Preface
William H. Mason, Professor Emeritus in the Kevin T. Crofton Department of Aerospace and Ocean Engineering at Virginia Tech, painstakingly prepared a comprehensive set of lecture notes while teaching the one-of-a-kind Configuration Aerodynamics course for more than two decades before he unexpectedly passed away in March 2019. The department is pleased to honor his notable contributions by offering Lecture Notes on Configuration Aerodynamics (an edited version of Mason’s manuscript of the lecture notes) as an online open access book to the aerospace engineering community at large and to the students and practitioners of aerodynamics in particular.
Bill Mason—a self-described lifelong student of airplanes and aerodynamics—developed the Configuration Aerodynamics course from scratch to serve as a much-needed companion to the capstone Aircraft Design courses that he began teaching in 1989 when he joined Virginia Tech after 15 years at Grumman. The original manuscript outlined his motivation for creating this course in a draft preface that is included below. Bill thoroughly enjoyed teaching the “ConfigAero” course every spring, and the students who elected to enroll enjoyed learning the use of engineering tools and processes for configuration aerodynamic design. More importantly, the students learned the thought processes that are essential to effectively applying basic aerodynamics theories in creating aircraft configurations that best meet customer needs. He made the draft version of his notes widely available through his personal website, ensuring that students at Virginia Tech and many other universities as well as professional aerodynamicists worldwide benefited from his insights.
It is unfortunate that the manuscript Mason left behind had a few blank sections with just topic captions that he intended to populate. However, even without these topics, the manuscript had more than enough material to warrant publication as a book. I, as the editor, made a good faith attempt to populate some of the blank sections using suitable material. For example, we added material on aircraft buffeting, AIAA Drag Prediction Workshops, and aircraft drag reduction technologies. Having known Bill for several decades, including our time as esteemed colleagues at Virginia Tech for seven years starting in 2012, I believe he would have approved of these additions. It is worth mentioning that we deliberately retained the conversational style of the entire manuscript to ensure that it remains Mason’s book!
The primary purpose of the book is to be a resource for educating the next generation of aerospace engineering students who aspire to engage in aerodynamic design of aircraft configurations. Although all aerospace engineering curricula include basic aerodynamics theory courses that students are required to take, several topics are often omitted out of necessity. Many of these topics relate to practical applications of aerodynamic theory, and they need to be reinforced due to their critical importance for practical aerodynamic design. This book bridges the gap between theory and practice by offering a design-oriented perspective of the development and analysis of aircraft aerodynamics typical of what a career in aerodynamics might entail.
Every time Mason taught the course, he added more relevant material to his lecture notes! We strongly recommend that anyone who wishes to adopt this book for teaching a course on Configuration Aerodynamics should consider adding examples of the latest developments in the aerodynamic design of aircraft because this book mainly covers ideas and configurations until and including the spring of 2019.
Completing a course based on this book will help students achieve the following key objectives:
- Develop the flow physics insight. Learn to form a “mental model” of each flow field or concept against which to gauge computational/experimental “reality.”
- Understand strengths and shortcomings of computational aerodynamics methods. Computational and experimental tools must be used together. Both have highly complementary strengths and weaknesses.
- Value analytical theory. Airplanes were built before computational aerodynamics methods became available. Analytical aerodynamics provides valuable insights into the role of key flow and configuration shape parameters.
- Answer the question based on physics. “What configuration do I want to develop to do this job?”
The scope of the book encompasses the aerodynamic design of flight vehicles with emphasis on nonlinear flow fields and configuration concepts. Mason’s manuscript covers methodologies for aerodynamic analysis and design for flows ranging from low speed to high speed. In addition, it includes case studies of classic configurations. The main body of the book is organized into ten chapters grouped in two parts. In addition, there are 7 appendices.
Part 1: Foundational Elements (Chapters 1 through 4)
Chapter 1 provides an overview of configuration aerodynamics, including its purpose and role in the design of innovative configurations. Chapter 2 reviews the physical description of flow fields in the mathematical terms that are used in modern computational aerodynamics. Those familiar with the equations and their derivations may skip this chapter altogether. Chapter 3 discusses fundamentals of aerodynamic drag, providing more depth on the topic than an entry-level aerodynamics course. Airplane drag is covered upfront as a foundational element since it is a crucial driver of configuration aerodynamic design. Chapter 4 provides an overview of the configuration aerodynamic design process and the increasingly important role of computational aerodynamics.
Part 2: Practical Considerations (Chapters 5 through 10)
Chapters 5 through 10 address practical considerations that are specific to the aerodynamic design of aircraft for operations in different flight regimes from subsonic through hypersonic. Subsonic flows are covered in Chapter 5 and transonic flows in Chapter 6. These are followed by Chapter 7 on aerodynamics of high-lift devices and Chapter 8 on aerodynamic considerations for flight with a high angle of attack. Supersonic flows are discussed in Chapter 9 and hypersonic flows in Chapter 10. To emphasize practical considerations and retain engagement, Mason made an attempt to integrate case histories and “amazing stories” to the extent possible.
Each chapter ends with a set of exercises. Most of the exercises have a specific learning objective spelled out at the beginning. For example, the first exercise in Chapter 3, Exercise 3.1, explains that it is targeted at demonstrating “the importance of streamlining.” In some of the exercises, Mason asks students to “comment on your results.” This reinforces the idea of open-ended problems having multiple possible results, and it helps students develop critical thinking skills to assess the “goodness” of their results by choosing appropriate metrics. In some exercises, a classic technical paper is assigned to the class and students write an essay on what they learned from reading it, sharing their findings in classroom discussion afterward. Such an exercise is a great way to help students develop two-way communication skills and an appreciation of how challenging it is to capture all ideas and concepts in a classic paper. In Mason’s own words: “The importance of working the exercises cannot be overstated.”
In addition to the ten chapters, there are seven appendices. Appendix A details pertinent information about geometric shapes of interest to aerodynamicists. This is followed by appendix B, which highlights a few key aspects to be considered in shaping a stealth aircraft design, and appendix C, which presents regulatory requirements that affect configuration aerodynamics. Appendix D provides examples of aerodynamic design studies conducted by students using aerodynamic design procedures and computational aerodynamic tools. A list of useful software tools for aerodynamic analysis and aircraft design is presented in appendix E. As is often the case with software, many of the tools have become dated, but the intention is to offer a set of tools that have proven applications for practical problems. Students/readers should not feel restricted to using only these tools. To the contrary, Mason encouraged students to use modern software tools as long as they fully understood what was required to obtain accurate and useful results. In appendix F, Mason’s recommended reading list points to several key papers that perfectly align with the primary themes of the book. The last appendix, appendix G, includes a short list of books and reports that Mason considered essential for any configuration aerodynamicist’s bookshelf.
Publication of Mason’s lecture notes as an online, open access book ensures that countless future students and professionals involved in aircraft design will have the opportunity to benefit from his insights. The book offers them the requisite information for applying the fundamentals of aerodynamics they have learned in standard textbooks. The present book, combined with Applied Computational Aerodynamics (which Mason coauthored with Cummings, Morton, and McDaniel), clearly attests to the rich legacy Mason has left behind. For me, it has been a great pleasure and a distinct privilege to serve as the editor and thereby play a small role in preserving Bill Mason’s legacy.
I want to thank Carol Bland, executor of the William H. Mason estate, for wholeheartedly supporting this endeavor aimed at perpetuating Mason’s legacy. I am truly grateful to Anita Walz of Virginia Tech for bringing her extensive planning and execution expertise to bear on this project and for patiently coaching and guiding me through the publication process. Special thanks go to Kindred Grey, Pranay Patel, Sullivan Madden, and Joseph Brooks for their invaluable assistance in converting Mason’s manuscript into a quality publication. We are extremely thankful to Russ Cummings of USAF Academy, Jason Merret of UIUC, and Jason Riopelle of Gulfstream (plus two others who wish to remain anonymous) for devoting their time and effort to critically reviewing a draft of the book and for providing numerous constructive suggestions that made the final version so much more impactful. We are particularly appreciative of the support and encouragement of Eric Paterson, Bob Canfield, and Ella Atkins, who were AOE Department Heads when this book was produced.
Pradeep Raj
Blacksburg, Virginia
This text is based on the notes for the Configuration Aerodynamics course I’ve given for 20 years at Virginia Tech. I started giving the class because it seemed to me that the students needed an aircraft aerodynamics–oriented course that elaborated on the fundamentals usually taught in such courses. It is an elective, generally taken by seniors and graduate students. However, second semester juniors can take the class without undo difficulty. They should have a basic text such as Bertin and Cummings or Anderson available to refresh their recollection of the fundamental aerodynamic theory. If possible, it would be desirable to take the class before their senior design project.
This is a text in “why” as opposed to a book on “how.” That part [“how”] of the education foundation is addressed in the companion volume, Applied Computational Aerodynamics, that was published in 2015, spearheaded by Russ Cummings, with Scott Morton, Dave McDaniel, and myself as collaborators. There is some overlap. Ideally students would take both classes at the same time. However, their course load doesn’t allow for this. With the powerful computational tools now available, students need to understand what they should be doing with them!
The importance of working the exercises cannot be overstated. They have been developed to bring out key points. Students learn much more by working the exercises than if they just sit in class passively listening. If the book is being studied independently, the exercises should not be overlooked. In addition, the text is integrated with a number of resources available on the web (a truly phenomenal development providing access to information). This includes both additional text material and software. In terms of the use of computational aerodynamics tools, the exercises try to strike a balance between emphasizing the validation of the tools (and the student’s skill in using them) and using them to explore aerodynamics ideas.
A configuration aerodynamicist straddles the artificial academic divide between fluid mechanics–oriented “aerodynamics” and classical flight mechanics, which has become less a class in bare airframe aerodynamics for the stability characteristics and the ability to generate moments with (primarily) aerodynamic control forces; now, classical flight mechanics is more of a class in electrical engineering–oriented control theory. My experience with fighter configurations was that it was easier to achieve performance goals than to make the airplane fly (i.e., good high-angle-of-attack characteristics, which we try to address).
W. H. Mason (1947–2019)
Blacksburg, Virginia
