of the investigation results

The project provides data that demonstrates that an advanced box wing design shows improved

efficiency in cruise configuration flight. Further research into non-planar wing designs is

recommended.

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Conclusion

A glance backwards…

There were 3 main aims of this project:

The design and analysis of a supercritical aerofoil, that has improved lift to drag performance

on current aerofoil.

The implementation of this supercritical aerofoil into a concept wing design for commercial

aircraft.

In-depth materials research and optimum material selection for use in the concept wing

design for commercial aircraft.

The results….

A great deal of research, testing and analysis has been undertaken throughout this project. In

summary the results show:

The performance of a supercritical aerofoil section was improved in terms of efficiency -

shown by the increase in the lift-to-drag performance of the supercritical aerofoil.

The improved supercritical aerofoil was achieved by a redesign/optimisation of other high

performing aerofoils.

The task of designing a completely new supercritical aerofoil with improved lift to drag

performance was unrealistic.

In depth understanding of desired parameters for supercritical aerofoils sections was vital in

the optimisation and S.U.A.D.6 which was a successful design.

In addition to this….

The supercritical aerofoil design was then implemented into a concept wing arrangement using

advanced non-Planar, advanced box wing technology using the Boeing 777x as the basis for the

concept wing design.

The results from an extensive simulation show that increased aircraft efficiency is theoretically

achievable through the use of advanced non-planar box wings designs. Four designs have been

tested during the course of the project with all four designs showing improved lift to drag in

comparison to a 777-300 that was also tested in the simulation. The best performing design was

777x concepts 3 which improved lift to drag performance by 30% when compared to the existing

777-300 aircraft.

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It is reasonable to conclude that an aircraft that includes an advanced box wing design may be seen

as an everyday design in the future of commercial air travel - non-planar designs provide a viable

alternative to blended wing aircraft.

The open question that remains, is what is a more feasible and beneficial design - the blended wing

concept or the advanced box wing concept?

Finally….

The material selection was successful in determining the optimum material for use in a concept wing

design for commercial aircraft. The final conclusion is that Cyanate ester and High Modulus carbon

fiber, composite, 0° Uni-Directional lamina provides the optimum performance of any current

material for use in a high performance aeronautical applications.

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Recommendations

There is no doubt that a significant limitation has affected the investigation. There are three

recommendations made to improve the future study of conceptual wing design for commercial

aircraft.

Recommendation 1 – Future studies would benefit from further computation fluid dynamics

simulations run on a version of ANSYS Fluent that allowed for increased detail on the model tested

and can run a simulation when the mesh reaches over 510,000 cells.

Recommendation 2 – Further investigation into concept aircraft is needed so that significant

conclusions can be reached in determining what aircraft design is best - advanced box wings or

blended wings.

Recommendation 3 – Further Research is needed into the benefits of next generation materials to

understand if they offer the opportunity to improve the performance for conceptual wing designs

for commercial aircraft.

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Bibliography

Abbott, I. H., 1959. Theory of wing sections. 1st ed. New York : Dover Publications .

Aerostudents.com, 2013. Aircraft Structures Summary. [Online]

Available at: http://aerostudents.com/files/aircraftStructures/aircraftStructuresFullVersion.pdf

[Accessed Febuary 2014].

Aircraft Recongnition, 2014. Supercritical aerofoil sections. [Online]

Available at: http://www.aircraftrecognition.co.uk/supercritical_wing.html

[Accessed march 2014].

Aerofoil investigation database, 2013. Compareing aerofoils. [Online]

Available at: http://www.aerofoil

db.com/foils/show_compare/?id%5B%5D=1370&id%5B%5D=1369&chord=6.5

[Accessed march 2014].

Applied Aerodynamics : A digital Textbook, 2013. Transonic Aerofoil Design. [Online]

Available at: http://www.desktop.aero/appliedaero/aerofoil s2/xsonicsections.html

[Accessed 16th January 2014].

Armstrong flight research centre (NASA), 2010. NASA Dryden Past Projects: X-48B Blended Wing

Body. [Online]

Available at: http://www.nasa.gov/centers/dryden/research/X-48B/#.U0v2nvldWSo

[Accessed March 2014].

Barnstorff, K., 2012. New Ideas Sharpen Focus for Greener Aircraft. [Online]

Available at: http://www.nasa.gov/topics/aeronautics/features/greener_aircraft.html#.U0v3tfldWSo

[Accessed April 2014].

Boeing , 2012. MSU Materials presentation. [Online]

Available at: www.coe.montana.edu/me/faculty/cairns/.../MS Materials.ppt

[Accessed 24th March 2014].

Boeing New airplane 777x, 2014. Customer highlights. [Online]

Available at: http://www.newairplane.com/777x/customerHighlights/

[Accessed April 2014].

Campbell, F. C., 2006. Manufacturing Technology For Aerospace Structural Materials. London:

Elsevier Science.

Cantrell, P., 2012. Aerofoil s. [Online]

Available at: http://www.copters.com/aero/aerofoil s.html

[Accessed 12th Novemeber 2013].

of 104



Center for Mechanics and Control, 2004. DARPA Morphing Programme. [Online]

Available at: http://dnc.tamu.edu/projects/flowcontrol/Morphing/public_html/darpa.html

[Accessed 28th October 2013].

Cutler, J., 2005. Understanding Aircraft Structures. Oxford: Blackwell.

Frediani, A., 2005. The Prandtl Wing. [Online]

Available at: http://www.engbrasil.eng.br/index_arquivos/art95.pdf

[Accessed January 2014].

Harris, C. D., 1990. NASA technical documents. [Online]

Available at:

http://www.southampton.ac.uk/~jps7/Aircraft%20Design%20Resources/aerodynamics/supercritical

%20aerofoils.pdf

[Accessed 27th September 2013].

HUANG, H., 2012. OPTIMAL DESIGN OF A FLYING-WING AIRCRAFT INNER WING. [Online]

Available at:

https://dspace.lib.cranfield.ac.uk/bitstream/1826/7439/1/Haidong_Huang_Thesis_2012.pdf

[Accessed March 2014].

I Kroo, 2005. NONPLANAR WING CONCEPTS FOR INCREASED AIRCRAFT EFFICIENCY. [Online]

Available at: http://aero.stanford.edu/reports/VKI_nonplanar_Kroo.pdf

[Accessed 16th January 2014].

Ishai, I. M. D. &. O., 1994. Engineering Mechanics of Composite Materials. 1st ed. Oxford : Oxford

University Press.

Jenkins, R., 1983. Reynolds number tests on an npl 910 aerofoils. [Online]

Available at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19840003073.pdf

[Accessed 12th march 2014].

Kaw, A. K., 2000. Mechanics of Compsite Materials. 2nd ed. Florida : CRC Press.

Lee, J., 1998. Historical and Future trends in Aircraft performance , emmisions and cost. [Online]

Available at:

http://www.southampton.ac.uk/~jps7/D8%20website/future%20trends%20in%20aircraft%20costs.p

df

[Accessed December 2013].

Middleton, D. H., 1990. Composite Materials in Aircraft Structures. 2nd ed. s.l.:Longman Scientific &

Technical.

Min, Z., 2008. Aircraft morphing wing concepts with radical geometry change. London: The IES

Journal Part A.

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NASA, 2004. The supercritical Aerofoil. [Online]

Available at: http://www.nasa.gov/sites/default/files/89232main_TF-2004-13-DFRC.pdf

[Accessed November 2013].

National Aeronautics and Space Adminstration, 2010. Parts of an Aircraft 'Wing Design'. [Online]

Available at: http://www.aeronautics.nasa.gov/pdf/wing_design_k-12.pdf

[Accessed 20th november 2013].

Sadrey, M., 2013. Wing Design. [Online]

Available at: http://faculty.dwc.edu/sadraey/Chapter%205.%20Wing%20Design.pdf

[Accessed 21st November 2013].

Skybrary, 2012. Supercritical Aerofoils. [Online]

Available at: http://www.skybrary.aero/index.php/Supercritical_Aerofoils

[Accessed 25th October 2013].

Smith, D. F., 2009. The use of composites in Aerospace past present and future. [Online]

Available at: http://avaloncsl.files.wordpress.com/2013/01/avalon-the-use-of-composites-in-

aerospace-s.pdf

[Accessed 20th November 2013].

Smith, h., 2009. New concepts for environmentally freindly aircraft. [Online]

Available at: http://www.oecd.org/sti/inno/44285687.pdf

[Accessed November 2013].

Tamkang University , 2012. Aerofoil Design. [Online]

Available at: http://mail.tku.edu.tw/095980/aerofoil %20design.pdf

[Accessed 20th Febuary 2014].

UIUC Applied Aerodynamics Group, 2013. UIUC Aerofoil Cooridnates database. [Online]

Available at: http://aerospace.illinois.edu/m-selig/ads/coord_database.html

[Accessed Novemeber 2013].

University, Illinois, 2013. Aerofoil Database - NPL 9510. [Online]

Available at: http://aerospace.illinois.edu/m-selig/ads/afplots/npl9510.gif

[Accessed 12 October 2013].

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APPENDIX A –

Drag terms

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Induced Drag - is defined as the drag occurring due to lift, the drag is created by the vortices

that are apparent at the wing tip. Air that is flowing on the top surface of the wing tends to flow

inwards due to the contradiction of pressure between upper and lower surfaces.. The effect of this is

wing effect or end effect with the air at the end of the wing spilling over and flowing in a

circular turbulent motion.

Parasitic Drag - occurs during the cruise configuration and consists of

primarily of the skin friction

roughness

Pressure drag of the major components. There is usually some additional parasite drag due to features such as:

fuselage upsweep

control surface gaps

base areas

http://www.pilotfriend.com/training/flight_training/aero/drag.htm

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APPENDIX B -

‘Technical literature review’

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Technical Literature Review

The aviation industry is built upon a culture of innovation and the current innovation ethos tends

towards aircraft efficiency rather than speed. This literature first produced for the research project

but added to and altered, further reviews research focused on different references which detail

firstly the design of aerofoils, moving on to research gathered in relation to advanced and concept

wing design.

the third area this literature review is the advanced design and use of modern materials in the

aviation industry and reviews developments made over time focusing on composite materials..

These research topics have been selected to aid the research of a final year project based upon

aerofoil profile and wing feature improvement in relation to overall Aircraft efficiency performance.

2.1 Aerofoil cross-section and theory

Ira H Abbott and Albert E Von Doenhoff – ‘Theory of wing sections’ (1959) is a publication from the

late 1950s which is sometime before the advent of supercritical aerofoil. The work is however is an

extremely proficient publication in describing the theory of how aerofoils work. The book logs data

for early NACA aerofoils, as well as providing graphical representation of lift coefficient VS angle of

attack amongst others. The publication also describes experimental aerofoil designs however, as the

book dates from 1959; the experimental designs in this book are standard modern aerofoil designs

due to the rapid development of aerofoils thanks to research by NASA in the early 1970s.

Following on from this is NASA technical document 2969 – written by Charles D Harris – (1990)

‘Supercritical aerofoils (a Matrix of supercritical aerofoils)’. This document firstly spends time

explaining the development of supercritical aerofoils and also the effect of changing aerofoil

parameters, e.g. chamber and upper-surface curvature. It goes on to log the data for the

supercritical family of NASA aerofoils (for example Aerofoil SC2-0714)3. This technical document is

extremely proficient and has proved most helpful of all internet sourced resources - it provided the

base knowledge of supercritical aerofoils which was vital in the early stages of research. This

document is a difficult resource to extract information from due to its complexity however, as will all

NASA documents, it is an extremely useful source.

http://www.dept.aoe.vt.edu/~mason/Mason_f/A380Roedts.pdf

The internet based resource from the UIUC – Applied Aerodynamics Group- 2013 - based at Illinois

University, is a database with over 1600 aerofoils logged within it .This internet resource also allows

for the aerofoils to be compared using http://aerofoil tools.com/compare/index .The Applied

Aerodynamics Group have gathered information relating to the most commercial relevant aerofoils

that have been designed within the database. There are a high number of transonic aerofoils

designed by NASA, Lockheed Martin and Boeing. The information is reliable and easy to access. This

resource has been vital in building knowledge of what parameters are used in the design of aerofoils,

e.g. Camber, Thickness and Chord. This source is visual and has shown how the parameters affect

shape and the trends of transonic aerofoils concerning their Cross-section.

3 Shown in appendix 3

http://airfoiltools.com/compare/index

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2.2 Experimental Wing Design

Mohammed Sadrey’s internet sourced document ‘Wing Design’ (2013) is a recently published

document that focuses on experimental wing design and suggests a process to follow in order to

achieve a desired result. Mohammed Sadrey suggests that, for the successful design of wings, 18

parameters should be considered a selection of e amples of this would include, ‘wing platform

area’, ‘number of wings’, ‘aerofoil cross-section’ and ‘horizontal position relative to the fuselage’.

Each parameter is explored in exceptional detail and the document provides a structured platform

explaining how to achieve good experimental wing design .The information is displayed in a

complex, difficult to understand format. However this is a technical document that would only be

reviewed by persons with a great deal of interest in the subject - the document is valuable because it

provides up to date information.

DEVELOPMENT OF A PRANDTLPLANE AIRCRAFT CONFIGURATION – A document sourced online

produced by (Frediani, 2005) along with a team at Pisa University in Italy studied the possibility of a

800+ Seated aircraft using a Prandtl wing or best wing system - which is extremely similar to a box

wing aircraft that this project designs.

The project suggests that a 1 per cent decrease in drag could save 400,000 litres of fuel a year. And

also states that a box wing lowers induced drag significantly and as this accounts for almost 40% of

drag in cruise configuration any reduction of induced drag has benefits for the commercial airline

industry.

Following further extensive research of this document and its ideology - 2 similar projects where

reviewed and provided further justification and motivation to study the idea of a box wing further

these projects where:

The Lockheed martin advanced box plane design, and the dragonfly k9 medium sized long haul

aircraft designed at Cranfield University.

2.3 Composite Materials

Donald H Middleton’s publication from the 1990s charts the history of composite materials and

some potential uses. There is an e periment demonstrating the “tensile strength, toughness and

Young’s modulus of Glass fibre reinforced plastics and carbon fibre reinforced plastics”. The direction

the book takes is to look at the composites used on Airbus aircraft from the 1990s - although the

information is presented well and interesting, the technology reviewed is almost 25 years old now.

In the second publication analysed ‘ nderstanding aircraft structures’ (2005) - John Cutler and

Jeremy Liber (2005) initially concentrate on defining a composite and explaining the reasons why

they are seen as so useful in the aviation industry. They state “these materials are easily formed into

complex curved shapes of almost any size giving very clean aerodynamically smooth surfaces”. They

go on to suggest glider manufacturers have seen the advantage of the smooth surfaces possible with

composites. Glass-fibre provided a strong light material with low skin surface drag that allowed

gliders to reach such high levels of aerodynamic prowess. The document also compares composite

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materials such as carbon and glass fibre against aluminium alloys in strength to weight ratio and

tensile strength tests.

F.C.Campbell, in his publication ‘Manufacturing Technology for Aerospace Structural Materials’

(2006) details that the “strength - density and modulus - density of high strength polymer matrix

fibre composites especially those that are carbon based, are higher than other comparable metallic

materials’. He suggests that:

-the performance of carbon based composites offer improved weight saving, greater aircraft range,

fuel savings and greater payloads

- the fatigue resistance and resistance to corrosion features of composites is a major advantage to

the use of metallic based alloys, this is because corrosion he states ‘is a major cost and constant

maintenance worry for both commercial and military aircraft’.

He also highlights the differences between polymer matrix composites and the less useful ceramic

matrix composites although he cites lack of fracture resistance for rendering these composites

almost useless in industry.

The final publications reviewed in this literature review move away from aviation to a broader view

of engineering composites. The first publication ‘Engineering mechanics of composite materials’ by

Isaac M Daniel and Ori Ishai (1994). The publication firstly defines the characteristics of a composite

for engineering applications

“A structural composite is a material system consisting of two or more phases on a macroscopic

scale whose mechanical performance and properties are designed to be superior for application”

They also develop a classification of different composite materials. This book provided a broader and

deeper understanding of the scientific field of engineering composites.

In addition to the books mentioned above, research in relation to composite materials was found

online. Dr Faye Smith (Avalon consultancy ltd) reviews the use of composites mainly in modern day

aviation - this source was most useful as it categorised composites within an easy to understand

“S.W.O.T analysis” before graphically representing the current use of carbon based composites in

new airliners – it goes on to e plain comple “manufacturing processes”.

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APPENDIX C –

Aerofoil database links

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Internet Location of Co-ordinates for researched aerofoils

NPL 9510 AEROFOIL - NPL 9510 transonic aerofoil

http://aerofoil tools.com/aerofoil /details?aerofoil =npl9510-il

DSMA-523A AEROFOIL - McDonnell/Douglas DSMA-523 transonic aerofoil with sharp trailing edge

http://aerofoil tools.com/aerofoil /details?aerofoil =dsma523a-il

NASA SC (2)-0610 AEROFOIL - NASA SC (2)-0610 aerofoil (NASA TP-2969)

http://aerofoil tools.com/aerofoil /details?aerofoil =sc20610-il

NYU/GRUMMAN K-1 AEROFOIL - NYU/Grumman K-1 transonic aerofoil (GAC .75-.63-11.6)

http://aerofoil tools.com/aerofoil /details?aerofoil =k1-il

RAE 2822 AEROFOIL - RAE 2822 transonic aerofoil

http://aerofoil tools.com/aerofoil /details?aerofoil =rae2822-il

http://airfoiltools.com/airfoil/details?airfoil=dsma523a-il

http://airfoiltools.com/airfoil/details?airfoil=sc20610-il

http://airfoiltools.com/airfoil/details?airfoil=k1-il

http://airfoiltools.com/airfoil/details?airfoil=rae2822-il

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Appendix D –

‘Boeing 777 Design parameters’

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The Boeing 777x aircraft – the model designed was designed to these parameters.

Fuselage length - 70m

Fuselage width 6.1m

Total height 19.7m

Wing span 71.1m

Wing sweep angle 37

Seating capacity 380

jonathon rowan-undergraduate project

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