Hypersonic flight has been with us since 22 September 1963, when Robert M. White flew the North American X-15 at 4520 mph at an altitude of 354; 200 ft-a Mach number of 6.7! This remarkable achievement was accomplished over six decades due to intensive research and development by a large number of scientists and engineers. In spite of that momentous achievement, designers have found the hypersonic environment to be harsh and non-forgiving. New programs since the 1960s have often uncovered the unknown unknowns, usually the hard way-early flights of new systems have often revealed problems of which the designers were unaware. Such problems include: the ineffectiveness of the body flap for the Space Shuttle Orbiter, the viscous/inviscid interactions produced by the umbilical fairings that damaged the conical section tile protection system of the Gemini Capsule, and the shock/shock interaction that damaged the X-15A-2 when it carried the hypersonic ramjet experiment. In order to continue to make advances in hypersonic flight a sustained and visionary effort is essential to generate required knowledge and technology. In order to better prepare for future developments in hypersonic flight, this article reviews the advances made within the past 50 years and then looks into the future, not just for new technological developments, but for new ways of thinking about the unknown challenges that lie ahead.

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The challenges in understanding hypersonic flight are discussed and critical hyper sonic aerothermodynamics issues are reviewed. The ability of current analytical meth ods, numerical methods, ground testing capabilities, and flight testing approaches to predict hypersonic flow are evaluated. The areas where aerothermodynamic short comings restrict our ability to design and analyze hypersonic vehicles are discussed, and prospects for future capabilities are reviewed. Considerable work still needs to be done before our understanding of hypersonic flow will allow for the accurate pre diction of vehicle flight characteristics throughout the flight envelope from launch to orbital insertion.

Now reissued by Cambridge University Press, this sixth edition covers the fundamentals of aerodynamics using clear explanations and real-world examples. Aerodynamics concept boxes throughout showcase real-world applications, chapter objectives provide readers with a better understanding of the goal of each chapter and highlight the key 'take-home' concepts, and example problems aid understanding of how to apply core concepts. Coverage also includes the importance of aerodynamics to aircraft performance, applications of potential flow theory to aerodynamics, high-lift military airfoils, subsonic compressible transformations, and the distinguishing characteristics of hypersonic flow. Supported online by a solutions manual for instructors, MATLAB® files for example problems, and lecture slides for most chapters, this is an ideal textbook for undergraduates taking introductory courses in aerodynamics, and for graduates taking preparatory courses in aerodynamics before progressing to more advanced study.

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