This book is for students, teachers, and practicing engineers and describes an industrial approach to gas turbine engine simulation, mainly for aircraft propulsion. The principles of performance model creation are covered, and the viability and accuracy of model-based performance analyses are demonstrated by their application to real-world examples, where measured data are scarce. Clear distinctions are made between design and off-design models, the keys to success being the recognition of the importance of scaling and validating compressor and turbine maps. This topic is discussed in more detail than in other sources. New descriptions of turbomachinery basics are offered, and it is shown how velocity diagrams can capture the quality of a compressor or turbine stage and the effects of changes. Non-dimensional performance is explained in an unusual way, without referring to higher mathematics. The influence of inlet flow distortion and heat transfer on engine operability during transient operation is also characterized. This second edition contains new material about engine starting and windmilling, supported by how to extend existing compressor and turbine maps down to speeds as low as 1%. Unique material on map interpretation is included. The design and operation of hybrid propulsion systems are also addressed. Not only a valuable engineering textbook but also a good read!