Introduction to UAV Systems. Mohammad H. Sadraey

the manner in which the UAV accomplishes its objectives and the techniques that the operator must use to make that happen.

      For a “subject matter expert” in any of the disciplines involved in the design of a UAV system, we hope that it will allow better understanding of the context in which his or her specialty must operate to produce success for the system as a whole and why other specialists may seem preoccupied with things that seem unimportant to him or her.

      Finally, for a technology manager, we hope that this book can help him or her understand how everything fits together, how important it is to consider the system‐integration issues early in the design process so that the integration issues are considered during the basic selection of subsystem designs, and help him or her understand what the specialists are talking about and, perhaps, ask the right questions at critical times in the development process.

      Part One contains a brief history and overview of UAVs in Chapter 1 and a discussion of classes and missions of UAVs in Chapter 2.

Part Two is devoted to the design of the air vehicle including basic aerodynamics, performance, stability and control, propulsion and loads, structures and materials in Chapters 3 through 7.

      Part Three discusses the mission planning, control function, and autopilot in Chapter 8 and operational control in Chapter 9.

      Part Four has three chapters addressing payloads. Chapter 10 discusses the most universal types of payloads, reconnaissance, and surveillance sensors. Chapter 11 discusses weapons payloads, a class of payloads that has become prominent since its introduction about 10 years ago. Chapter 12 discusses a few of the many other types of payloads that may be used on UAVs.

      Part Five covers data links, the communication subsystems used to connect the air vehicle to the ground controllers, and delivers the data gathered by the air‐vehicle payloads. Chapter 13 describes and discusses basic data‐link functions and attributes. Chapter 14 covers the factors that affect the performance of a data link, including the effects or intentional and unintentional interference. Chapter 15 addresses the impact on the operator and system performance of various approaches to reducing the data‐rate requirements of the data link to accommodate limitations on available bandwidth. Chapter 16 summarizes data‐link tradeoffs, which are one of the key elements in the overall system tradeoffs.

      Part Six describes approaches for the launch and recovery of UAVs, including ordinary takeoff and landing, but extending to many approaches not used for manned aircraft. Chapter 17 describes launch systems and Chapter 18 recovery systems. Chapter 19 summarizes the tradeoffs between the many different launch and recovery approaches. Chapter 20 – a new chapter in this edition – is dedicated to fundamentals, control, and characteristics of rotary‐wing UAVs and quadcopters.

      Introduction to UAV Systems was first published in 1992. Much has happened in the UAV world in the 30 years since the first edition was written. In the Preface to the second edition (1998), we commented that there had been further problems in the development process for tactical UAVs but that there had been some positive signs in the use of UAVs in support of the Bosnian peace‐keeping missions and that there even was some talk of the possible use of “uninhabited” combat vehicles within the US Air Force that was beginning for the first time to show some interest in UAVs. At that time, we concluded that “despite some interest, and real progress in some areas, however, we believe that the entire field continues to struggle for acceptance, and UAVs have not come of age and taken their place as proven and established tools.”

      In the 30 years since we made that statement, the situation has changed dramatically. UAVs have been widely adopted in the military world, unmanned combat vehicles have been deployed and used in highly visible ways, often featured on the evening news, and unmanned systems now appear to be serious contenders for the next generation of fighters and bombers.

      While civilian applications still lag, impeded by the very‐real issues related to mixing manned and unmanned aircraft in the general airspace, the success of military applications has encouraged attempts to resolve these issues and establish unmanned aircraft in nonmilitary roles.

      The Fifth Edition has been extensively revised and restructured. The revisions have, we hope, made some of the material clearer and easier to understand and have added a number of new subjects in areas that have become more prominent in the UAV world during the last two decades, such as quadcopter, automatic flight control systems, new payloads, and the various levels of autonomy that may be given to an air vehicle. It also revises a number of details that have clearly been overtaken by events, and all chapters have been brought up to date to introduce some of the new terminology, concepts, and specific UAV systems that have appeared over the last 12 years. However, the basic subsystems that make up a UAV “system of systems” have not greatly changed, and at the level that this text addresses them, the basic issues and design principles have not changed since the first edition was published.

The first two authors – sadly, now deceased ‐ met while participating in a “red team” that was attempting to diagnose and solve serious problems in an early UAV program. The eventual diagnosis was that there had been far too little “systems engineering” during the design process and that various subsystems did not work together as required for system‐level success. This book grew out of a desire to write down at least some of the “lessons learned” during that experience and make them available to those who design UAV systems in the future.

      Supplementary materials, including answers to end‐of‐chapter questions, are available for registered instructors who adopt this book as a course text. Please visit www.wiley.com/go/fahlstrom/uavsystems5e for information and to register for access to these resources.

      We believe that most of those lessons learned are universal enough that they are just as applicable today as they were when they were learned years ago, and hope that this book can help future UAV system designers apply them and avoid having to learn them again the “hard way.”

      Mohammad Hashem Sadraey

      September 2021

      The Kettering Bug (Photograph courtesy of Norman C. “Dutch” Heilman)

Series Preface

      This book is a welcome addition to the Aerospace Series, continuing the tradition of the Series in providing clear and practical advice to practitioners in the field of aerospace. This