This book is a modern treatment of the aerodynamic principles of helicopters and rotating-wing vertical lift aircraft. Part one covers the technical history of helicopter flight, basic methods of rotor aerodynamics, and performance-related design issues. Part two contains advanced topics in helicopter aerodynamics, including airfoil flows, unsteady aerodynamics, dynamic stall, rotor wakes, and rotor-airframe aerodynamic interactions. Part three contains chapters on autogiros and advanced aerodynamic analysis and a new chapter on the aerodynamics of wind turbines. The book is extensively illustrated and contains homework problems.