Since the first edition of this book appeared in 2008, the Uninhabited Aerial Vehicle (UAV) has gained wider interest and market share in aircraft industry. As a result, the second edition has a new chapter dedicated to General Aviation and UAV Propulsion Systems. The remaining changes to the second edition stem from technological advances in propulsion in recent years. For example in the commercial transport sector, we have witnessed the development of Ultra-High Bypass (UHB) turbofan engines with bypass ratio above 12. An enabling technology to UHB is the Geared Turbofan, which has also received an introductory coverage in the second edition. Other technological advances include Chevron Nozzle, Alternative “drop-in” Jet Fuels (AJF) and advanced heat exchanger in airbreathing rocket engine for single-stage-to-orbit application, which are introduced in the new edition.

Some of the reviewers and readers suggested an introductory presentation on propeller theory could well be integrated with the presentation of the turboprop engines. In response, I have added a section on propeller theory prior to the turboprop cycle analysis section. The instructors often wrote and asked for more problems at the end of chapters and as a result the new edition has about 50% more end-of-chapter problems than the first edition (i.e., 446 in 2E vs. 305 in 1E). There is an increased interest in Aerospace Engineering (AE) programs to offer propulsion system design as one of the capstone design options in AE curriculum. Towards that goal, additional design guidelines are added to each component chapter in 2E. A new section on aircraft engines performance testing and basic instrumentation in ground facilities is added to Chapter 11: Aircraft Engine Component Matching and Off-Design Analysis.

Two new appendices are created in the second edition. The first one is an assembly of 45 Ten-Minute Quizzes that I had given to my propulsion students at KU in the past three decades. These 10-minute closed books/notes quizzes were given to students at the beginning of my class and concentrated on recent materials. The goal is to show the importance of fundamental concepts, governing laws, important definitions to students and hopefully develop an engineering sense for “ballpark” numbers in propulsion system engineering. The quizzes may be used as an assessment tool by the instructors or the learners themselves. To help the students with the “Rules of Thumb” and Trends in aircraft propulsion, a second new appendix is created. Students of propulsion and practicing system engineers should find the new appendix on “Rules of Thumb” and Trends particularly useful.