In this textbook, the authors show that a few fundamental principles can provide students of mechanical and aeronautical engineering with a deep understanding of all modes of aircraft and spacecraft propulsion. The book also demonstrates how these fundamental principles can lead directly to useful quantitative assessments of performance as well as possibilities for improvement. The second edition provides a wide range of new illustrative material on modern aircraft and rocket engines. The author s have also improved their explanations of pertinent physical phenomena and have introduced preliminary design procedures in this edition.