This book explores the whirl flutter phenomenon, including theoretical and practical as well as analytical and experimental aspects of the matter. Topics include: a general overview of aeroelasticity; physical principle and the occurrence of whirl flutter in aerospace practice; experimental research including earlier activities performed, particularly from the sixties, as well as recent developments; analytical methods such as basic and advanced linear models, and non-linear and CFD based methods; certification issues including regulation requirements, a description of possible certification approaches and several examples of aircraft certification from the aerospace practice. --