Overview

The engine may be considered the heart of any powered-aircraft system. This book is not concerned with engine design, but it covers the information needed by aircraft designers to find a matched engine, install it on an aircraft, and evaluate its performance. The chapter begins with an introduction to the evolution of an engine followed by the classification of engine types available and their domain of application. This chapter primarily discusses gas turbines (both jet- and propeller-driven) and – to a lesser extent – piston engines, which are used only in smaller general aviation aircraft. Therefore, a discussion of propeller performance is also included in the chapter. The derivation of thrust equations precedes propeller theory.

It is difficult to obtain industry-standard engine-performance data for coursework because the information is proprietary. The performance of some types of engines in nondimensional form is described in Section 10.11. Readers must be careful when applying engine data – an error could degrade or upgrade the aircraft performance and corrupt the design. Verification and substantiation of aircraft design are accomplished through performance flight tests. It is difficult to locate the source of any discrepancy between predicted and tested performance, whether the discrepancy stems from the aircraft, the engine, or both. The author suggests that appropriate engine data may be obtained beyond what is provided in the scope of this book. As mentioned previously, the U.S. contribution to aeronautics is indispensable and its data are generated using the FPS system.