Aircraft Design

This book is about the conceptual phase of a fixed-winged aircraft design project. It is primarily concerned with commercial aircraft design, although it does not ignore military aircraft design considerations. The level of sophistication of the latter is such that were I to discuss advanced military aircraft design, I would quickly devi­ate from the objective of this book, which is for introductory but extensive course – work and which provides a text for those in the industry who wish to broaden their knowledge. The practicing aircraft design engineer also will find the book helpful. However, this book is primarily meant for intensive undergraduate and introductory postgraduate coursework.

A hundred years after the first controlled flight of a manned, heavier-than-air vehicle, we can look back with admiration at the phenomenal progress that has been made in aerospace science and technology. In terms of hardware, it is second to none; furthermore, integration with software has made possible almost anything imaginable. Orville and Wilbur Wright and their contemporaries would certainly be proud of their progenies. Hidden in every mind is the excitement of participating in such feats, whether as operator (pilot) or creator (designer): I have enjoyed both no less than the Wright brothers.

The advancement of aerospace science and technology has contributed most powerfully to the shaping of society, regardless to which part of the world one refers. Sadly, of course, World War II was a catalyst for much of what has been achieved in the past six decades. My career spans the 1960s to the beginning of the twenty-first century, possibly the “golden age” of aeronautics! In that period, investment in the aerospace sector by both government and private organizations led to rapid changes in the acquisition, application, and management of resources. Aerospace design and manufacturing practices were transformed into their present manifestation.

The continuous changes in aircraft design and manufacturing procedures and methodologies have resulted in leaner aerospace infrastructure (sometimes to an “anorexic” level). New graduate-level engineers are expected to contribute to the system almost immediately, with minimal supervision, and to “do it right the first time.” The route to the design office through apprentice training is not open to as many as it once was. Life is now more stressful for both employers and employ­ees than it was the day I started my career: Organizational survivability and con­sequent loyalty are not what they used to be. The singular aim of this book is to prepare readers as much as possible for industry-standard engineering practices. The methodology adopted herein is in line with what is practiced in industry; the simplifications adopted for classroom use are supported by explanations so that an appreciation of industry expectations will not be lost. Aircraft conceptual design necessarily entails an iterative process. In the classroom, one or two iterations should prove sufficient as a time-efficient procedure to refine component sizes and to freeze aircraft configurations.

My student days were almost devoid of any aircraft design book. Wood [1] and Corning [2] were the early books that brought aircraft design into textbook form, followed by an excellent text written by Nicolai [3]. In 1982, Torenbeek [4] covered substantial ground with contemporary treatises in his book. Roskam’s compilation [5] furthered the cause. I have benefited greatly from the works of these five authors. Gradually, more aircraft design books have appeared in the literature [6-18], each with its own strength. There is still considerable scope to advance the subject, specif­ically by preparing new engineers to cope with the demand for a high level of profi­ciency in the industry. (I recommend that readers review the Virginia Tech Web site of aircraft design bibliographies [18]. It is a comprehensive compilation of aircraft design information sources.)

One-third of my career has been spent in academia and two-thirds in aircraft design. I can see a clear gap between academic pursuits and what industry expects from new graduates as finished university “products.” The United States and the United Kingdom are aware of this problem [19-24], and both make periodic recom­mendations. However, the problem is acute in the developing world, where tasks among scientists with advanced degrees and engineers are not as clearly defined as they are in the West. (If I may digress slightly, I have found from personal expe­rience that a major hindrance to progress in some of the developing world comes from the inability to administrate technological goals even when there is no dearth of technical manpower – those who perform better when working in the advanced world. People know about political asylum. However, professional asylum, also known as the “brain drain,” is a real issue. Although design is not accomplished via the democratic process, the design culture should encourage the free sharing of knowledge and liberal distribution of due recognition to subordinates. Lack of accountability in higher offices is a root cause of the failure to exploit the full poten­tial of natural and human resources.) In time, things are changing but unfortunately slower than its potential because higher management still maintains older attitudes that masquerade behind seemingly modern views. Technology can be purchased, but progress has to be earned. I hope to prepare the readers to contribute to the progress.

The roles of scientists and engineers are well defined. According to Von Karman, “A scientist discovers what already exists. An engineer creates what never was” [25]. Converting ideas into reality for customer use proves more difficult than adding any number of publications to a list (except those papers that break new ground or advance a cause that is being adapted to enrich a generation). Perhaps the measure by which to judge scientists should be like that of engineers – namely, how much wealth has the work generated (where wealth is defined in broad terms as all that encompasses the commonweal). It should be clearly understood that scientists and engineers have to work together and not in a fallacious hierarchy in which advanced degrees stand above significant experience. Consider engineers such as

Johnson, Mitchell, and Dassault – these are the people to whom I refer. Today’s engineers must have strong analytical and applied abilities to convert ideas into profitable products. I hope that this book serves this cause by combining analytical methods and engineering practices and adapting them to aircraft design. Prerequi­sites are second-year (U. K.) or junior-level (U. S.) mathematics and aerodynamics. It is not difficult to acquire these prerequisites – simply a semester of effort in a class found in any university syllabus. Of course, by including “experience,” this book offers more than just analysis; aircraft design must be practiced.

Engineering design is a process, and today’s practices have so matured that they demonstrate systematic patterns despite the differences that exist between compa­nies or countries, whether military or civil. The laws that govern the behavior of nature are universal. The differences are in the governing rules and practices of resource acquisition and management. The resulting products within the course still remain in close competition and may even show similarities in presentation and per­formance, not necessarily dependent on any 007 work!

I thank my teachers, supervisors, colleagues, students, shop-floor workers, and all those who taught and supported me during my career. I remember (in no partic­ular order) the late Professor Holt Ashley of Stanford University; Professor Arthur Messiter of the University of Michigan; James Palmer of Cranfield University; Pro­fessor Shankar Lal of the Indian Institute of Technology, where I was Professor; Kenneth Hoefs of the new airplane project group of the Boeing Company, who taught me aircraft sizing and drag estimation; James Fletcher of Short Brothers and Harland, who baptized me into the aircraft industry; Tom Johnston, Director and Chief Engineer of Bombardier Aerospace-Shorts (BAS) who provided con­siderable help in bringing out this book; the late Dr. Vikram Sarabhai, who gave me the opportunity to be associated with the Indian Space Research Organisation; and Wing Commander Baljit Kapur, Chairman of Hindustan Aeronautics Limited (HAL [26]), where I served as the Chief Aircraft Designer. My special thanks to Dr. Tom Cummings of BAS; Noel Weir of Canadair Ltd; Stephen Snyder, formerly of the Boeing Company and now an independent consultant; and B. C. Chamundaiah and the shop-floor workers of HAL, who stood by me during difficult days. I derive tremendous pleasure from teaching and have valued interaction with students in India, Iraq, the United Kingdom, and the United States. They came to me as a bou­quet of flowers. I aver that they have taught me no less than I have taught them. This book reflects the universal demands of students. In their company, I was able to remember my youth.

I am thankful to my former colleagues Colin Elliott, Director of Engineering; David Riordan, Chief Engineer; and James Tweedie, Senior Engineer, BAS, who have helped me bring out an industry-standard book on aircraft design. David’s review work is thankfully acknowledged. The contribution of BAS is gratefully acknowledged. I started my aeronautical career with BAS (then Short Brothers and Harland Ltd.) and, after a long break, rejoined and then retired from the company, the first aerospace company to celebrate its centenary.

The aim of this book is to enable new graduates to seamlessly join the industry in order to become productive as soon as possible. The book also could be used in the industry for training purposes. In today’s world, engineers may need to be retrained in broader disciplines to offer support in areas beyond their main area of special­ization. To ensure continuity and overcome any current deficiencies in a second edition, I will be grateful for readers’ suggestions and criticisms. Please contact the publisher or email the author at a. kundu@qub. ac. uk with any relevant information.

I am indebted to Jane’s All the World Aircraft Manual [27], NASA, Airbus, Saweed, BAE Systems, Hamilton Standard Propellers, Europa Aircraft Company, Dr. John McMasters (Boeing Aircraft Company), Professor Michael Niu, Professor Jan Roskam (DARcorp), Professor Egbert Torenbeek, Dr. Bill Gunston, and the late Dr. L. Pazmany. There are many excellent Web sites in the public domain. I am thankful to Richard. Ferriere. free. fr/3vues, Aerosite, and Virtual Aircraft Museum for permitting me to use some of their diagrams. I gratefully acknowledge the help of many other Web sites. The wisdom of these organizations and people will take the next generation forward with confidence as they substantiate what is learned in classrooms. To familiarize readers with many types of aircraft, I provide dia­grams of various types (some are not operational). I apologize if I have inadver­tently infringed on any proprietary diagrams for educational purposes. For a few of the many diagrams I have collected over the years, the sources have gotten lost. Please forgive me for the error. Any infringement on proprietary information was not deliberate and I hope may be overlooked for the sake of preparing the next gen­eration. If brought to my notice, I will acknowledge sources and make any necessary corrections in the next edition of this book.

I am indebted to many people at The Queen’s University Belfast (QUB) for suggestions on how to improve the quality of this book. They include my present and former colleagues and former students. (I must have done a good job – it is a pleasure to learn from them.) In no particular order, they are Dr. John Watter – son, Dr. Mark Price, Dr. Adrian Murphy, Dr. Simon Hall, Dr. Neil Forsythe, Dr. Rachel Moore, Dr. Brendan Sloan, Damien Quinn, and David Lisk. I typed the entire manuscript and therefore am responsible for any loss of quality in the text due to typographical and grammatical errors. I am grateful to QUB for providing all of the facilities necessary to complete this book.

Peter Gordon, Senior Editor of the respected Cambridge University Press, offered me the finest support throughout the writing of this book. The hard, tire­less work of Eleanor Umali of Aptara gave this book its shape. I offer my personal and heartfelt thanks to both of them and their organizations.

I owe thanks to my grandfather, the late Dr. Kunja Behari Kundu; my father, the late Dr. Kamakhya Prosad Kundu; and my cousin-brother, the late Dr. Gora Chand Kundu. They inspired and motivated me to remain studious. I cannot con­clude without thanking my wife, Gouri. I did not give her much choice, but it was not a problem. She kept me nourished and maintained all domestic systems. When I sometimes pushed to the maximum permissible speed limits – her patience was remarkable.

I was educated in the United Kingdom (Cranfield University and QUB) and in the United States (University of Michigan and Stanford University); I also worked in the United Kingdom (BAS) and in North America (Boeing and Canadair). I have found that nature is the same on both sides of the Atlantic, as is the language. Any differences are trivial. In today’s world of cooperative ventures among countries, es­pecially in the defense sector, the methodologies adopted in this book should apply.

I dedicate this book to both sides of the Atlantic to where I immigrated, and to those who gave me their best education, their best jobs, and their fine homes. I left only to return and take this opportunity to write.