In air combat there is no Second Place Award. Jet engines are a key part of self-reliance and freedom. Precision manufacturing backed by rigorous theory from many fields, delivers machines that operate reliably for over 8000 hours at the edge of performance. Today Digital Twins capture and advance knowledge on these machines from inception to end-of-life, setting the stage for improved successors through efficient, swift Generative Engineering. The theory is developed starting at the high school graduate level, and advances through the author's 35-year experience of teaching and guiding practitioners in this demanding field. We see how to calculate the interior properties of engines, with under 1% uncertainty in matching specified performance. PYTHON coding provides a low entry threshold, before going to higher sophistication. Rigorous theory is spiced with "Drama in Real Life" anecdotes and examples from the author's classes. While a Digital Twin appears to be a monumental ambition, its core is developed with what is presented here, the process is laid out and clear path shown to the rest. Short chapters on Materials, Rocket Propulsion and Engine Dynamics provide breadth and low entry thresholds. The book is suitable for undergraduates, serving them well as they become practitioners, researchers, teachers and program leaders. Hope you enjoy working with in this field (no, it is not just light reading!) as much as the author does.