Aircraft Design Projects - part 1 docx

6.4 Information retrieval 6.4.1 Existing aircraft 6.4.2 Configurational analysis 6.4.3 Electrical propulsion system 6.6 Initial sizing 6.6.1 Initial mass estimations 6.6.2 Initial aerodyn

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Dedications

To Jessica, Maria, Edward, Robert and Jonothan – in their hands rests the future

To my father, J F Marchman, Jr, for passing on to me his love of airplanes and to my teacher, Dr Jim Williams, whose example inspired me to pursue a career in education

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for engineering students

Lloyd R Jenkinson

James F Marchman III

OXFORD AMSTERDAM BOSTON LONDON NEW YORK PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO

xiii xvi xvii

2.3.1 Market and mission issues

2.3.2 Airworthiness and other standards

2.3.3 Environmental and social issues

2.3.4 Commercial and manufacturing considerations

2.5 Initial baseline sizing

2.5.1 Initial mass (weight) estimation

2.5.2 Initial layout drawing

2.7 Refining the initial layout

2.7.1 Constraint analysis

2.7.2 Trade-off studies

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2.9 Parametric and trade studies

2.9.1

parametric studies 2.10 Final baseline configuration

2.10.1 Additional technical considerations 2.10.2 Broader-based considerations 2.11 Type specification

2.11.1 Report format 2.11.2 Illustrations, drawings and diagrams References

3 Introduction to the project studies

4.2 Project brief

4.2.1 Project requirements 4.3 Project analysis

4.3.1 Payload/range 4.3.2 Passenger comfort 4.3.3 Field requirements 4.3.4 Technology assessments

4.3.6 Alternative roles 4.3.7 Aircraft developments 4.3.8 Commercial analysis 4.4 Information retrieval

4.5.1 Conventional layout(s) 4.5.2 Braced wing/canard layout 4.5.3 Three-surface layout 4.5.4 Blended body layout

4.6 Initial sizing and layout

4.6.1 Mass estimation 4.6.2 Engine size and selection

Contents

4.8.3 Field performance studies

4.8.4 Wing geometry studies

4.8.5 Economic analysis

4.9 Initial ‘type specification’

4.9.1 General aircraft description

4.9.2 Aircraft geometry

4.9.3 Mass (weight) and performance statements

4.9.4 Economic and operational issues

5.9 Revised baseline layout

6.4 Information retrieval

6.4.1 Existing aircraft 6.4.2 Configurational analysis 6.4.3 Electrical propulsion system

6.6 Initial sizing

6.6.1 Initial mass estimations 6.6.2 Initial aerodynamic considerations 6.6.3 Propeller analysis

6.7 Initial performance estimation

7.2 Project brief (flying car or roadable aircraft?)

7.3 Initial design considerations

7.5 Initial layout

7.6 Initial estimates

7.6.2 Powerplant selection 7.6.3 Weight and balance predictions 7.6.4 Flight performance estimates 7.6.5 Structural details

7.6.6 Stability, control and ‘roadability’ assessment 7.6.7 Systems

7.6.8 Vehicle cost assessment

Contents

8.4 Design concepts and selection

8.5 Initial sizing and layout

8.6 Initial estimates

8.6.1 Initial mass estimations

8.6.2 Initial aerodynamic estimations

9.6.2 Joined wing layout

9.6.3 Flying wing layout

9.6.4 Braced wing layout

9.6.5 Configuration selection

9.7 Initial sizing and layout

9.7.1 Aircraft mass estimation

9.7.2 Fuel volume assessment

9.7.3 Wing loading analysis

9.7.4 Aircraft speed considerations

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9.7.6 Engine sizing 9.7.7 Initial aircraft layout 9.7.8 Aircraft data summary 9.8 Initial estimates

10.5 Initial layout and sizing

10.5.1 Wing selection 10.5.2 Engine selection 10.5.3 Hull design 10.5.4 Sponson design 10.5.5 Other water operation considerations 10.5.6 Other design factors

10.6 Initial estimates

10.6.1 Aerodynamic estimates 10.6.2 Mass and balance 10.6.3 Performance estimations 10.6.4 Stability and control 10.6.5 Structural details 10.7 Baseline layout

10.8 Revised baseline layout

11.2.1 Team development

Contents

11.2.2 Team member responsibilities

11.2.3 Team leadership requirements

11.2.4 Team operating principles

11.2.5 Brainstorming

11.3.1 Prior to the meeting

11.3.2 Minutes of the meeting

11.3.3 Dispersed meetings

11.4 Writing technical reports

11.4.1 Planning the report

11.4.2 Organising the report

11.4.3 Writing the report

11.4.4 Referencing

11.4.5 Use of figures, tables and appendices

11.4.6 Group reports

11.4.7 Review of the report

11.5 Making a technical presentation

11.5.1 Planning the presentation

11.5.2 Organising the presentation

11.5.3 Use of equipment

11.5.4 Management of the presentation

11.5.5 Review of the presentation

11.6 Design course structure and student assessment

Some useful constants (standard values)

Appendix B: Design data sources

Technical books (in alphabetical order)

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There are many excellent texts covering aircraft design from a variety of perspectives.Some of these are aimed at specific audiences ranging from practising aerospace engi-neers, to engineering students, to amateur airplane builders Others cover specialized aspects of the subject such as undercarriage or propulsion system design Some of these are quite detailed in their presentation of the design process while others are very general in scope Some are overviews of all the basic aeronautical engineering subjects that come together in the creation of a design

University faculty that teach aircraft design courses often face difficult choices when evaluating texts or references for their students’ use Many texts that are suitable for use

in a design class are biased toward particular classes of aircraft such as military aircraft, general aviation, or airliners A text that gives excellent coverage of design basics may prove slanted toward a class of aircraft different from that year’s project Alternatively, those that emphasize the correct type of vehicle may treat design fundamentals in

an unfamiliar manner The situation may be further complicated in classes that have several teams of students working on different types of designs, some of which ‘fit’ the chosen text while others do not

Most teachers would prefer a text that emphasizes the basic thought processes of preliminary design Such a text should encourage students to seek an understanding

of the approaches and constraints appropriate to their design assignment before they venture too far into the analytical processes On the other hand, students would like a text which simply tells them where to input their design objectives into a ‘black-box’ computer code or generalized spreadsheet, and preferably, where to catch the final design drawings and specifications as they are printed out Faculty would like their students to begin the design process with a thorough review of their previous courses

in aircraft performance, aerodynamics, structures, flight dynamics, propulsion, etc Students prefer to start with an Internet search, hoping to find a solution to their problem that requires only minimal ‘tweaking’

The aim of this book is to present a two pronged approach to the design process It

is expected to appeal to both faculty and students It sets out the basics of the design thought process and the pathway one must travel in order to reach an aircraft design goal for any category of aircraft Then it presents a variety of design case studies These are intended to offer examples of the way the design process may be applied

to conceptual design problems typical of those actually used at the advanced level in academic and other training curricula It does not offer a step-by-step ‘how to’ design guide, but shows how the basic aircraft preliminary design process can be successfully applied to a wide range of unique aircraft In so doing, it shows that each set of design objectives presents its own peculiar collection of challenges and constraints It also shows how the classical design process can be applied to any problem

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Case studies provide both student and instructor with a valuable teaching/learning tool, allowing them to examine the way others have approached particular design chal-lenges In the 1970s, the American Institute of Aeronautics and Astronautics (AIAA) published an excellent series of design case studies2 taken from real aircraft project developments These provided valuable insights into the development of several, then current, aircraft Some other texts have employed case studies taken from industrial practice Unfortunately, these tend to include aspects of design that are beyond the conceptual phase, and which are not covered in academic design courses While these are useful in teaching design, they can be confusing to the student who may have diffi-culty discerning where the conceptual aspects of the design process ends and detailed design ensues The case studies offered in this text are set in the preliminary design phase They emphasize the thought processes and analyses appropriate at this stage of vehicle development

Many of the case studies presented in this text were drawn from student projects Hence, they offer an insight into the conceptual design process from a student per-spective The case studies include design projects that won top awards in national and international design competitions These were sponsored by the National Aeronautics and Space Administration (NASA), the US Federal Aviation Administration (FAA), and the American Institute of Aeronautics and Astronautics (AIAA)

The authors bring a unique combination of perspectives and experience to this text

It reflects both British and American academic practices in teaching aircraft design to undergraduate students in aeronautical and aerospace engineering Lloyd Jenkinson has taught aircraft design at both Loughborough University and Southampton University in the UK and Jim Marchman has taught both aircraft and spacecraft design

at Virginia Tech in the US They have worked together since 1997 in an experiment that combines students from Loughborough University and Virginia Tech in interna-tional aircraft design teams.3 In this venture, teams of students from both universities have worked jointly on a variety of aircraft design projects They have used exchange visits, the Internet and teleconference communications to work together progressively, throughout the academic year, on the conceptual design of a novel aircraft

In this book, the authors have attempted to build on their experience in international student teaming They present processes and techniques that reflect the best in British and American design education and which have been proven to work well in both academic systems Dr Jenkinson also brings to this text his prior experience in the aerospace industry of the UK, having worked on the design of several successful British aircraft Professor Marchman’s contribution to the text also reflects his experiences in working with students and faculty in Thailand and France in other international design team collaborative projects

The authors envision this text as supplementing the popular aircraft design textbooks, currently in use at universities around the world Books such as those reviewed by Mason1 could be employed to present the detailed aspects of the preliminary design process Working within established conceptual design methodology, this book will provide a clearer picture of the way those detailed analyses may be adapted to a wide range of aircraft types

It would have been impossible to write this book without the hard work and asm shown by many of our students over more years than we care to remember Their continued interest in aircraft design project work and the smoothing of the difficulties they sometimes experienced in progressing through the work was our inspiration We have also benefited from the many colleagues and friends who have been generous in sharing their encouragement and knowledge with us Aircraft design educators seem

enthusi-Preface xv

to be a special breed of engineers who selflessly give their effort and time to inspire

anyone who wants to participate in their common interest We are fortunate to count

them as our friends

References

craft design education’, Journal of Aircraft Design, Vol 3, No 4, pp 239–247, Elsevier,

December 2000

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To all the students and staff at Loughborough and Southampton Universities who have, over many years, contributed directly and indirectly to my understanding of the design of aircraft, I would like to express my thanks and appreciation For their help with proof reading and technical advice, I thank my friends Paul Eustace and Keith Payne Our gratitude to all those people in industry who have provided assistance with the projects Finally, to my wife and family for their support and understanding over the time when my attention was distracted by the writing of the book

Lloyd Jenkinson

I would like to acknowledge the work done by the teams of Virginia Tech and Loughborough University aircraft design students in creating the designs which I attempted to describe in Chapters 7 and 10 and the contributions of colleagues such

as Bill Mason, Nathan Kirschbaum, and Gary Page in helping guide those students in the design process Without these people these chapters could not have been written

Jim Marchman

It is tempting to title this book ‘Flights of Fancy’ as this captures the excitement and expectations at the start of a new design project The main objective of this book is

to try to convey this feeling to those who are starting to undertake aircraft conceptual design work for the first time This often takes place in an educational or industrial training establishment Too often, in academic studies, the curiosity and fascination of project work is lost under a morass of mathematics, computer programming, analytical methods, project management, time schedules and deadlines This is a shame as there are very few occasions in your professional life that you will have the chance to let your imagination and creativity flow as freely as in these exercises As students or young engineers, it is advisable to make the most of such opportunities

When university faculty or counsellors interview prospective students and ask why they want to enter the aeronautics profession, the majority will mention that they want

to design aircraft or spacecraft They often tell of having drawn pictures of aeroplanes since early childhood and they imagine themselves, immediately after graduation, pro-ducing drawings for the next generation of aircraft During their first years in the university, these young men and women are often less than satisfied with their basic courses in science, mathematics, and engineering as they long to ‘design’ something When they finally reach the all-important aircraft design course, for which they have yearned for so long, they are often surprised They find that the process of design requires far more than sketching a pretty picture of their dream aircraft and entering the performance specifications into some all-purpose computer program which will print out a final design report

Design is a systematic process It not only draws upon all of the student’s previous engineering instruction in structures, aerodynamics, propulsion, control and other subjects, but also, often for the first time, requires that these individual academic subjects be applied to a problem concurrently Students find that the best aerodynamic solution is not equated to the best structural solution to a problem Compromises must be made They must deal with conflicting constraints imposed on their design

by control requirements and propulsion needs They may also have to deal with real world political, environmental, ethical, and human factors In the end, they find they must also do practical things like making sure that their ideal wing will pass through the hangar door!

This book seeks to guide the student through the preliminary stages of the aircraft design process This is done by both explaining the process itself (Chapters 1 and 2) and by providing a variety of examples of actual student design projects (Chapters 3