The National Aeronautics and Space Administration (NASA) is currently developing advanced technologies to form the foundation for the next breakthrough in civil aviation: an economically viable, environmentally acceptable supersonic transport. NASA's High Speed Research Program works in conjunction with industry to identify and address critical technological challenges to initiating commercial development of a practical supersonic transport. The key technical areas investigated are engine emissions, fuel efficiency, service life, and weight; community noise; aircraft range and payload; and weight and service life of airframe structures. Areas of particular interest include the ability of technologies under development to meet program goals related to noise, emissions, service life, weight, range, and payload. This book examines aircraft design requirements, assesses the program's planning and progress, and recommends changes that will help the program achieve its overall objectives.