The measurement of performance during an airplane's flight testing is one of the more important tasks to be accomplished during its development as it impacts on both the airplane's safety and its marketability. Performance sells airplanes. This discusses performance for both propeller-driven and jet aircraft. However, its emphasis is on propeller-driven aircraft since much of the methodology for testing of propeller driven aircraft has been lost with time. This is intended for those teaching courses in fixed-wing flight testing. It is also a reference for those involved in flight test on a daily basis or those who need knowledge of flight testing to manage those activities. The book is divided into three sections: Performance; Stability and Controller; and Hazardous Flight Tests, provide information based upon more than 30 years of experience in performing and directing such tests.